MyBatis实践--Mapper与DAO_MySQL
MyBatis简介
MyBatis前身是iBatis,是一个基于Java的数据持久层/对象关系映射(ORM)框架.
![\](http://img.bitscn.com/upimg/allimg/c160328/14591412QY060-1TY.jpg "\")
MyBatis是对JDBC的封装,使开发人员只需关注SQL本身,而不需花费过多的精力去处理如注册驱动、设置参数、创建Connection/Statement、解析结果集等JDBC过程性代码.MyBatis基于XML/注解的方式配置Statement,执行SQL,并将执行结果映射成Java对象, 大大降低了数据库开发的难度.
MyBatis is a first class persistence framework with support for custom SQL, stored procedures and advanced mappings. MyBatis eliminates almost all of the JDBC code and manual setting of parameters and retrieval of results. MyBatis can use simple XML or Annotations for configuration and map primitives, Map interfaces and Java POJOs (Plain Old Java Objects) to database records.
– MyBatis项目地址/在线文档.
初识MyBatis
使用MyBatis需要在pom.xml中添加如下依赖:
<code class="hljs xml"><dependency>
<groupid>org.mybatis</groupid>
<artifactid>mybatis</artifactid>
<version>3.3.0</version>
</dependency>
<dependency>
<groupid>mysql</groupid>
<artifactid>mysql-connector-java</artifactid>
<version>5.1.36</version>
</dependency></code>로그인 후 복사
Select
配置mybatis/<strong>mybatis-configuration.xml</strong><br />
作为MyBatis的全局配置文件,其配置了MyBatis的运行环境信息(如数据源/mapper文件等).
<code class="hljs xml"><code class="hljs xml"><!--{cke_protected}{C}%3C!%2D%2D%3Fxml%20version%3D%221.0%22%20encoding%3D%22UTF-8%22%20%3F%2D%2D%3E-->
<configuration>
<environments default="development">
<environment id="development">
<!--{cke_protected}{C}%3C!%2D%2D%20%E9%85%8D%E7%BD%AEJDBC%E4%BA%8B%E5%8A%A1%E7%AE%A1%E7%90%86%2D%2D%3E-->
<transactionmanager type="JDBC">
<!--{cke_protected}{C}%3C!%2D%2D%20%E9%85%8D%E7%BD%AE%E6%95%B0%E6%8D%AE%E6%BA%90%2D%2D%3E-->
<datasource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver">
<property name="url" value="jdbc:mysql://host:port/db?characterEncoding=utf-8">
<property name="username" value="username">
<property name="password" value="password">
</property></property></property></property></datasource>
</transactionmanager></environment>
</environments>
<!--{cke_protected}{C}%3C!%2D%2D%20%E5%8A%A0%E8%BD%BDmapper%E6%98%A0%E5%B0%84%E6%96%87%E4%BB%B6%20%2D%2D%3E-->
<mappers>
<mapper resource="mybatis/mapper/UserDAO.xml">
</mapper></mappers>
</configuration></code></code>로그인 후 복사
<code class="hljs xml">书写UserDAO(mapper映射)<br />
最为MyBatis最核心的部分,配置了操作数据库的<strong>SQL语句</strong>:
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><!--{cke_protected}{C}%3C!%2D%2D%3Fxml%20version%3D%221.0%22%20encoding%3D%22UTF-8%22%20%3F%2D%2D%3E-->
<mapper namespace="namespace">
<select id="selectUserById" parametertype="java.lang.Integer" resulttype="com.fq.domain.User">
SELECT * FROM user WHERE id = #{id};
</select>
<select id="selectUserByName" parametertype="java.lang.String" resulttype="com.fq.domain.User">
SELECT * FROM user WHERE name LIKE '%${value}%';
</select>
</mapper></code></code></code>로그인 후 복사
<code class="hljs xml"><code class="hljs xml">属性 |
<code class="hljs xml"><code class="hljs xml">描述 |
|---|---|
<code class="hljs xml"><code class="hljs xml">namespace |
<code class="hljs xml"><code class="hljs xml">命名空间,用于隔离SQL语句 |
<code class="hljs xml"><code class="hljs xml">parameterType |
<code class="hljs xml"><code class="hljs xml">定义SQL输入映射类型,MyBatis通过<strong><em>OGNL</em></strong>从输入对象中获取参数传入SQL语句. |
<code class="hljs xml"><code class="hljs xml">resultType |
<code class="hljs xml"><code class="hljs xml">定义SQL输出映射类型,MyBatis将SQL查询结果的<strong>一行记录</strong>映射为resultType指定的类型. |
<code class="hljs xml"><code class="hljs xml">mapper映射文件名有<em>UserDAO.xml</em>/<em>UserMapper.xml</em>/<em>User.xml</em>等几种形式, 其一般存放在与mybatis-configuration.xml同级的mapper目录下,由于其主要作用为定义SQL语句与映射关系, 因此一般统称为<strong><em>mapper映射文件</em></strong>.
<code class="hljs xml"><code class="hljs xml">定义PO类<br />
PO类主要作用为SQL(输入/输出)映射,通常与数据库表对应:
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java">/**
* @author jifang
* @since 15/12/31 下午2:27.
*/
public class User {
private Integer id;
private String name;
private String password;
public User() {
}
public User(Integer id, String name, String password) {
this.id = id;
this.name = name;
this.password = password;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", name='" + name + '\'' +
", password='" + password + '\'' +
'}';
}
}</code></code></code></code>로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java">UserDAO(Java对象)<br />
获得SqlSession,执行SQL语句, 得到映射结果:
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java">/**
* @author jifang
* @since 16/2/24 下午6:15.
*/
public class UserDAO {
private SqlSessionFactory factory;
@Before
public void setUp() throws IOException {
String resource = "mybatis/mybatis-configuration.xml";
factory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream(resource));
}
@Test
public void selectUserById() {
try (SqlSession session = factory.openSession()) {
User user = session.selectOne("namespace.selectUserById", 1);
System.out.println(user);
}
}
@Test
public void selectUserByName() {
try (SqlSession session = factory.openSession()) {
List<user> users = session.selectList("namespace.selectUserByName", "student");
for (User user : users) {
System.out.println(user);
}
}
}
}</user></code></code></code></code></code>로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java">Insert
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java">mapper
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><insert id="insertUser" parametertype="com.fq.domain.User">
INSERT INTO user(name, password) VALUES(#{name}, #{password});
</insert></code></code></code></code></code></code>로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript">UserDAO
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java">@Test
public void insertUser() {
try (SqlSession session = factory.openSession()) {
User user = new User();
user.setName("new_name1");
user.setPassword("new_password");
session.insert("namespace.insertUser", user);
session.commit();
}
}</code></code></code></code></code></code></code>로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java">自增主键返回
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java">修改mapper文件,添加<selectkey>,可以将MySQL的自增主键(即刚刚插入数据时生成的ID)返回:</selectkey>
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><insert id="insertUser" parametertype="com.fq.domain.User">
<selectkey keyproperty="id" order="AFTER" resulttype="java.lang.Integer">
SELECT LAST_INSERT_ID();
</selectkey>
INSERT INTO user(name, password) VALUES(#{name}, #{password});
</insert></code></code></code></code></code></code></code></code>로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml">属性 |
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml">描述 |
|---|---|
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml">keyProperty |
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml">指定存储到DO中的哪个属性; |
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml">order |
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml">selectKey执行顺序(相对于insert语句),AFTER/BEFORE; |
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml">resultType |
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml">主键返回类型(DO中对应属性的类型); |
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml">LAST_INSERT_ID() |
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml">MySQL函数,返回<strong><em>auto_increment</em></strong>自增列新记录值. |
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml">UserDAO
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs">@Test
public void insertUser() {
try (SqlSession session = factory.openSession()) {
System.out.println(session);
User user = new User(null, "new_name", "new_password");
session.insert("namespace.insertUser", user);
// 需要在commit之后才能获得自增主键
session.commit();
System.out.println(user.getId());
}
}</code></code></code></code></code></code></code></code></code>로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs">该功能还可以通过<insert>的useGeneratedKeys/keyProperty两个属性合作完成, 详见MyBatis文档.</insert>
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs">Update
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs">mapper
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><update id="updateUserById" parametertype="com.fq.domain.User">
UPDATE user SET name = #{name}, password = #{password} WHERE id = #{id};
</update></code></code></code></code></code></code></code></code></code></code>로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml">UserDAO
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java">@Test
public void updateUserById() {
try (SqlSession session = factory.openSession(true)) {
session.update("namespace.updateUserById",
new User(1, "feiqing", "ICy5YqxZB1uWSwcVLSNLcA=="));
}
}</code></code></code></code></code></code></code></code></code></code></code>로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java">Delete
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java">mapper
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><delete id="deleteUserById" parametertype="java.lang.Integer">
DELETE FROM user WHERE id = #{id};
</delete></code></code></code></code></code></code></code></code></code></code></code></code>로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver">UserDAO
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java">@Test
public void deleteUserById() {
try (SqlSession session = factory.openSession(true)) {
session.delete("namespace.deleteUserById", 51615);
}
}</code></code></code></code></code></code></code></code></code></code></code></code></code>로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java">小结
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java">#{}/${}
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java">#{}: 表示一个占位符号,实现向PreparedStatement占位符中设置值(#{}表示一个占位符?),自动进行Java类型到JDBC类型的转换(因此#{}可以有效防止SQL注入).#{}可以接收简单类型或PO属性值,如果parameterType传输的是单个简单类型值,#{}花括号中可以是value或其它名称. ${}: 表示拼接SQL串,通过${}可将parameterType内容<strong><em>拼接</em></strong>在SQL中而<em>不进行JDBC类型转换</em>,${}可以接收简单类型或PO属性值,如果parameterType传输的是单个简单类型值,${}花括号中只能是value.<br />
虽然${}不能防止SQL注入,但有时${}会非常方便(如order by排序,需要将列名通过参数传入SQL,则用ORDER BY ${column},使用#{}则无法实现此功能(详见JDBC基础关于PreparedStatement的讨论).
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java">SqlSession<br />
提供操作数据库的方法(如:selectOne/selectList).但SqlSession是线程不安全的,因此最好将其定义成局部变量使用.
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java">MyBatis优点(与JDBC相比)<br />
SQL写在Java代码中导致不易维护, 而MyBatis将SQL写在mapper中,XML与Java代码分离. 向SQL语句传参繁琐(如:SQL的<strong>where条件</strong>不一,SQL数据类型与Java不同),MyBatis通过parameterType自动将Java对象映射至SQL语句. 结果集解析麻烦(SQL变化导致解析代码变化,SQL数据类型与Java不同),MyBatis通过resultType自动将SQL执行结果映射成Java对象.
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java">附: 最好在pom.xml中添加一个日志系统实现(logback/log4j), 这样会在调试程序时打印日志信息,便于查错, 以logback为例:
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java">pom.xml
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><dependency>
<groupid>ch.qos.logback</groupid>
logback-classic</artifactid>
<version>1.1.2</version>
</dependency></code></code></code></code></code></code></code></code></code></code></code></code></code></code>로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml">logback.xml
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><configuration>
<property name="logRoot" value="/data/logs">
<property name="pattern" value="%d{HH:mm:ss.SSS} [%thread] %-5level %logger{0} - %msg%n">
<appender class="ch.qos.logback.core.ConsoleAppender" name="STDOUT">
<encoder>
<pattern>${pattern}</pattern>
</encoder>
</appender>
<appender class="ch.qos.logback.core.rolling.RollingFileAppender" name="FILE">
<rollingpolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
<filenamepattern>${logRoot}/common-server.%d{yyyy-MM-dd}.log</filenamepattern>
<maxhistory>7</maxhistory>
</rollingpolicy>
<encoder>
<pattern>${pattern}</pattern>
</encoder>
</appender>
<root level="DEBUG">
<appender-ref ref="STDOUT">
<appender-ref ref="FILE">
</appender-ref></appender-ref></root>
</property></property></configuration></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code>로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml">其他关于MyBatis日志的详细信息可参考MyBatis文档日志部分.
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml">DAO开发
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml">使用MyBatis开发DAO有两个方法,<strong>原始DAO开发</strong>与<strong>Mapper映射DAO开发</strong>.
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml">原始DAO开发
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml">原始DAO开发需要开发人员编写DAO接口与DAO实现,如根据ID查询用户信息:
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml">mapper(同前)
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><select id="selectUserById" parametertype="java.lang.Integer" resulttype="com.fq.domain.User">
SELECT * FROM user WHERE id = #{id};
</select></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code>로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet">UserDAO接口
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java">/**
* @author jifang
* @since 16/2/22 上午10:20.
*/
public interface UserDAO {
User selectUserById(Integer id) throws Exception;
}</code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code>로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java">UserDAO实现
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java">public class UserDAOImpl implements UserDAO {
private SqlSessionFactory factory;
public UserDAOImpl(SqlSessionFactory factory) {
this.factory = factory;
}
@Override
public User selectUserById(Integer id) throws Exception {
SqlSession session = factory.openSession();
User user = session.selectOne("namespace.selectUserById", id);
session.close();
return user;
}
}</code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code>로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java">Client
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs">public class MyBatisClient {
@Test
public void originalClient() throws Exception {
UserDAO dao = new UserDAOImpl(new SqlSessionFactoryBuilder().
build(ClassLoader.getSystemResourceAsStream("mybatis/mybatis-configuration.xml")));
User user = dao.selectUserById(1);
System.out.println(user);
}
}</code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code>로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs">原始DAO开发中存在的问题:<br />
1) DAO实现方法体中存在很多过程性代码.<br />
2) 调用SqlSession的方法(select/insert/update)需要指定<em>Statement</em>的id,存在硬编码,不利于代码维护.
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs">Mapper映射开发
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs">mapper映射开发方法只需编写DAO接口,MyBatis根据接口定义与mapper文件中的SQL语句动态创建接口实现.
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs">mapper
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><!--?xml version="1.0" encoding="UTF-8" ?-->
<mapper namespace="com.fq.mybatis.UserDAO">
<select id="selectUserById" parametertype="java.lang.Integer" resulttype="com.fq.domain.User">
SELECT * FROM user WHERE id = #{id};
</select>
</mapper></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code>로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml">注意: 此时namespace必须与UserDAO接口的全限定名相同.
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml">UserDAO接口与前面相同, 但不再使用UserDAOImpl Client
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java">/**
* @author jifang
* @since 16/2/22 下午2:57.
*/
public class MyBatisClient {
private SqlSession session;
private SqlSessionFactory factory;
@Before
public void setUp() {
factory = new SqlSessionFactoryBuilder().
build(ClassLoader.getSystemResourceAsStream("mybatis/mybatis-configuration.xml"));
session = factory.openSession();
}
@Test
public void mapperClient() throws Exception {
UserDAO dao = session.getMapper(UserDAO.class);
User user = dao.selectUserById(1);
System.out.println(user);
}
@After
public void tearDown() {
session.close();
}
}</code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code>로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java">mapper映射开发方法需要遵循以下规范:<br />
mapper文件中的namespace与DAO接口的全限定名相同; mapper文件中的<em>Statement</em>的id与DAO接口方法名相同; mapper文件中的<em>Statement</em>的parameterType/resultType与DAO方法的入参/回参类型相同.
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java">Mapper映射
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java">mapper映射文件(如UserDAO.xml)主要作用是定义SQL语句(每个SQL是一个<em>Statement</em>),是MyBatis的核心.
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java">MyBatis官方推荐使用mapper映射的方法来开发DAO,因此我们以后就不再过多介绍原始DAO的开发.
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java">输入映射
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java">多个形参
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java">传递简单类型前面示例已经使用过,在此就不再赘述.当需要传递多个形参时,不再需要设置parameterType参数:
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java">mapper
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java"><code class="hljs haml"><update id="updateUserById">
UPDATE user SET name = #{1}, password = #{2} WHERE id = #{0};
</update></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code>로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java"><code class="hljs haml">UserDAO
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java"><code class="hljs haml"><code class="hljs lasso">void updateUserById(Integer id, String name, String password) throws Exception;</code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code>
로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java"><code class="hljs haml"><code class="hljs lasso">传入PO
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java"><code class="hljs haml"><code class="hljs lasso">MyBatis使用<strong>OGNL</strong>表达式解析对象属性值:
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java"><code class="hljs haml"><code class="hljs lasso">mapper
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java"><code class="hljs haml"><code class="hljs lasso"><code class="hljs vbnet"><select id="selectUserByNamePassword" parametertype="com.fq.domain.User" resulttype="com.fq.domain.User">
SELECT *
FROM user
WHERE name = #{name} AND password = #{password};
</select></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code>로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java"><code class="hljs haml"><code class="hljs lasso"><code class="hljs vbnet">UserDAO
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java"><code class="hljs haml"><code class="hljs lasso"><code class="hljs vbnet"><code class="hljs java">User selectUserByNamePassword(User user) throws Exception;</code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code>
로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java"><code class="hljs haml"><code class="hljs lasso"><code class="hljs vbnet"><code class="hljs java">传入Map
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java"><code class="hljs haml"><code class="hljs lasso"><code class="hljs vbnet"><code class="hljs java">mapper
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java"><code class="hljs haml"><code class="hljs lasso"><code class="hljs vbnet"><code class="hljs java"><code class="hljs vbnet"><select id="selectUserByMap" parametertype="java.util.Map" resulttype="com.fq.domain.User">
SELECT *
FROM user
WHERE name = #{name} AND password = #{password};
</select></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code>로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java"><code class="hljs haml"><code class="hljs lasso"><code class="hljs vbnet"><code class="hljs java"><code class="hljs vbnet">#{}花括号内对应Map的key.
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java"><code class="hljs haml"><code class="hljs lasso"><code class="hljs vbnet"><code class="hljs java"><code class="hljs vbnet">UserDAO
<code class="hljs xml"><code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java"><code class="hljs haml"><code class="hljs lasso"><code class="hljs vbnet"><code class="hljs java"><code class="hljs vbnet"><code class="hljs vhdl">User selectUserByMap(Map<string, object=""> map) throws Exception;</string,></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code></code>
로그인 후 복사
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java"><code class="hljs haml"><code class="hljs lasso"><code class="hljs vbnet"><code class="hljs java"><code class="hljs vbnet"><code class="hljs vhdl">输出映射
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code class="hljs java"><code class="hljs cs"><code class="hljs xml"><code class="hljs java"><code class="hljs haml"><code class="hljs lasso"><code class="hljs vbnet"><code class="hljs java"><code class="hljs vbnet"><code class="hljs vhdl">输出简单类型
<code class="hljs xml"><code class="hljs xml"><code class="hljs java"><code class="hljs java"><code class="hljs applescript"><code class="hljs java"><code class="hljs xml"><code class="hljs cs"><code class="hljs haml"><code class="hljs java"><code class="hljs livecodeserver"><code class="hljs java"><code class="hljs xml"><code class="hljs xml"><code class="hljs vbnet"><code class="hljs java"><code cl>
본 웹사이트의 성명
본 글의 내용은 네티즌들의 자발적인 기여로 작성되었으며, 저작권은 원저작자에게 있습니다. 본 사이트는 이에 상응하는 법적 책임을 지지 않습니다. 표절이나 침해가 의심되는 콘텐츠를 발견한 경우 admin@php.cn으로 문의하세요.
핫 AI 도구
Undresser.AI Undress
사실적인 누드 사진을 만들기 위한 AI 기반 앱
AI Clothes Remover
사진에서 옷을 제거하는 온라인 AI 도구입니다.
Undress AI Tool
무료로 이미지를 벗다
Clothoff.io
AI 옷 제거제
AI Hentai Generator
AI Hentai를 무료로 생성하십시오.
인기 기사
R.E.P.O. 에너지 결정과 그들이하는 일 (노란색 크리스탈)
2 몇 주 전
By 尊渡假赌尊渡假赌尊渡假赌
스플릿 소설을이기는 데 얼마나 걸립니까?
1 몇 달 전
By DDD
R.E.P.O. 파일 저장 위치 : 어디에 있고 그것을 보호하는 방법은 무엇입니까?
1 몇 달 전
By DDD
R.E.P.O. 최고의 그래픽 설정
2 몇 주 전
By 尊渡假赌尊渡假赌尊渡假赌
어 ass 신 크리드 그림자 : 조개 수수께끼 솔루션
1 몇 주 전
By DDD
뜨거운 도구
메모장++7.3.1
사용하기 쉬운 무료 코드 편집기
SublimeText3 중국어 버전
중국어 버전, 사용하기 매우 쉽습니다.
스튜디오 13.0.1 보내기
강력한 PHP 통합 개발 환경
드림위버 CS6
시각적 웹 개발 도구
SublimeText3 Mac 버전
신 수준의 코드 편집 소프트웨어(SublimeText3)
뜨거운 주제
Gmail 이메일의 로그인 입구는 어디에 있나요?
7393
15
7393
15
자바 튜토리얼
1630
14
1630
14
Cakephp 튜토리얼
1357
52
1357
52
라라벨 튜토리얼
1268
25
1268
25
PHP 튜토리얼
1217
29
1217
29
Alter Table 문을 사용하여 MySQL에서 테이블을 어떻게 변경합니까?
Mar 19, 2025 pm 03:51 PM
이 기사는 MySQL의 Alter Table 문을 사용하여 열 추가/드롭 테이블/열 변경 및 열 데이터 유형 변경을 포함하여 테이블을 수정하는 것에 대해 설명합니다.
MySQL 연결에 대한 SSL/TLS 암호화를 어떻게 구성합니까?
Mar 18, 2025 pm 12:01 PM
기사는 인증서 생성 및 확인을 포함하여 MySQL에 대한 SSL/TLS 암호화 구성에 대해 설명합니다. 주요 문제는 자체 서명 인증서의 보안 영향을 사용하는 것입니다. [문자 수 : 159]
MySQL에서 큰 데이터 세트를 어떻게 처리합니까?
Mar 21, 2025 pm 12:15 PM
기사는 MySQL에서 파티셔닝, 샤딩, 인덱싱 및 쿼리 최적화를 포함하여 대규모 데이터 세트를 처리하기위한 전략에 대해 설명합니다.
인기있는 MySQL GUI 도구는 무엇입니까 (예 : MySQL Workbench, Phpmyadmin)?
Mar 21, 2025 pm 06:28 PM
기사는 MySQL Workbench 및 Phpmyadmin과 같은 인기있는 MySQL GUI 도구에 대해 논의하여 초보자 및 고급 사용자를위한 기능과 적합성을 비교합니다. [159 자].
드롭 테이블 문을 사용하여 MySQL에서 테이블을 어떻게 드롭합니까?
Mar 19, 2025 pm 03:52 PM
이 기사에서는 Drop Table 문을 사용하여 MySQL에서 테이블을 떨어 뜨리는 것에 대해 설명하여 예방 조치와 위험을 강조합니다. 백업 없이는 행동이 돌이킬 수 없으며 복구 방법 및 잠재적 생산 환경 위험을 상세하게합니다.
외국 키를 사용하여 관계를 어떻게 표현합니까?
Mar 19, 2025 pm 03:48 PM
기사는 외국 열쇠를 사용하여 데이터베이스의 관계를 나타내고 모범 사례, 데이터 무결성 및 피할 수있는 일반적인 함정에 중점을 둡니다.
JSON 열에서 인덱스를 어떻게 생성합니까?
Mar 21, 2025 pm 12:13 PM
이 기사에서는 PostgreSQL, MySQL 및 MongoDB와 같은 다양한 데이터베이스에서 JSON 열에서 인덱스를 작성하여 쿼리 성능을 향상시킵니다. 특정 JSON 경로를 인덱싱하는 구문 및 이점을 설명하고 지원되는 데이터베이스 시스템을 나열합니다.
일반적인 취약점 (SQL 주입, 무차별 적 공격)에 대해 MySQL을 어떻게 보호합니까?
Mar 18, 2025 pm 12:00 PM
기사는 준비된 명령문, 입력 검증 및 강력한 암호 정책을 사용하여 SQL 주입 및 무차별 적 공격에 대한 MySQL 보안에 대해 논의합니다 (159 자)
