Use hibernate to implement operations on the person data table

Hibernate is an open source ORM framework. As the name suggests, its core idea is ORM (Object Relational Mapping), which can operate information in the database through objects. It is said that developers are not very familiar with database SQL at the beginning. Statements, this also contributes to the power of hibernate. It does not require developers to be familiar with SQL statements to operate the database. Hibernate can automatically generate SQL statements and execute them automatically.

Using hibernate allows developers to fully use object-oriented thinking to operate the database, so the following demonstration will not contain a single SQL statement. If there is, please treat it as if I did not say this!

This article uses hibernate to implement simple basic add, delete, modify and query operations on a person data table.

Preparation

Environment: win7+eclipse

Toolkit: hibernate package, which can be downloaded. In this example, Version 4;

Database connection driver package, in this example mysql is used

Program structure diagram

##pojo layer entity class

package demo.pojo;
public class Person {private Integer id;private String name;private String gender;private Integer age;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 getGender() {return gender;}public void setGender(String gender) {this.gender = gender;}public Integer getAge() {return age;}public void setAge(Integer age) {this.age = age;}@Overridepublic String toString() {return "Person [id=" + id + ", name=" + name + ", gender=" + gender + ", age=" + age + "]";}}

Core configuration file hibernate.cfg.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- 以下四行分别为：数据库驱动类、Drivermanager获取连接的参数URL、用户名、密码  -->
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://127.0.0.1/web?characterEcoding=utf-8</property>
<property name="connection.username">root</property>
<property name="connection.password">123456</property>
<!-- 设置方言，hibernate会根据数据库的类型相应生成SQL语句 -->
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<!-- 控制台显示生成的sql语句，默认为false -->
<property name="show_sql">true</property>
<!-- 映射配置源文件的位置 -->
<mapping resource="demo/pojo/Person.hbm.xml"/>
</session-factory>
</hibernate-configuration>

Mapping file Person.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<!-- name是实体类全名，table为数据表名 -->
<class name="demo.pojo.Person" table="Person">
<id name="id" column="id">
<!-- 主键生成方式，native是让hibernate自动识别 -->
<generator class="native"></generator>
</id>
<!--

Notes:
0. The name value is the attribute name in the entity class, and column is the field name in the data table;
1. When the attribute name in the entity class is the same as the corresponding data table field name, the following column can be omitted, and hibernate will automatically Match, for example, age below;
2. On the contrary, when the attribute name in the entity class is different from the field name of the corresponding data table, both items must be written, for example, gender and sex below
-->

<property name="name" column="name"></property>
<property name="gender" column="sex"></property>
<property name="age"></property>
</class>
</hibernate-mapping>

Session Factory Class

package demo.util;
import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.cfg.Configuration;import org.hibernate.service.ServiceRegistry;import org.hibernate.service.ServiceRegistryBuilder;
public class HibernateSessionFactory {private static SessionFactory factory;private static ThreadLocal<Session> thread = new ThreadLocal<Session>();private static String path = "hibernate.cfg.xml";private static Configuration config = new Configuration();static {config.configure(path);ServiceRegistry service = new ServiceRegistryBuilder()//定义一个服务注册机.applySettings(config.getProperties()).buildServiceRegistry();factory = config.buildSessionFactory(service);//创建Session工厂类}/** * 从hibernate的session工厂类里创建一个session * @return * */public static Session getSession() {Session session = thread.get();if(session == null || !session.isOpen()) {session = factory.openSession();thread.set(session);}return session;}public static void closeSession() {Session session = thread.get();if(session != null && session.isOpen()) {session.close();thread.set(null);}}}

DAO layer encapsulates the methods of data operations

package demo.dao;
import java.io.Serializable;import org.hibernate.Session;import org.hibernate.Transaction;import demo.pojo.Person;import demo.util.HibernateSessionFactory;
public class PersonDaoImpl {//增删改查，此处以增为例public boolean add(Person p) {Session session = HibernateSessionFactory.getSession();//创建SessionTransaction trans = session.beginTransaction();//开启事务try {Serializable id = session.save(p);//添加记录并获取主键值System.out.println(id+"为获取的主键值");//控制台查看主键值trans.commit();//提交事务return true;} catch (Exception e) {trans.rollback();//获取异常，则事务回滚} finally {HibernateSessionFactory.closeSession();//关闭Session}return false;}}

Test class TestPerson

package demo.test;
import org.junit.Test;import demo.dao.PersonDaoImpl;import demo.pojo.Person;
public class TestPerson {@Testpublic void testAdd() {//创建一个人类对象Person p = new Person();p.setName("张三");p.setGender("男");p.setAge(18);//创建dao层类对象并调用添加方法PersonDaoImpl dao = new PersonDaoImpl();dao.add(p);}}

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