Javaweb新手,配置jndi后连接数据后总出现异常
报错出现在 myConn = ds.getConnection();
修改my.ini后还是会出现这种问题
配置jndi的context.xml文件
<?xml version="1.0" encoding="UTF-8"?>
<Context path="/" reloadable="true">
<Resource name="jdbc/studentinfo" auth="Container" type="javax.sql.DataSource"
maxActive="100" maxIdle="30" maxWait="10000"
username="root" password="000000"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/studentinfo?">
</Resource>
</Context>
web.xml文件
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
version="3.1">
<resource-ref>
<res-ref-name>jdbc/studentinfo</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
<servlet>
<servlet-name>StudentServlet</servlet-name>
<servlet-class>init.StudentServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>StudentServlet</servlet-name>
<url-pattern>/StudentServlet</url-pattern>
</servlet-mapping>
</web-app>
java文件
public class StudentServlet extends HttpServlet{
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=GB2312");
PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head><title>StudentInfo</title></head>");
if((request.getParameter("sno") == null || request.getParameter("sno").equals("input number"))){
out.println("<form method='post' action='/Servlet/StudentServlet' >");
out.println("");
out.println("学号查询：<input type='text' name='sno' value='input number' />");
out.println("<input type='submit' value='查询' /><br>");
out.println("</form>");
}else if (!(request.getParameter("sno").equals("input number"))){
Vector vc = new Vector();
out.println("<form method='post' action='/Servlet/StudentServlet' >");
out.println("");
out.println("学生学号：<input type'text' name='sno' />");
out.println("</form>");
out.println("<br>");
out.println("<table border='1'>");
out.println("<tr><th>学号</th><th>姓名</th><th>语文</th><th>数学</th></tr>");
try {
if((vc = accessDB(Integer.parseInt((String)request.getParameter("sno")))) != null){
out.println("<tr>");
out.println("<td>" + vc.elementAt(0) + "</td>");
out.println("<td>" + vc.elementAt(1) + "</td>");
out.println("<td>" + vc.elementAt(2) + "</td>");
out.println("<td>" + vc.elementAt(3) + "</td>");
out.println("</tr>");
}
}catch (Exception e){
out.println("<tr>");
out.println("<td>没有记录：</td>");
out.println("</tr>");
out.println("数据库里没有你要查询得记录");
e.printStackTrace();
}
out.println("</table>");
}
out.println("</body>");
out.println("</html>");
out.flush();
out.close();
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
@Override
public void init() throws ServletException {
}
public Vector accessDB(int id){
Vector vc = new Vector();
DataSource ds = null;
Context ctx;
Connection myConn = null;
try {
ctx = new InitialContext();
ds = (DataSource) ctx.lookup("java:comp/env/jdbc/studentinfo");
}catch (Exception e){
e.printStackTrace();
}
if (ds == null){
System.out.println("Error");
}else {
System.out.println("Connection is OK!");
}
PreparedStatement statement = null;
ResultSet mySet = null;
try {
myConn = ds.getConnection();
statement = myConn.prepareStatement("SELECT * FROM info WHERE sno=?");
statement.setInt(1,id);
mySet = statement.executeQuery();
while (mySet.next()){
vc.add(Integer.toString(mySet.getInt("sno")));
vc.add(mySet.getString("sname"));
vc.add(Integer.toString(mySet.getInt("chinese")));
vc.add(Integer.toString(mySet.getInt("math")));
}
statement.close();
mySet.close();
myConn.close();
return vc;
}catch (Exception e){
e.printStackTrace();
}
return vc;
}
public static void main(String[] args) {
StudentServlet aa = new StudentServlet();
System.out.println(aa.accessDB(100).elementAt(1));
}
}
修改context.xml的urlurl="jdbc:mysql://localhost:3306/studentinfo?useSSL=true"
还是会出现异常如下：
java.sql.SQLException: Cannot create PoolableConnectionFactory (Unknown system variable 'lower_case_table_names')
at org.apache.tomcat.dbcp.dbcp2.BasicDataSource.createPoolableConnectionFactory(BasicDataSource.java:2303)
at org.apache.tomcat.dbcp.dbcp2.BasicDataSource.createDataSource(BasicDataSource.java:2043)
at org.apache.tomcat.dbcp.dbcp2.BasicDataSource.getConnection(BasicDataSource.java:1543)
at init.StudentServlet.accessDB(StudentServlet.java:102)
at init.StudentServlet.doGet(StudentServlet.java:47)
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이유: MySQL은 상위 버전에서 SSL 연결을 수행할지 여부를 표시해야 합니다
해결책:
으아아아문제: 알 수 없는 시스템 변수 'lower_case_table_names'
mysql-connector-java jar 버전을 낮추어 보세요