JavaEE--JNDI(下,实现)

参考:https://blog.csdn.net/ouyida3/article/details/46699023

　　 https://www.landui.com/help/show-6158.html

　　 https://blog.csdn.net/yan372397390/article/details/50450332

以tomcat,mysql为例.

1配置tomcat的conf/context.xml

<Resource
　　driverClassName="com.mysql.jdbc.Driver"
　　maxActive="4"
　　maxIdle="2"
　　maxWait="50"
　　name="jdbc/mysql"
　　password="mysql"
　　type="javax.sql.DataSource" url="jdbc:mysql://192.168.3.138:3306/test"
　　username="root"
/>

2将mysql的jar包放入tomcat的lib下.

3在项目的web.xml中引入

<resource-ref>
  <res-ref-name>jdbc/mysql</res-ref-name>
  <res-type>javax.sql.DataSource</res-type>
  <res-auth>Container</res-auth>
</resource-ref>

注意res-ref-name要和context.xml中配置的name一致.

4获取连接

 Context ctx = new InitialContext();
 DataSource ds = (DataSource) ctx.lookup("java:comp/env/jdbc/mysql");
 Connection conn = ds.getConnection();

源码:

 package org.wzh.testjndi.controller;

 import java.io.IOException;
 import java.io.PrintWriter;
 import java.sql.Connection;
 import java.sql.ResultSet;
 import java.sql.Statement;

 import javax.naming.Context;
 import javax.naming.InitialContext;
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import javax.sql.DataSource;

 @SuppressWarnings("serial")
 public class ServletDemo extends HttpServlet {

     @Override
     protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
         try (PrintWriter pw = resp.getWriter()) {
             pw.print(0);
             Context ctx = new InitialContext();
             DataSource ds = (DataSource) ctx.lookup("java:comp/env/jdbc/mysql");
             Connection conn = ds.getConnection();

             Statement statement = conn.createStatement();
             ResultSet resultSet = statement.executeQuery("select * from info");
             while(resultSet.next()) {
                 System.out.println(resultSet.getInt(1) + " **** " + resultSet.getString(2));
                 pw.print(resultSet.getInt(1) + " **** " + resultSet.getString(2));
             }
             pw.print(1);
         } catch (Exception e) {
             // TODO: handle exception
             e.printStackTrace();
         }
     }

 }

 <?xml version="1.0" encoding="UTF-8"?>
 <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xmlns="http://java.sun.com/xml/ns/javaee"
     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
     id="WebApp_ID" version="2.5">
     <display-name>TestJndi</display-name>
     <welcome-file-list>
         <welcome-file>index.html</welcome-file>
         <welcome-file>index.htm</welcome-file>
         <welcome-file>index.jsp</welcome-file>
         <welcome-file>default.html</welcome-file>
         <welcome-file>default.htm</welcome-file>
         <welcome-file>default.jsp</welcome-file>
     </welcome-file-list>

     <resource-ref>
         <res-ref-name>jdbc/mysql</res-ref-name>
         <res-type>javax.sql.DataSource</res-type>
         <res-auth>Container</res-auth>
     </resource-ref>

     <servlet>
         <servlet-name>demo</servlet-name>
         <servlet-class>org.wzh.testjndi.controller.ServletDemo</servlet-class>
     </servlet>
     <servlet-mapping>
         <servlet-name>demo</servlet-name>
         <url-pattern>/demo</url-pattern>
     </servlet-mapping>
 </web-app>