struts2--数据源应用

刺骨的言语ヽ痛彻心扉 2024-02-18 14:25 16阅读 0赞

1、在WebRoot/MWTA-INF下创建一个名为context.xml的配置文件，文件内容如下。

<?xml version="1.0" encoding="UTF-8"?>
    <Context path = "/dbtom" docBase = "dbtom" reloadable = "true" crossContext = "true">
      <Resource
       name = "jdbc/dbtom"
       type = "javax.sql.DataSource"
       username = "root"
       password = "root"
       driverClassName = "com.mysql.jdbc.Driver"
       url = "jdbc:mysql://localhost:3306/user"
      />
    </Context>

在<Resource>元素中，以上几个属性均为必填属性。

2、创建java类（DbPool.java）

package com.conDB;
    
    import java.sql.Connection;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    
    import javax.naming.Context;
    import javax.naming.InitialContext;
    import javax.sql.DataSource;
    
    public class DbPool {
      private Connection connection;
      public void getConn() {
    	  try {
    			Context initcContext = new InitialContext(); //初始化context对象
    			Context envContext = (Context) initcContext.lookup("java:comp/env");	
    			DataSource dSource = (DataSource) envContext.lookup("jdbc/dbtom"); //获取数据源
    			
    			connection = dSource.getConnection();
    			System.out.println("获取连接成功");
    	} catch (Exception e) {
    		System.out.println("获取连接失败");
    	}
    }
      
      public ResultSet query(String sql) {
    	ResultSet rs = null;
    	if(connection == null){
    		getConn();//如果为空，则获取连接
    	}
    	
    	PreparedStatement ps;
    	try {
    		ps = connection.prepareStatement(sql);
    		rs = ps.executeQuery();
    	} catch (Exception e) {
    		System.out.println("query is failed!");
    	}
        return rs;	
    }
    }

3、在jsp页面查询数据库中的信息：

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
    <%@ taglib prefix = "s" uri = "/struts-tags" %>
    <%@ page import="java.sql.*"%>
    <%@ page import="com.conDB.*" %>
    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
    <html>
      <head>
      </head>
      
      <body>
        <%
          DbPool pool = new DbPool();  //初始化实例对象
          String sql = "select * from info";
          ResultSet rs = pool.query(sql);
          if(rs != null)
          while(rs.next()){
          out.print("姓名："+rs.getString(1));
          out.print("         密码："+rs.getString(2));
          out.print("<br>");
          }
          else System.out.println("rs is null");
         %>
      </body>
    </html>

根据数据库中的信息，查询结果如下：

![Center][]

[Center]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/d8d4b1c58e67401f9ab34856a372ded2.png