Tomcat下的数据库连接池的配置与使用

实验环境：Eclipse Neon.3 (4.6.3)、MySQL、Tomcat 9.0

一、在web应用下的META-INF下新建context.xml文件，配置数据源。

<?xml version="1.0" encoding="UTF-8"?>
<Context>
	<Resource name="DBPool"
	type="javax.sql.DataSource" 
	auth="Container"
	driverClassName="com.mysql.jdbc.Driver" 
	url="jdbc:mysql://localhost:3306/newsdb" 
	username="root"
	password="root" 
	maxActive="5" 
	maxIdle="2" 
	maxWait="6000" />
</Context>

二、使用JNDI访问数据库连接池

package com.drathin.db;

import java.sql.*;

import javax.naming.*;
import javax.sql.DataSource;


public class Dbpool {

	protected static Statement s = null;
	protected static ResultSet rs = null;
	protected static Connection conn = null;
	
	public static Connection getConnection()
	{
		try
		{
			//Context是javax.name包中的一个接口，用于查找数据库连接池的配置文件
			Context ctx = new InitialContext();  //向上转型
			ctx = (Context) ctx.lookup("java:comp/env");
			
			DataSource ds = (DataSource) ctx.lookup("DBPool");
			conn = ds.getConnection();
		}catch(Exception e)
		{
			e.printStackTrace();
			//System.out.println("FAil");
		}
		return conn;
	}

	public static Statement getS() {
		return s;
	}

	public static void setS(Statement s) {
		Dbpool.s = s;
	}

	public static ResultSet getRs() {
		return rs;
	}

	public static void setRs(ResultSet rs) {
		Dbpool.rs = rs;
	}

	public static Connection getConn() {
		return conn;
	}

	public static void setConn(Connection conn) {
		Dbpool.conn = conn;
	}

	

}

三、用JSP脚本测试

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"
    import="com.drathin.db.Dbpool"
    import="java.sql.*"
    %>
<!DOCTYPE html>
<html>
<head>

<title>Tomcat连接池测试</title>
</head>
<body>
<%
	Dbpool.setConn(Dbpool.getConnection());	

	
	try {
		Dbpool.setS(Dbpool.getConn().createStatement());
		Dbpool.setRs(Dbpool.getS().executeQuery("select * from user"));
		while(Dbpool.getRs().next()){
			out.print("  id：" + Dbpool.getRs().getInt(1));
			out.print(";  username：" + Dbpool.getRs().getString(2));
			out.print(";  password：" + Dbpool.getRs().getString(3));
			out.print("\n");
		}
	} catch (SQLException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	}
%>

</body>
</html>

注意：测试程序切勿用java应用程序，因为这是Tomcat的数据库连接池，如果在eclipse下run运行，会导致Tomcat关闭，而运行抛出异常，也可以用servlet去实现，然后运行在Tomcat下。

package com.drathin.db;

import java.io.IOException;
import java.sql.SQLException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


@WebServlet("/DBPoolServlet")
public class DBPoolServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    public DBPoolServlet() {
        super();

    }

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		response.getWriter().append("Served at: ").append(request.getContextPath());
		Dbpool.setConn(Dbpool.getConnection());	

		try {
			Dbpool.setS(Dbpool.getConn().createStatement());
			Dbpool.setRs(Dbpool.getS().executeQuery("select * from user"));
			while(Dbpool.getRs().next()){
				System.out.print("  id：" + Dbpool.getRs().getInt(1));
				System.out.print(";  username：" + Dbpool.getRs().getString(2));
				System.out.print(";  password：" + Dbpool.getRs().getString(3));
				System.out.print("\n");
			}
		} catch (SQLException e) {
		
			e.printStackTrace();
		}
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		doGet(request, response);
	}

}

Tomcat下的数据库连接池的配置与使用

注意：测试程序切勿用java应用程序，因为这是Tomcat的数据库连接池，如果在eclipse下run运行，会导致Tomcat关闭，而运行抛出异常，也可以用servlet去实现，然后运行在Tomcat下。

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