数据库连接池负责分配、管理和释放数据库连接，它允许应用程序重复使用一个现有的数据库连接，而不是再重新建立一个，应用程序和数据库创建连接需要消耗很大的资源。
package com.lbx.myDataSource;
import javax.sql.DataSource;
import java.io.PrintWriter;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.SQLFeatureNotSupportedException;
import java.util.LinkedList;
import java.util.logging.Logger;
/**
* @Author:
* @date 2018/4/2 9:53
*/
public class MyDataSource implements DataSource {
//数据库连接信息
String url = "jdbc:mysql://172.31.12.180:3306/bos";
String user = "root";
String password = "liaoBAOxin123...";
//创建一个连接池,因为频繁需要增删，所以选择链表数据结构，LinkedList
LinkedList<Connection> poll = new LinkedList<Connection>();
public MyDataSource() {
try {
//注册驱动
Class.forName("com.mysql.jdbc.Driver");
//初始化两条连接
for (int i = 0; i < 2; i++) {
//创建连接
Connection conn = DriverManager.getConnection(url, user, password);
poll.add(conn);
}
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public Connection getConnection() throws SQLException {
//并发情况下，只能一个线程进去
synchronized (this) {
//如果池中没有连接，则创建连接
if (poll.isEmpty()) {
for (int i = 0; i < 2; i++) {
//创建连接
Connection conn = DriverManager.getConnection(url, user, password);
poll.add(conn);
}
}
//removeFirst执行方法的返回值是connection
final Connection conn = poll.removeFirst();
//利用动态代理技术，增强close方法
Connection proxyconn = (Connection) Proxy.newProxyInstance(conn.getClass().getClassLoader(), conn.getClass().getInterfaces(), new InvocationHandler() {
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
if (method.getName().equals("close")) {
System.out.println("方法名称" + method.getName());
System.out.println("连接给回给连接池");
return poll.add(conn);
} else {
return method.invoke(conn, args);
}
}
});
return proxyconn;
}
}
@Override
public Connection getConnection(String username, String password) throws SQLException {
return null;
}
@Override
public <T> T unwrap(Class<T> iface) throws SQLException {
return null;
}
@Override
public boolean isWrapperFor(Class<?> iface) throws SQLException {
return false;
}
@Override
public PrintWriter getLogWriter() throws SQLException {
return null;
}
@Override
public void setLogWriter(PrintWriter out) throws SQLException {
}
@Override
public void setLoginTimeout(int seconds) throws SQLException {
}
@Override
public int getLoginTimeout() throws SQLException {
return 0;
}
@Override
public Logger getParentLogger() throws SQLFeatureNotSupportedException {
return null;
}
}“`
package com.lbx.myDataSource;
import org.junit.Test;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
public class MyTest {
@Test
public void fun1() throws SQLException {
Connection conn = null;
PreparedStatement pstmt = null;
// 1.创建自定义连接池对象
MyDataSource dataSource = new MyDataSource();
try {
// 2.从池子中获取连接
conn = dataSource.getConnection();
String sql = "insert into t_user values(?)";
pstmt = conn.prepareStatement(sql);
pstmt.setString(1, "张三");
int rows = pstmt.executeUpdate();
if (rows > 0) {
System.out.println("添加成功!");
} else {
System.out.println("添加失败!");
}
} catch (Exception e) {
throw new RuntimeException(e);
}finally {
conn.close();
}
}
}