java数据库连接池简单实现

package cn.lmj.utils;





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.util.LinkedList;

import javax.sql.DataSource;





public class JdbcPool implements DataSource

{

//选用LinkedList方便移除链接

public static LinkedList<Connection> list = new LinkedList<Connection>();



static

{

try

{

Class.forName("com.mysql.jdbc.Driver");

//初始化20个链接

for(int i = 0;i<20;i++)

{

final Connection conn = DriverManager.getConnection("jdbc:mysql:///test","root","root");

//利用jdk动态代理实现增强Connection的close方法

Connection proxy = (Connection) Proxy.newProxyInstance(JdbcPool.class.getClassLoader(),conn.getClass().getInterfaces(),new InvocationHandler()

{

public Object invoke(Object obj, Method m, Object[] arg)

throws Throwable

{

if("close".equals(m.getName()))

{

//加到池中供其他线程訪问

list.addLast(conn);

}



return m.invoke(conn,arg);

}

});

list.add(proxy);

}

}

catch (Exception e)

{

e.printStackTrace();

}

}



public PrintWriter getLogWriter() throws SQLException

{

return null;

}





public int getLoginTimeout() throws SQLException

{

// TODO Auto-generated method stub

return 0;

}





public void setLogWriter(PrintWriter arg0) throws SQLException

{

// TODO Auto-generated method stub



}





public void setLoginTimeout(int arg0) throws SQLException

{

// TODO Auto-generated method stub



}





public boolean isWrapperFor(Class<?> arg0) throws SQLException

{

// TODO Auto-generated method stub

return false;

}





public <T> T unwrap(Class<T> arg0) throws SQLException

{

// TODO Auto-generated method stub

return null;

}





public Connection getConnection() throws SQLException

{

if(list.size()<=0)

{

new RuntimeException("数据库忙。稍后再来");

}

//移除第一个引用。不能用get,由于get不能移除引用

return list.removeFirst();

}





public Connection getConnection(String arg0, String arg1)

throws SQLException

{

// TODO Auto-generated method stub

return null;

}



}