动态代理写connection连接池Demo

 public class JdbcUtil2 {
     //声明连接池<放到LinkedList中，操作其中对象的速度快 只需要改变连接>
     private static LinkedList<Connection> connectionspool=new LinkedList<Connection>();
     //静态代码块
     static{
         try {
             String url="jdbc:mysql://localhost:3306/jdbcdb";
             String user="root";
             String password="mysql";
             Class.forName("com.mysql.jdbc.Driver");
             //创建3个连接并将它们代理
             for(int i=0;i<3;i++)
             {
                 final Connection conn=DriverManager.getConnection(url, user, password);
                 //对conn进行代理
                 Object proxyobj= Proxy.newProxyInstance(
                         JdbcUtil2.class.getClassLoader(),
                         new Class[]{Connection.class},
                         new InvocationHandler() {
                             public Object invoke(Object proxy, Method method, Object[] args)
                                     throws Throwable {
                                     //是否是close方法
                                     if(method.getName().equals("close"))
                                     {
                                         synchronized(connectionspool){
                                             connectionspool.addLast((Connection)proxy);
                                             connectionspool.notify();
                                         }
                                         return null;//如果调用的是close()方法，不会调用代理类的方法，会调用代理
                                     }
                                     return method.invoke(conn, args);
                             }
                         });

                 connectionspool.add((Connection)proxyobj);

             }
         } catch (SQLException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         } catch (ClassNotFoundException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }
     }

     public static Connection getConnection()
     {
         synchronized(connectionspool)
         {
             if(connectionspool.size()==0)
             {
                 try {
                     connectionspool.wait();
                 } catch (InterruptedException e) {
                     // TODO Auto-generated catch block
                     e.printStackTrace();
                 }
                 return getConnection();
             }
             else {
                 Connection conn=connectionspool.removeFirst();
                 System.err.println("pool中还有连接数："+connectionspool.size());
                 return conn;
             }
         }
     }
 }

利用多线程测试代理连接池

 public class TestProxy  {
     public static void main(String[] args) {
         for(int i=0;i<3000;i++)
         {
             new MyThread().start();
         }
     }
 }

 class MyThread extends Thread
 {
     @Override
     public void run() {
         Connection con = null;
         try{
             con = JdbcUtil2.getConnection();
             System.err.println(this.getName()+","+con);
             con.setAutoCommit(false);//设置事务的开始
             String sql = "insert into users values('"+this.getName()+"','Tom','44')";
             Statement st = con.createStatement();
             st.execute(sql);
             con.commit();
             System.err.println(this.getName()+"子线程执行完成。。。。。");
         }catch(Exception e){
             e.printStackTrace();
         }finally{
             try {
                 con.setAutoCommit(true);
                 con.close();
             } catch (SQLException e) {
                 e.printStackTrace();
             }
         }
     }
 }