关于连接池里Connection的地址错误问题

[wqdsb]

//自定义连接池，初始连接数5，最大为10
public class mypool {
	public static final String DRIVER = "com.mysql.jdbc.Driver";
	public static final String URL = "jdbc:mysql://localhost:8078/test";
	public static final String USER = "root";
	public static final String PASSWORD = "22222";
	
	private LinkedList<Connection> pool=new LinkedList<>();
	
	private int initCount=5;
	private int currentCount=0;
	private int max=10;
	static{
		try {
			Class.forName(DRIVER);
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
	}
	
	public mypool(){
		for(int i=0;i<initCount;i++){
			pool.addLast(createConnection());
			currentCount++;
		}
	}
	
	private Connection createConnection(){
		Connection conn=null;
		try {
			conn= DriverManager.getConnection(URL,USER,PASSWORD);
			myConnection mc=new myConnection(conn,this);
			return mc;
		} catch (SQLException e) {
			e.printStackTrace();
			throw new RuntimeException(e);
		}
		
	}
	
	public Connection getConnetion(){
		if(pool.size()>0){    //<5
			return pool.removeFirst();
		}
		if(currentCount<max){   //5-10
			currentCount++;
			System.out.println(currentCount);
			return createConnection();
			
		}
		//超过最大连接数
		throw new RuntimeException("超过最大连接数");
	}
	
	public void closeConnection(Connection c){
		pool.addLast(c);
	}

	public LinkedList<Connection> getPool() {
		return pool;
	}
	
}

//这是代理类
public class myConnection implements Connection{
	
	private mypool mo;
	private Connection conn;  //真实的Connection
	//private 
	public myConnection(Connection c,mypool pool){
		conn=c;
		mo=pool; 
	}
	/*
	 * 只重写close()
	 */
	@Override
	public void close() throws SQLException {
		System.out.println("关闭");
		mo.closeConnection(conn);
	}
	
//	@Override
//	public String toString() {
//		return " conn=" + conn ;
//	}
........其它的调用Connection 的方法
}

//测试类
public class test {
	public static void main(String[] args) {
		mypool mp=new mypool();
		for(int i=0;i<6;i++){
			Connection conn=mp.getConnetion();
			System.out.println(conn);
			if(i==3){
				try {
					conn.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}
			}
		}
}

在myConnection 类是否重写了toString()方法的结果如下
无toString
JDBC_15.myConnection@b81eda8
JDBC_15.myConnection@68de145
JDBC_15.myConnection@27fa135a
JDBC_15.myConnection@46f7f36a
关闭
JDBC_15.myConnection@421faab1
com.mysql.jdbc.JDBC4Connection@2b71fc7e

有toString
conn=com.mysql.jdbc.JDBC4Connection@b81eda8
conn=com.mysql.jdbc.JDBC4Connection@68de145
conn=com.mysql.jdbc.JDBC4Connection@27fa135a
conn=com.mysql.jdbc.JDBC4Connection@46f7f36a
关闭
conn=com.mysql.jdbc.JDBC4Connection@421faab1
com.mysql.jdbc.JDBC4Connection@46f7f36a

为什么无toString的结果中放回去的Connection地址变了，按理说放回池中了地址不会变啊