使用包裝設計模式，實現標準連接池

public class MyDataSource implements DataSource{

	private LinkedList<Connection> pool = new LinkedList<Connection>();
	
	public MyDataSource() {
		String driverClassName = "com.mysql.jdbc.Driver";
		String url = "jdbc:mysql://localhost:3306/oa";
		String username = "root";
		String password = "root";
		
		try {
			Class.forName(driverClassName);
			for(int i=0; i<3; i++){
				Connection conn = DriverManager.getConnection(url, username, password); // conn-->com.mysql.jdbc.Jdbc4Connection@df255
				// 對上述conn,進行包裝。myConnection-->standardConnPool.MyDataSource$MyConnection@1e13d52
				MyConnectionWrapper myConnection = new MyConnectionWrapper(conn);
				
				// 將包裝的Connection類，放入到pool中
				pool.add(myConnection);
				
			}	
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	
	
	public Connection getConnection() throws SQLException {
		synchronized (pool) {
			// 如果線程池中的Connection大小爲0，等待
			if(pool.size() == 0){
				try {
					pool.wait();
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
				return getConnection();
			}
			Connection conn = pool.removeFirst();
			System.out.println("size :" + pool.size() + " " + conn);
			return conn;
		}
		
	}
	
	/**
	 * 內部類，對Connection進行包裝。重寫close方法
	 * @author zhurudong
	 *
	 */
	class MyConnectionWrapper implements Connection {
		
		private Connection connection;
		
		public MyConnectionWrapper(Connection connection) {
			this.connection = connection;
		}

		
		public void close() throws SQLException {
			synchronized (pool) {
				System.out.println("對象：" + this + " 關閉連接");
				// 把要關閉連接的對象，重新放回pool中。喚醒正在wait的線程
				pool.add(this);
				pool.notify();
			}
		}