Java数据库编程

class DBConnectionPool { private String jdbcUrl; private String username; private String password; private LinkedList<Connection> pool; //保存闲置的Connection对象 public DBConnectionPool(String driver,String jdbcUrl) throws ClassNotFoundException { this.jdbcUrl = jdbcUrl; Class.forName(driver); pool = new LinkedList<Connection>(); } public DBConnectionPool(String driver,String jdbcUrl,String username,String password) throws ClassNotFoundException { this.jdbcUrl = jdbcUrl; this.username = username; this.password = password; Class.forName(driver); pool = new LinkedList<Connection>(); }
//为了可以在多线程环境下使用，对一些方法使用synchronized关键字同步 public synchronized Connection getConnection() throws SQLException { Connection conn = null; if(pool.size() > 0) conn = pool.poll(); else { final Connection connection = DriverManager.getConnection(jdbcUrl, username, password);
//创建代理对象，并强制转换为Connection接口类型，InvocationHandler接口表示调用处理器 conn = (Connection)Proxy.newProxyInstance(null,new Class[]{Connection.class},new InvocationHandler(){ public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { if(method.getName() == "close" && method.getParameterTypes().length == 0) { pool.add((Connection)proxy); //执行close方法时，替换原方法的逻辑 return null; } else //执行其他方法时，保持原方法的逻辑 return method.invoke(connection,args); } }); } return conn; } public synchronized Connection getConnection(String username, String password) throws SQLException { Connection conn = null; if(pool.size() > 0) conn = pool.poll(); else { final Connection connection = DriverManager.getConnection(jdbcUrl, username, password); conn = (Connection)Proxy.newProxyInstance(null,new Class[]{Connection.class},new InvocationHandler(){ public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { if(method.getName() == "close" && method.getParameterTypes().length == 0) { pool.add((Connection)proxy); return null; } else return method.invoke(connection,args); } }); } return conn; } public synchronized void reduce() throws SQLException { int size = pool.size(); while(pool.size() > (size / 2) ) pool.poll().close(); } public synchronized void close() throws SQLException { while(pool.size() > 0) pool.poll().close(); } }

 

  

Java数据库编程

标签：