commons.net.SocketClient下connect方法报错Cannot assign requested address: JVM_Bind

public void connect(InetAddress host, int port,
                        InetAddress localAddr, int localPort)
    throws SocketException, IOException
    {
        _socket_ = _socketFactory_.createSocket(host, port, localAddr, localPort);
        _connectAction_();
    }
[size=18px]当localAddr变量为访问网站客户端的地址时，报错：Cannot assign requested address: JVM_Bind。
当localAddr变量为网站地址时，则链接成功。[/size]这是为什么？
急啊！