如何连接和关闭插座?

This thread Socket.isConnected 如果已成功连接,则返回true。

从上面的线程:

当你使用 Socket() 你似乎忽略了, Socket.isConnected() 告诉你 Socket.connect() 已调用 不管怎样。同样适用于 isClosed() close()

混淆这些方法是由于混淆了 插座 ,在应用程序的控制下 整体的 连接 isConnected() 和 告诉我你对插座做了什么。 连接。

医生说:

如果套接字成功连接到服务器,则返回true

如果套接字连接到服务器,则返回true ".

可以通过查看套接字的源来确认该行为:

public boolean isConnected() {
    // Before 1.3 Sockets were always connected during creation
    return connected || oldImpl;
}

Socket s = new Socket();

System.out.println("isConnected: " + s.isConnected() +
                  " isBound: "     + s.isBound() +
                  " isClosed: "    + s.isClosed());

s.connect(new InetSocketAddress("google.com", 80));

System.out.println("isConnected: " + s.isConnected() +
                   " isBound: "    + s.isBound() +
                   " isClosed: "   + s.isClosed());

s.close();

System.out.println("isConnected: " + s.isConnected() +
                   " isBound: "    + s.isBound() +
                   " isClosed: "   + s.isClosed());

打印内容:

isConnected: false isBound: false isClosed: false
isConnected: true isBound: true isClosed: false
isConnected: true isBound: true isClosed: true