java - 无法接收来自远程服务器的响应

Question

我正在尝试编写一段代码，允许我连接到远程服务器并接收来自它的响应。远程地址是:www.euref-ip.net:2101

当尝试从网页连接到它时，它工作正常。然而，当我尝试通过我的 java 代码连接时，我无法得到任何响应。这是到目前为止我的代码:

public class Client implements Runnable{
private String nServer = "";
private int nPort = 0;

public Client(String server, int port){
    this.nServer = server;
    this.nPort = port;
}

@Override
public void run() {
    try {
        SocketAddress sockaddr = new InetSocketAddress(nServer, nPort);
        Socket s = new Socket();
        s.connect(sockaddr, 10 * 1000);
        if (s.isConnected()) {
            s.setSoTimeout(20 * 1000);
            DataOutputStream out = new DataOutputStream (s.getOutputStream());
            DataInputStream in = new DataInputStream (s.getInputStream());
            while (true) {
                // send a message to the server
                String requestmsg = "GET / HTTP/1.0\r\n";
                requestmsg += "User-Agent: Client v1\r\n";
                requestmsg += "Accept: */* \r\n";
                requestmsg += "Connection: keep alive\r\n";
                out.write(requestmsg.getBytes());
                out.flush();

                // receive a response 
                int ln = in.available();
                byte [] bytes  = new byte [ln];
                in.read(bytes);
                System.out.println(new String(bytes) + "\n");
                Thread.sleep(2000);
            }
        }
    } 
    catch (UnknownHostException ex) {System.out.println(ex);} 
    catch (IOException ex) {System.out.println(ex);} 
    catch (InterruptedException ex) {System.out.println(ex);}
}}

现在 ln 变量始终为 0，并且我正在读取空响应。我究竟做错了什么？有什么建议么？任何帮助，将不胜感激。

Answer 1

您的 HTTP 请求不完整，您需要在末尾添加一个额外的空行，指示 header 部分的结尾，这也是请求的结尾。

试试这个:

String requestmsg = "GET / HTTP/1.0\r\n";
...
requestmsg += "Connection: keep alive\r\n";
requestmsg += "\r\n";