java - 当我尝试发送请求时出现未知主机异常

Question

我正在尝试检查是否有多个端口打开，以及 80 端口是否打开 - 发送 http 请求，然后在控制台中显示结果。每个端口都在自己的线程中进行检查。

我发送这样的请求

public static void send(Socket sock, String host) throws IOException{
    PrintWriter pw = new PrintWriter(sock.getOutputStream());
    pw.println("GET / HTTP/1.1");
    pw.println("Host: " + host);
    pw.println("");
    pw.flush();
} 

在类 TCPClient 中，我使用它并以字节形式返回结果，然后将其显示在控制台上。

    try {
        sock = new Socket(host, port);
        System.out.println("port " + port + " is in use");
        // send request
        HttpSender.send(sock, host);
        BufferedReader bf = new BufferedReader(new InputStreamReader(sock.getInputStream()));
        StringBuffer response = new StringBuffer(); 
        String line = "";
        while((line = bf.readLine()) != null) {
          response.append(line);
          response.append('\r');
        }
        bf.close();
        return String.valueOf(response).getBytes(); // in method run I show it
    } catch (SocketException e) {
        return ("port " + port + " is free").getBytes();
    }

我创建线程池用于端口检查。

public class ThreadPool {

private static int MAX_THREADS = 5;
private static String DESTINATION = "http://stackoverflow.com/";
private ExecutorService es = null;

public ThreadPool() {
    es = Executors.newFixedThreadPool(MAX_THREADS);
}

public void perform(int start, int end) throws UnknownHostException {
    for (int i = start; i <= end; i++) {
        Runnable req = new TCPClient(DESTINATION, i);
        es.execute(req);
    }
    es.shutdown();
    while (!es.isTerminated()) {
    }
    ;
    System.out.println("all ports checked!");
}

}

当我将目的地设置为 www.stackoverflow.com 并获得带有文本的文档时，它已永久移动到 http://stackoverflow.com/。当我设置此目的地时 - 我遇到了 UnknownhostException。

问题出在哪里？

Answer 1

您是否尝试过private static String DESTINATION = "stackoverflow.com";？字符串 "http://stackoverflow.com" 不是主机名，而是 URL。