Question

我对Stack Overflow有点新意，所以如果我做错了什么，请随时告诉我。我还没找到另一篇文章以对我有意义的方式解决这个问题。

所以我的最终目标是用Java编写多线程HTTP代理服务器，但作为第一步，我只是尝试将通过浏览器建立的连接的输入流写入窗口。

这是我的代码：

private static ServerSocket welcomeSocket;
private static Socket connectionSocket;

private static Socket clientSocket;

private static OutputStream clientOutput;
private static InputStream proxyInput;

private static BufferedReader reader;

private static InetSocketAddress clientStream;

public static void main(String[] args) throws IOException, URISyntaxException {

    // Create socket, port 12345, for incoming request
    welcomeSocket = new ServerSocket(12345);
    while(true){
        try(Socket clientSocket = welcomeSocket.accept()){
        BufferedReader reader = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(clientSocket.getOutputStream()));

        Thread t = new Thread(){  
            public void run(){
                System.out.println("running\n");
                try{
                    System.out.println("trying\n");
                    String lineIn;
                    while((lineIn = reader.readLine()) != null){
                        System.out.println("writing\n");
                        writer.write(lineIn);
                        writer.newLine();
                    }
                }
                catch(IOException i){
                    try {                            
                        Logger.getLogger(EECS325_Project1.class.getName()).log(Level.SEVERE, null, i);
                        throw i;
                    } catch (IOException ex) {
                        Logger.getLogger(EECS325_Project1.class.getName()).log(Level.SEVERE, null, ex);
                    }
                }
            }
        };
        t.start();
        }
    }

}

但是，当我在浏览器中访问localhost：12345时，出现以下异常：

     Nov 04, 2015 9:53:44 AM eecs325_project1.EECS325_Project1$1 run
     SEVERE: null
     java.net.SocketException: socket closed
     at java.net.SocketInputStream.socketRead0(Native Method)
     at java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
     at java.net.SocketInputStream.read(SocketInputStream.java:170)
     at java.net.SocketInputStream.read(SocketInputStream.java:141)
     at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:284)
     at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:326)
     at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:178)
     at java.io.InputStreamReader.read(InputStreamReader.java:184)
     at java.io.BufferedReader.fill(BufferedReader.java:161)
     at java.io.BufferedReader.readLine(BufferedReader.java:324)
     at java.io.BufferedReader.readLine(BufferedReader.java:389)
     at eecs325_project1.EECS325_Project1$1.run(EECS325_Project1.java:46)

大多数帖子都说当关闭读取器/写入器，有效关闭套接字时会发生此异常。但是，我决不会关闭阅读器，写入器或套接字。

非常感谢任何帮助！

Answer 1

您的try-with-resources块在Thread执行之前关闭客户端套接字 - 这意味着当线程尝试使用它们时reader和writer引用已关闭的底层流。

解决方案将try-with-resources块移动到线程内部：

final Socket clientSocket = welcomeSocket.accept();
Thread t = new Thread(){  
  @Override public void run(){
    // BufferedReader/Writer close the underlying stream when they
    // are closed, so the socket will be closed when this
    // try-with-resources block finishes.
    try (BufferedReader reader = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())));
         BufferedWriter writer = ...) {
      // Do whatever.
    } catch (IOException e) {
      // Handle the exception.
    }
  }
};
t.start();

这意味着在线程运行之前不会发生结束，更具体地说，在您完成reader和writer的操作之后。

注意：您必须注意确保Socket 始终关闭：如果在创建Thread或创建BufferedReader时出现异常，则不会发生这种情况。这些情况有点粗糙，并涉及一些额外的try / catch / finally块;我宁愿不将这些添加到答案中，因为我认为它们只是模糊了主要想法。

Answer 2

rivate static ServerSocket welcomeSocket;
private static Socket connectionSocket;

private static Socket clientSocket;

private static OutputStream clientOutput;
private static InputStream proxyInput;

private static BufferedReader reader;

private static InetSocketAddress clientStream;

这些数据项中没有一个应该是静态的，与特定客户端（接受的套接字，其上游套接字及其流）相关的数据项应该位于单独的Runnable连接处理程序类中，每个接受的套接字实例化，并创建一个Thread来运行它。

多线程Java代理服务器

2 个答案: