java - 无法刷新 Groovy Socket

Question

我对 java.net.SocketOutputStream 拒绝正确刷新感到沮丧!我一定是忽略了显而易见的事情。在下面的 Groovy 脚本中，我尝试连接到在我的 Galaxy Nexus Android 4.0.2 手机上运行的简单套接字服务器，它在 5 秒超时到期后立即给我一个套接字关闭异常。

SocketClient.groovy

import java.net.*
socket = new Socket()
socket.connect(new InetSocketAddress(InetAddress.getByAddress([172,17,57,21] as byte[]), 58789), 5000)
println "Connected!"
socket.withStreams { input, output ->
    println "Processing ${input.class.name} and ${output.class.name} streams..."
    output.withWriter {
        it << 'echo testing\n\n'; 
        it.flush();
        output.flush()
        def readerThread = Thread.start {
            println "Request written, reading response..."; println input.text
        }
        println "Waiting 5 secs for read to complete."
        readerThread.join(5000)
    }
    println "Stream closed!"
}

我尝试了所有不同的刷新方法，包括直接刷新输出流到使用写入器间接包装和刷新。在流关闭之前，服务器上不会出现任何数据，这会导致套接字关闭，从而导致从套接字读取的任何尝试崩溃。我究竟做错了什么？我也会在下面内联我的 Android 代码。这是启动套接字服务器的简单 Activity 。

MyServer.java

package com.example;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

public class MyServer extends Activity
{
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        RawSocketServer rawSocketServer = new RawSocketServer();
        String port = rawSocketServer.getLocalPort();
        TextView textView = (TextView) this.findViewById(R.id.mainTextView);
        textView.setText("Server bound to port " + port);
        rawSocketServer.start();
    }
}

RawSocketServer.java

package com.example;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

/**
 * Created by IntelliJ IDEA.
 * User: cliff
 * Date: 5/9/12
 * Time: 4:03 PM
 */
public class RawSocketServer {

    public static final int PORT = 0;
    private ServerSocket serverSocket;

    public RawSocketServer() {
        this(PORT);
    }

    public RawSocketServer(int port) {
        try {
            this.serverSocket = new ServerSocket(port);
        } catch (IOException e) {
            e.printStackTrace();
            throw new RuntimeException("server cannot bind to port " + port);
        }
    }

    public void start() {
        new Thread(new Runnable() {
            public void run() {
                go();
            }
        }).start();
    }

    private void go() {
        Socket socket = null;
        while (true) {
            try {
                socket = this.serverSocket.accept();
            } catch (IOException e) {
                e.printStackTrace();
                throw new RuntimeException("cannot accept from server socket" + e);
            }
            BufferedReader reader = null;
            try {
                reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            } catch (IOException e) {
                e.printStackTrace();
                throw new RuntimeException("Could not get input stream from socket. " + e);
            }
            PrintWriter writer = null;
            try {
                writer = new PrintWriter(socket.getOutputStream());
            } catch (IOException e) {
                e.printStackTrace();
                throw new RuntimeException("Could not get output stream from socket. " + e);
            }
            try {
                for (String line = reader.readLine(); line !=null; line = reader.readLine()) {
                    writer.print(line);
                }
            } catch (IOException e) {
                e.printStackTrace();
                throw new RuntimeException("Error reading/writing from/to socket. " + e);
            }
        }
    }

    public String getLocalPort() {
        return "" + serverSocket.getLocalPort();
    }
}

Answer 1

我想知道......你那里有“它<<'回声测试'”。在 Writer 上使用它意味着没有写入行尾。由于您的服务器使用 readLine，因此它需要一个行结尾。因此，数据可能到达，但 readLine 尚未完成，因为它等待行尾。修复方法是执行“it << 'echotesting\n'”或“it<<'echotesting'<<'\n'”。

现在我不太了解Android API，但是你的服务器可能在“writer.print(line);”中遇到同样的问题，因为我认为用readLine读取的行不包含行结尾不再了。不过既然没有再读，目前应该没有问题。