java套接字InputStream在客户端和服务器上都挂起/阻塞

大家好

我最近正在开发一个小程序，旨在远程关闭浏览器。 基本程序如下：
服务器端：

创建一个SocketServer以侦听某个特定端口

接受连接并创建相应的套接字对象

从已创建的套接字读取InputStream（在此端口上被阻止 操作）

---

客户端：

创建套接字对象以建立与服务器的连接

通过写入来发送关闭服务器端浏览器的命令 要输出流的字节数

在的InputStream上使用Read（）读取来自服务器的反馈 套接字（在此操作中被阻止）

---

下面的代码：

Server.java

package socket;

import java.io.IOException;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Enumeration;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class Server {

private static ExecutorService es = Executors.newFixedThreadPool(5);

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

    InetAddress targetAddress = null;
    NetworkInterface ni = NetworkInterface.getByName("eth2");
    System.out.println(ni);
    Enumeration<InetAddress> inetAddresses = ni.getInetAddresses();
    while(inetAddresses.hasMoreElements()) {
        InetAddress inetAddress = inetAddresses.nextElement();
        if(inetAddress.toString().startsWith("/10")) {
            targetAddress = inetAddress;
            break;
        }
    }
    ServerSocket sSocket = new ServerSocket(11111, 0, targetAddress);
    while(true) {
        System.out.println("Server is running...");
        Socket client = sSocket.accept();
        System.out.println("Client at: " + client.getRemoteSocketAddress());
        es.execute(new ClientRequest(client));
    }

}
}

package socket;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;

public class ClientRequest implements Runnable {

private Socket client;

public ClientRequest(Socket client) {
    this.client = client;
}

@Override
public void run() {

    try {
        System.out.println("Handled by: " + Thread.currentThread().getName());
        // get input/output streams for client socket
        InputStream cis = client.getInputStream();
        OutputStream cos = client.getOutputStream();

        // buffer size : 1024 ?
        byte[] buffer = new byte[1024];
        int recvSize;
        int totalRecvSize = 0;
        while(-1 != (recvSize = cis.read(buffer, totalRecvSize, 1024 - totalRecvSize))) {
            totalRecvSize += recvSize;
        }

        String command = new String(buffer, "utf-8");
        System.out.println("Command from client: " + command);

        String commandNative = CommandMap.getNativeCommand(command.trim());
        if(null != commandNative) {
            Process np = Runtime.getRuntime().exec(commandNative);
            InputStream is = np.getInputStream();
            byte[] bufferProcess = new byte[1024];
            int bytesRead;
            int totalBytesRead = 0;
            while(-1 != (bytesRead = is.read(bufferProcess, totalBytesRead, 1024 - totalBytesRead))) {
                totalBytesRead += bytesRead;
            }
            // give feed back of process output
            cos.write(bufferProcess);

            // close process input stream
            is.close();
        } 
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if(null != client) {
            try {
                client.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

package socket;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.net.UnknownHostException;
import java.nio.charset.Charset;

public class Client {

private static final int BUF_SIZE = 1024;

// feedback message size will not exceed 1024 bytes
private static final byte[] BUFFER = new byte[BUF_SIZE];

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

    Socket socket = new Socket("10.117.37.176", 11111);
    System.out.println("Connected to Server...");
    OutputStream os = socket.getOutputStream();
    InputStream is = socket.getInputStream();

    String command = "kill ie";
    byte[] commandBytes = command.getBytes(Charset.forName("utf-8"));

    System.out.println("Send: " + command);
    os.write(commandBytes);
    System.out.println("After send: " + command);

    int totalRecv = 0;
    int recvSize;

    while(-1 != (recvSize = is.read(BUFFER, totalRecv, BUF_SIZE - totalRecv))) {
        totalRecv += recvSize;
    }

    String feedback = new String(BUFFER, "utf-8");
    System.out.println("Feedback: " + feedback);

    socket.close();
}
}

最后，Client.java

package socket;

import java.io.IOException;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Enumeration;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class Server {

private static ExecutorService es = Executors.newFixedThreadPool(5);

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

    InetAddress targetAddress = null;
    NetworkInterface ni = NetworkInterface.getByName("eth2");
    System.out.println(ni);
    Enumeration<InetAddress> inetAddresses = ni.getInetAddresses();
    while(inetAddresses.hasMoreElements()) {
        InetAddress inetAddress = inetAddresses.nextElement();
        if(inetAddress.toString().startsWith("/10")) {
            targetAddress = inetAddress;
            break;
        }
    }
    ServerSocket sSocket = new ServerSocket(11111, 0, targetAddress);
    while(true) {
        System.out.println("Server is running...");
        Socket client = sSocket.accept();
        System.out.println("Client at: " + client.getRemoteSocketAddress());
        es.execute(new ClientRequest(client));
    }

}
}

package socket;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;

public class ClientRequest implements Runnable {

private Socket client;

public ClientRequest(Socket client) {
    this.client = client;
}

@Override
public void run() {

    try {
        System.out.println("Handled by: " + Thread.currentThread().getName());
        // get input/output streams for client socket
        InputStream cis = client.getInputStream();
        OutputStream cos = client.getOutputStream();

        // buffer size : 1024 ?
        byte[] buffer = new byte[1024];
        int recvSize;
        int totalRecvSize = 0;
        while(-1 != (recvSize = cis.read(buffer, totalRecvSize, 1024 - totalRecvSize))) {
            totalRecvSize += recvSize;
        }

        String command = new String(buffer, "utf-8");
        System.out.println("Command from client: " + command);

        String commandNative = CommandMap.getNativeCommand(command.trim());
        if(null != commandNative) {
            Process np = Runtime.getRuntime().exec(commandNative);
            InputStream is = np.getInputStream();
            byte[] bufferProcess = new byte[1024];
            int bytesRead;
            int totalBytesRead = 0;
            while(-1 != (bytesRead = is.read(bufferProcess, totalBytesRead, 1024 - totalBytesRead))) {
                totalBytesRead += bytesRead;
            }
            // give feed back of process output
            cos.write(bufferProcess);

            // close process input stream
            is.close();
        } 
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if(null != client) {
            try {
                client.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

package socket;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.net.UnknownHostException;
import java.nio.charset.Charset;

public class Client {

private static final int BUF_SIZE = 1024;

// feedback message size will not exceed 1024 bytes
private static final byte[] BUFFER = new byte[BUF_SIZE];

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

    Socket socket = new Socket("10.117.37.176", 11111);
    System.out.println("Connected to Server...");
    OutputStream os = socket.getOutputStream();
    InputStream is = socket.getInputStream();

    String command = "kill ie";
    byte[] commandBytes = command.getBytes(Charset.forName("utf-8"));

    System.out.println("Send: " + command);
    os.write(commandBytes);
    System.out.println("After send: " + command);

    int totalRecv = 0;
    int recvSize;

    while(-1 != (recvSize = is.read(BUFFER, totalRecv, BUF_SIZE - totalRecv))) {
        totalRecv += recvSize;
    }

    String feedback = new String(BUFFER, "utf-8");
    System.out.println("Feedback: " + feedback);

    socket.close();
}
}

要重申这些问题：

• 服务器端无法通过调用read（buffer， 套接字的InputStream对象上的偏移量，len）。它会阻塞
• 客户端无法通过调用read（buffer， 其套接字的InputStream对象上的偏移量，len）。它会阻塞
• 但当我在中注释掉反馈读取操作时 java，服务器和客户端都能正常工作

---

我想知道这些代码中隐藏的原因是什么？

---

希望有人能帮助我，谢谢

您的套接字读取代码正在读取，直到EOF。在关闭插座之前，您不会收到EOF。因此，您的代码永远不会继续

如果只想在套接字连接上发送一个命令，则在写入命令后关闭OutputStream（使用

socket.shutdownOutput（）

）

---

如果您想在一个套接字连接上发送多个命令，那么您需要找到一种方法来界定每个命令（）。

您正在读取两端的EOS，这是一个糟糕的选择，因为您无法“发送”EOS而不失去在同一连接上发送更多数据的能力。您需要重新设计应用程序协议，以便可以一次读取命令，而无需关闭连接即可完成。例如，发送行、字长前缀、自描述协议（如XML或Java对象序列化）或任何可以通过DataInputStream读取而不依赖EOFEException的内容。

感谢您的精彩回答！但是仍然存在一个问题，客户端希望获得一些反馈，在我的例子中，反馈应该是本机命令的输出（旨在关闭浏览器）。如果我添加os.close（），当我在InputStream上调用read（）方法时，将抛出一个SocketException，并显示消息“socket closed”，我如何处理这个问题？非常感谢。@destiny1020-你试过我的建议了吗？关闭outputstream独立于关闭inputstream。是的，我已经尝试了您的建议，我在Client.java中的os.write（）之后添加了一行os.close（）。但是当我尝试调用in.read（）方法时有一个例外：socketclosed，可能close底层OutputStream会间接关闭Socket连接？我对此感到困惑。谢谢你的回复！我用自己的close（）方法关闭输出流，实际上应该调用socket.shutdownOutput（），我已经弄明白了。谢谢你的建议，太棒了@destiny1020-啊，很抱歉，我会更新我的答案。我认为直接关闭outputstream是实现这一点的方法。我已经有一段时间没有使用套接字了。谢谢你的建议，我的应用程序确实存在一些设计问题。非常感谢。