ObjectInputStream（socket.getInputStream（））; 不起作用

Question

我正在编程一个类以与服务器进行通信，但是当它尝试在inputstream的帮助下构造ObjectInputStream时，程序将冻结。没有异常，程序仍在运行，但挂在试图构造ObjectInputstream的行中。

这是我的问题所在的方法的代码：

@Override
public void connect(String ip, int port) throws UnknownHostException, IOException {
    Socket socket = new Socket(ip, port);
    out = new ObjectOutputStream(socket.getOutputStream());
    InputStream is = socket.getInputStream();
    in = new ObjectInputStream(is);
}

这是整个类的代码：

package Client;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;


public class MessageStreamerImpl implements MessageStreamer {
    ObjectOutputStream out;
    ObjectInputStream in;

    public MessageStreamerImpl(String ip, int port) throws UnknownHostException, IOException{
        connect(ip, port);
    }

    public MessageStreamerImpl(){
    }

    @Override
    public void send(Object message) throws IOException {
        if(out == null) throw new IOException();
        out.writeObject(message);
        out.flush();
    }

    @Override
    public Object receive() throws IOException{
        try {
            return in.readObject();
        } catch (ClassNotFoundException e) {
            throw new IOException();
        }
    }

    @Override
    public void connect(String ip, int port) throws UnknownHostException, IOException {
        Socket socket = new Socket(ip, port);
        out = new ObjectOutputStream(socket.getOutputStream());
        InputStream is = socket.getInputStream();
        in = new ObjectInputStream(is);
    }

}

在查看Google时，我发现了这一点：http : //www.coderanch.com/t/232944/threads/java/Socket-
getInputStream-block
。但是我仍然不知道如何解决该问题，因为我的ObjectOutputStream构造函数在ObjectInputStream的构造函数之前。

这是我的服务器代码，也许会有所帮助;）

package Server;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketException;
import java.util.ArrayList;

public class Server {
    ArrayList<Socket> clients = new ArrayList<Socket>();

    public Server(int port){
        try {
            ServerSocket mySocket = new ServerSocket(port);
            waitForClients(mySocket);
        } catch (IOException e) {
            System.out.println("Unable to start.");
            e.printStackTrace();
        }
    }

    private void waitForClients(ServerSocket mySocket) {
        while(true){
            try {
                System.out.println("Ready to receive");
                Socket client = mySocket.accept();
                clients.add(client);
                System.out.println(client.getInetAddress().getHostAddress()+" connected to the Server");
                Thread t = new Thread(new ClientHandler(client));
                t.start();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }

    public void shareToAll(Object objectToSchare){
        for(Socket client:clients){
            ObjectOutputStream oos;
            try {
                oos = new ObjectOutputStream(client.getOutputStream());
                oos.writeObject(objectToSchare);
                oos.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }

    private class ClientHandler implements Runnable{
        Socket clientSocket;

        public ClientHandler(Socket clientSocket){
            this.clientSocket = clientSocket;
        }
        @Override
        public void run() {
            try {
                ObjectInputStream ois = new ObjectInputStream(clientSocket.getInputStream());
                while(true){
                    try {
                        ois.readObject();

                    } catch (ClassNotFoundException | IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }
            }catch(SocketException e){
                System.out.println(clientSocket.getInetAddress().getHostAddress()+" disconnected from the Server");
                clients.remove(clientSocket);
            }catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
}

感谢您的帮助，我发现了问题。它是在服务器类上，看起来像这样：

package Server;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketException;
import java.util.ArrayList;

public class Server {
    ArrayList<ObjectOutputStream> clientstreams = new ArrayList<ObjectOutputStream>();

    public Server(int port){
        try {
            ServerSocket mySocket = new ServerSocket(port);
            waitForClients(mySocket);
        } catch (IOException e) {
            System.out.println("Unable to start.");
            e.printStackTrace();
        }
    }

    private void waitForClients(ServerSocket mySocket) {
        while(true){
            try {
                System.out.println("Ready to receive");
                Socket client = mySocket.accept();
                clientstreams.add(new ObjectOutputStream(client.getOutputStream()));
                System.out.println(client.getInetAddress().getHostAddress()+" connected to the Server");
                Thread t = new Thread(new ClientHandler(client));
                t.start();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }

    public void shareToAll(Object objectToSchare){
        for(ObjectOutputStream stream:clientstreams){
            try {
                stream.writeObject(objectToSchare);
                stream.flush();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }

    private class ClientHandler implements Runnable{
        Socket clientSocket;

        public ClientHandler(Socket clientSocket){
            this.clientSocket = clientSocket;
        }
        @Override
        public void run() {
            try {
                ObjectInputStream ois = new ObjectInputStream(clientSocket.getInputStream());
                while(true){
                    try {
                        ois.readObject();

                    } catch (ClassNotFoundException | IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }
            }catch(SocketException e){
                System.out.println(clientSocket.getInetAddress().getHostAddress()+" disconnected from the Server");
                clientstreams.remove(clientSocket);
            }catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }   
}

您在方法waitForClients（）上看到的更改最多，但是我也更改了ArrayList和shareToAll方法的概念。

Answer 1

ObjectInputStream构造函数从给定的InputStream读取数据。为了使它起作用， 必须
在构造后立即刷新ObjectOutputStream（以写入初始标头），然后再尝试打开ObjectInputStream。同样，如果您希望每个连接发送多个对象，则必须打开一次ObjectOutputStream并将其用于套接字的生命周期（例如您的shareToAll方法）。