Java通過TCP套接字從隊列或堆棧發送對象

Question

我想使用TCP在客戶端/服務器之間發送/接收12個對象。 對象是唯一的，但順序始終相同。 例如：客戶端始終以發送“對象1”開始，服務器始終以“對象2”進行響應。 如何設置隊列或堆棧來執行此操作，並僅使用Java標准庫來同步對象的發送/接收？ 我已經處理了下面的代碼（來自1個程序包的3個類文件），但它不起作用（文件結尾錯誤），但它顯示了我的工作能力：

import java.net.*;
import java.io.*;

class SimpleClient {
    public static void main(String args[]){
        int counter = 0;
        try{
            Socket s = new Socket("localhost",2002);
            OutputStream os = s.getOutputStream();
            ObjectOutputStream oos = new ObjectOutputStream(os);
            testobject to = new testobject(1,"object 1","field1","field2","field3","field4");
            System.out.println("sending object 1"); //debug
            oos.writeObject(to);
            //Socket ss = s.accept();
            InputStream is = s.getInputStream();
            ObjectInputStream ois = new ObjectInputStream(is);
            testobject too = (testobject)ois.readObject();
            while (counter != 2) {
                while ( too.value != 3 ) {
                    if (to==null) {
                        System.out.println("object is null!");
                    } else if (to.value==1){
                        System.out.println("receiving object 2"); //debug
                        System.out.println(to.id);
                        os = s.getOutputStream();
                        oos = new ObjectOutputStream(os);
                        testobject to0 = new testobject(2,"object 3","field1","field2","field3","field4");
                        oos.writeObject(to0);
                        System.out.println("object 3 sent!");
                    } else if (to.value==2){
                        System.out.println("receiving object 4"); //debug
                        System.out.println(to.id);
                        os = s.getOutputStream();
                        oos = new ObjectOutputStream(os);
                        testobject to0 = new testobject(3,"object 5","field1","field2","field3","field4");
                        oos.writeObject(to0);
                        System.out.println("sending object 5");
                    }
                }
                is.close();
                s.close();
                //System.out.println((String)ois.readObject());
                counter = counter + 1;
            }
            oos.close();
            os.close();
            s.close();
        } catch(Exception e) {
            System.out.println(e);
        }
    }
}

class SimpleServer {
    public static void main(String args[]) {
        int port = 2002;
        int counter = 0;
        try {
            ServerSocket ss = new ServerSocket(port);
            while (counter != 1) {
                Socket s = ss.accept();
                InputStream is = s.getInputStream();
                ObjectInputStream ois = new ObjectInputStream(is);
                testobject to = (testobject)ois.readObject();
                while ( to.value != 1 ) {
                    if (to==null) {
                        System.out.println("object is null!");
                    } else if (to.value==1){
                        System.out.println("receiving object 1"); //debug
                        System.out.println(to.id);
                        OutputStream os = s.getOutputStream();
                        ObjectOutputStream oos = new ObjectOutputStream(os);
                        testobject to0 = new testobject(2,"object 2","field1","field2","field3","field4");
                        oos.writeObject(to0);
                        System.out.println("sending object 2");
                    } else if (to.value==2){
                        System.out.println("receiving object 3"); //debug
                        System.out.println(to.id);
                        OutputStream os = s.getOutputStream();
                        ObjectOutputStream oos = new ObjectOutputStream(os);
                        testobject to0 = new testobject(4,"object 4","field1","field2","field3","field4");
                        oos.writeObject(to0);
                        System.out.println("sending object 4");
                    }
                }
                is.close();
                s.close();
                counter = counter + 1;
            }
            ss.close();
        } catch(Exception e) {
            System.out.println(e);
        }
    }
}

class testobject implements Serializable {
    int value;
    String id;
    String field1;
    String field2;
    String field3;
    String field4;
    public testobject(int v, String s, String s1, String s2, String s3, String s4) {
        this.value=v;
        this.id=s;
        this.field1 = s1;
        this.field2 = s2;
        this.field3 = s3;
        this.field4 = s4;
    }
}

Answer 1

您代碼中的EOFException

問題似乎出在您的while (to.value != 1) 。 服務器接收到第一個值為1的對象。它根本不執行while循環，而是立即關閉套接字。 因此，當客戶端嘗試從該套接字的輸入流創建ObjectInputStream ，它將遇到一個封閉的連接，在該連接處它會期望有一個對象流標頭。 因此EOFException 。

進行對話

實現對話的最簡單方法是完全避免循環。 畢竟，您需要執行循環，然后在循環內進行區分大小寫，以在每次遍歷中執行特殊代碼。 您也可以編寫一個線性程序，並在需要時將通用代碼分解為方法調用，盡管您的示例幾乎沒有通用代碼。

class SimpleClient {
    public static void main(String args[]) throws Exception {

        // Connection setup
        Socket s = new Socket("localhost",2002);
        OutputStream os = s.getOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(os);
        InputStream is = s.getInputStream();
        ObjectInputStream ois = new ObjectInputStream(is);
        testobject to;

        // Conversation

        System.out.println("sending object 1");
        to = new testobject(1,"object 1","field1","field2","field3","field4");
        oos.writeObject(to);

        System.out.println("receiving object 2");
        to = (testobject)ois.readObject();
        System.out.println(to.id);

        System.out.println("sending object 3");
        to = new testobject(2,"object 3","field1","field2","field3","field4");
        oos.writeObject(to);

        System.out.println("receiving object 4");
        to = (testobject)ois.readObject();
        System.out.println(to.id);

        // Connection shutdown
        ois.close();
        oos.close();
        s.close();
    }
}

class SimpleServer {
    public static void main(String args[]) throws Exception {

        // Connection setup
        ServerSocket ss = new ServerSocket(2002);
        Socket s = ss.accept(); // only handle a single connection
        ss.close(); // so we can immediately stop listening for more
        OutputStream os = s.getOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(os);
        InputStream is = s.getInputStream();
        ObjectInputStream ois = new ObjectInputStream(is);
        testobject to;

        // Conversation

        System.out.println("receiving object 1");
        to = (testobject)ois.readObject();
        System.out.println(to.id);

        System.out.println("sending object 2");
        to = new testobject(2,"object 2","field1","field2","field3","field4");
        oos.writeObject(to);

        System.out.println("receiving object 3");
        to = (testobject)ois.readObject();
        System.out.println(to.id);

        System.out.println("sending object 4");
        to = new testobject(4,"object 4","field1","field2","field3","field4");
        oos.writeObject(to);

        // Connection shutdown
        ois.close();
        oos.close();
        s.close();
    }
}

發送和接收隊列

如果您真的想從隊列中發送內容，則只需對其進行迭代。

import java.net.*;
import java.io.*;
import java.util.*;

class SimpleClient {
    public static void main(String args[]) throws Exception {

        // Preparing the queues
        List<testobject> sendQueue = Arrays.asList(
            new testobject(1,"object 1","field1","field2","field3","field4"),
            new testobject(2,"object 3","field1","field2","field3","field4"));
        List<testobject> receiveQueue = new ArrayList<testobject>();

        // Connection setup
        Socket s = new Socket("localhost",2002);
        OutputStream os = s.getOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(os);
        InputStream is = s.getInputStream();
        ObjectInputStream ois = new ObjectInputStream(is);
        testobject to;

        // Conversation, we start by sending
        for (testobject toSend: sendQueue) {
            System.out.println("Sending " + toSend.id);
            oos.writeObject(toSend);
            testobject received = (testobject)ois.readObject();
            System.out.println("Received " + received.id);
            receiveQueue.add(received);
        }

        // Connection shutdown
        ois.close();
        oos.close();
        s.close();
    }
}

class SimpleServer {
    public static void main(String args[]) throws Exception {

        // Preparing the queues
        List<testobject> sendQueue = Arrays.asList(
            new testobject(2,"object 2","field1","field2","field3","field4"),
            new testobject(4,"object 4","field1","field2","field3","field4"));
        List<testobject> receiveQueue = new ArrayList<testobject>();

        // Connection setup
        ServerSocket ss = new ServerSocket(2002);
        Socket s = ss.accept(); // only handle a single connection
        ss.close(); // so we can immediately stop listening for more
        OutputStream os = s.getOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(os);
        InputStream is = s.getInputStream();
        ObjectInputStream ois = new ObjectInputStream(is);
        testobject to;

        // Conversation, we start by receiving
        for (testobject toSend: sendQueue) {
            testobject received = (testobject)ois.readObject();
            System.out.println("Received " + received.id);
            receiveQueue.add(received);
            System.out.println("Sending " + toSend.id);
            oos.writeObject(toSend);
        }

        // Connection shutdown
        ois.close();
        oos.close();
        s.close();
    }
}

但是，由於在這種情況下，所有數據都是預先知道的，因此您可以不進行交錯處理，而是通過使用單獨的線程來接收數據，而在兩端立即發送所有數據，從而節省一些網絡往返時間。 但是，與您的示例相距甚遠，因此我將不包含代碼。