将对象写入 ObjectOutputStream 不起作用

Question

我正在编写（测试）一个简单的客户端-服务器应用程序，我需要通过套接字的 ObjectOutputStream 发送一些对象，然后通过套接字的 ObjectInputStream 读取它。问题是 ObjectOutputStream writeObject 方法不能正常工作（或者我做错了什么......）。我正在用同样的方法写作和阅读。

java-版本：

java version "1.8.0_201"
Java(TM) SE Runtime Environment (build 1.8.0_201-b09)
Java HotSpot(TM) 64-Bit Server VM (build 25.201-b09, mixed mode)

这是我的代码：

ServerTest.java

ExecutorService tp = Executors.newFixedThreadPool(2);
public ServerTest(String info) {
    System.out.println("SERVER TEST HAVE BEEN STARTED FROM " + info);
    try {
        System.out.println("Starting server ...");
        tp.submit(new ServerTask());
        System.out.println("Server started ...");
        Thread.sleep(1000);
        System.out.println("Starting client ...");
        tp.submit(new Client(new Socket("localhost", 3333)));
        System.out.println("Client started at localhost on port 3333 ...");
    } catch (IOException | InterruptedException ex) {
        Logger.getLogger(ServerTest.class.getName()).log(Level.SEVERE, null, ex);
    } 
}
public static void main(String[] args) {
    try {
        new ServerTest("SERVER TEST MAIN STATIC METHOD");
        Thread.sleep(100000);
    } catch (InterruptedException ex) {
        Logger.getLogger(ServerTest.class.getName()).log(Level.SEVERE, null, ex);
    }
}

ClientTask.java（实现 Runnable）

private Socket socket;
private ObjectOutputStream oos;
private ObjectInputStream ois;    
public ClientTask(Socket socket) {
    System.out.println("CLIENT TASK SOCKET : " + socket);
    this.socket = socket;
    try {
        oos = new ObjectOutputStream(socket.getOutputStream());
        oos.flush();
        ois = new ObjectInputStream(socket.getInputStream());
    } catch (IOException ex) {
        Logger.getLogger(ClientTask.class.getName()).log(Level.SEVERE, null, ex);
    }
}

@Override
public void run() {
    System.out.println("client task running ...");
    for (int i = 0; i < 1; i++) {
        try {
            Thread.sleep(1000);
            SimpleObject so = new SimpleObject(100, "test_str");
            System.out.println("Trying to serialize object into output stream...");
            System.out.println("Object to be written " + so.toString());
            oos.writeObject(so);
            oos.flush();
            System.out.println("Check if the object had been serialized properly ...");
            System.out.println("Bytes in stream : " + ois.available());
            if (ois.available() <= 0) {
                System.out.println("Object had not been serialized ...");
                continue;
            }
            System.out.println("Trying to deserialize object from input stream ...");
            SimpleObject desObj = (SimpleObject) ois.readObject();
            System.out.println("Read object: " + desObj.toString());
            System.out.println("Aborting from method ...");
        } catch (InterruptedException ex) {
            Logger.getLogger(ClientTask.class.getName()).log(Level.SEVERE, null, ex);
        } catch (IOException ex) {
            Logger.getLogger(ClientTask.class.getName()).log(Level.SEVERE, null, ex);
        } catch (ClassNotFoundException ex) {
            Logger.getLogger(ClientTask.class.getName()).log(Level.SEVERE, null, ex);
        } finally {
            try {
                ois.close();
                oos.close();
            } catch (IOException ex) {
                Logger.getLogger(ClientTask.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
    }
    System.out.println("Exiting client task ...");
}

ServerTask.java（实现 Runnable）

ExecutorService tp = Executors.newFixedThreadPool(10);
@Override
public void run() {
    System.out.println("Server task run start ...");
    try {
        ServerSocket ss = new ServerSocket(3333);
        for (;;) {
            System.out.println("Server socket start ...");
            Socket s = ss.accept();
            s.setSoTimeout(0);
            System.out.println("Connection: " + s.getInetAddress().toString() + " " + s.getPort());
            System.out.println("Starting client task ...");
            tp.submit(new ClientTask(s));
            System.out.println("Client task started ...");
            System.out.println("Server socket end ...");
        }
    } catch (IOException ex) {
        ex.printStackTrace();
    }
    System.out.println("Server task run end ...");
}

Client.java（实现 Runnable）

private Socket socket;
private ObjectOutputStream oos;
private ObjectInputStream ois;
public Client(Socket socket) {
    System.out.println("CLIENT SOCKET : " + socket.toString());
    this.socket = socket;
    try {
        oos = new ObjectOutputStream(socket.getOutputStream());
        oos.flush();
        ois = new ObjectInputStream(socket.getInputStream());
    } catch (IOException ex) {
        Logger.getLogger(ClientTask.class.getName()).log(Level.SEVERE, null, ex);
    }
}

@Override
public void run() {
    for (int i = 0; i < 10; i++) {
        //System.out.println("client running ...");
        try {
            Thread.sleep(1000);
        } catch (InterruptedException ex) {
            Logger.getLogger(Client.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
}

SimpleObject.java（实现可序列化）

private static final long serialVersionUID = 4L;
private Integer integer;
private String string;
public SimpleObject(Integer integer, String string) {
    this.integer = integer;
    this.string = string;
}
//getters,setters, toString method ...

输出是

run:
SERVER TEST HAVE BEEN STARTED FROM SERVER TEST MAIN STATIC METHOD
Starting server ...
Server started ...
Server task run start ...
Server socket start ...
Starting client ...
CLIENT SOCKET : Socket[addr=localhost/127.0.0.1,port=3333,localport=57703]
Connection: /127.0.0.1 57703
Starting client task ...
CLIENT TASK SOCKET : Socket[addr=/127.0.0.1,port=57703,localport=3333]
Client started at localhost on port 3333 ...
Client task started ...
Server socket end ...
Server socket start ...
client task running ...
Trying to serialize object into output stream...
Object to be written SimpleObject{integer=100, string=test_str}
Check if the object had been serialized properly ...
Bytes in stream : 0
Object had not been serialized ...
Exiting client task ...

这是一个简单的应用程序，但它不起作用...我不明白为什么。请帮助我。

Answer 1

您是否希望客户端和服务器使用相同的输入流？我希望客户端和服务器在不同的线程上（或者在不同的 java 进程中），在这种情况下，客户端输出流将映射到服务器输入流，而客户端输入流将映射到服务器输出溪流。这是一个很好的例子：baeldung。com/a-guide-to-java-sockets（注意：这并不是要支持 Baeldun。但这个例子很好。）

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