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socket的ObjectOutputStream发送一些对象，然后通过socket't ObjectInputStream读取它。问题是ObjectOutputStream writeObject方法无法正常工作（或者我可能做错了......）。我正在用同样的方法写作和阅读。

java -version：

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：

server test.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Serializable）

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。请帮我。

Answer 1

您是否希望客户端和服务器都使用相同的输入流？我希望客户端和服务器位于不同的线程上（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，客户端输入流将映射到服务器输出流。以下是一个很好的例子：baeldung.com/a-guide-to-java-sockets（注意：这并不意味着支持Baeldun。但这个例子很好。）