Java中socket使用getInputStream()阻塞问题怎么解决

2023-06-22 01:58

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这篇文章主要介绍“Java中socket使用getInputStream()阻塞问题怎么解决”，在日常操作中，相信很多人在Java中socket使用getInputStream()阻塞问题怎么解决问题上存在疑惑，小编查阅了各式资料，整理出简单好用的操作方法，希望对大家解答”Java中socket使用getInputStream()阻塞问题怎么解决”的疑惑有所帮助！接下来，请跟着小编一起来学习吧！

socket使用getInputStream()阻塞

今天用socket进行编程练习时，发现程序到了getInputStream(）这里就进行不下去了

Socket socket = new Socket("127.0.0.1", 800);ObjectInputStream reader = new ObjectInputStream(socket.getInputStream());System.out.println("a");ObjectOutputStream writer = new ObjectOutputStream(socket.getOutputStream());

就这样的一个测试代码，a不会打印出来

后来发现是getInputStream(）会一直阻塞在那里阻塞

我把两行代码调了一下就好了，还不太清楚原因，先记下来

Socket socket = new Socket("127.0.0.1", 800);ObjectOutputStream writer = new ObjectOutputStream(socket.getOutputStream());System.out.println("a");ObjectInputStream reader = new ObjectInputStream(socket.getInputStream());

用线程解决Socket的getInputStream阻塞

1.背景

在Socket通信中，当我们希望传输对象时，往往会用到输入/输出对象流。

ObjectInputStream in=new ObjectInputStream(socket.getInputStream());ObjectOutputStream out=new ObjectOutputStream(socket.getOutputStream());

2.问题

当程序调用socket.getInputStream()程序被被卡住。

3.原因

socket.getInputStream()方法会导致程序阻塞，直到inputStream收到对方发过来的报文消息，程序才会继续往下执行。

public ObjectInputStream(InputStream in) throws IOException的官方API显示：
Creates an ObjectInputStream that reads from the specified InputStream. A serialization stream header is read from the stream and verified. This constructor will block until the corresponding ObjectOutputStream has written and flushed the header. [1]

4.解决办法

用线程的方式处理输入流。以下为示例代码：

//===============客户端代码 SocketClient.java=====================

import java.io.IOException;import java.io.ObjectInputStream;import java.io.ObjectOutputStream;import java.net.Socket;import java.net.UnknownHostException;  public class SocketClient {private Socket socket;private ObjectOutputStream out;private ObjectInputStream in;public SocketClient(){try {socket=new Socket("localhost",8081);out=new ObjectOutputStream(socket.getOutputStream());ReadThread readThread=new ReadThread();readThread.start();} catch (UnknownHostException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}}public void sendMessage(String msg){System.out.println("send message:"+msg);try {out.writeObject(msg);out.flush();} catch (IOException e) {e.printStackTrace();}}class ReadThread extends Thread{boolean runFlag=true;public void run(){try {in=new ObjectInputStream(socket.getInputStream());} catch (IOException e1) {e1.printStackTrace();}while(runFlag){if(socket.isClosed()){return;}try {Object obj=in.readObject();if(obj instanceof String){System.out.println("Client recive:"+obj);}} catch (IOException e) {e.printStackTrace();} catch (ClassNotFoundException e) {e.printStackTrace();}}}public void exit(){runFlag=false;}}public static void main(String[] args) {SocketClient socketClient=new SocketClient();System.out.println("build socketClient");try {Thread.sleep(1000);} catch (InterruptedException e) {e.printStackTrace();}socketClient.sendMessage("Hello first.");try {Thread.sleep(1000);} catch (InterruptedException e) {e.printStackTrace();}socketClient.sendMessage("Hello second.");} }

//============服务器端代码 SocketService.java===========

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.Date; public class SocketService {ServerSocket serverSocket;public SocketService(){try {serverSocket=new ServerSocket(8081);while(true){Socket socket=serverSocket.accept();SocketServiceThread sst=new SocketServiceThread(socket);sst.start();}} catch (IOException e) {e.printStackTrace();}}class SocketServiceThread extends Thread{Socket socket;ObjectInputStream in;ObjectOutputStream out;boolean runFlag=true;public SocketServiceThread(Socket socket){if(null==socket){runFlag=false;return;}this.socket=socket;try {out=new ObjectOutputStream(socket.getOutputStream());} catch (IOException e) {e.printStackTrace();}}public void run(){if(null==socket){System.out.println("socket is null");return;}try {in=new ObjectInputStream(socket.getInputStream());while(runFlag){if(socket.isClosed()){System.out.println("socket is closed");return;}try {String obj=(String)in.readObject();if(obj instanceof String){System.out.println("Server recive:"+obj);Date date=new Date();out.writeObject("["+date+"]"+obj);out.flush();}else{System.out.println("Server recive:"+obj);}} catch (ClassNotFoundException e) {e.printStackTrace();}catch (SocketException e){e.printStackTrace();return;}catch (IOException e){e.printStackTrace();}}} catch (IOException e1) {e1.printStackTrace();return;} catch (Exception e){return;}}public void exit(){runFlag=false;}}public static void main(String[] args) {System.out.println("===============start service===============");new SocketService();} }