JAVA实现SOCKET多客户端通信的案例

一、ServerSocket

1.为了方便调试，先创建一个界面用于显示客户端连接信息

基于javafx包写的一个简单界面！

 javafx.scene.control.TextArea ta = new javafx.scene.control.TextArea();
 @Override
 public void start(Stage primaryStage) throws Exception {
  scene = new Scene(ta,450,200);
  primaryStage.setTitle("SocketServer");
  primaryStage.setScene(scene);
  primaryStage.show();
  pStage = primaryStage;
  new Thread(new MyServer()).start(); //创建线程启动Socket服务
  }

2.启动Socket服务

public class MyServer implements Runnable{
  @Override
  public void run() {
   try{
    java.net.ServerSocket serverSocket = new java.net.ServerSocket(8000);
    ta.appendText("Server started at " + new Date()+"\n");
    while(true){
     Socket socket = serverSocket.accept(); //程序会在这里阻塞，直到等到客户端连接
     clientNumber++;
     /*
     这里就是在界面中输出一些服务器、和连接的客户端信息
      */
     Platform.runLater(()->{
      ta.appendText("Starting thread for client " + clientNumber + " at " +
        new Date() +"\n");
      InetAddress inetAddress = socket.getInetAddress();
      ta.appendText("Client "+clientNumber + "'s host name is" +inetAddress.getHostName()
      +"\n");
      ta.appendText("Client"+clientNumber + "'s IP address is "+ inetAddress.getHostAddress()+"\n");
     });
     /*
     每有一个客户端连接服务器就创建一个线程，进行通信处理
      */
     new Thread(new HandleServer(socket)).start();
     try{
      Thread.sleep(100); //多个客户端连续快速连接服务器时，可能出现问题，这里设置延时
     }catch (InterruptedException e){
      e.printStackTrace();
     }
    }

   }catch (IOException e){
    e.printStackTrace();
   }
  }
 }

这一段代码主要作用就是循环等待客户端连接服务器：

Socket socket = serverSocket.accept();

在写这篇博客时，突然想知道阻塞的原理就去查了一下。。。。

然而并没有看懂。。这个应该涉及到操作系统层面，等之后把操作系统搞明白了在来补充吧。

3.服务器处理类HandleServer

class HandleServer implements Runnable {
  private Socket socket;
  private int name;
  private int toClientID;
  private DataOutputStream outputStream;
  private DataInputStream inputStream;
  public HandleServer(Socket socket){
   this.socket = socket;
   ServerTools.Tools().add(this);
   this.name = clientNumber;
  }
  @Override
  public void run() {
   try{
    inputStream = new DataInputStream(socket.getInputStream());
    outputStream = new DataOutputStream(socket.getOutputStream());
    outputStream.writeUTF("Your ID is:"+clientNumber);
    while (true){
     toClientID = inputStream.readInt();
     String messageGET = inputStream.readUTF();
     int err = ServerTools.Tools().MyWriteUTF(messageGET,toClientID); //MyWriteUTF 是一个自定义方法，serverTools.Tools()是一个工具类，一个静态对象。
     if (err==0){
      outputStream.writeUTF("No have this ID!");
     }
     Platform.runLater(()->{
      ta.appendText(socket.getInetAddress().getHostName()+" Message received from client:" + messageGET +"\n" );
     });
     System.out.println(clientNumber);
    }
   }catch (IOException e){
    clientNumber--;
    System.out.println(clientNumber);
    System.err.println("Client is closed!");
   }

  }

这一块的代码主要就是创建输入输出数据流了

inputStream = new DataInputStream(socket.getInputStream());

outputStream = new DataOutputStream(socket.getOutputStream());

4.一些方法方便ServerTools类实现

  public void MyWriteUTF(String message){
   try {
    outputStream.writeUTF(message);
   } catch (IOException e) {
    ServerTools.Tools().remove(this);
    e.printStackTrace();
   }
  }

  public int getName() {
   return name;
  }

二、ServerTools

1.实现指定服务器ID输出信息的工具

public class ServerTools {

 private static final ServerTools servertools = new ServerTools();
 public static ServerTools Tools(){
  return servertools;
 }

 Vector<MyServerSocket.HandleServer> vector = new Vector<MyServerSocket.HandleServer>();
 public void add(MyServerSocket.HandleServer cs){
  vector.add(cs);
 }
 public void remove(MyServerSocket.HandleServer cs){
  vector.remove(cs);
 }

 public int MyWriteUTF(String message,int target) {
  for (int i = 0; i <= target; i++){
   try {
    if (vector.get(i).getName() == target) {
     MyServerSocket.HandleServer MSSHC = vector.get(i);
     MSSHC.MyWriteUTF(message);
     return 1;
    }
   }catch (ArrayIndexOutOfBoundsException e){
    e.printStackTrace();
    return 0;
   }
  }
  return 0;

 }
}

vector用于保存客户端连接信息

一个粗糙的处理方式，逻辑上缺陷还很严重，主要我好像没找到这样的框架？？？

缺陷：因为服务器要返回客户端的ID让客户端将ID显示到交互界面，所以存在情况客户端多次连接断开后会使返回的ID出现重复

三、ClientSocket

1.同样的先建一个简单的界面用于输出信息和显示信息

第一个编辑框就是 输入要发送指定客户端的ID 例如：1 或 2 这样的？？？

第二个编辑框就是 输入你要发送的信息了，很清楚

下面的就是显示框，嗯！

public class MyClientSocket extends Application {

 private Socket socket;
 private DataOutputStream toServer = null;
 private DataInputStream fromServer = null;
 private String ID;
 private int targetID = 0;
 private TextArea ta;

 @Override
 public void start(Stage primaryStage) throws Exception {
  BorderPane paneForTextField = new BorderPane();
  paneForTextField.setPadding(new Insets(5,5,5,5));
  paneForTextField.setStyle("-fx-border-color: green");
  paneForTextField.setLeft(new Label("Enter a Message:"));

  TextField tf = new TextField();
  tf.setAlignment(Pos.BOTTOM_RIGHT);
  paneForTextField.setCenter(tf);

  BorderPane ID_lable = new BorderPane();
  ID_lable.setPadding(new Insets(5,5,5,5));
  ID_lable.setStyle("-fx-border-color: green");
  ID_lable.setLeft(new Label("Enter a ID for send message:"));

  TextField getId = new TextField();
  getId.setAlignment(Pos.BOTTOM_RIGHT);
  ID_lable.setCenter(getId);
  paneForTextField.setTop(ID_lable);

  BorderPane mainPane = new BorderPane();
  ta = new TextArea();
  mainPane.setCenter(new ScrollPane(ta));
  mainPane.setTop(paneForTextField);

  Scene scene = new Scene(mainPane,450,200);
  primaryStage.setTitle("SocketClient");
  primaryStage.setScene(scene);
  primaryStage.show();

  tf.setOnAction(new EventHandler<ActionEvent>() {
   @Override
   public void handle(ActionEvent event) {
    targetID = Integer.parseInt(getId.getText().trim());
    if (targetID > 0 || targetID!=Integer.parseInt(ID));
    else return;
    try {
     String putMessage = tf.getText().trim();
     toServer.writeInt(targetID);
     toServer.writeUTF(putMessage);
     toServer.flush();
     ta.appendText("PUT message is :"+ putMessage +"\n");
     tf.setText("");
    }catch (IOException ex ){
     System.err.println(ex);
    }
   }
  });

  try{
   socket = new Socket("localhost",8000);
   fromServer = new DataInputStream(socket.getInputStream());
   toServer = new DataOutputStream(socket.getOutputStream());
   ID = fromServer.readUTF();
   paneForTextField.setRight(new Label("Your ID is:"+ID));
   new Thread(new getMessage(socket,fromServer)).start();
  }catch (IOException ex){
   ta.appendText(ex.toString() +"\n");
  }
 }
}

一样的要new一个Socket 去连接服务器，socket()，括号里的就是服务器的IP，和程序的端口号了，这种基于tcp协议的好像都是一个样？？？

2.创建一个线程用于循环获取信息并显示

 class getMessage implements Runnable{
  private Socket socket;
  private DataInputStream formServer;
  public getMessage(Socket socket,DataInputStream formServer){
   this.socket = socket;
   this.formServer = formServer;
  }
  @Override
  public void run() {
   try {
    while (true) {
     String Message = formServer.readUTF();
     try{
      Thread.sleep(100);
     }catch (InterruptedException e) {
      e.printStackTrace();
     }
     ta.appendText("GET message from server is:" + Message + "\n");

    }
   }catch (IOException e){
    System.err.println(e);
   }

  }
 }

很简单了，依旧是输入输出数据流，然后循环等待信息并输出。

3.新建一个TestClient类 这个类 和ClientSocket 一模一样 就是拿来测试的

四、总结

java写socket 是真的简单！！！^_ ^!

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