我有这个代码，如果它与服务器窗口断开连接，我需要在标签中显示“已断开连接”。我的问题是我不知道如何检测我是否断开连接。我想检测连接状态，即使没有连接或没有来自另一端的触发器。
// Copyright 2012
// Android Remote Desktop Server Ver. 1.0
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.net.*;
import java.util.Random;
public class ServerWindow implements ActionListener{
private RemoteDataServer server;
private Thread sThread; //server thread
private static final int WINDOW_HEIGHT = 200;
private static final int WINDOW_WIDTH = 350;
private String ipAddress;
private JFrame window = new JFrame("Remote Control for Android");
private JLabel addressLabel = new JLabel("");
private JLabel portLabel = new JLabel("Android Remote Control Port: ");
private JTextArea[] buffers = new JTextArea[3];
private JTextField portTxt = new JTextField(5);
private JLabel serverMessages = new JLabel("Not Connected");
private JButton connectButton = new JButton("Start Server");
private JButton disconnectButton = new JButton("Stop Server");
public boolean connected = false;
public ServerWindow(){
server = new RemoteDataServer();
window.setSize(WINDOW_WIDTH, WINDOW_HEIGHT);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
connectButton.addActionListener(this);
disconnectButton.addActionListener(this);
Container c = window.getContentPane();
c.setLayout(new FlowLayout());
try{
InetAddress ip = InetAddress.getLocalHost();
ipAddress = ip.getHostAddress();
addressLabel.setText("Android Remote Control Server IP Address: "+ipAddress);
}
catch(Exception e){addressLabel.setText("IP Address Could Not be Resolved");}
int x;
for(x = 0; x < 3; x++){
buffers[x] = new JTextArea("", 1, 30);
buffers[x].setEditable(false);
buffers[x].setBackground(window.getBackground());
}
portTxt.setEditable(false);
Random portRandom = new Random();
for (int i = 0; i < 10; i++) {
int port = portRandom.nextInt(4998) + 1;
int portNum = 5000+port;
String portString = Integer.toString(portNum);
portTxt.setText(portString);
}
c.add(addressLabel);
c.add(buffers[0]);
c.add(portLabel);
//portTxt.setText("5444");
c.add(portTxt);
c.add(buffers[1]);
c.add(connectButton);
c.add(disconnectButton);
c.add(buffers[2]);
c.add(serverMessages);
window.setLocationRelativeTo(null);
window.setVisible(true);
window.setResizable(false);
}
public void actionPerformed(ActionEvent e){
Object src = e.getSource();
if(src instanceof JButton){
if((JButton)src == connectButton){
int port = Integer.parseInt(portTxt.getText());
runServer(port);
}
else if((JButton)src == disconnectButton){
closeServer();
}
}
}
public void runServer(int port){
if(port <= 9999){
server.setPort(port);
sThread = new Thread(server);
sThread.start();
}
else{
serverMessages.setText("The port Number must be less than 10000");
}
}
public void closeServer(){
serverMessages.setText("Disconnected");
server.shutdown();
connectButton.setEnabled(true);
}
public static void main(String[] args){
new ServerWindow();
}
public class RemoteDataServer implements Runnable{
int PORT;
private DatagramSocket server;
private byte[] buf;
private DatagramPacket dgp;
private String message;
private AutoBot bot;
public RemoteDataServer(int port){
PORT = port;
buf = new byte[1000];
dgp = new DatagramPacket(buf, buf.length);
bot = new AutoBot();
serverMessages.setText("Not Connected");
}
public RemoteDataServer(){
buf = new byte[1000];
dgp = new DatagramPacket(buf, buf.length);
bot = new AutoBot();
serverMessages.setText("Not Connected");
}
public String getIpAddress(){
String returnStr;
try{
InetAddress ip = InetAddress.getLocalHost();
returnStr = ip.getCanonicalHostName();
}
catch(Exception e){ returnStr = new String("Could Not be Resolve Ip Address");}
return returnStr;
}
public void setPort(int port){
PORT = port;
}
public void shutdown(){
try{server.close();
serverMessages.setText("Disconnected");}
catch(Exception e){}
}
public void run(){
//boolean connected = false;
try {InetAddress ip = InetAddress.getLocalHost();
serverMessages.setText("Waiting for connection on " + ip.getCanonicalHostName());
server = new DatagramSocket(PORT, ip);
connected = true;
connectButton.setEnabled(false);
}
catch(BindException e){ serverMessages.setText("Port "+PORT+" is already in use. Use a different Port"); }
catch(Exception e){serverMessages.setText("Unable to connect");}
while(connected){
//Runtime.getRuntime().exit(0);
// get message from sender
try{ server.receive(dgp);
// translate and use the message to automate the desktop
message = new String(dgp.getData(), 0, dgp.getLength());
if (message.equals("Connectivity")){
//send response to confirm connectivity
serverMessages.setText("Trying to Connect");
server.send(dgp); //echo the message back
}else if(message.equals("Connected")){
server.send(dgp); //echo the message back
}else if(message.equals("Close")){
serverMessages.setText("Controller has Disconnected. Trying to reconnect."); //echo the message back
}else{
serverMessages.setText("Android Phone Connected to ARD Server");
bot.handleMessage(message);
server.receive(dgp);
}
}catch(Exception e){
serverMessages.setText("Disconnected");
connected = false;}
}
}
}
}
答案 0 :(得分：1)
由于您使用UDP，因此两个对等体之间没有“真正的”连接，您可能需要从客户端执行某种定期的保持活动请求。 如果没有收到该保持活动的响应，则表示您已断开连接。