我真的不知道我是怎么在我的应用程序中显示这个，因为我只是不知道我将要使用的确切代码是什么。我正在创建一个简单的聊天客户端服务器，其中两个或多个客户端可以在输入/输出流和serversocket的帮助下相互聊天。我想要做的是，在一个人登录后，它会在JtextArea中弹出一条消息，说某个人在线，如果该人关闭了该应用程序，则会向其他客户发送一条消息，说明某个人离线
这是ChatClient的代码，它将显示用于绘制消息的JtextArea，用于键入消息的JtextField和用于向发送回客户端的发送者发送消息的JButton。
JTextArea incoming;
JTextArea outgoing;
BufferedReader reader;
PrintWriter writer;
Socket sock;
static JFrame frame;
JButton send;
JPanel mainPanel;
static String userName;
public void createAndShowGUI(){
frame = new JFrame("chat client");
mainPanel = new JPanel();
mainPanel.setBackground(new Color(53,53,53));
incoming = new JTextArea(15, 50);
incoming.setLineWrap(true);
incoming.setWrapStyleWord(true);
incoming.setEditable(false);
JScrollPane qScroller = new JScrollPane(incoming);
qScroller.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
qScroller.setHorizontalScrollBarPolicy (ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
//create GridBagLayout and GridBagConstraints for Layouting
GridBagLayout gbl = new GridBagLayout();
GridBagConstraints gbc = new GridBagConstraints();
//assign gbl inside componentPanel
mainPanel.setLayout(gbl);
//for layouting JTextArea
gbc.fill = GridBagConstraints.FIRST_LINE_START;
gbc.ipady = 0;
gbc.ipadx = 20;
gbc.gridx = 0;
gbc.gridy = 0;
gbc.gridwidth = 2;
gbc.gridheight = 1;
//add labelLogin in componentPanel
gbl.setConstraints(qScroller, gbc);
mainPanel.add(qScroller);
//for layouting JTextField
outgoing = new JTextArea();
outgoing.setLineWrap(true);
outgoing.setWrapStyleWord(true);
JScrollPane oScroller = new JScrollPane(outgoing);
qScroller.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
qScroller.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
oScroller.setPreferredSize(new Dimension(500,60));
gbc.fill = GridBagConstraints.FIRST_LINE_START;
gbc.ipady = 0;
gbc.ipadx = 20;
gbc.gridx = 0;
gbc.gridy = 5;
gbc.gridwidth = 1;
gbc.gridheight = 0;
//add labelLogin in componentPanel
gbl.setConstraints(oScroller, gbc);
mainPanel.add(oScroller);
//instantiate JButton
send = new JButton("send");
send.addActionListener(new SendButtonListener());
send.setPreferredSize(new Dimension(48,60));
send.setBorder(BorderFactory.createEtchedBorder(1));
send.setBackground(new Color(248,181,63));
send.setFont(new Font("verdana",Font.BOLD,12));
gbc.fill = GridBagConstraints.NONE;
gbc.anchor = GridBagConstraints.LINE_START;
gbc.ipady = 0;
gbc.ipadx = 20;
gbc.gridy = 5;
gbc.gridx = 1;
gbc.gridwidth = 2;
gbc.gridheight = 0;
gbl.setConstraints(send, gbc);
mainPanel.add(send);
setUpNetworking();
//confirmation();
Thread readerThread = new Thread(new IncomingReader());
readerThread.start();
frame.add(mainPanel);
frame.setSize(605, 355);
frame.setVisible(true);
frame.setResizable(false);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}//end createAndShowGUI
private void setUpNetworking() {
try {
sock = new Socket("00.000.00.00", 5000);
InputStreamReader streamReader = new InputStreamReader(sock.getInputStream());
reader = new BufferedReader(streamReader);
writer = new PrintWriter(sock.getOutputStream());
System.out.println("network established");
}
catch(IOException ex)
{
// ex.printStackTrace();
JOptionPane.showMessageDialog(null, "could not connect to server!","error", JOptionPane.ERROR_MESSAGE );
System.exit(0);
}
}
public String getUserName(){
return userName;
}
public void setUserName(String uname){
userName = uname;
}
//is this a right method...?
public void confirmation(){
writer.println(getUserName());
writer.flush();
//System.out.print(getUserName() + " is online " + "\n");
//incoming.append(getUserName() + " is online " + "\n");
}
public class SendButtonListener implements ActionListener {
public void actionPerformed(ActionEvent ev) {
try {
writer.println(getUserName());
writer.print(" : ");
writer.println(outgoing.getText());
writer.flush();
}
catch (Exception ex) {
ex.printStackTrace();
}
outgoing.setText("");
outgoing.requestFocus();
}
}
class IncomingReader implements Runnable {
LoginForm lf = new LoginForm();
public void run() {
String message;
String username;
try {
while ((username = reader.readLine()) != null) {
message = reader.readLine();
incoming.append(username + message + "\n");
//if else here?
}
} catch (IOException ex)
{
ex.printStackTrace();
}
}
}
public static void main(String [] args){
new ChatClient().createAndShowGUI();
}//end main
}//end class
下面是ChatServer，其中来自ChatClients的所有邮件都发送到ChatServer并再次发送回来，以便所有客户端都能阅读邮件。
public class ChatServer {
String uname, userName, confirmation;
ArrayList clientOutputStreams;
public class ClientHandler implements Runnable {
BufferedReader reader;
Socket sock;
public ClientHandler(Socket clientSOcket) {
try {
sock = clientSOcket;
InputStreamReader isReader = new InputStreamReader(
sock.getInputStream());
reader = new BufferedReader(isReader);
} catch (Exception ex) {
ex.printStackTrace();
}
}
public void run() {
String message;
try {
// I wonder if the code below is right.?
confirmation = reader.readLine();
System.out.println(confirmation + " is online");
while ((userName = reader.readLine()) != null) {
message = reader.readLine();
// System.out.print(userName);
// System.out.print(message + "\n");
tellEveryone(userName);
tellEveryone(message);
}
} catch (Exception ex) {
System.out.println(confirmation + " is offline");
// System.out.println("connection reset!");
// ex.printStackTrace();
}
}
}
public static void main(String[] args) {
new ChatServer().go();
}
public void go() {
clientOutputStreams = new ArrayList();
try {
ServerSocket serverSock = new ServerSocket(5001);
while (true) {
Socket clientSocket = serverSock.accept();
PrintWriter writer = new PrintWriter(
clientSocket.getOutputStream());
// writer.println(confirmation);
clientOutputStreams.add(writer);
Thread t = new Thread(new ClientHandler(clientSocket));
t.start();
System.out.println("got a connection");
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
public void tellEveryone(String message) {
Iterator it = clientOutputStreams.iterator();
while (it.hasNext()) {
try {
PrintWriter writer = (PrintWriter) it.next();
writer.println(message);
writer.flush();
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
}