我有三个类，分别是TCPClient.java，TCPProtocol.java，TCPServer.java。
*更新，我也粘贴了我的完整TCPServer.java
首先，用户将在TCPProtocol GUI窗口中输入文本（使用JTextarea），然后单击“发送”按钮。如果用户单击“发送”，TCPClient将从TCPProtocol获取输入，最后将发送到TCPServer。所以问题是，我的TCPClient永远不会从TCPProtocol获得输入。
TCPServer.java
import java.net.*;
import java.io.*;
public class TCPServer {
public static void main(String[] args) throws IOException {
//TCP component
ServerSocket serverSocket = null;
Socket clientSocket = null;
int port = 8081;
TCPProtocol nis = new TCPProtocol();//create an object to call method in protocol class
try {
serverSocket = new ServerSocket(port);
System.out.println("Waiting for connection...");
System.out.println();
} catch (IOException e) {
System.out.println(e.toString() + " :Could not listen on port: " + port);
System.exit(1);
}
try {
clientSocket = serverSocket.accept();
System.out.println("TCP Session established.");
nis.frame.setVisible(true);
nis.frame.setAlwaysOnTop(true);
System.out.println();
} catch (IOException e) {
System.out.println(e.toString() + " :Accept failed.");
System.exit(1);
}
PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);
BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
String inputLine, outputLine;
outputLine = nis.processAnswer(null);//get Learn Learn English line
out.println(outputLine);//and send the line out to client
nis.Jservertxt.setText(outputLine);
while ((inputLine = in.readLine()) != null) {
outputLine = nis.processAnswer(inputLine);
out.println(outputLine);
nis.Jservertxt.setText(outputLine);
if (outputLine.equalsIgnoreCase("Don't miss me! Bye Bye!"))
break;
else if (outputLine.equalsIgnoreCase("Thank For Your Guessing. Have a Nice Day =)"))
break;
}
//End connection
out.flush();
out.close();
in.close();
nis.frame.setVisible(false);
if (!clientSocket.isClosed())
clientSocket.close();
nis.frame.setVisible(false);
if (!serverSocket.isClosed())
serverSocket.close();
nis.frame.setVisible(false);
System.out.println("TCP session closed.");
}
}
这是我的TCPProtocol.java代码
public volatile boolean getPressed;
Jsend.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String Data = Jusertxt.getText();
Jusertxt.setText(null);
System.out.println(Data);
getPressed=true;
}
});
}
public boolean getPressed()
{
return getPressed;
}
我不会在这里粘贴完整的代码，因为我只是显示出问题所在的部分。
这是我的TCPClient代码
import java.io.*;
import java.net.*;
public class TCPClient{
public static void main(String[] args) throws IOException, InterruptedException{
//TCP component
int port = 8081;
String host = "localhost";
Socket nisSocket = null;
PrintWriter out = null;
BufferedReader in = null;
TCPProtocol pro = new TCPProtocol();
try {
nisSocket = new Socket(host, port);
out = new PrintWriter(nisSocket.getOutputStream(), true);
in = new BufferedReader(new InputStreamReader(nisSocket.getInputStream()));
} catch (UnknownHostException e) {
System.out.println(e.toString() + " :Don't know about " + host);
System.exit(1);
} catch (IOException e) {
System.out.println(e.toString() + " :Couldn't get I/O for the connection to " + host);
System.exit(1);
}
BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));
String fromServer, fromUser;
while ((fromServer = in.readLine()) != null) {
System.out.println("Server: " + fromServer);
if (fromServer.equalsIgnoreCase("Don't miss me! Bye Bye!"))
break;
if (fromServer.equalsIgnoreCase("Thank For Your Guessing. Have a Nice Day =)"))
break;
if (pro.getPressed())
{
fromUser = pro.Jusertxt.getText();
if (fromUser != null) {
System.out.println("\nClient: " + fromUser);
out.println(fromUser);
}
}
System.out.println("fail liao");
}
System.out.println("try again");
//End connection
out.flush();
out.close();
in.close();
stdIn.close();
//if (!nisSocket.isClosed())
nisSocket.close();
System.out.println("TCP session closed.");
}
}
那么，如果只有getPressed（）方法为真，我怎么才能让TCPClient.java进程。
我尝试使用volatile布尔变量但不能正常工作。或者我应该使用synchronized？
更改后解决从服务器到客户端调用GUI代码
while ((fromServer = in.readLine()) != null) {
System.out.println("Server: " + fromServer);
if (fromServer.equalsIgnoreCase("Don't miss me! Bye Bye!"))
break;
if (fromServer.equalsIgnoreCase("Thank For Your Guessing. Have a Nice Day =)"))
break;
pro.frame.setVisible(true);
pro.frame.setAlwaysOnTop(true);
pro.Jservertxt.setText(fromServer);
if(pro.getPressed()){
fromUser = pro.getMessage();
if (fromUser != null) {
System.out.println("\nClient: " + fromUser);
out.println(fromUser);
}
}
}
答案 0 :(得分：1)
这是一个主线程的一个小例子（将其视为您的TCPClient），等待用户点击按钮（将此部分视为您的TCPProtocol）：
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextArea;
public class Test extends JFrame {
public Object lock = new Object();
private JTextArea area = new JTextArea();
public Test() {
super("test");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JButton send = new JButton("send");
send.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
synchronized (lock) {
lock.notify();
}
}
});
add(area);
add(send, BorderLayout.SOUTH);
}
public String pullText() {
String result = area.getText();
area.setText("");
return result;
}
public static void main(String[] args) {
Test t = new Test();
t.setSize(200, 200);
t.setVisible(true);
while (true) {
synchronized (t.lock) {
try {
t.lock.wait();
System.out.println(t.pullText());
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
也许您可以对您的系统应用类似的方法。
警告：这只是一个快速而肮脏的例子，请您仔细检查。通常，在处理同步时应该非常小心。
编辑： 作为起点，您可以修改TCPProtocol类（您发布的部分），如下所示：
public volatile boolean getPressed;
private Object lock = new Object(); // added lock for wait/notify coordination
private String Data; //changed scope to make it accessible in getMessage()
Jsend.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
synchronized(lock){
Data = Jusertxt.getText(); // no more a local variable, it's an instance attribute now, see declaration above
Jusertxt.setText(null);
System.out.println(Data);
getPressed=true;
lock.notify(); // notify client that user performed action
}
});
}
public boolean getPressed(){
synchronized (lock) {
try {
lock.wait(); // wait for user to perform action...
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
return getPressed; // ...then return value (I guess getPressed will always be true at this point)
}
public String getMessage(){ // call this in TCPClient instead of pro.Jusertxt.getText()
return Data;
}
我添加了一个锁定对象来启用wait / notify机制并将其应用于actionPerformed和getPressed方法。 我还改变了Data变量的范围，并添加了一个公共方法来获取它的值（getMessage（））。如果你仔细检查你的代码，你会发现你总是从TCPClient.java中的pro.Jusertxt.getText（）得到null，因为你在actionPerformed中将它设置为null。因此，在TCPClient.java中将pro.Jusertxt.getText（）更改为pro.getMessage（）。
// [...]
fromUser = pro.getMessage(); // used to be fromUser = pro.Jusertxt.getText();
// [...]
如果你使这个原始版本工作，那么你可以改进和重构它，使它更干净和一致。 （例如，我怀疑你实际上并不需要getPressed变量，因为它实际上总是如此）
我承认我没有测试过这段代码，所以你可能需要稍微修改或调整一下，但我希望它能说明我的意思是你可以应用我发布到你系统的代码。
希望它有所帮助。
祝你好运： - ）答案 1 :(得分：0)
你可以试试这个：
while (!pro.getPressed()) {
System.out.println("still not true");
Thread.sleep(1000);
}
System.out.println("getPressed is true");