我正在测试问题的解决方案
Will new instance of JVM or reflection help in this case
我遇到的是，如果我尝试调用Real Estate game等应用程序，则此解决方案不起作用。因此，在调用Applic2
Frame[] f2 = JFrame.getFrames();
for(Frame fx: f2){
if (fx instanceof JFrame) {
JFrame aFrame = (JFrame)fx;
aFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
}
}
我创建了一个异步线程，不断将操作JFrame.EXIT_ON_CLOSE更改为JFrame.DISPOSE_ON_CLOSE，如下所示
import java.awt.Frame;
import javax.swing.JFrame;
public class FrameMonitor extends Thread{
@Override
public void run(){
while(true){
Frame[] f2 = JFrame.getFrames();
for(Frame fx : f2){
if(fx instanceof JFrame){
JFrame aframe =(JFrame)fx;
aframe.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
}
}
}
}
}
并通过MyApp类中的start方法调用此线程实例。但解决方案无效。我仍然面临关闭一帧时所有帧关闭的相同问题。为什么会发生任何建议以及如何克服这个？
请完成以下问题：
让我更详细地介绍问题
将Real Estate game代码添加到工作区
将以下包添加到RealEstate代码
package MyApplication;
import java.awt.Frame;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import javax.swing.JFrame;
import edu.ncsu.realestate.gui.Main;
public class MYApp {
@SuppressWarnings({ "unchecked", "rawtypes" })
public static void main(String arg[]){
FrameMonitor monitor = new FrameMonitor();
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setSize(200,200);
f.setVisible(true);
Class cls = Main.class;
Object[] actuals = { new String[] {} };
// cls.
Method[] mts=cls.getMethods();
for(Method m : mts){
//System.out.println(m);
}
Method m = null;
try {
m=cls.getMethod("main", new Class[] { String[].class } );
} catch (NoSuchMethodException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SecurityException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
m.invoke(null,actuals);
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InvocationTargetException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Frame[] f2 = JFrame.getFrames();
for(Frame fx: f2){
System.out.println(fx.getTitle());
// fx.setVisible(false);
if (fx instanceof JFrame) {
// System.out.println("M here");
// System.out.println(fx.getTitle());
System.out.println(fx.getName());
JFrame aFrame = (JFrame)fx;
aFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
}
}
}
}
package MyApplication;
import java.awt.Frame;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.Timer;
public class FrameMonitor{
public FrameMonitor(){
Timer timer = new Timer(10000, new FrameMonitor2());
timer.setCoalesce(true);
timer.setRepeats(true);
timer.start();
}
public static class FrameMonitor2 implements ActionListener {
@Override
public void actionPerformed(ActionEvent ae) {
Frame[] frames = Frame.getFrames();
for (Frame frame : frames) {
if (frame instanceof JFrame) {
JFrame change = (JFrame) frame;
System.out.println("Before = " + change.getTitle() + " = " + change.getDefaultCloseOperation());
((JFrame)frame).setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
System.out.println("After = " + change.getTitle() + " = " + change.getDefaultCloseOperation());
}
}
}
}
}
现在调用MyApplication包的主要部分，然后调用RealEstate游戏。这是解决方案不起作用的地方，尝试关闭不同的RealEstate帧并查看整个应用程序关闭。
答案 0 :(得分：5)
我快速检查了房地产游戏的代码，并在MainWindow.java中找到了问题：
this.addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
我不确定如果你仍然希望窗户关闭，你可以从外面做什么，如果有的话。
答案 1 :(得分：2)
所以，我做了一个快速测试，我可以让它工作正常。
首先，我创建了三个JFrame（所有相同的原因我都很匆忙），默认关闭值设置为EXIT_ON_CLOSE。
我确认如果我关闭了一个，它就会关闭所有三个。
然后，我使用javax.swing.Timer重复循环显示可用框架列表，并将默认关闭值设置为DISPOSE_ON_CLOSE
Timer timer = new Timer(1000, new UpdateTask());
timer.setCoalesce(true);
timer.setRepeats(true);
timer.start();
...
public static class UpdateTask implements ActionListener {
@Override
public void actionPerformed(ActionEvent ae) {
Frame[] frames = Frame.getFrames();
for (Frame frame : frames) {
if (frame instanceof JFrame) {
JFrame change = (JFrame) frame;
System.out.println("Before = " + change.getTitle() + " = " + change.getDefaultCloseOperation());
((JFrame)frame).setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
System.out.println("After = " + change.getTitle() + " = " + change.getDefaultCloseOperation());
}
}
}
}
执行后，我能够监控以下输出
Before = Frame 01 = 3
After = Frame 01 = 2
Before = Frame 02 = 3
After = Frame 02 = 2
Before = Frame 03 = 3
After = Frame 03 = 2
Before = Frame 01 = 2
After = Frame 01 = 2
Before = Frame 02 = 2
After = Frame 02 = 2
Before = Frame 03 = 2
After = Frame 03 = 2
如你所见。在第一次迭代中，帧从“3”变为“2”并保持这种状态，直到我厌倦输出并终止程序。
我还检查过关闭一个或多个框架 NOT 退出程序。
现在，一个重要的注意事项。我相信这只适用于已经实现的帧（在屏幕上可见），但是你可以测试它并看看你得到了什么;）
答案 2 :(得分：1)
一种方式（不一定是最好的）是实现自定义安全管理器。
import java.awt.*;
import java.awt.event.*;
import java.security.Permission;
/** NoExit demonstrates how to prevent 'child'
applications from ending the VM with a call
to System.exit(0).
@author Andrew Thompson */
public class NoExit extends Frame implements ActionListener {
Button frameLaunch = new Button("Frame"),
exitLaunch = new Button("Exit");
/** Stores a reference to the original security manager. */
ExitManager sm;
public NoExit() {
super("Launcher Application");
sm = new ExitManager( System.getSecurityManager() );
System.setSecurityManager(sm);
setLayout(new GridLayout(0,1));
frameLaunch.addActionListener(this);
exitLaunch.addActionListener(this);
add( frameLaunch );
add( exitLaunch );
pack();
setSize( getPreferredSize() );
}
public void actionPerformed(ActionEvent ae) {
if ( ae.getSource()==frameLaunch ) {
TargetFrame tf = new TargetFrame();
} else {
// change back to the standard SM that allows exit.
System.setSecurityManager(
sm.getOriginalSecurityManager() );
// exit the VM when *we* want
System.exit(0);
}
}
public static void main(String[] args) {
NoExit ne = new NoExit();
ne.setVisible(true);
}
}
/** This example frame attempts to System.exit(0)
on closing, we must prevent it from doing so. */
class TargetFrame extends Frame {
static int x=0, y=0;
TargetFrame() {
super("Close Me!");
add(new Label("Hi!"));
addWindowListener( new WindowAdapter() {
public void windowClosing(WindowEvent we) {
System.out.println("Bye!");
System.exit(0);
}
});
pack();
setSize( getPreferredSize() );
setLocation(++x*10,++y*10);
setVisible(true);
}
}
/** Our custom ExitManager does not allow the VM
to exit, but does allow itself to be replaced by
the original security manager.
@author Andrew Thompson */
class ExitManager extends SecurityManager {
SecurityManager original;
ExitManager(SecurityManager original) {
this.original = original;
}
/** Deny permission to exit the VM. */
public void checkExit(int status) {
throw( new SecurityException() );
}
/** Allow this security manager to be replaced,
if fact, allow pretty much everything. */
public void checkPermission(Permission perm) {
}
public SecurityManager getOriginalSecurityManager() {
return original;
}
}