如何在Java Swing应用程序中管理控制器的视图更新 [英] How to manage view updates from controllers in a Java Swing app
问题描述
我发现使用Swing编写好的OO代码是非常困难的。我的问题基本上是我有一个视图（JPanel）有动作侦听器。动作侦听器确定哪个按钮被点击并调用适当的控制器方法。问题是，这个控制器方法需要更新另一个视图。所以我的问题是我有意见被传递到控制器的所有地方。下面是一个例子。
I'm finding that writing good OO code with Swing is incredibly hard. My problem is essentially that I have a view (a JPanel) that has action listeners. The action listeners figure out which button was clicked and call the appropriate controller method. The issue is that this controller method needs to update another view. So the issue I'm having is I have views being passed all over the place to controllers. Here's an example.
public class MyView extends JPanel implements ActionListener {
private final MyController controller = new MyController();
@Override public void actionPerformed(ActionEvent e) {
this.controller.updateOtherView();
}
}
这实际上是我想要的，
This is essentially what I want, but this is what ends up happening.
public class MyView extends JPanel implements ActionListener {
private MyController controller = new MyController();
private OtherView otherView;
public MyView(MyOtherView otherView) {
this.otherView = otherView;
}
@Override public void actionPerformed(ActionEvent e) {
this.controller.updateOtherView(otherView);
}
}
你可以看到，需要更新增加和看起来像这样增加的类的数量，视图本质上是全局变量，代码变得复杂和不清楚。我遇到的另一个问题是这个其他视图通常不直接传递到MyView，但它必须通过MyView的父母去到MyView，这真的只是我的错误。
And you can see that as the number of views that need to be updated increase and the number of classes that look like this increase, the views are essentially global variables and the code becomes complex and unclear. Another problem I'm running into is this other view usually isn't directly passed into MyView, but it has to go through the parents of MyView to get to MyView, which really just bugs me.
对于这个的一个真实的例子，让我说一个菜单和这个MyView。 MyView有一个播放按钮，播放一些音乐一段时间，它禁用（灰色）播放按钮，直到音乐完成。如果我有一个菜单选项称为播放，现在我需要访问其他视图播放按钮，所以我可以灰色出来。我怎么能这样做，没有这个讨厌的传递的意见到处？虽然可能有这个问题的具体解决方案，我正在寻找一些解决这个视图访问问题在一般情况下。
For a real example of this, lets say I have a Menu and this MyView. MyView has a play button, which plays some music for a while and it disables (greys out) the play button until the music is finished. If I have a menu option called play, now I need to access the other views play button so I can grey it out. How can I do this without this annoying passing of views everywhere? Although there might be specific solutions for this problem, I'm looking for something that will solve this view access problem in the general case.
我不确定如何解决这个。我现在使用MVC模式术语，而不使用MVC模式，这可能是也可能不是必要的。任何帮助是赞赏。
I'm not sure at all how to fix this. I'm kind of using MVC pattern terminology at the moment without using the MVC pattern, which may or may not necessary. Any help is appreciated.
推荐答案
一个解决方案：只需让控制器更新模型。然后附加到模型的监听器将更新视图。您还可以使JMenuItem和相应的JButtons共享相同的Action，因此，当您禁用Action时，它将禁用使用该Action的所有按钮/菜单/等。
One solution: simply have the controller update the model. Then listeners attached to the model would update the views. You can also have the JMenuItems and corresponding JButtons share the same Action, and thereby when you disable the Action it will disable all buttons/menus/etc that use that Action.
例如，主类：
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
public class MvcExample {
private static void createAndShowGui() {
MyView view = new MyView();
MyMenuBar menuBar = new MyMenuBar();
MyModel model = new MyModel();
MyControl control = new MyControl(model);
control.addProgressMonitor(view);
control.addView(view);
control.addView(menuBar);
model.setState(MyState.STOP);
JFrame frame = new JFrame("MVC Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(view.getMainPanel());
frame.setJMenuBar(menuBar.getMenuBar());
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
private static final byte[] DATA_ARRAY = { 0x43, 0x6f, 0x70, 0x79, 0x72,
0x69, 0x67, 0x68, 0x74, 0x20, 0x46, 0x75, 0x62, 0x61, 0x72, 0x61,
0x62, 0x6c, 0x65, 0x2c, 0x20, 0x30, 0x36, 0x2f, 0x31, 0x36, 0x2f,
0x32, 0x30, 0x31, 0x32, 0x2e, 0x20, 0x46, 0x75, 0x62, 0x61, 0x72,
0x61, 0x62, 0x6c, 0x65, 0x20, 0x52, 0x75, 0x6c, 0x65, 0x73, 0x21 };
}
控制：
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.ArrayList;
import java.util.List;
import javax.swing.AbstractAction;
@SuppressWarnings("serial")
public class MyControl {
private MyModel model;
private PlayAction playAction = new PlayAction();
private PauseAction pauseAction = new PauseAction();
private StopAction stopAction = new StopAction();
private List<MyProgressMonitor> progMonitorList = new ArrayList<MyProgressMonitor>();
public MyControl(MyModel model) {
this.model = model;
model.addPropertyChangeListener(new MyPropChangeListener());
}
public void addProgressMonitor(MyProgressMonitor progMonitor) {
progMonitorList.add(progMonitor);
}
public void addView(MySetActions setActions) {
setActions.setPlayAction(playAction);
setActions.setPauseAction(pauseAction);
setActions.setStopAction(stopAction);
}
private class MyPropChangeListener implements PropertyChangeListener {
@Override
public void propertyChange(PropertyChangeEvent pcEvt) {
if (MyState.class.getName().equals(pcEvt.getPropertyName())) {
MyState state = (MyState) pcEvt.getNewValue();
if (state == MyState.PLAY) {
playAction.setEnabled(false);
pauseAction.setEnabled(true);
stopAction.setEnabled(true);
} else if (state == MyState.PAUSE) {
playAction.setEnabled(true);
pauseAction.setEnabled(false);
stopAction.setEnabled(true);
} else if (state == MyState.STOP) {
playAction.setEnabled(true);
pauseAction.setEnabled(false);
stopAction.setEnabled(false);
}
}
if (MyModel.PROGRESS.equals(pcEvt.getPropertyName())) {
for (MyProgressMonitor progMonitor : progMonitorList) {
int progress = (Integer) pcEvt.getNewValue();
progMonitor.setProgress(progress);
}
}
}
}
private class PlayAction extends AbstractAction {
public PlayAction() {
super("Play");
putValue(MNEMONIC_KEY, KeyEvent.VK_P);
}
@Override
public void actionPerformed(ActionEvent e) {
model.play();
}
}
private class StopAction extends AbstractAction {
public StopAction() {
super("Stop");
putValue(MNEMONIC_KEY, KeyEvent.VK_S);
}
@Override
public void actionPerformed(ActionEvent e) {
model.stop();
}
}
private class PauseAction extends AbstractAction {
public PauseAction() {
super("Pause");
putValue(MNEMONIC_KEY, KeyEvent.VK_A);
}
@Override
public void actionPerformed(ActionEvent e) {
model.pause();
}
}
}
A状态枚举：
public enum MyState {
PLAY, STOP, PAUSE
}
其中一个视图界面：
import javax.swing.Action;
public interface MySetActions {
void setPlayAction(Action playAction);
void setPauseAction(Action pauseAction);
void setStopAction(Action stopAction);
}
另一个视图界面：
public interface MyProgressMonitor {
void setProgress(int progress);
}
主GUI视图：
import java.awt.BorderLayout;
import java.awt.GridLayout;
import javax.swing.Action;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
public class MyView implements MySetActions, MyProgressMonitor {
private JButton playButton = new JButton();
private JButton stopButton = new JButton();
private JButton pauseButton = new JButton();
private JPanel mainPanel = new JPanel();
private JProgressBar progressBar = new JProgressBar();
public MyView() {
progressBar.setBorderPainted(true);
JPanel btnPanel = new JPanel(new GridLayout(1, 0, 5, 0));
btnPanel.add(playButton);
btnPanel.add(pauseButton);
btnPanel.add(stopButton);
mainPanel.setLayout(new BorderLayout(0, 5));
mainPanel.setBorder(BorderFactory.createEmptyBorder(5, 15, 5, 15));
mainPanel.add(btnPanel, BorderLayout.CENTER);
mainPanel.add(progressBar, BorderLayout.PAGE_END);
}
@Override
public void setPlayAction(Action playAction) {
playButton.setAction(playAction);
}
@Override
public void setStopAction(Action stopAction) {
stopButton.setAction(stopAction);
}
@Override
public void setPauseAction(Action pauseAction) {
pauseButton.setAction(pauseAction);
}
@Override
public void setProgress(int progress) {
progressBar.setValue(progress);
}
public JComponent getMainPanel() {
return mainPanel;
}
}
视图的菜单栏部分：
import java.awt.event.KeyEvent;
import javax.swing.Action;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
public class MyMenuBar implements MySetActions {
private JMenuItem playMenItem = new JMenuItem();
private JMenuItem pauseMenuItem = new JMenuItem();
private JMenuItem stopMenItem = new JMenuItem();
private JMenuBar menuBar = new JMenuBar();
public MyMenuBar() {
JMenu menu = new JMenu("Main Menu");
menu.setMnemonic(KeyEvent.VK_M);
menu.add(playMenItem);
menu.add(pauseMenuItem);
menu.add(stopMenItem);
menuBar.add(menu);
}
public JMenuBar getMenuBar() {
return menuBar;
}
@Override
public void setPlayAction(Action playAction) {
playMenItem.setAction(playAction);
}
@Override
public void setStopAction(Action stopAction) {
stopMenItem.setAction(stopAction);
}
@Override
public void setPauseAction(Action pauseAction) {
pauseMenuItem.setAction(pauseAction);
}
}
最后，模型： / p>
And finally, the model:
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.beans.PropertyChangeListener;
import javax.swing.Timer;
import javax.swing.event.SwingPropertyChangeSupport;
public class MyModel {
public final static String PROGRESS = "progress";
protected static final int MAX_PROGRESS = 100;
private MyState state = null;
private SwingPropertyChangeSupport pcSupport = new SwingPropertyChangeSupport(
this);
private Timer timer;
private int progress = 0;
public MyState getState() {
return state;
}
public void setState(MyState state) {
MyState oldValue = this.state;
MyState newValue = state;
this.state = newValue;
pcSupport.firePropertyChange(MyState.class.getName(), oldValue, newValue);
}
public int getProgress() {
return progress;
}
public void setProgress(int progress) {
Integer oldValue = this.progress;
Integer newValue = progress;
this.progress = newValue;
pcSupport.firePropertyChange(PROGRESS, oldValue, newValue);
}
public void play() {
MyState oldState = getState();
setState(MyState.PLAY);
if (oldState == MyState.PAUSE) {
if (timer != null) {
timer.start();
return;
}
}
int timerDelay = 50;
// simulate playing ....
timer = new Timer(timerDelay, new ActionListener() {
int timerProgress = 0;
@Override
public void actionPerformed(ActionEvent actEvt) {
timerProgress++;
setProgress(timerProgress);
if (timerProgress >= MAX_PROGRESS) {
setProgress(0);
MyModel.this.stop();
}
}
});
timer.start();
}
public void pause() {
setState(MyState.PAUSE);
if (timer != null && timer.isRunning()) {
timer.stop();
}
}
public void stop() {
setState(MyState.STOP);
setProgress(0);
if (timer != null && timer.isRunning()) {
timer.stop();
}
timer = null;
}
public void addPropertyChangeListener(PropertyChangeListener listener) {
pcSupport.addPropertyChangeListener(listener);
}
public void removePropertyChangeListener(PropertyChangeListener listener) {
pcSupport.removePropertyChangeListener(listener);
}
}
请问这是否有点混乱。
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