在Java应用中实现只读模式的切换方法与技巧

有没有办法切换只读模式,所以当您单击窗口中的任何对象时,它只返回您单击的内容,忽略对象的常规事件处理？ IE,在这种“只读”模式下,如果你点击一个按钮,它只是返回按钮,而不是实际按下按钮.然后我可以这样做：

if ("thing pressed" == button) "do this";
else if ("thing pressed" == panel) "do that";
else "do nothing";


这是我的代码,它是一个带有3个彩色框的框架.单击第二个框,第三个框或背景将显示一条消息.单击框1不执行任何操作.我喜欢使用新的鼠标适配器,所以我想这样做.

现在我想要的是当您单击框1时,框1被视为已选中(如果这有助于您获得图片).然后,如果你点击任何地方,包括方框1,则取消选择方框1,而不显示任何其他内容(意味着将显示方框2,方框3或背景信息).那时,只有在单击框2或3时,它们仍然不会显示正常消息,但会显示不同的消息.

如果我有点短暂,我很抱歉.

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class Labels {
public static void main(String[] args) {
new Labels();
}
Square l1, l2, l3;
public Labels() {
JFrame frame = new JFrame();
JPanel panel = new JPanel();
l1 = new Square();
l2 = new Square();
l3 = new Square();
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(120, 150);
frame.setResizable(false);
panel.setVisible(true);
panel.setLayout(null);
l1.setLocation(5, 5);
l2.setLocation(5, 60);
l3.setLocation(60, 5);
l2.setColor("yellow");
l3.setColor("black");
l1.addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent e) {//do nothing
}
});
l2.addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent e) {System.out.println("Pushed label 2");
}
});
l3.addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent e) {System.out.println("Pushed label 3");
}
});
panel.addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent e) {System.out.println("pushed background");
}
});
frame.add(panel);
panel.add(l1);
panel.add(l2);
panel.add(l3);
}
class Square extends JLabel{
Color color = Color.blue;
public Square() {
// TODO Auto-generated constructor stub\
setVisible(true);
setSize(50,50);
}
public void paint(Graphics g) {
super.paint(g);
g.setColor(color);
g.fillRect(0, 0, 50, 50);
}
public void setColor(String color){
if (color == "white") this.color = Color.white;
else if (color == "black") this.color = Color.black;
else if (color == "yellow") this.color = Color.yellow;
else {System.out.println("Invalid color");return;
}
repaint();
}
}
}


解决方法:

不要禁用任何东西.只需更改类的状态,可能使用一些布尔标志变量/字段,并根据按下的内容更改这些标志.

所以有名为label1PressedLast,label2PressedLast和label3PressedLast等类似的布尔字段,当按下标签时,检查所有其他标志的状态,并根据这些标志的状态和刚刚按下的标签改变程序的行为.然后将所有标志设置为false,除了与刚刚按下的标签对应的标志.

例如,只有在第一个和第三个JLabel被按下时,这个小程序才会做出反应：

import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.*;
public class FlagEg extends JPanel {
private static final int LABEL_COUNT = 3;
private JLabel[] labels = new JLabel[LABEL_COUNT];
private boolean[] flags = new boolean[LABEL_COUNT];
public FlagEg() {
setLayout(new GridLayout(1, 0, 20, 0));
setBorder(BorderFactory.createEmptyBorder(15, 15, 15, 15));
// panel mouse listener
addMouseListener(new MouseAdapter() {
@Override
public void mousePressed(MouseEvent arg0) {
inactivateAll();
}
});
MouseListener labelsMouseListener = new MouseAdapter() {
@Override
public void mousePressed(MouseEvent mouseEvt) {
myMousePressed(mouseEvt);
}
};
// create JLabels and add MouseListener
for (int i = 0; i labels[i] = new JLabel("Label " + (i + 1));
labels[i].addMouseListener(labelsMouseListener);
labels[i].setOpaque(true);
labels[i].setBorder(BorderFactory.createLineBorder(Color.black));
add(labels[i]);
}
}
private void inactivateAll() {
for (int i = 0; i labels[i].setBackground(null);
flags[i] = false;
}
}
private void myMousePressed(MouseEvent mouseEvt) {
JLabel label = (JLabel) mouseEvt.getSource();
// which label was pressed?
int index = -1;
for (int i = 0; i if (label == labels[i]) {
index = i;
}
}
// check if first label and then third pressed:
if (flags[0] && index == 2) {
System.out.println("first and then third label pressed!");
}
// reset all labels and flags to initial state
inactivateAll();
// set pressed label background color and set flag of label just pressed
labels[index].setBackground(Color.pink);
flags[index] = true;
}
private static void createAndShowGui() {
FlagEg mainPanel = new FlagEg();
JFrame frame = new JFrame("Flag Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}


逻辑迭代二：只有标签1是“引物”JLabel.这实际上更容易实现,因为现在您只需要一个布尔标志,表示按下标签1：

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
@SuppressWarnings("serial")
public class FlagEg2 extends JPanel {
private static final int LABEL_COUNT = 3;
private JLabel[] labels = new JLabel[LABEL_COUNT];
private boolean label1Flag = false;
public FlagEg2() {
setLayout(new GridLayout(1, 0, 20, 0));
setBorder(BorderFactory.createEmptyBorder(15, 15, 15, 15));
// panel mouse listener
addMouseListener(new MouseAdapter() {
@Override
public void mousePressed(MouseEvent arg0) {
inactivateAll();
}
});
MouseListener labelsMouseListener = new MouseAdapter() {
@Override
public void mousePressed(MouseEvent mouseEvt) {
myMousePressed(mouseEvt);
}
};
// create JLabels and add MouseListener
for (int i = 0; i labels[i] = new JLabel("Label " + (i + 1));
labels[i].addMouseListener(labelsMouseListener);
labels[i].setOpaque(true);
labels[i].setBorder(BorderFactory.createLineBorder(Color.black));
add(labels[i]);
}
}
private void inactivateAll() {
for (int i = 0; i labels[i].setBackground(null);
label1Flag = false;
}
}
private void myMousePressed(MouseEvent mouseEvt) {
JLabel label = (JLabel) mouseEvt.getSource();
// which label was pressed?
int index = -1;
for (int i = 0; i if (label == labels[i]) {
index = i;
}
}
if (label1Flag) {
if (index == 1) {
System.out.println("Label 1 and label 2 pressed");
} else if (index == 2) {
System.out.println("Label 1 and label 3 pressed");
}
}
// reset all labels and flags to initial state
inactivateAll();
// if label1, then activate it
if (index == 0) {
labels[0].setBackground(Color.pink);
label1Flag = true;
}
}
private static void createAndShowGui() {
FlagEg2 mainPanel = new FlagEg2();
JFrame frame = new JFrame("Flag Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}