我已经看过许多类似问题的答案，但是它们似乎都说是在借鉴我正在做的JPanel，所以我不明白如何使矩形不闪烁。

我正在制作一个屏幕截图制作程序，就像Mac上的CMD + SHIFT + 4功能一样。 我可以进行所有操作，例如，拖动矩形时它会拍照，但是您选择的矩形会一直闪烁。

import java.awt.*;

import java.awt.event.MouseEvent;

import java.awt.event.MouseListener;

import java.awt.event.KeyEvent;

import java.awt.event.KeyListener;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.awt.image.BufferedImage;

import java.awt.image.BufferStrategy;

import java.io.FileReader;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.File;

import java.io.PrintWriter;

import javax.swing.*;

import javax.swing.event.*;

import javax.imageio.ImageIO;

import java.text.SimpleDateFormat;

import java.util.*;

import java.awt.geom.Area;

public class ScreenShotter extends JPanel implements MouseListener {

static JPanel contentPane;

private static JPanel picture1;

static int startX, startY, endX, endY;

static int width;

static int height;

int x, y;

int radius = 2;

SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd kk.mm.ss");

static File f = new File("ScreenShotter.txt");

static String filePath = f.getPath();

static String screenshotPath = "";

JFileChooser chooser;

String chooserTitle = "Select the folder to store your screenshots";

static Point currentPoint;

static Point startPoint;

static boolean clicked = false;

static BufferStrategy bs;

public ScreenShotter() {

setLayout(new BorderLayout());

contentPane = new JPanel(new BorderLayout());

contentPane.requestFocus();

picture1 = new JPanel();

picture1.addMouseListener(this);

picture1.setPreferredSize(new Dimension(width, height));

contentPane.add(picture1);

}

public ScreenShotter(boolean bool){

final String[] labels = {"Screen width: ", "Screen Height: "};

int labelsLength = labels.length;

final JTextField[] textField = new JTextField[labelsLength];

final JPanel p = new JPanel(new SpringLayout());

for(int i = 0; i < labelsLength; i++){

JLabel l = new JLabel(labels[i], JLabel.TRAILING);

p.add(l);

textField[i] = new JTextField(10);

l.setLabelFor(textField[i]);

p.add(textField[i]);

}

final JButton button = new JButton("Submit");

p.add(new JLabel());

p.add(button);

SpringUtilities.makeCompactGrid(p,

labelsLength + 1, 2,

7, 7,

7, 7);

final JFrame frame = new JFrame("File Maker");

button.addActionListener(new ActionListener(){

public void actionPerformed(ActionEvent e){

//for(int i = 0; i < labels.length; i++){

//System.out.println(labels[i]+"->"+textField[i].getText());

//screenshotPath = textField[0].getText();

width = Integer.parseInt(textField[0].getText());

height = Integer.parseInt(textField[1].getText());

//}

chooser = new JFileChooser();

chooser.setCurrentDirectory(new File("."));

chooser.setDialogTitle(chooserTitle);

chooser.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);

chooser.setAcceptAllFileFilterUsed(false);

if(chooser.showOpenDialog(button) == JFileChooser.APPROVE_OPTION){

System.out.println("getCurrentDirectory(): " + chooser.getCurrentDirectory());

System.out.println("getSelectedFile(): " + chooser.getSelectedFile());

screenshotPath = slashConverter(chooser.getSelectedFile().toString());

} else {

System.out.println("No selection.");

}

frame.dispose();

createFile();

}

});

frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

p.setOpaque(true);

frame.setContentPane(p);

frame.pack();

frame.setSize(210, 123);

frame.setResizable(false);

frame.setVisible(true);

}

@Override

public Dimension getPreferredSize(){

return new Dimension(210, 123);

}

public static void main(String[] args){

try {UIManager.setLookAndFeel( UIManager.getSystemLookAndFeelClassName());}

catch (UnsupportedLookAndFeelException e) {}

catch (ClassNotFoundException e) {}

catch (InstantiationException e) {}

catch (IllegalAccessException e) {}

if(f.exists()){

width = getWidthFromFile(filePath);

height = getHeightFromFile(filePath);

startScreenShotter();

}

if(!f.exists()){

JFrame fileMaker = new JFrame("File Maker");

fileMaker.add(new ScreenShotter(true));

}

}

public static void startScreenShotter(){

JFrame frame = new JFrame("ScreenShotter");

frame.add(new ScreenShotter());

frame.setSize(width, height);

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

frame.setUndecorated(true);

frame.setOpacity(0.33f);

frame.setContentPane(contentPane);

frame.setVisible(true);

frame.addKeyListener(new KeyListener(){

public void keyPressed(KeyEvent ke) {

if(ke.getKeyCode() == ke.VK_ESCAPE){

System.exit(0);

}

}

public void keyReleased(KeyEvent ke) {}

public void keyTyped(KeyEvent ke) {}

});

while(true){

currentPoint = MouseInfo.getPointerInfo().getLocation();

if(currentPoint != startPoint && clicked){

drawRectangle(startPoint, currentPoint, picture1);

}

//System.out.println(currentPoint);

//delay(1);

}

}

public static void drawRectangle(Point start, Point current, Object source){

if(source instanceof JPanel){

picture1.repaint();

//delay(1);

Rectangle r = new Rectangle(rectChecker(start.x, start.y, current.x, current.y));

Graphics g = ((JComponent) source).getGraphics();

g.fillRect((int)r.getX(), (int)r.getY(), (int)r.getWidth(), (int)r.getHeight());

g.setColor(new Color(255, 255, 255, 50));

//delay(1);

}

}

public static void delay(int time){

try{

Thread.sleep(time);

} catch(InterruptedException e){

System.out.println("wot");

}

}

public void mousePressed(MouseEvent e) {

x = e.getX();

y = e.getY();

//drawCircle(e.getX()-(radius/2), e.getY()-(radius/2), e.getSource(), true);

//repaint();

startX = x;

startY = y;

startPoint = new Point(startX, startY);

clicked = true;

//System.out.println("(" + startX + ", " + startY + ")");

}

public void mouseReleased(MouseEvent e) {

x = e.getX();

y = e.getY();

//drawCircle(e.getX()-(radius/2), e.getY()-(radius/2), e.getSource(), true);

//repaint();

endX = x;

endY = y;

//System.out.println("(" + endX + ", " + endY + ")");

Frame[] f = Frame.getFrames();

for(int i = 0; i < f.length; i++){

f[i].dispose();

}

try {

robo(rectChecker(startX, startY, endX, endY));

System.exit(0);

} catch(Exception ex){

System.exit(1);

}

}/*

public void drawCircle(int x, int y, Object source, boolean fill) {

if(source instanceof JPanel) {

Graphics g = ((JComponent) source).getGraphics();

g.drawOval(x - radius, y - radius, 2 * radius, 2 * radius);

g.setColor(Color.RED);

if (fill) {

g.fillOval(x - radius, y - radius, 2 * radius, 2 * radius);

}

} // else ignore

}*/

public void robo(Rectangle r) throws Exception{

Calendar now = Calendar.getInstance();

Robot robot = new Robot();

BufferedImage screenshot = robot.createScreenCapture(r);

ImageIO.write(screenshot, "PNG", new File(getPath(filePath) + "Screenshot "+formatter.format(now.getTime())+".png"));

}

public static String getPath(String file){

if(f.exists()){

try(BufferedReader br = new BufferedReader(new FileReader(file))){

String sCurrentLine;

while((sCurrentLine = br.readLine()) != null){

return sCurrentLine;

}

} catch(IOException e){

e.printStackTrace();

}

return null;

}

return null;

}

public static int getWidthFromFile(String file){

if(f.exists()){

try(BufferedReader br = new BufferedReader(new FileReader(file))){

br.readLine();

int width = Integer.parseInt(br.readLine());

return width;

} catch(IOException e){

e.printStackTrace();

}

}

return 0;

}

public static int getHeightFromFile(String file){

if(f.exists()){

try(BufferedReader br = new BufferedReader(new FileReader(file))){

br.readLine();

br.readLine();

int height = Integer.parseInt(br.readLine());

return height;

} catch(IOException e){

e.printStackTrace();

}

}

return 0;

}

public static Rectangle rectChecker(int x0, int y0, int x1, int y1){

if(x0 > x1 && y0 < y1){

int x = x1;

int y = y0;

int width = x0 - x1;

int height = y1 - y0;

Rectangle r = new Rectangle(x, y, width, height);

return r;

}

if(x0 < x1 && y0 > y1){

int x = x0;

int y = y1;

int width = x1 - x0;

int height = y0 - y1;

Rectangle r = new Rectangle(x, y, width, height);

return r;

}

if(x0 > x1 && y0 > y1){

int x = x1;

int y = y1;

int width = x0 - x1;

int height = y0 - y1;

Rectangle r = new Rectangle(x, y, width, height);

return r;

}

int x = x0;

int y = y0;

int width = x1 - x0;

int height = y1 - y0;

Rectangle r = new Rectangle(x, y, width, height);

return r;

}

public static void createFile(){

System.out.println(width + " " + height + " " + filePath);

try(PrintWriter writer = new PrintWriter(filePath, "UTF-8")){

writer.println(screenshotPath);

writer.println(width);

writer.println(height);

writer.close();

} catch(IOException ioe){

System.out.println("Call a doctor!");

}

startScreenShotter();

}

public static String slashConverter(String str){

if(str.contains("\\")){

str = str.replace("\\", "/");

if(str.charAt(str.length()-1) != '/'){

str = str + "/";

}

return str;

}

return str;

}

//public void mousePressed(MouseEvent e) {}

//public void mouseReleased(MouseEvent e) {}

public void mouseClicked(MouseEvent e) {}

public void mouseEntered(MouseEvent e) {}

public void mouseExited(MouseEvent e) {}

}