Java 模拟 QQ 微信截图功能

这只是简单的模拟，功能略显简陋，可供学习参考。

QQ 截图，点击截图按钮，桌面画面会定住不动，画矩形框截取矩形框内容。若这时你在播放视频你会发现截图时视频画面停止了，但是背景音乐还在继续播放，其实这时只是个障眼法，一张全屏静止图片覆盖了整个电脑屏幕，然后用矩形裁剪静止图片。

这里我们使用 JFrame，两个类，启动类 MainFrame，图片窗口类 ImageFrame。代码参考自网络并作些许修改。

MainFrame

启动类，按钮截全屏并传图片给图片容器 ImageFrame 显示。

import javax.swing.*;
import java.awt.*;
import java.awt.image.BufferedImage;

public class MainFrame extends JFrame {
    JButton capture;

    public MainFrame() {capture = new JButton(" 截图 ");
        Container container = getContentPane();
        container.add(capture);
        setSize(130, 80);
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setAlwaysOnTop(true);
//        居中显示按钮 这里我就不给居中了 直接显示右下角
//        setLocationRelativeTo(null);
        setLocation(Toolkit.getDefaultToolkit().getScreenSize().width - 180, Toolkit.getDefaultToolkit().getScreenSize().height - 100);
        capture.addActionListener(e -> {
//                使自己隐藏
            setVisible(false);
//                截图
            Robot robot = null;
            try {robot = new Robot();
            } catch (AWTException awtException) {awtException.printStackTrace();
            }
            Toolkit toolkit = Toolkit.getDefaultToolkit();
            int width = toolkit.getScreenSize().width;
            int height = toolkit.getScreenSize().height;
            System.out.println(width + "x" + height);
            BufferedImage capture = robot.createScreenCapture(new Rectangle(width, height));
            new ImageFrame(capture);
//                截图后显示
            setVisible(true);
        });
        setVisible(true);
    }

    public static void main(String[] args) {new MainFrame();
    }
}

ImageFrame

显示启动类传来的全屏图片，按住鼠标左键拖动绘制矩形，松开鼠标按 Enter 键保存图片至剪切板，双击鼠标左键保存图片至剪切板并且提示保存至本地的 Windows 图片文件夹。

import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

public class ImageFrame extends JFrame {
    BufferedImage image;
    //    记录鼠标坐标 宽高
    int x, y;
    int w, h;
    boolean flag = false;
    boolean clickState = false;
    Graphics graphics;

    public ImageFrame(BufferedImage image) {
        this.image = image;
        Toolkit toolkit = Toolkit.getDefaultToolkit();
        Dimension screenSize = toolkit.getScreenSize();
        int height = screenSize.height;
        int width = screenSize.width;
        setSize(width, height);
//        无修饰边框
        setUndecorated(true);
        setVisible(true);
//        一旦显示整个面板就绘制图片
        repaint();
        addKeyListener(new KeyListener() {
            @Override
            public void keyTyped(KeyEvent e) { }

            @Override
            public void keyPressed(KeyEvent e) { }

            @Override
            public void keyReleased(KeyEvent e) {System.out.println(e.getKeyCode());
//                esc 退出
                if (e.getKeyCode() == 27) {dispose();
                }
//                Enter 键直接复制图片到剪切板
                if (e.getKeyCode() == 10) {
                    Robot robot = null;
                    try {robot = new Robot();
                        BufferedImage screenCapture = robot.createScreenCapture(new Rectangle(x, y, w, h));
                        setClipboardImage(screenCapture);
                    } catch (AWTException awtException) {awtException.printStackTrace();
                    }
                    dispose();}
            }
        });
//        绘制矩形 注册鼠标监听
//        鼠标按下获取开始坐标 鼠标释放时获得终点坐标
        addMouseListener(new MouseListener() {
            @Override
            public void mouseClicked(MouseEvent e) {
//                鼠标双击截图保存到文件
                if (flag && e.getClickCount() == 2) {
//                    保存矩形内截图
                    try {Robot robot = new Robot();
                        BufferedImage screenCapture = robot.createScreenCapture(new Rectangle(x, y, w, h));
                        setClipboardImage(screenCapture);
                        JFileChooser chooser = new JFileChooser();
                        String dateString = LocalDateTime.now().format(DateTimeFormatter.ofPattern("yyyyMMddHHmmssSSS"));
//                        截图保存 Windows 用户文件夹
                        String imgPath = System.getProperties().getProperty("user.home") + "\\Pictures\\" + dateString + ".jpg";
                        chooser.setSelectedFile(new File(imgPath));
                        int xz = chooser.showSaveDialog(null);
                        String absolutePath = null;
                        if (xz == 0) {
//                      获得用户选择文件
                            File selectedFile = chooser.getSelectedFile();
                            absolutePath = selectedFile.getAbsolutePath();
                            System.out.println(absolutePath);
                        }
//                        写入图片
                        if (absolutePath != null)
                            ImageIO.write(screenCapture, "jpeg", new File(absolutePath));
                    } catch (AWTException | IOException awtException) {awtException.printStackTrace();
                    }
                    dispose();}
            }

            @Override
            public void mousePressed(MouseEvent e) {
                clickState = true;
                if (!flag) {x = e.getXOnScreen();
                    y = e.getY();}
            }

            @Override
            public void mouseReleased(MouseEvent e) {
                clickState = false;
                if (!flag) {w = e.getX() - x;
                    h = e.getY() - y;
                    repaint();
                    flag = true;
                }
            }

            @Override
            public void mouseEntered(MouseEvent e) { }

            @Override
            public void mouseExited(MouseEvent e) {}});

        addMouseMotionListener(new MouseMotionListener() {
            @Override
            public void mouseDragged(MouseEvent e) {if (clickState) {
            //          鼠标移动重绘矩形
                    w = e.getX() - x;
                    h = e.getY() - y;
                    repaint();}
            }

            @Override
            public void mouseMoved(MouseEvent e) {}});

    }

    public static void main(String[] args) {new ImageFrame(null);
    }

    @Override
    public void paint(Graphics g) {super.paint(g);
        g.drawImage(image, 0, 0, null);
        graphics = g;
        g.drawRect(x, y, w, h);
    }


    /**
     * 设置图片到剪切板
     *
     * @param image
     */
    public static void setClipboardImage(final Image image) {Transferable trans = new Transferable() {
            @Override
            public DataFlavor[] getTransferDataFlavors() {return new DataFlavor[]{DataFlavor.imageFlavor};
            }

            @Override
            public boolean isDataFlavorSupported(DataFlavor flavor) {return DataFlavor.imageFlavor.equals(flavor);
            }

            @Override
            public Object getTransferData(DataFlavor flavor)
                    throws UnsupportedFlavorException, IOException {if (isDataFlavorSupported(flavor))
                    return image;
                throw new UnsupportedFlavorException(flavor);
            }

        };
        Toolkit.getDefaultToolkit().getSystemClipboard().setContents(trans,
                null);
    }
}