Android 使用java通过摄像头做人脸识别

要使用Java通过摄像头进行人脸识别，需要使用OpenCV库和JavaCV库。以下是基本步骤：

1. 下载安装OpenCV和JavaCV库
2. 创建一个Java工程
3. 在工程中导入OpenCV和JavaCV库
4. 编写代码，调用摄像头并实现人脸识别功能

示例代码：

import org.bytedeco.javacpp.opencv_core;
import org.bytedeco.javacpp.opencv_objdetect;
import org.bytedeco.javacv.FrameGrabber;
import org.bytedeco.javacv.FrameGrabber.Exception;
import org.bytedeco.javacv.OpenCVFrameGrabber;
import org.bytedeco.javacv.OpenCVFrameConverter;
import org.bytedeco.javacv.Java2DFrameConverter;
import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.Graphics;
import java.awt.image.BufferedImage;

public class FaceDetection {

    public static void main(String[] args) throws Exception, InterruptedException {

        //加载OpenCV库
        System.loadLibrary(opencv_core.class.getSimpleName());

        //创建FrameGrabber对象，调用摄像头
        FrameGrabber grabber = new OpenCVFrameGrabber(0);
        grabber.start();

        //创建JFrame窗口，用于显示摄像头的视频流
        JFrame jFrame = new JFrame("Face Detection");
        jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        jFrame.setSize(640, 480);
        JPanel jPanel = new JPanel() {
            private static final long serialVersionUID = 1L;

            @Override
            public void paint(Graphics g) {
                super.paint(g);
                g.drawImage(image, 0, 0, this);
            }
        };
        jFrame.setContentPane(jPanel);
        jFrame.setVisible(true);

        //创建OpenCVFrameConverter对象，将Frame对象转换为Mat对象
        OpenCVFrameConverter.ToMat converterToMat = new OpenCVFrameConverter.ToMat();

        //创建Java2DFrameConverter对象，将Frame对象转换为BufferedImage对象
        Java2DFrameConverter converterToImage = new Java2DFrameConverter();

        //创建CascadeClassifier对象，用于人脸识别
        opencv_objdetect.CascadeClassifier classifier = new opencv_objdetect.CascadeClassifier(
                "haarcascade_frontalface_alt.xml");

        while (true) {

            //获取摄像头的视频流
            opencv_core.Mat mat = converterToMat.convert(grabber.grab());

            //进行人脸识别
            opencv_core.RectVector faces = new opencv_core.RectVector();
            classifier.detectMultiScale(mat, faces);

            //将人脸框出并显示在JFrame窗口中
            BufferedImage image = converterToImage.convert(converterToMat.convert(mat));
            Graphics graphics = jPanel.getGraphics();
            graphics.drawImage(image, 0, 0, null);
            for (int i = 0; i < faces.size(); i++) {
                opencv_core.Rect face = faces.get(i);
                graphics.drawRect(face.x(), face.y(), face.width(), face.height());
            }
            Thread.sleep(100);
        }

    }

}

在该示例中，我们创建了一个JFrame窗口用于显示摄像头的视频流，并使用CascadeClassifier对象进行人脸识别。最后，我们将人脸框出并显示在JFrame窗口中。