在页面中嵌入Applet使用opencv调用摄像头，并显示实时摄像头内容

目的：在页面中嵌入Applet使用opencv调用摄像头，并在applet中显示实时视频中的内容。

软件：opencv.2.4.9

jdk：jdk1.8_0_91

浏览器：IE、火狐

相关技术要点：

1、配置客户端的jdk权限，在jre的lib包目录下java.policy文件中配置需要使用到的权限，在文件最后加上以下内容：

permission java.util.PropertyPermission "java.class.path", "read";
permission java.util.PropertyPermission "sun.arch.data.model", "read";
permission java.util.PropertyPermission "file.encoding","read";
permission java.lang.RuntimePermission "loadLibrary.D:/opencv/build/java/x86/opencv_java249.dll","read"; //  32位jdk

permission java.lang.RuntimePermission "loadLibrary.D:/opencv/build/java/x64/opencv_java249.dll","read"; //  64位jdk

2、在applet添加2个按钮控件，并且添加上【开始】、【停止】的点击事件。在进行开始时启动摄像头并且运行，在停止时关闭摄像头。注意，点击事件时，如果事件没有结束，那么其他的按钮事件是无法同时响应的，所以需要使用多线程的技术进行处理。

3、在opencv中把获取到的mat转换成为bufferedImage对象，使用applet的graphics对象在applet进行渲染。

好了，废话少说，直接上代码：

package test.applet;import java.applet.Applet;import java.awt.Graphics;import java.awt.event.MouseEvent;import java.awt.event.MouseListener;import java.awt.image.BufferedImage;import javax.swing.JButton;import org.opencv.core.Mat;import org.opencv.highgui.VideoCapture;import tools.ImageUtils;public class TestOpencvApplet extends Applet {static boolean isStart = true;static boolean isFristStart = true;/* * (non-Javadoc) *  * @see java.awt.Container#paint(java.awt.Graphics) 每一次切入页面时，都会被调用的该方法 */@Overridepublic void paint(Graphics g) {super.paint(g);System.out.println("this is paint start..."+TestOpencvApplet.isStart);System.out.println("this is paint end...");}@Overridepublic void init() {super.init();this.setLayout(null);this.setSize(640,480);//JButton btnStart = new JButton("开始");btnStart.setBounds(300, 430, 80, 40);btnStart.addMouseListener(new btnListener(this, true));this.add(btnStart);JButton btnStop = new JButton("停止");btnStop.setBounds(400, 430, 80, 40);btnStop.addMouseListener(new btnListener(this, false));this.add(btnStop);//System.out.println(" load library x86 start...");// 32位版本的dll,//String opencv249so = "D:/opencv/build/java/x86/opencv_java249.dll"; String dataModel = System.getProperty("sun.arch.data.model"); // 32还是64位  if("32".equals(dataModel)){ System.load("D:/opencv/build/java/x86/opencv_java249.dll"); }else{ System.load("D:/opencv/build/java/x64/opencv_java249.dll"); }System.out.println(" load library end ...");System.out.println("this is init");}@Overridepublic void destroy() {super.destroy();System.out.println("this is destroy");}@Overridepublic void start() {super.start();System.out.println("this is start"); }public void startCamera() {try {VideoCapture vc = new VideoCapture();//System.out.println("start..capture");//vc.open(0);Graphics g = this.getGraphics();for (int i = 1; i <= 1000 && isStart ; i++) {Mat mat = new Mat();vc.retrieve(mat);BufferedImage image = ImageUtils.Mat2BufferedImage(mat);g.drawImage(image,10,10,400,400,this);if(i%100 == 0){System.out.println("i="+i);}//Thread.sleep(1000);// save// 坑人的地方是第一个参数是height,第二个参数是width// Mat newMat = Mat.eye(mat.height(),mat.width(),mat.type());// Mat newMat = new Mat();// newMat.put(0, 0, b);// byte[] b2 = new byte[len];// newMat.get(0, 0, b2);// System.out.println("newMat.channels()="+newMat.channels()+":"+newMat.type()+":"+newMat.depth());//}g.dispose(); vc.release();} catch (Exception err) {err.printStackTrace();}}@Overridepublic void stop() {// TODO Auto-generated method stubsuper.stop();isStart = false;System.out.println("this is stop");}}class btnListener implements MouseListener,Runnable{TestOpencvApplet applet ;boolean isStartBtn;boolean isBusy = false; public btnListener(TestOpencvApplet applet,boolean isStartBtn) {this.applet = applet;this.isStartBtn = isStartBtn;}@Overridepublic void mouseClicked(MouseEvent e) {// TODO Auto-generated method stub}@Overridepublic void mouseEntered(MouseEvent e) {// TODO Auto-generated method stub}@Overridepublic void mouseExited(MouseEvent e) {// TODO Auto-generated method stub}@Overridepublic void mousePressed(MouseEvent e) {System.out.println("action start? "+isStartBtn+":"+isBusy);TestOpencvApplet.isStart = isStartBtn;System.out.println(System.getProperty("java.class.path"));// 同一时间只允许一个任务if(isStartBtn){if(isBusy){}else{isBusy = true;// 使用多线程进行，否则会等待方法结束才能响应下一次的按钮事件Thread t = new Thread(this);t.start();}}}@Overridepublic void run() {System.out.println("this is run...");applet.startCamera(); isBusy = false;}@Overridepublic void mouseReleased(MouseEvent e) {}}

另外一个工具类代码：

package tools;import java.awt.AlphaComposite;import java.awt.Graphics2D;import java.awt.image.BufferedImage;import java.awt.image.DataBufferByte;import java.io.ByteArrayInputStream;import java.io.IOException;import java.io.InputStream;import javax.imageio.ImageIO;import org.opencv.core.CvType;import org.opencv.core.Mat;import org.opencv.core.MatOfByte;import org.opencv.highgui.Highgui;public class ImageUtils {/** * @description 把BufferedImage转换成为opencv的mat * @param in * @return *  *         public static Mat img2Mat(BufferedImage in){ Mat out; byte[] *         data; int r, g, b; int w = in.getWidth(), h = in.getHeight(); *  *         out = new Mat(h, w, CvType.CV_8UC3); data = new byte[w * h * *         (int) out.elemSize()]; int[] dataBuff = in.getRGB(0, 0, w, h, *         null, 0, w); for (int i = 0; i < dataBuff.length; i++) { data[i * *         3] = (byte) ((dataBuff[i] >> 0) & 0xFF); data[i * 3 + 1] = (byte) *         ((dataBuff[i] >> 8) & 0xFF); data[i * 3 + 2] = (byte) *         ((dataBuff[i] >> 16) & 0xFF); } out.put(0, 0, data); return out; *         } */public static Mat bufferedImage2Mat(BufferedImage in) {BufferedImage image = new BufferedImage(in.getWidth(), in.getHeight(),BufferedImage.TYPE_3BYTE_BGR);// Draw the image onto the new bufferGraphics2D g = image.createGraphics();try {g.setComposite(AlphaComposite.Src);g.drawImage(in, 0, 0, null);} finally {g.dispose();}byte[] pixels = ((DataBufferByte) image.getRaster().getDataBuffer()).getData();Mat mat = Mat.eye(image.getHeight(), image.getWidth(), CvType.CV_8UC3);mat.put(0, 0, pixels);return mat;}public static BufferedImage Mat2BufferedImage(Mat image){BufferedImage buf = null;MatOfByte mob = new MatOfByte(); Highgui.imencode(".jpg", image, mob); byte[] byteArray = mob.toArray(); InputStream in = new ByteArrayInputStream(byteArray); try {buf = ImageIO.read(in);} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();} return buf;}}