如何使用java从系统摄像头拍摄快照。（How to take a snapshot from system camera using java.）

问题描述 (Problem Description)

如何使用java从系统摄像头拍摄快照。

解决方案 (Solution)

以下是使用java从系统摄像头拍摄快照的程序。

import java.awt.image.BufferedImage;
import java.awt.image.DataBufferByte;
import java.awt.image.WritableRaster;
import java.io.FileNotFoundException;
import java.io.IOException;
import javafx.application.Application;
import javafx.embed.swing.SwingFXUtils;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.image.ImageView;
import javafx.scene.image.WritableImage;
import javafx.stage.Stage;
import org.opencv.core.Core; 
import org.opencv.core.Mat; 
import org.opencv.videoio.VideoCapture;  
public class TakingSnapshotUsingCamera extends Application { 
   Mat matrix = null; 
   @Override 
   public void start(Stage stage) throws FileNotFoundException, IOException {        
      //Capturing the snapshot from the camera 
      TakingSnapshotUsingCamera obj = new TakingSnapshotUsingCamera(); 
      WritableImage writableImage = obj.capureSnapShot();  
      //Setting the image view 
      ImageView imageView = new ImageView(writableImage); 
      //setting the fit height and width of the image view 
      imageView.setFitHeight(400); 
      imageView.setFitWidth(600); 
      //Setting the preserve ratio of the image view 
      imageView.setPreserveRatio(true);  
      //Creating a Group object  
      Group root = new Group(imageView); 
      //Creating a scene object 
      Scene scene = new Scene(root, 600, 400); 
      //Setting title to the Stage 
      stage.setTitle("Capturing an image"); 
      //Adding scene to the satge 
      stage.setScene(scene); 
      //Displaying the contents of the stage 
      stage.show();       
   }
   public WritableImage capureSnapShot() { 
      WritableImage WritableImage = null; 
      //Loading the OpenCV core library  
      System.loadLibrary( Core.NATIVE_LIBRARY_NAME );        
      //Instantiating the VideoCapture class (camera:: 0) 
      VideoCapture capture = new VideoCapture(0);     
      //Reading the next video frame from the camera 
      Mat matrix = new Mat(); 
      capture.read(matrix); 
      //If camera is opened  
      if(capture.isOpened()) { 
         //If there is next video frame 
         if (capture.read(matrix)) {      
            //Creating BuffredImage from the matrix 
            BufferedImage image = new BufferedImage(matrix.width(), matrix.height(), 
               BufferedImage.TYPE_3BYTE_BGR); 
            WritableRaster raster = image.getRaster(); 
            DataBufferByte dataBuffer = (DataBufferByte) raster.getDataBuffer(); 
            byte[] data = dataBuffer.getData(); 
            matrix.get(0, 0, data); 
            this.matrix = matrix; 
            //Creating the Writable Image 
            WritableImage = SwingFXUtils.toFXImage(image, null); 
         } 
      }
      return WritableImage; 
   }  
   public static void main(String args[]) {  
      launch(args);  
   }  
}

输出 (Output)