我的Java代码访问限制错误

Question

我正在尝试从我的网络摄像头捕获图像,但我的saveJPG方法中出现了错误.

错误:

Multiple markers at this line
    - Access restriction: The type JPEGCodec is not accessible due to restriction on required library C:\Program Files\Java\jre7\lib\rt.jar
    - Access restriction: The method createJPEGEncoder(OutputStream) from the type JPEGCodec is not accessible due to restriction on required library C:
     \Program Files\Java\jre7\lib\rt.jar
    - Access restriction: The type JPEGImageEncoder is not accessible due to restriction on required library C:\Program Files\Java\jre7\lib\rt.jar

我的saveJPG方法在我所拥有的行中发生此错误

JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
JPEGEncodeParam param = encoder.getDefaultJPEGEncodeParam(bi);  
param.setQuality(0.5f,false);   
encoder.setJPEGEncodeParam(param);    

码:

JButton startC = new JButton("Capturar");
    startC.setPreferredSize(new Dimension(100,22));

    startC.addActionListener(new ActionListener()
            {

                @Override
                public void actionPerformed(ActionEvent e)
                {                   
                      // Grab a frame   
                      FrameGrabbingControl fgc = (FrameGrabbingControl) 
                      player.getControl("javax.media.control.FrameGrabbingControl");    
                      buf = fgc.grabFrame();       

                      // Convert it to an image 
                      btoi = new BufferToImage((VideoFormat)buf.getFormat());   
                      img = btoi.createImage(buf);       

                      // show the image 
                      //imgpanel.setImage(img);       

                      // save image 
                      saveJPG(img,"c:\\test.jpg");
                }
            });     



    public static void saveJPG(Image img, String s) 
          { 
            BufferedImage bi = new BufferedImage(img.getWidth(null), img.getHeight(null), BufferedImage.TYPE_INT_RGB);  
            Graphics2D g2 = bi.createGraphics();    
            g2.drawImage(img, null, null);  
            FileOutputStream out = null;

            try 
            {   
              out = new FileOutputStream(s);    
            }   
            catch (java.io.FileNotFoundException io)    
            {   
              System.out.println("File Not Found"); 
            }   

            JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);

            JPEGEncodeParam param = encoder.getDefaultJPEGEncodeParam(bi);  
            param.setQuality(0.5f,false);   
            encoder.setJPEGEncodeParam(param);     

            try 
            {   
              encoder.encode(bi);   
              out.close();  
            }   
            catch (java.io.IOException io)  
            {   
              System.out.println("IOException");    
            }
          }

进口:

import static com.googlecode.javacv.jna.highgui.cvCreateCameraCapture;
import static com.googlecode.javacv.jna.highgui.cvGrabFrame;
import static com.googlecode.javacv.jna.highgui.cvReleaseCapture;
import com.googlecode.javacv.CanvasFrame;
import com.googlecode.javacv.FrameGrabber;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;
import javax.swing.JApplet;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JComponent;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import com.colorfulwolf.webcamapplet.gui.LabelPanel;
import com.colorfulwolf.webcamapplet.gui.LoadingScreen;
import com.googlecode.javacv.jna.highgui.CvCapture;
import java.awt.BorderLayout;
import javax.media.*;
import javax.media.protocol.*;
import javax.media.util.BufferToImage;
import javax.swing.*;
import java.awt.*;
import java.util.*;
import javax.media.control.*;
import javax.media.format.*;
import com.sun.image.codec.jpeg.*;

Answer 1

Eclipse Java编译器试图阻止您使用非公共API.在经典Java中,可见性概念非常原始,因此库设计者通常必须放入仅供内部使用的公共空间类.对于诸如OSGi之类的更进化的框架,情况并非如此.

如果您仍想访问此课程,可以按照此博客文章中的说明进行操作.

Answer 2

通过遵循以下建议,我能够摆脱这个错误:

1. 打开项目属性.
2. 选择Java Build Path节点.
3. 选择"库"选项卡.
4. 删除JRE系统库.
5. 添加库JRE系统库.