我的 Java 代码上的访问限制错误

Access restriction error on my Java Code

提问by Lucas_Santos

I'm trying to capture the image from my webcam, but I got the error in my saveJPGmethod.

我正在尝试从我的网络摄像头捕获图像，但我的saveJPG方法出错了。

ERROR:

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

This error occurs in my saveJPGmethod in the line where I have

这个错误发生在我的saveJPG方法中

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

CODE:

代码：

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");    
            }
          }

IMPORTS:

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.*;

回答by S. Cambon

The Eclipse Java compiler attempts to prevent you from using non-public APIs. In classic Java, the visibility concept is quite primitive and therefore library designers often have to put in the public space classes solely created for internal use. This is not the case with more evolved frameworks such as OSGi.

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，因此库设计者通常不得不将专为内部使用而创建的公共空间类放入。更先进的框架（如 OSGi）并非如此。

If you still want to access this class, you can do as described in this blog post.

如果你仍然想访问这个类，你可以按照这篇博文中的描述进行。

回答by user2542398

I was able to get rid of this error by following the suggestion:

我能够按照建议摆脱这个错误：

1. Open project properties.
2. Select Java Build Path node.
3. Select Libraries tab.
4. Remove JRE System Library.
5. Add Library JRE System Library.

1. 打开项目属性。
2. 选择 Java 构建路径节点。
3. 选择库选项卡。
4. 删除 JRE 系统库。
5. 添加库 JRE 系统库。