向JFrame添加图像时出现问题 [英] problem in adding image to JFrame

问题描述

我在向JFrame添加图片时遇到问题，缺少探测器或写入错误。
这里是类：

I'm having problems in adding a picture into JFrame, something is missing probebly or written wrong. here are the classes:

主类：

public class Tester

    {
        public static void main(String args[])
        {
            BorderLayoutFrame borderLayoutFrame = new BorderLayoutFrame();
            borderLayoutFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            borderLayoutFrame.setSize(600,600);
            borderLayoutFrame.setVisible(true);
        }
    }

public class BorderLayoutFrame extends JFrame implements ActionListener 
 {
     private JButton buttons[]; // array of buttons to hide portions
     private final String names[] = { "North", "South", "East", "West", "Center" };
     private BorderLayout layout; // borderlayout object
     private PicPanel picture = new PicPanel();

     // set up GUI and event handling

     public BorderLayoutFrame()
     {
         super( "Philosofic Problem" );
         layout = new BorderLayout( 5, 5 ); // 5 pixel gaps
         setLayout( layout ); // set frame layout
         buttons = new JButton[ names.length ]; // set size of array

         // create JButtons and register listeners for them

         for ( int count = 0; count < names.length; count++ ) 
         {
             buttons[ count ] = new JButton( names[ count ] );
             buttons[ count ].addActionListener( this );
         }
         add( buttons[ 0 ], BorderLayout.NORTH ); // add button to north
         add( buttons[ 1 ], BorderLayout.SOUTH ); // add button to south
         add( buttons[ 2 ], BorderLayout.EAST ); // add button to east
         add( buttons[ 3 ], BorderLayout.WEST ); // add button to west
         add( picture, BorderLayout.CENTER ); // add button to center
    }

    // handle button events

    public void actionPerformed( ActionEvent event )
    {

    } 

  }

我试图将图像添加到

这里是图像类：

public class PicPanel extends JPanel
{
    Image img;
    private int width = 0;
    private int height = 0;

    public PicPanel()
    {
        super();
        img = Toolkit.getDefaultToolkit().getImage("table.jpg");
    }
    public void paintComponent(Graphics g)
    {
         super.paintComponents(g);
         if ((width <= 0) || (height <= 0))
         {
             width = img.getWidth(this);
             height = img.getHeight(this);
         }
         g.drawImage(img,0,0,width,height,this);
    }
}

请你帮忙，有什么问题？
谢谢

Please your help, what is the problem? thanks

BTW：我正在使用eclipse，该图像假定为哪个目录？

BTW: i'm using eclipse, which directory the image suppose to be in?

推荐答案

您发布的代码有几个问题：

There's several issues with the code you've posted:

• 您应该使用 getContentPane（）。add（）而不是简单的 add（）在你的 BorderLayoutFrame class。


• 您应该真正使用 SwingUtilities.invokeLater（）从测试员类启动JFrame。这样的：

• You should use getContentPane().add() instead of simply add() in your BorderLayoutFrame class.
• You should really use SwingUtilities.invokeLater() to launch your JFrame from the tester class. Something like this:

 SwingUtilities.invokeLater(new Runnable() {
    @Override
    public void run() {
        System.setProperty("DEBUG_UI", "true");

        BorderLayoutFrame blf = new BorderLayoutFrame();
        blf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        blf.setSize(600,600);
        blf.setVisible(true);
    }
});

• 不要使用Toolkit加载图片！在下面的代码中，如果Table.jpg与PicPanel在同一个包中，图像将正确加载。



public PicPanel() {
    super();
    try {
        rUrl = getClass().getResource("Table.jpg");
        if (rUrl != null) {
            img = ImageIO.read(rUrl);
        }
    } catch (IOException ex) {
        Logger.getLogger(PicPanel.class.getName()).log(Level.SEVERE, null, ex);
    }
}







• 在 PicPanel.PaintComponent（）你调用 super.paintComponents（）是's'a typeo？



• 在 PicPanel.PaintComponent（）中，您不要需要所有宽度/高度的东西，只需执行以下操作：

  • In PicPanel.PaintComponent() you call super.paintComponents() is the 's' a typeo?

  • In PicPanel.PaintComponent(), you don't need all the width/height stuff, just do this:

    g.drawImage（img，0，0，getWidth（），getHeight（），this）; / p>

  
  

  g.drawImage(img, 0, 0, getWidth(), getHeight(), this);

  避免将super.paintComponent调用在一起，因为您正在绘制图像，为什么要面板要完全绘制？

  And avoid the call to super.paintComponent all together because you're painting an image, why do you want the panel to paint at all?

  我的最终实现你的东西：

  My final implementation of your stuff:

  public class Main {
  
      /**
       * @param args the command line arguments
       */
      public static void main(String[] args) {
          SwingUtilities.invokeLater(new Runnable() {
              @Override
              public void run() {
                  System.setProperty("DEBUG_UI", "true");
  
                  BorderLayoutFrame blf = new BorderLayoutFrame();
                  blf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                  blf.setSize(600,600);
                  blf.setVisible(true);
              }
          });
      }
  
  }
  
  class BorderLayoutFrame extends JFrame implements ActionListener
  {
      private final BorderLayout layout;
      private final JButton[] buttons;
      private final String names[] = {"North", "South", "East", "West", "Center"};
  
      public BorderLayoutFrame() {
          super( "Philosofic Problem" );
          layout = new BorderLayout( 5, 5 );
          getContentPane().setLayout( layout );
          buttons = new JButton[ names.length ];
  
          for (int i=0; i<names.length; i++)
          {
              buttons[i] = new JButton(names[i]);
              buttons[i].addActionListener(this);
          }
  
          getContentPane().add(buttons[0], BorderLayout.NORTH);
          getContentPane().add(buttons[1], BorderLayout.SOUTH);
          getContentPane().add(buttons[2], BorderLayout.EAST);
          getContentPane().add(buttons[3], BorderLayout.WEST);
          getContentPane().add(new PicPanel(), BorderLayout.CENTER);
      }
  
      public void actionPerformed(ActionEvent e) {
          // ignore
      }
  
  }
  
  class PicPanel extends JPanel
  {
      private URL rUrl;
      private BufferedImage img;
  
  
  
      public PicPanel() {
          super();
          try {
              rUrl = getClass().getResource("UtilBtn.png");
              if (rUrl != null) {
                  img = ImageIO.read(rUrl);
              }
          } catch (IOException ex) {
              Logger.getLogger(PicPanel.class.getName()).log(Level.SEVERE, null, ex);
          }
      }
  
      @Override
      protected void paintComponent(Graphics g) {
          //super.paintComponent(g);
  
          g.drawImage(img, 0, 0, getWidth(), getHeight(), this);
      }
  
  }
  

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