java 2D 語法問題

Question

import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.net.URL;

public class RightSizer
    extends ApplicationFrame {
  private Image mImage;
  private MyImgOb imgob;
  
  public static void main(String[] args) throws Exception {
    String url = &#92;"http://java.oreilly.com/&#92;" + 
        &#92;"news/knudsen/graphics/bite-size_banner.gif&#92;";
    if (args.length > 0) url = args[0];
    new RightSizer(new URL(url));        <-------------------------這一行，該怎麼解釋？    
    
  }
  
  public RightSizer(URL url) {
    super(&#92;"RightSizer v1.0&#92;");
    mImage = (Toolkit.getDefaultToolkit()).getImage(url);
    imgob=new MyImgOb(this);
    rightSize();
  }
  
  protected void rightSize() {
    int width = mImage.getWidth(imgob);
    int height = mImage.getHeight(imgob);
    System.out.println(&#92;"Width= &#92;" + width);
    if (width == -1 || height == -1) return;
    addNotify();
    Insets insets = getInsets();
    setSize(width + insets.left + insets.right,
        height + insets.top + insets.bottom);
    center();
    setVisible(true);
  }

public void update(Graphics g) {
    paint(g);
  }
  
  public void paint(Graphics g) {
    Insets insets = getInsets();
    g.drawImage(mImage, insets.left, insets.top, imgob);
  }
}

Ahiru · Accepted Answer

因為這個程式需要一張圖片( "http://java.oreilly.com/" +
"news/knudsen/graphics/bite-size_banner.gif";)

所以他在開始run的時候, 會建立一個URL物件, 也就是 new URL(url), 傳給這個程式, 讓程式知道到哪裡去download這張圖

java 2D 語法問題

1 Answer