AWT 中加载和显示图像的方法[zz]

Java 提供大量加载和显示图像的方法，可以使用 ImageIO，Jimi 或 JAI 中提供的一些 API，在这里简单地说几种 AWT 中加载和显示图像的方法。

1、使用 java.applet.Applet 提供的 getImage() 方法

abstract  Image	getImage(String filename)           Returns an image which gets pixel data from the specified file, whose format can be either GIF, JPEG or PNG.
abstract  Image	getImage(URL url)           Returns an image which gets pixel data from the specified URL.

import java.net.URL;
import java.applet.Applet;
import java.awt.Graphics;
import java.awt.Image;

public class ImageTestAppletSimple
    extends Applet {
  private Image im;

  public void init() {
    // 指定这个 applet 位置的 URL
    URL codebase = getCodeBase();

    im = getImage(codebase, "lena.jpg");
  }

  public void paint(Graphics g) {
    g.drawImage(im, 0, 0, this);
  }
}

2、使用 java.awt.Toolkit 提供的 getImage() 方法

abstract  Image	getImage(String filename)           Returns an image which gets pixel data from the specified file, whose format can be either GIF, JPEG or PNG.
abstract  Image	getImage(URL url)           Returns an image which gets pixel data from the specified URL.

import java.awt.*;
import java.awt.event.*;

public class ImageTestApplication
    extends Frame {
  Insets insets;
  Image im;

  static public void main(String args[]) {
    ImageTestApplication app = new ImageTestApplication();
    app.show();
  }

  public ImageTestApplication() {
    super("Image Test");
    im = Toolkit.getDefaultToolkit().getImage("lena.jpg");

    addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent event) {
        dispose();
        System.exit(0);
      }
    });
  }

  public void addNotify() {
    super.addNotify();
    insets = getInsets();
    setBounds(100, 100, 300 + insets.left, 300 + insets.top);
  }

  public void paint(Graphics g) {
    g.drawImage(im, insets.left, insets.top, this);
  }
}

3、将图像作为资源加载

·java.lang.Class<t></t> 提供的下面2个方法加载资源

URL	getResource(String name)           Finds a resource with a given name.
InputStream	getResourceAsStream(String name)           Finds a resource with a given name.

·java.awt.Component 中提供方法来创建图像

Image	createImage(ImageProducer producer)           Creates an image from the specified image producer.
Image	createImage(int width, int height)           Creates an off-screen drawable image to be used for double buffering.

·java.awt.Toolkit 中提供方法来创建图像

Image	createImage(byte[] imagedata)           Creates an image which decodes the image stored in the specified byte array.
abstract  Image	createImage(byte[] imagedata, int imageoffset, int imagelength)           Creates an image which decodes the image stored in the specified byte array, and at the specified offset and length.
abstract  Image	createImage(ImageProducer producer)           Creates an image with the specified image producer.
abstract  Image	createImage(String filename)           Returns an image which gets pixel data from the specified file.
abstract  Image	createImage(URL url)           Returns an image

 

import java.applet.Applet;
import java.net.URL;
import java.awt.*;
import java.awt.image.ImageProducer;
import java.awt.event.*;

public class Test
    extends Applet {
  Image im;

  public void start() {
    URL url = getClass().getResource("lena.jpg");

    try {
      im = createImage( (ImageProducer) url.getContent());

      if (im == null) {
        System.out.println("null image");
      }

    }
    catch (Exception e) {
      e.printStackTrace();
    }
  }

  public void paint(Graphics g) {
    Insets insets = getInsets();

    g.drawImage(im, insets.left, insets.top, this);
  }

  public void update(Graphics g) {
    paint(g);
  }
}