java ImageIO很强大，很好用

转载自http://blog.csdn.net/cdl2008sky/article/details/7775681很受益，谢谢

package com.mapbar.graphics;

import java.awt.Graphics;
import java.awt.Image;
import java.awt.Rectangle;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Arrays;
import java.util.Iterator;


import javax.imageio.ImageIO;
import javax.imageio.ImageReadParam;
import javax.imageio.ImageReader;
import javax.imageio.metadata.IIOMetadata;
import javax.imageio.stream.ImageInputStream;


import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;


/**
 * 
 * Class ImageIOTest.java
 * 
 * Description javax.imageio 操作
 * 
 * Company mapbar
 * 
 * author Chenll E-mail: [email protected]
 * 
 * Version 1.0
 * 
 * Date 2012-7-23 上午11:16:17
 */
public class ImageIOTest {


/**
* Java Image I/O API 支持的读入，写出普通的格式，如果需要开发其它格式，还需要第三方插件，eg JIMI, JMagic
*/
public void formatImageNames() {


String[] imageFormats = ImageIO.getReaderFormatNames();
// [jpg, BMP, bmp, JPG, wbmp, jpeg, png, PNG, JPEG, WBMP, GIF, gif]
System.out.println(Arrays.asList(imageFormats));


String[] imageFormats1 = ImageIO.getWriterFormatNames();
// [BMP, bmp, jpg, JPG, wbmp, jpeg, png, PNG, JPEG, WBMP, GIF, gif]
System.out.println(Arrays.asList(imageFormats1));


}


/**
* Image I/O高级操作 ImageReader ImageWriter 通过ImageReader
* 可以获取图片信息而不用把整张图片数据都读入内存。
* 
* @throws IOException
*/
public void imageReaderOp() throws IOException {
Iterator readers = ImageIO
.getImageReadersByFormatName("JPG");
ImageReader reader = readers.next();
// 构造输入源
File bigFile = new File("E:\\big.JPG");
ImageInputStream iis = ImageIO.createImageInputStream(bigFile);
// 输入源和ImageReader关联
reader.setInput(iis, true);
// 获取第一张图片的高度,试图解码文件的必要部分，去获取图片的宽度，而不用读取任何一个象素
int imageIndex = 0;
int width = reader.getWidth(imageIndex);
}


/**
* 控制图片操作，ImageReadParam 可以让程序更好的控制内存，比如指定一个感兴趣的区域
* 
* @throws IOException
*/
public void imageReadParamOp() throws IOException {
int imageIndex = 0;
Iterator readers = ImageIO
.getImageReadersByFormatName("JPG");
ImageReader reader = readers.next();
File bigFile = new File("E:\\big.JPG");
ImageInputStream iis = ImageIO.createImageInputStream(bigFile);
reader.setInput(iis, true);
ImageReadParam irp = reader.getDefaultReadParam();
int halfWidth = reader.getWidth(imageIndex) / 2;
int halfHeight = reader.getHeight(imageIndex) / 2;
Rectangle rect = new Rectangle(0, 0, halfWidth, halfHeight);
irp.setSourceRegion(rect);
BufferedImage bi = reader.read(imageIndex, irp);
ImageIO.write(bi, "JPG", new File("E:\\big_half.JPG"));
}


/**
* 图片元信息
* 
* @throws IOException
*/
public void ImageMetadata() throws IOException {
int imageIndex = 0;
Iterator readers = ImageIO
.getImageReadersByFormatName("JPG");
ImageReader reader = readers.next();
File bigFile = new File("E:\\big.JPG");
ImageInputStream iis = ImageIO.createImageInputStream(bigFile);
reader.setInput(iis, true);
IIOMetadata metadata = reader.getImageMetadata(imageIndex);
}


/**
* 生成缩略图
* 
* @throws IOException
*/
public void generateSmall() throws IOException {
File bigFile = new File("E:\\big.JPG");
Image image = ImageIO.read(bigFile);
int width = image.getWidth(null); // 3264
int height = image.getHeight(null); // 2448
BufferedImage buffi = new BufferedImage(width / 2, height / 2,
BufferedImage.TYPE_INT_RGB);
Graphics g = buffi.getGraphics();
g.drawImage(image, 0, 0, width / 2, height / 2, null);
g.dispose();
ImageIO.write(buffi, "JPG", new File("E:\\small.JPG"));// width:1632 height:1224
}


public static void main(String[] args) throws IOException {
ImageIOTest iot = new ImageIOTest();
iot.generateSmall();
iot.formatImageNames();
iot.imageReaderOp();
iot.imageReadParamOp();
iot.ImageMetadata();
}


}