java ImageIO处理

javax.imageio
使用 ImageIO 类的静态方法可以执行许多常见的图像 I/O 操作。 　　
此包包含一些基本类和接口，有的用来描述图像文件内容（包括元数据和缩略图）(IIOImage)；

有的用来控制图像读取过程（ImageReader、ImageReadParam）和控制图像写入过程（ImageWriter 和 ImageWriteParam）；

详细 java ImageIO处理图像的封装例子     http://www.gzhost.net/Artdetail-1609-649.html

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();
	}

}