java压缩图片大小

package com.xxq.util;
import java.awt.Image;
//旧的jpeg处理类
//import com.sun.image.codec.jpeg.*; 
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;

import javax.imageio.IIOImage;
import javax.imageio.ImageIO;
import javax.imageio.ImageTypeSpecifier;
import javax.imageio.metadata.IIOMetadata;
import javax.imageio.plugins.jpeg.JPEGImageWriteParam;
import javax.imageio.stream.ImageOutputStream;

import com.sun.imageio.plugins.jpeg.JPEGImageWriter;



/**
 * 
 * @author Administrator
 *
 */
public class ImgCompressUtil {

	/**
	 * log4j
	 */
	private final static Logger logger = Logger.getLogger(ImgCompressUtil.class
			.getName());

	/**
	 * 图片压缩测试
	 * 
	 * @param args
	 */
	public static void main(String args[]) {
		// 图片url，压缩后的宽和高
		String url = "D:/111.jpg";
		int w = 700;
		int h = 500;
		//压缩后的图片路径
			String newName = MD5Util.MD5(url);
			String newDir = "D:/";
			String filePath = newDir + newName + "_"
					+ w + "_" + h + url.substring(url.indexOf("."));
		//压缩
		ImgCompress(url,url,w,h);//url,filePath,w,h
	}

	/**
	 * 外部调用方法
	 * @param url
	 * @param w
	 * @param h
	 */
	public static String ImgCompress(String url, String filePath, int w, int h) {
			// 压缩质量 百分比
			float JPEGcompression = 0.7f;

			// 本地图片存储路径
			String name = url.substring(url.lastIndexOf("/") + 1);
						
			// 截取url中最后一个“/”之后的字符串为name
			logger.info("url：===========" + url);
			logger.info("name：=========" + name);
			
			//压缩主方法
			 return ImgCompress(filePath, url, name, w, h, JPEGcompression);
		
	}
	
	/**
	 * 图片压缩主方法
	 * 
	 * @param newDir
	 *            图片所在的文件夹路径
	 * @param file
	 *            图片路径
	 * @param name
	 *            图片名
	 * @param w
	 *            目标宽
	 * @param h
	 *            目标高
	 * @param JPEGcompression
	 *            压缩质量/百分比
	 * @author zhouqz
	 */
	public static String ImgCompress(String filePath, String url, String name,
			int w, int h, float JPEGcompression) {
		File file = new File(url);
		if (!(file.exists() && file.canRead())) {
			filePath = "/var/upload/404.jpg";
		}else{
			try {
				BufferedImage bufferedImage =  ImageIO.read(file);

				int new_w = w;
				int new_h = h; 

				BufferedImage image_to_save = new BufferedImage(new_w, new_h,
						bufferedImage.getType());
				image_to_save.getGraphics().drawImage(
						bufferedImage.getScaledInstance(new_w, new_h, Image.SCALE_SMOOTH), 0,
						0, null);
				FileOutputStream fos = new FileOutputStream(filePath); // 输出到文件流

				// 旧的使用 jpeg classes进行处理的方法
				// JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(fos);
				// JPEGEncodeParam jep =
				// JPEGCodec.getDefaultJPEGEncodeParam(image_to_save);
				/* 压缩质量 */
				// jep.setQuality(per, true);
				// encoder.encode(image_to_save, jep);

				// 新的方法
				int dpi = 300;//分辨率
				saveAsJPEG(dpi, image_to_save, JPEGcompression, fos);
				//关闭输出流
				fos.close();
				//返回压缩后的图片地址
			} catch (IOException ex) {
				logger.log(Level.SEVERE, null, ex);
				filePath = "/var/upload/404.jpg";
			}
		}
		
		return filePath;
		
	}

	/**
	 * 以JPEG编码保存图片
	 * 
	 * @param dpi
	 *            分辨率
	 * @param image_to_save
	 *            要处理的图像图片
	 * @param JPEGcompression
	 *            压缩比
	 * @param fos
	 *            文件输出流
	 * @throws IOException
	 */
	public static void saveAsJPEG(Integer dpi, BufferedImage image_to_save,
			float JPEGcompression, FileOutputStream fos) throws IOException {

		// useful documentation at
		// http://docs.oracle.com/javase/7/docs/api/javax/imageio/metadata/doc-files/jpeg_metadata.html
		// useful example program at
		// http://johnbokma.com/java/obtaining-image-metadata.html to output
		// JPEG data

		// old jpeg class
		// com.sun.image.codec.jpeg.JPEGImageEncoder jpegEncoder =
		// com.sun.image.codec.jpeg.JPEGCodec.createJPEGEncoder(fos);
		// com.sun.image.codec.jpeg.JPEGEncodeParam jpegEncodeParam =
		// jpegEncoder.getDefaultJPEGEncodeParam(image_to_save);

		// Image writer
		JPEGImageWriter imageWriter = (JPEGImageWriter) ImageIO
				.getImageWritersBySuffix("jpg").next();
		ImageOutputStream ios = ImageIO.createImageOutputStream(fos);
		imageWriter.setOutput(ios);
		// and metadata
		IIOMetadata imageMetaData = imageWriter.getDefaultImageMetadata(
				new ImageTypeSpecifier(image_to_save), null);

		// if(dpi != null && !dpi.equals("")){
		//
		// //old metadata
		// //jpegEncodeParam.setDensityUnit(com.sun.image.codec.jpeg.JPEGEncodeParam.DENSITY_UNIT_DOTS_INCH);
		// //jpegEncodeParam.setXDensity(dpi);
		// //jpegEncodeParam.setYDensity(dpi);
		//
		// //new metadata
		// Element tree = (Element)
		// imageMetaData.getAsTree("javax_imageio_jpeg_image_1.0");
		// Element jfif =
		// (Element)tree.getElementsByTagName("app0JFIF").item(0);
		// jfif.setAttribute("Xdensity", Integer.toString(dpi) );
		// jfif.setAttribute("Ydensity", Integer.toString(dpi));
		//
		// }

		if (JPEGcompression >= 0 && JPEGcompression <= 1f) {

			// old compression
			// jpegEncodeParam.setQuality(JPEGcompression,false);

			// new Compression
			JPEGImageWriteParam jpegParams = (JPEGImageWriteParam) imageWriter
					.getDefaultWriteParam();
			jpegParams.setCompressionMode(JPEGImageWriteParam.MODE_EXPLICIT);
			jpegParams.setCompressionQuality(JPEGcompression);

		}

		// old write and clean
		// jpegEncoder.encode(image_to_save, jpegEncodeParam);

		// new Write and clean up
		imageWriter.write(imageMetaData,
				new IIOImage(image_to_save, null, null), null);
		ios.close();
		imageWriter.dispose();

	}

}