java图片压缩

声明：（转载自http://bbs.it-home.org/thread-1036-1-1.html），只做学习交流使用！ 
Java代码： 
/** 
*  缩略图实现，将图片(jpg、bmp、png、gif等等)真实的变成想要的大小 
*/ 
package com.joewalker.test; 

import java.awt.Image; 
import java.awt.p_w_picpath.BufferedImage; 
import java.io.File; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import javax.p_w_picpathio.ImageIO; 
import com.sun.p_w_picpath.codec.jpeg.JPEGCodec; 
import com.sun.p_w_picpath.codec.jpeg.JPEGImageEncoder; 

/******************************************************************************* 
* 缩略图类（通用） 本java类能将jpg、bmp、png、gif图片文件，进行等比或非等比的大小转换。 具体使用方法 
* compressPic(大图片路径,生成小图片路径,大图片文件名,生成小图片文名,生成小图片宽度,生成小图片高度,是否等比缩放(默认为true)) 
*/ 
public class CompressPicDemo { 
         private File file = null; // 文件对象 
         private String inputDir; // 输入图路径 
         private String outputDir; // 输出图路径 
         private String inputFileName; // 输入图文件名 
         private String outputFileName; // 输出图文件名 
         private int outputWidth = 100; // 默认输出图片宽 
         private int outputHeight = 100; // 默认输出图片高 
         private boolean proportion = true; // 是否等比缩放标记(默认为等比缩放) 
         public CompressPicDemo() { // 初始化变量 
                 inputDir = ""; 
                 outputDir = ""; 
                 inputFileName = ""; 
                 outputFileName = ""; 
                 outputWidth = 100; 
                 outputHeight = 100; 
         } 
         public void setInputDir(String inputDir) { 
                 this.inputDir = inputDir; 
         } 
         public void setOutputDir(String outputDir) { 
                 this.outputDir = outputDir; 
         } 
         public void setInputFileName(String inputFileName) { 
                 this.inputFileName = inputFileName; 
         } 
         public void setOutputFileName(String outputFileName) { 
                 this.outputFileName = outputFileName; 
         } 
         public void setOutputWidth(int outputWidth) { 
                 this.outputWidth = outputWidth; 
         } 
         public void setOutputHeight(int outputHeight) { 
                 this.outputHeight = outputHeight; 
         } 
         public void setWidthAndHeight(int width, int height) { 
                 this.outputWidth = width; 
                 this.outputHeight = height; 
         } 
         
         /* 
          * 获得图片大小 
          * 传入参数 String path ：图片路径 
          */ 
         public long getPicSize(String path) { 
                 file = new File(path); 
                 return file.length(); 
         } 
         
         // 图片处理 
         public String compressPic() { 
                 try { 
                         //获得源文件 
                         file = new File(inputDir + inputFileName); 
                         if (!file.exists()) { 
                                 return ""; 
                         } 
                         Image img = ImageIO.read(file); 
                         // 判断图片格式是否正确 
                         if (img.getWidth(null) == -1) { 
                                 System.out.println(" can't read,retry!" + "<BR>"); 
                                 return "no"; 
                         } else { 
                                 int newWidth; int newHeight; 
                                 // 判断是否是等比缩放 
                                 if (this.proportion == true) { 
                                         // 为等比缩放计算输出的图片宽度及高度 
                                         double rate1 = ((double) img.getWidth(null)) / (double) outputWidth + 0.1; 
                                         double rate2 = ((double) img.getHeight(null)) / (double) outputHeight + 0.1; 
                                         // 根据缩放比率大的进行缩放控制 
                                         double rate = rate1 > rate2 ? rate1 : rate2; 
                                         newWidth = (int) (((double) img.getWidth(null)) / rate); 
                                         newHeight = (int) (((double) img.getHeight(null)) / rate); 
                                 } else { 
                                         newWidth = outputWidth; // 输出的图片宽度 
                                         newHeight = outputHeight; // 输出的图片高度 
                                 } 
                                 BufferedImage tag = new BufferedImage((int) newWidth, (int) newHeight, BufferedImage.TYPE_INT_RGB); 
                                 
                                 /* 
                                 * Image.SCALE_SMOOTH 的缩略算法 生成缩略图片的平滑度的 
                                 * 优先级比速度高 生成的图片质量比较好 但速度慢 
                                 */ 
                                 tag.getGraphics().drawImage(img.getScaledInstance(newWidth, newHeight, Image.SCALE_SMOOTH), 0, 0, null); 
                                 FileOutputStream out = new FileOutputStream(outputDir + outputFileName); 
                                 // JPEGImageEncoder可适用于其他图片类型的转换 
                                 JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out); 
                                 encoder.encode(tag); 
                                 out.close(); 
                         } 
                 } catch (IOException ex) { 
                         ex.printStackTrace(); 
                 } 
                 return "ok"; 
        } 
        public String compressPic (String inputDir, String outputDir, String inputFileName, String outputFileName) { 
                // 输入图路径 
                this.inputDir = inputDir; 
                // 输出图路径 
                this.outputDir = outputDir; 
                // 输入图文件名 
                this.inputFileName = inputFileName; 
                // 输出图文件名 
                this.outputFileName = outputFileName; 
                return compressPic(); 
        } 
        public String compressPic(String inputDir, String outputDir, String inputFileName, String outputFileName, int width, int height, boolean gp) { 
                // 输入图路径 
                this.inputDir = inputDir; 
                // 输出图路径 
                this.outputDir = outputDir; 
                // 输入图文件名 
                this.inputFileName = inputFileName; 
                // 输出图文件名 
                this.outputFileName = outputFileName; 
                // 设置图片长宽 
                setWidthAndHeight(width, height); 
                // 是否是等比缩放 标记 
                this.proportion = gp; 
                return compressPic(); 
        } 
        
        // main测试 
        // compressPic(大图片路径,生成小图片路径,大图片文件名,生成小图片文名,生成小图片宽度,生成小图片高度,是否等比缩放(默认为true)) 
        public static void main(String[] arg) { 
                CompressPicDemo mypic = new CompressPicDemo(); 
                System.out.println("输入的图片大小：" + mypic.getPicSize("e:\\1.jpg")/1024 + "KB"); 
                int count = 0; // 记录全部图片压缩所用时间 
                for (int i = 0; i < 100; i++) { 
                        int start = (int) System.currentTimeMillis();        // 开始时间 
                        mypic.compressPic("e:\\", "e:\\test\\", "1.jpg", "r1"+i+".jpg", 120, 120, true); 
                        int end = (int) System.currentTimeMillis(); // 结束时间 
                        int re = end-start; // 但图片生成处理时间 
                        count += re; System.out.println("第" + (i+1) + "张图片压缩处理使用了: " + re + "毫秒"); 
                        System.out.println("输出的图片大小：" + mypic.getPicSize("e:\\test\\r1"+i+".jpg")/1024 + "KB"); 
                } 
                System.out.println("总共用了：" + count + "毫秒"); 
        }