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.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import javax.imageio.ImageIO;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.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");
        }
}java图片压缩