方案一：（压缩效果不理想）

  1. package com.soyuan.bigdata;
  3. import com.sun.image.codec.jpeg.JPEGCodec;
  4. import com.sun.image.codec.jpeg.JPEGEncodeParam;
  5. import com.sun.image.codec.jpeg.JPEGImageEncoder;
  7. import javax.imageio.ImageIO;
  8. import java.awt.*;
  9. import java.awt.image.BufferedImage;
  10. import java.io.*;
  12. public class PicReduce {
  13.     /**
  14.      * 直接指定压缩后的宽高：
  15.      * (先保存原文件，再压缩、上传)
  16.      * 壹拍项目中用于二维码压缩
  17.      * @param oldFile 要进行压缩的文件全路径
  18.      * @param width 压缩后的宽度
  19.      * @param height 压缩后的高度
  20.      * @param quality 压缩质量
  21.      * @param smallIcon 文件名的小小后缀(注意，非文件后缀名称),入压缩文件名是yasuo.jpg,则压缩后文件名是yasuo(+smallIcon).jpg
  22.      * @return 返回压缩后的文件的全路径
  23.      */
  24.     public static String zipImageFile(String oldFile, int width, int height,
  25.                                       float quality, String smallIcon) {
  26.         if (oldFile == null) {
  27.             return null;
  28.         }
  29.         String newImage = null;
  30.         try {
  31.             /**对服务器上的临时文件进行处理 */
  32.             Image srcFile = ImageIO.read(new File(oldFile));
  33.             /** 宽,高设定 */
  34.             BufferedImage tag = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
  35.             tag.getGraphics().drawImage(srcFile, 0, 0, width, height, null);
  36.             String filePrex = oldFile.substring(0, oldFile.indexOf('.'));
  37.             /** 压缩后的文件名 */
  38.             newImage = filePrex + smallIcon    + oldFile.substring(filePrex.length());
  39.             /** 压缩之后临时存放位置 */
  40.             FileOutputStream out = new FileOutputStream(newImage);
  41.             JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
  42.             JPEGEncodeParam jep = JPEGCodec.getDefaultJPEGEncodeParam(tag);
  43.             /** 压缩质量 */
  44.             jep.setQuality(quality, true);
  45.             encoder.encode(tag, jep);
  46.             out.close();
  47.         } catch (FileNotFoundException e) {
  48.             e.printStackTrace();
  49.         } catch (IOException e) {
  50.             e.printStackTrace();
  51.         }
  52.         return newImage;
  53.     }
  55.     /**
  56.      * 保存文件到服务器临时路径(用于文件上传)
  57.      * @param fileName
  58.      * @param is
  59.      * @return 文件全路径
  60.      */
  61.     public static String writeFile(String fileName, InputStream is) {
  62.         if (fileName == null || fileName.trim().length() == 0) {
  63.             return null;
  64.         }
  65.         try {
  66.             /** 首先保存到临时文件 */
  67.             FileOutputStream fos = new FileOutputStream(fileName);
  68.             byte[] readBytes = new byte[512];// 缓冲大小
  69.             int readed = 0;
  70.             while ((readed = is.read(readBytes)) > 0) {
  71.                 fos.write(readBytes, 0, readed);
  72.             }
  73.             fos.close();
  74.             is.close();
  75.         } catch (FileNotFoundException e) {
  76.             e.printStackTrace();
  77.         } catch (IOException e) {
  78.             e.printStackTrace();
  79.         }
  80.         return fileName;
  81.     }
  83.     /**
  84.      * 等比例压缩算法：
  85.      * 算法思想：根据压缩基数和压缩比来压缩原图，生产一张图片效果最接近原图的缩略图
  86.      * @param srcURL 原图地址
  87.      * @param deskURL 缩略图地址
  88.      * @param comBase 压缩基数
  89.      * @param scale 压缩限制(宽/高)比例  一般用1：
  90.      * 当scale>=1,缩略图height=comBase,width按原图宽高比例;若scale<1,缩略图width=comBase,height按原图宽高比例
  91.      * @throws Exception
  92.      * @author shenbin
  93.      * @createTime 2014-12-16
  94.      * @lastModifyTime 2014-12-16
  95.      */
  96.     public static void saveMinPhoto(String srcURL, String deskURL, double comBase,
  97.                                     double scale) throws Exception {
  98.         File srcFile = new File(srcURL);
  99.         Image src = ImageIO.read(srcFile);
  100.         int srcHeight = src.getHeight(null);
  101.         int srcWidth = src.getWidth(null);
  102.         int deskHeight = 0;// 缩略图高
  103.         int deskWidth = 0;// 缩略图宽
  104.         double srcScale = (double) srcHeight / srcWidth;
  105.         /**缩略图宽高算法*/
  106.         if ((double) srcHeight > comBase || (double) srcWidth > comBase) {
  107.             if (srcScale >= scale || 1 / srcScale > scale) {
  108.                 if (srcScale >= scale) {
  109.                     deskHeight = (int) comBase;
  110.                     deskWidth = srcWidth * deskHeight / srcHeight;
  111.                 } else {
  112.                     deskWidth = (int) comBase;
  113.                     deskHeight = srcHeight * deskWidth / srcWidth;
  114.                 }
  115.             } else {
  116.                 if ((double) srcHeight > comBase) {
  117.                     deskHeight = (int) comBase;
  118.                     deskWidth = srcWidth * deskHeight / srcHeight;
  119.                 } else {
  120.                     deskWidth = (int) comBase;
  121.                     deskHeight = srcHeight * deskWidth / srcWidth;
  122.                 }
  123.             }
  124.         } else {
  125.             deskHeight = srcHeight;
  126.             deskWidth = srcWidth;
  127.         }
  128.         BufferedImage tag = new BufferedImage(deskWidth, deskHeight, BufferedImage.TYPE_3BYTE_BGR);
  129.         tag.getGraphics().drawImage(src, 0, 0, deskWidth, deskHeight, null); //绘制缩小后的图
  130.         FileOutputStream deskImage = new FileOutputStream(deskURL); //输出到文件流
  131.         JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(deskImage);
  132.         encoder.encode(tag); //近JPEG编码
  133.         deskImage.close();
  134.     }
  136.     public static void main(String args[]) throws Exception {
  137. //        zipImageFile("/Users/tony/Desktop/index.jpg ", 1280, 1280, 1f, "x2");
  138.         String baseDir = "/Users/twx/code-space/company/bigdata/dashboard-heartbeat/heart-beat-core/src/main/resources/static/img/";
  139.         String outDir = "/Users/twx/code-space/company/bigdata/dashboard-heartbeat/heart-beat-core/src/main/resources/static/compress/";
  140.         File dir = new File(baseDir);
  141.         File[] files = dir.listFiles();
  142.         for (File file : files) {
  143.             String name = file.getName();
  144.             System.out.println(file.getPath());
  145.             String suffix = name.substring(name.indexOf(".") + 1);
  146.             if (suffix.equals("png")) {
  147.                 saveMinPhoto(file.getPath(),outDir+name,2000,1);
  148.             }
  149.         }
  150.         /*saveMinPhoto("/Users/twx/code-space/company/bigdata/dashboard-heartbeat/heart-beat-core/src/main/resources/static/img/out_dalian.png",
  151.                 "/Users/twx/code-space/company/bigdata/dashboard-heartbeat/heart-beat-core/src/main/resources/static/img/out_dalian_1.png",
  152.                 2000, 1);*/
  153.     }
  154. }

方案二：（推荐）

github地址：https://github.com/coobird/thumbnailator

pom

<dependency>
  <groupId>net.coobird</groupId>
  <artifactId>thumbnailator</artifactId>
  <version>0.4.8</version>
</dependency>

java

//压缩
Thumbnails.of(filePath)
    .scale(1f)
    .outputQuality(0.5f)
    .toFile(filePath);