java图片压缩工具类

　　1:先导入依赖                      net.coobird             thumbnailator             0.4.8         
　　2:创建工具类import net.coobird.thumbnailator.Thumbnails; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream;  /**  * @PROJECT_NAME: water_chivalry  * @AUTHOR: Hanson-Hsc  * @DATE: 2020-07-27 09:08  * @DESCRIPTION: 图片压缩工具  * @VERSION:  */ public class PicUtils { 　　//以下是常量,按照阿里代码开发规范,不允许代码中出现魔法值     private static final Logger logger = LoggerFactory.getLogger(PicUtils.class);     private static final Integer ZERO = 0;     private static final Integer ONE_ZERO_TWO_FOUR = 1024;     private static final Integer NINE_ZERO_ZERO = 900;     private static final Integer THREE_TWO_SEVEN_FIVE = 3275;     private static final Integer TWO_ZERO_FOUR_SEVEN = 2047;     private static final Double ZERO_EIGHT_FIVE = 0.85;     private static final Double ZERO_SIX = 0.6;     private static final Double ZERO_FOUR_FOUR = 0.44;     private static final Double ZERO_FOUR = 0.4;      /**      * 根据指定大小压缩图片      *      * @param imageBytes  源图片字节数组      * @param desFileSize 指定图片大小，单位kb      * @return 压缩质量后的图片字节数组      */     public static byte[] compressPicForScale(byte[] imageBytes, long desFileSize) {         if (imageBytes == null || imageBytes.length <= ZERO || imageBytes.length < desFileSize * ONE_ZERO_TWO_FOUR) {             return imageBytes;         }         long srcSize = imageBytes.length;         double accuracy = getAccuracy(srcSize / ONE_ZERO_TWO_FOUR);         try {             while (imageBytes.length > desFileSize * ONE_ZERO_TWO_FOUR) {                 ByteArrayInputStream inputStream = new ByteArrayInputStream(imageBytes);                 ByteArrayOutputStream outputStream = new ByteArrayOutputStream(imageBytes.length);                 Thumbnails.of(inputStream)                         .scale(accuracy)                         .outputQuality(accuracy)                         .toOutputStream(outputStream);                 imageBytes = outputStream.toByteArray();             }             logger.info(＂图片原大小={}kb | 压缩后大小={}kb＂,                     srcSize / ONE_ZERO_TWO_FOUR, imageBytes.length / ONE_ZERO_TWO_FOUR);         } catch (Exception e) {             logger.error(＂【图片压缩】msg=图片压缩失败!＂, e);         }         return imageBytes;     }      /**      * 自动调节精度(经验数值)      *      * @param size 源图片大小      * @return 图片压缩质量比      */     private static double getAccuracy(long size) {         double accuracy;         if (size < NINE_ZERO_ZERO) {             accuracy = ZERO_EIGHT_FIVE;         } else if (size < TWO_ZERO_FOUR_SEVEN) {             accuracy = ZERO_SIX;         } else if (size < THREE_TWO_SEVEN_FIVE) {             accuracy = ZERO_FOUR_FOUR;         } else {             accuracy = ZERO_FOUR;         }         return accuracy;     } }
　　3:在上传图片接口处进行压缩
　　/*** 图片上传(招租广告图片专用入口)*/ @PostMapping(＂file/img＂) @ApiOperation(value = ＂图片上传接口(广告图片专用入口)＂) public ResultVo imgUploads(@RequestParam(＂file＂) MultipartFile file) throws IOException {   //压缩图片到指定120K以内,不管你的图片有多少兆,都不会超过120kb,精度还算可以,不会模糊   byte[] bytes = PicUtils.compressPicForScale(file.getBytes(), 120);   ByteArrayInputStream inputStream = new ByteArrayInputStream(bytes);//生成保存在服务器的图片名称，统一修改原后缀名为:jpg   String newFileName = UUID.randomUUID() + ＂.jpg＂;   OSSUtil.upload2(newFileName, inputStream);   JSONObject result = new JSONObject();   result.put(＂url＂, OSSUtil.getUrl2(newFileName, ＂＂));   return ResultVoUtil.success(result); }
　　4.还有一个压缩图片工具类,但是不能指定压缩大小,可是很有用,压缩不会丢失精度,图片也很清晰:
　　import com.bamboo.water_chivalry.common.enums.ResultEnum; import com.bamboo.water_chivalry.common.exception.GlobalException; import org.springframework.web.multipart.MultipartFile; import javax.imageio.ImageIO; import java.awt.*; import java.awt.image.BufferedImage; import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.InputStream;  /**  @DESCRIPTION: 图片压缩工具  @VERSION:*/ public class ImgCompression {  public static InputStream getImageCom(MultipartFile file) throws IOException {   //获取文件输入流   InputStream inputStream = file.getInputStream();   try {     // 把图片读入到内存中     BufferedImage bufImg = ImageIO.read(inputStream);     // 压缩代码,存储图片文件byte数组     ByteArrayOutputStream bos = new ByteArrayOutputStream();     //防止图片变红,这一步非常重要     BufferedImage bufferedImage = new BufferedImage(bufImg.getWidth(), bufImg.getHeight(), BufferedImage.TYPE_INT_RGB);     bufferedImage.createGraphics().drawImage(bufImg,0,0, Color.WHITE,null);     //先转成jpg格式来压缩,然后在通过OSS来修改成源文件本来的后缀格式     ImageIO.write(bufferedImage,＂jpg＂,bos);     //获取输出流     inputStream = new ByteArrayInputStream(bos.toByteArray());     return inputStream;   } catch (IOException e) {     e.printStackTrace();     throw new GlobalException(ResultEnum.IMG_UPLOAD_ERROR);   }finally {     inputStream.close();   } } }