java实现图片压缩功能

加哥最近在写代码过程中需要将上传的图片进行自动压缩，但是又不能借助插件，下来就把代码分享给志同道合的小伙伴吧，在运行过程中一定需要注意图片路径输入正确。

1.java借助awt实现图片的压缩的方式一

public static void main(String[] args) {
        try {
            String inputImagePath = "D:\\500540b041a30ad044b5a19344f1b24f.png"; // 输入图片路径
            String outputImagePath = "D:\\500540b041a30ad044b5a19344f1b24f.png"; // 输出图片路径
            int targetSizeKB = 8; // 目标压缩大小（KB）
            BufferedImage image = ImageIO.read(new File(inputImagePath));
            Image compressedImage = compressImage(image, targetSizeKB);
            ImageIO.write((BufferedImage) compressedImage, "jpg", new File(outputImagePath));
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }
    public static Image compressImage(BufferedImage image, int targetSizeKB) {
        // 计算目标图片的尺寸
        long targetSizeBytes = targetSizeKB * 1024;
        long originalSizeBytes = getImageSize(image);
        double compressionRatio = (double) targetSizeBytes / originalSizeBytes;
        int targetWidth = (int) (image.getWidth() * Math.sqrt(compressionRatio));
        int targetHeight = (int) (image.getHeight() * Math.sqrt(compressionRatio));
        // 使用ImageIO进行压缩
        BufferedImage compressedImage = new BufferedImage(targetWidth, targetHeight, BufferedImage.TYPE_INT_RGB);
        compressedImage.getGraphics().drawImage(image.getScaledInstance(targetWidth, targetHeight, Image.SCALE_SMOOTH), 0, 0, null);
        return compressedImage;
    }
    public static long getImageSize(BufferedImage image) {
        File tempFile;
        try {
            tempFile = File.createTempFile("temp", ".tmp");
            ImageIO.write(image, "jpg", tempFile);
            long size = tempFile.length();
            tempFile.delete();
            return size;
        } catch (IOException ex) {
            ex.printStackTrace();
            return 0;
        }
    }

2.java借助awt实现图片的压缩的方式二

public static void main(String[] args) throws IOException {

   // 读取图片文件

  /**File input = new File("D:\\1691455935941.jpg");

   BufferedImage image = ImageIO.read(input);

   // 压缩图片

   BufferedImage compressedImage = compress(image, 0.5f);

   // 保存压缩后的图片

   File output = new File("D:\\");

   ImageIO.write(compressedImage, "jpg", output);**/

  File img = new File("D:\\500540b041a30ad044b5a19344f1b24f.jpg");

   System.out.println("输入的图片大小：" + img.length()/1024 + "KB");

   String outputDir = "D:\\";

   PicUtils.thumbnail_w_h(img, 0,0, outputDir);

}

public static BufferedImage compress(BufferedImage image, float quality) throws IOException {

   // 创建新的图片对象

   BufferedImage compressedImage = new BufferedImage(image.getWidth(), image.getHeight(), BufferedImage.TYPE_INT_RGB);

   // 设置压缩质量

   java.util.Iterator<ImageWriter> iterator = ImageIO.getImageWritersByFormatName("jpg");

   ImageWriter writer = iterator.next();

   ImageWriteParam param = writer.getDefaultWriteParam();

   param.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);

   param.setCompressionQuality(quality);

   // 压缩图片

   writer.setOutput(ImageIO.createImageOutputStream(compressedImage));

   writer.write(null, new IIOImage(image, null, null), param);

   return compressedImage;

}

/**

* 按照指定的宽高压缩原图

* @param img

* @param outputDir

*/

public static void thumbnail(File img, int destWidth, int destHeight,String outputDir){

   System.out.println("图片压缩开始");

   long startTime = System.currentTimeMillis();

   try {

       //读取源图

       BufferedImage BI = ImageIO.read(img);

       double srcWidth = BI.getWidth(); // 源图宽度

       double srcHeight = BI.getHeight(); // 源图高度

       if ((int)srcWidth >= destWidth && (int)srcHeight >= destHeight) {

           String imageFullName = img.getName();

           String prefix = imageFullName.substring(0,imageFullName.lastIndexOf("."));

           String suffix = imageFullName.substring(imageFullName.lastIndexOf("."));

           String newName = prefix+suffix ;

           OutputStream fos =new FileOutputStream(outputDir+File.separatorChar+newName);

           Image image = BI.getScaledInstance(destWidth, destHeight, Image.SCALE_SMOOTH);

           BufferedImage tag = new BufferedImage(destWidth, destHeight,BufferedImage.TYPE_INT_RGB);

           Graphics g = tag.getGraphics();

           g.setColor(Color.RED);

           g.drawImage(image, 0, 0, null); //绘制处理后的图

           g.dispose();

           ImageIO.write(tag, "JPEG", fos);

           System.out.println("图片压缩结束");

           long endTime = System.currentTimeMillis();

           System.out.println("图片压缩共计耗时：" +(endTime-startTime)+"毫秒" );

       }

   } catch (FileNotFoundException e) {

       // TODO Auto-generated catch block

       e.printStackTrace();

   } catch (IOException e) {

       // TODO Auto-generated catch block

       e.printStackTrace();

   }

}

/**

* 按照宽高等比例缩放(缩小或放大)

* @param img

* @param width

* @param height

* @param outputDir

*/

public static void thumbnail_w_h(File img,int destWidth,int destHeight,String outputDir){

   try {

       BufferedImage bi = ImageIO.read(img);

       double srcWidth = bi.getWidth(); // 源图宽度

       double srcHeight = bi.getHeight(); // 源图高度

       double scale = 1;//缩放比例因子，大于1表示放大，小于1表示缩小

       if (destWidth > 0 && destHeight > 0) {

           //下面这个缩放比例因子取值很好理解，目标尺寸和原图尺寸的比值越大，

           //表示缩放的比率越小，也就代表图片变形的越小，就取影响图片变形小的比例因子

           scale = destHeight/srcHeight < destWidth/srcWidth ? destHeight/srcHeight : destWidth/srcWidth;

       }

       thumbnail(img, (int)(srcWidth * scale),(int)(srcHeight * scale),outputDir);

   } catch (IOException e) {

       // TODO Auto-generated catch block

       e.printStackTrace();

   }

}