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 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();
    }
}