Java 使用Thumbnails对大图片压缩

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

/**
   * 指定大小进行缩放
   * 
   * @throws IOException
   */
  private void test1() throws IOException {
    /*
     * size(width,height) 若图片横比200小，高比300小，不变
     * 若图片横比200小，高比300大，高缩小到300，图片比例不变 若图片横比200大，高比300小，横缩小到200，图片比例不变
     * 若图片横比200大，高比300大，图片按比例缩小，横为200或高为300
     */
    Thumbnails.of("images/test.jpg").size(200, 300).toFile("C:/image_200x300.jpg");
    Thumbnails.of("images/test.jpg").size(2560, 2048).toFile("C:/image_2560x2048.jpg");
 }

/**
   * 按照比例进行缩放
   * scale 图片的压缩比例 值在0-1之间，1f就是原图，0.5就是原图的一半大小   * outputQuality 图片压缩的质量 值在0-1 之间，越接近1质量越好，越接近0 质量越差
   * @throws IOException
   */
 private void test2() throws IOException {
    /**
     * scale(比例)
     */
    Thumbnails.of("images/test.jpg").scale(0.25f).outputQuality(0.8f).toFile("C:/image_25%.jpg");
    Thumbnails.of("images/test.jpg").scale(0.75f).outputQuality(0.8f).toFile("C:/image_110%.jpg"); }

/**
   * 不按照比例，指定大小进行缩放
   * 
   * @throws IOException
   */
 private void test3() throws IOException {
    /**
     * keepAspectRatio(false) 默认是按照比例缩放的
     */
    Thumbnails.of("images/test.jpg").size(120, 120).keepAspectRatio(false).toFile("C:/image_120x120.jpg"); }

/**
   * 旋转
   * 
   * @throws IOException
   */
 private void test4() throws IOException {
    /**
     * rotate(角度),正数：顺时针 负数：逆时针
     */
    Thumbnails.of("images/test.jpg").size(1280, 1024).rotate(90).toFile("C:/image+90.jpg");
    Thumbnails.of("images/test.jpg").size(1280, 1024).rotate(-90).toFile("C:/iamge-90.jpg");
 }

/**
   * 水印
   * 
   * @throws IOException
   */
 private void test5() throws IOException {
    /**
     * watermark(位置，水印图，透明度)
     */
    Thumbnails.of("images/test.jpg").size(1280, 1024).watermark(Positions.BOTTOM_RIGHT, ImageIO.read(new File("images/watermark.png")), 0.5f)
        .outputQuality(0.8f).toFile("C:/image_watermark_bottom_right.jpg");
    Thumbnails.of("images/test.jpg").size(1280, 1024).watermark(Positions.CENTER, ImageIO.read(new File("images/watermark.png")), 0.5f)
        .outputQuality(0.8f).toFile("C:/image_watermark_center.jpg");
 }

/**
   * 裁剪
   * 
   * @throws IOException
   */
  private void test6() throws IOException {
    /**
     * 图片中心400*400的区域
     */
    Thumbnails.of("images/test.jpg").sourceRegion(Positions.CENTER, 400, 400).size(200, 200).keepAspectRatio(false)
        .toFile("C:/image_region_center.jpg");
    /**
     * 图片右下400*400的区域
     */
    Thumbnails.of("images/test.jpg").sourceRegion(Positions.BOTTOM_RIGHT, 400, 400).size(200, 200).keepAspectRatio(false)
        .toFile("C:/image_region_bootom_right.jpg");
    /**
     * 指定坐标
     */
    Thumbnails.of("images/test.jpg").sourceRegion(600, 500, 400, 400).size(200, 200).keepAspectRatio(false).toFile("C:/image_region_coord.jpg");

  }

/**
   * 转化图片格式
   * 
   * @throws IOException
   */
  private void test7() throws IOException {
    /**
     * outputFormat(图像格式)
     */
    Thumbnails.of("images/test.jpg").size(1280, 1024).outputFormat("png").toFile("C:/image_1280x1024.png");
    Thumbnails.of("images/test.jpg").size(1280, 1024).outputFormat("gif").toFile("C:/image_1280x1024.gif");
  }

/**
   * 输出到OutputStream
   * 
   * @throws IOException
   */
  private void test8() throws IOException {
    /**
     * toOutputStream(流对象)
     */
    OutputStream os = new FileOutputStream("C:/image_1280x1024_OutputStream.png");
    Thumbnails.of("images/test.jpg").size(1280, 1024).toOutputStream(os);
 }

/**
   * 输出到BufferedImage
   * 
   * @throws IOException
   */
  private void test9() throws IOException {
    /**
     * asBufferedImage() 返回BufferedImage
     */
    BufferedImage thumbnail = Thumbnails.of("images/test.jpg").size(1280, 1024).asBufferedImage();
    ImageIO.write(thumbnail, "jpg", new File("C:/image_1280x1024_BufferedImage.jpg"));
 }

/**
   * 对内存中的图片文件进行Base64处理
   * 
   * @throws IOException
  */
  public String Base64ImageByMemory(BufferedImage pic) {
    String imgString = "";
    ByteArrayOutputStream newBaos = new ByteArrayOutputStream();//io流
    try {
      ImageIO.write(pic, "jpg", newBaos);//写入流中
      byte[] bytes = newBaos.toByteArray();//转换成字节
      imgString = URLEncoder.encode(new BASE64Encoder().encode(bytes), "UTF-8");
    } catch (Exception e) {
      e.printStackTrace();
    }
    return imgString;
  }

/**
 * 输出到OutputStream
 * 
 * @throws IOException
 */
 public void getImageFileSize(){
  int size;
  URLConnection conn;
  try {
    String path="";
    path="https://bkimg.cdn.bcebos.com/pic/a8773912b31bb051c36044e93b7adab44bede0af";//世界地图
    //path="http://10.30.23.217:9017/image/0c09ca36-abea-4efa-85b0-99b6d261f66c"; //服务器上图片
    URL url = new URL(path);
    conn = url.openConnection();
    size = conn.getContentLength();
    if (size < 0){
     System.out.println("Could not determine file size.");
    }else{
     System.out.println("The size of file is = " + size + " bytes"); 
     BigDecimal filesize = new BigDecimal(size);
     BigDecimal megabyte = new BigDecimal(1024 * 1024);
     float returnValue = filesize.divide(megabyte, 2, BigDecimal.ROUND_UP).floatValue();
     System.out.println("The size of file is = "+returnValue+"M"); 
    }
    conn.getInputStream().close();
   } catch (IOException e) {
   e.printStackTrace();
  }
 }