Java图片裁剪和生成缩略图的实例方法

public class ImageUtil {
 private Logger log = LoggerFactory.getLogger(getClass());
 private static String DEFAULT_PREVFIX = "thumb_";
 private static Boolean DEFAULT_FORCE = false;//建议该值为false
 /**
  * <p>Title: thumbnailImage</p>
  * <p>Description: 根据图片路径生成缩略图 </p>
  * @param imagePath 原图片路径
  * @param w   缩略图宽
  * @param h   缩略图高
  * @param prevfix 生成缩略图的前缀
  * @param force  是否强制按照宽高生成缩略图(如果为false，则生成最佳比例缩略图)
  */
 public void thumbnailImage(String imagePath, int w, int h, String prevfix, boolean force){
  File imgFile = new File(imagePath);
  if(imgFile.exists()){
   try {
    // ImageIO 支持的图片类型 : [BMP, bmp, jpg, JPG, wbmp, jpeg, png, PNG, JPEG, WBMP, GIF, gif]
    String types = Arrays.toString(ImageIO.getReaderFormatNames());
    String suffix = null;
    // 获取图片后缀
    if(imgFile.getName().indexOf(".") > -1) {
     suffix = imgFile.getName().substring(imgFile.getName().lastIndexOf(".") + 1);
    }// 类型和图片后缀全部小写，然后判断后缀是否合法
    if(suffix == null || types.toLowerCase().indexOf(suffix.toLowerCase()) < 0){
     log.error("Sorry, the image suffix is illegal. the standard image suffix is {}." + types);
     return ;
    }
    log.debug("target image's size, width:{}, height:{}.",w,h);
    Image img = ImageIO.read(imgFile);
    if(!force){
     // 根据原图与要求的缩略图比例，找到最合适的缩略图比例
     int width = img.getWidth(null);
     int height = img.getHeight(null);
     if((width*1.0)/w < (height*1.0)/h){
      if(width > w){
       h = Integer.parseInt(new java.text.DecimalFormat("0").format(height * w/(width*1.0)));
       log.debug("change image's height, width:{}, height:{}.",w,h);
      }
     } else {
      if(height > h){
       w = Integer.parseInt(new java.text.DecimalFormat("0").format(width * h/(height*1.0)));
       log.debug("change image's width, width:{}, height:{}.",w,h);
      }
     }
    }
    BufferedImage bi = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
    Graphics g = bi.getGraphics();
    g.drawImage(img, 0, 0, w, h, Color.LIGHT_GRAY, null);
    g.dispose();
    String p = imgFile.getPath();
    // 将图片保存在原目录并加上前缀
    ImageIO.write(bi, suffix, new File(p.substring(0,p.lastIndexOf(File.separator)) + File.separator + prevfix +imgFile.getName()));
    log.debug("缩略图在原路径下生成成功");
   } catch (IOException e) {
    log.error("generate thumbnail image failed.",e);
   }
  }else{
   log.warn("the image is not exist.");
  }
 }
 public static void main(String[] args) {
  new ImageUtil().thumbnailImage("C:/Users/cm/Desktop/我的页面/images/girlNoImg.jpg", 100, 150,DEFAULT_PREVFIX,DEFAULT_FORCE);
 }
}

public class ImageUtil2 {
 private Logger log = LoggerFactory.getLogger(getClass());
 private static String DEFAULT_CUT_PREVFIX = "cut_";
 /**
  * Description: 根据原图与裁切size截取局部图片
  * @param srcImg 源图片
  * @param output 图片输出流
  * @param rect 需要截取部分的坐标和大小
  */
 public void cutImage(File srcImg, OutputStream output,java.awt.Rectangle rect) {
  if (srcImg.exists()) {
   java.io.FileInputStream fis = null;
   ImageInputStream iis = null;
   try {
    fis = new FileInputStream(srcImg);
    // ImageIO 支持的图片类型 : [BMP, bmp, jpg, JPG, wbmp, jpeg, png, PNG,
    // JPEG, WBMP, GIF, gif]
    String types = Arrays.toString(ImageIO.getReaderFormatNames())
      .replace("]", ",");
    String suffix = null;
    // 获取图片后缀
    if (srcImg.getName().indexOf(".") > -1) {
     suffix = srcImg.getName().substring(srcImg.getName().lastIndexOf(".") + 1);
    }// 类型和图片后缀全部小写，然后判断后缀是否合法
    if (suffix == null
      || types.toLowerCase().indexOf(suffix.toLowerCase() + ",") < 0) {
     log.error("Sorry, the image suffix is illegal. the standard image suffix is {}."+ types);
     return;
    }
    // 将FileInputStream 转换为ImageInputStream
    iis = ImageIO.createImageInputStream(fis);
    // 根据图片类型获取该种类型的ImageReader
    ImageReader reader = ImageIO.getImageReadersBySuffix(suffix).next();
    reader.setInput(iis, true);
    ImageReadParam param = reader.getDefaultReadParam();
    param.setSourceRegion(rect);
    BufferedImage bi = reader.read(0, param);
    ImageIO.write(bi, suffix, output);
    log.info("图片生成成功，请到目录下查看");
   } catch (FileNotFoundException e) {
    e.printStackTrace();
   } catch (IOException e) {
    e.printStackTrace();
   } finally {
    try {
     if (fis != null)
      fis.close();
     if (iis != null)
      iis.close();
    } catch (IOException e) {
     e.printStackTrace();
    }
   }
  } else {
   log.warn("the src image is not exist.");
  }
 }
 //生成目标文件路径
 public void cutImage(File srcImg, String destImgPath,java.awt.Rectangle rect) {
  File destImg = new File(destImgPath);
  if (destImg.exists()) {
   String p = destImg.getPath();
   try {
    if (!destImg.isDirectory())
     p = destImg.getParent();
    if (!p.endsWith(File.separator))
     p = p + File.separator;
    cutImage(srcImg,new java.io.FileOutputStream(p + DEFAULT_CUT_PREVFIX+ "_"+ srcImg.getName()), rect);
   } catch (FileNotFoundException e) {
    log.warn("the dest image is not exist.");
   }
  } else
   log.warn("the dest image folder is not exist.");
 }
 public void cutImage(String srcImg, String destImg, int x, int y, int width,
   int height) {
  cutImage(new File(srcImg), destImg, new java.awt.Rectangle(x, y, width, height));
 }
 public static void main(String[] args) {
  new ImageUtil2().cutImage("C:/Users/cm/Desktop/我的页面/images/boyNoImg.jpg", "C:/Users/cm/Desktop/我的页面/images/imgs",0, 0, 61, 166);
  //new ImageUtil2().cutImage("C:/Users/cm/Desktop/Jcrop-master/demos/demo_files/sago.jpg", "C:/Users/cm/Desktop/我的页面/images/imgs",124, 110, 196, 176);
 }
}