按一定比例裁剪图片

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package com.cmcc.util;

import java.awt.Rectangle;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.util.Iterator;

import javax.imageio.ImageIO;
import javax.imageio.ImageReadParam;
import javax.imageio.ImageReader;
import javax.imageio.stream.ImageInputStream;
public class ImgHelper {
    /**
     * 剧中裁剪任意比例,理论支持所有图片格式
     * @param file
     * @param a 比例宽度
     * @param b 比例高度
     * @return
     * @throws IOException
     */
     public static InputStream cutCenterImage(File file,int a ,int b) throws IOException{
         ImageInputStream iis = ImageIO.createImageInputStream(file);

         Iterator<ImageReader> iter = ImageIO.getImageReaders(iis);
         ImageReader reader =iter.next();
         String ext=(reader.getFormatName());
        
         reader.setInput(iis, true);
         ImageReadParam param = reader.getDefaultReadParam();
         int imageIndex = 0;
         int x=reader.getWidth(imageIndex);
         int y=reader.getHeight(imageIndex);
         int w,h;
         if((x/y)>=(a/b)){
             if(a/b>1){
                 w=x;
                 h=x*b/a;
             }else{
                 w=y*a/b;
                 h=y;
             }
         }else{
             if(a/b<1){
                 w=y*a/b;
                 h=y;
             }else{
                 w=x;
                 h=x*b/a;
             }
         }
         Rectangle rect = new Rectangle((x-w)/2, (y-h)/2, w, h); 
         param.setSourceRegion(rect);
         BufferedImage bi = reader.read(0,param);  
         ByteArrayOutputStream os = new ByteArrayOutputStream();
         ImageIO.write(bi, ext, os);
         InputStream is = new ByteArrayInputStream(os.toByteArray());
         iis.close();
         return is;
     }
}

 

小伙伴们，我开了一家海淘护肤品淘宝店，搜索店铺“禾子蝶的海淘铺”，正品保证，欢迎进店选购哦。谢谢！