图片压缩和缩略图[JAVA]

图片压缩和缩略图[JAVA]

最近工作需要对服务器上面的文件进行压缩，并且把原来一些缩略图进行压缩。贴出代码片断供大家交流。
搜略图实现规定大小画布上缩小图片，方便列表显示。
图片压缩提供了2种方法。1、可以自定义压缩比。2、采用ImageIO进行默认压缩（更安全一些，不会出现内存溢出）。

     private   void  doThumbCompress(File file) {
        
        BufferedImage bis = null ;
        
        BufferedImage bid = null ;
        
         try {

             int  nw =   113 ;  //  定义宽为113
             int  nh =   84 ;  //   定义高为84
            
            bis  =  ImageIO.read(file);
             int  c_w =  bis.getWidth();
             int  c_h =  bis.getHeight();

             if (c_w < 114   &&  file.length() < MIN_LENGTH) {        
                bis  =   null ;
                 return ;
            }
             if (c_w > WIDTH) {
                nw   =  WIDTH;
                nh  =  c_h  *  (WIDTH) / c_w;
                c_h = nh;
                c_w = nw;
            }     
            
             if (c_h > HEIGHT) {
                nh  =  HEIGHT;
                nw   =  c_w  *  (HEIGHT) / c_h;             
            }
            
            
            
            bid =   new  BufferedImage(WIDTH, HEIGHT,BufferedImage.TYPE_INT_RGB);                        
            Graphics g  =  bid.getGraphics();

            g.setColor(Color.white);

            g.fillRect( 0 , 0 , WIDTH, HEIGHT);
            
            g.drawImage(bis,(WIDTH - nw) / 2 , 0 ,nw,nh, null );
            
            
            
             long  oldFileSize = file.length();
            
             
             if (isOverlay) {
                ImageIO.write(bid,  " jpeg " , file);
            }   else {
                ImageIO.write(ImageIO.read(file),  " jpeg " ,  new  File(outPath
                                 + File.separator + file.getName()));
            }
             long  newFileSize = file.length();
            log( " ok: " + file + " \t " + oldFileSize + " \t " + newFileSize);
        }   catch  (Exception e) {
            log(file + "  error: " + e.getMessage());
             
        }
        
        
        bis = null ;
        
        bid = null ;
    }
        

     压缩图片代码：

     /** */ /**
     * 可以自定义压缩比例
     * @param file
     */
     private   void  doCompressQuality(File file)   {
        BufferedImage src = null;
        FileOutputStream out =  null;
        JPEGImageEncoder encoder = null;
        JPEGEncodeParam  param   = null;
        
        try{
            src= ImageIO.read(file);//or png.
            if(isOverlay){
                out= new FileOutputStream(file);
            }else{
                out= new FileOutputStream(outPath+File.separator+file.getName());
            }
            encoder= JPEGCodec.createJPEGEncoder(out);
            param= encoder.getDefaultJPEGEncodeParam(src);            
            param.setQuality(imageQuality, false);
            encoder.setJPEGEncodeParam(param);            
            encoder.encode(src);//近JPEG编码
            out.close();
            //ImageIO.write(src, "jpeg", new File(outPath+File.separator+file.getName()));            
            log("over:"+file.getPath());
        } catch (IOException e){
            log("compress error:"+file.getPath()+";error:"+e.getMessage());
        }
        out = null;
        encoder = null;
        param   = null;
        src     = null;
    }

     /** */ /**
     * 压缩图片，默认压缩比例75%
     * @param file
     */
     private   void  doCompress(File file) {
        File descFile = null;
        boolean writeOk=false;
        long fileSize=file.length();

        try{
            
            if(isOverlay){                
                descFile = file;
                writeOk = ImageIO.write(ImageIO.read(file), "jpeg", descFile);
            }else{
                descFile = new File(outPath+File.separator+file.getName());
                writeOk = ImageIO.write(ImageIO.read(file), "jpeg", descFile);
            }        
            
            if(writeOk){
                log("ok:"+file.getPath()+"\t"+fileSize+"\t"+descFile.length());
            }else{
                log("fail:"+file.getPath()+"\t"+fileSize+"\t"+descFile.length());
            }            
            
        } catch (Exception e){
            log("compress error:"+file.getPath()+";descFile="+descFile+";error:"+e.getMessage());
        }
        descFile=null;
    }