jsp程序实现生成缩略图代码

    java.io.File file = new java.io.File(saveurl);        //读入刚才上传的文件
    String newurl=request.getRealPath("/") url "min_" filename "." ext;  //新的缩略图保存地址
    Image src = javax.imageio.ImageIO.read(file);                     //构造Image对象
    float tagsize=200;
    int old_w=src.getWidth(null);                                     //得到源图宽
    int old_h=src.getHeight(null);  
    int new_w=0;
    int new_h=0;                            //得到源图长
    int temps 教程ize;
    float tempdouble;
    if(old_w>old_h){
     tempdouble=old_w/tagsize;
    }else{
     tempdouble=old_h/tagsize;
    }
    new_w=Math.round(old_w/tempdouble);
    new_h=Math.round(old_h/tempdouble);//计算新图长宽
    BufferedImage tag = new BufferedImage(new_w,new_h,BufferedImage.TYPE_INT_RGB);
    tag.getGraphics().drawImage(src,0,0,new_w,new_h,null);       //绘制缩小后的图
    FileOutputStream newimage=new FileOutputStream(newurl);          //输出到文件流
    JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(newimage);      
    encoder.encode(tag);                                               //近JPEG编码
   
    newimage.close();