jcrop+java 后台

 //jcrop 用法  lpf
 //页面引入
 //<link rel="stylesheet" href="${basePath}/scripts/jcrop/jquery.Jcrop.css" type="text/css" />
 //<script src="${basePath}/scripts/jcrop/jquery.Jcrop.js"></script>
 //图片位置<img src="" id="target" style="width: 100%;height:100%;"/>
 //赋值框<form action="${basePath}/success.jsp" method="post" >
         //x轴:<input type="text" size="4" id="x1" name="x" />
         //y轴:<input type="text" size="4" id="y1" name="y"/>
         //宽度:<input type="text" size="4" id="w" name="w"/>
         //高度:<input type="text" size="4" id="h" name="h"/>
         //显示图片宽:<input type="text" size="4" id="tw" name="tw"/>
         //<input type="button" value="裁剪" onclick="uploadImage();"/>
 //</form>
 jQuery(function($){
 //浏览器宽高
 var width=$(window).width();
 var height=$(window).height();
 //图片工具对象
 var jcrop_api,
 boundx="",
 boundy="",
 $preview = $('#preview-pane'),
 $pcnt = $('#preview-pane .preview-container'),
 $pimg = $('#preview-pane .preview-container img'),
 xsize = $pcnt.width(),
 ysize = $pcnt.height();
  $('#target').Jcrop({
     onChange:showCoords,//获取选中的值
     onSelect:showCoords,//获取拖拽的值
     keySupport:true,
     aspectRatio:,
     boxWidth:width,
     boxHeight:height
  },function(){
       var bounds = this.getBounds();
       boundx = bounds[];
       boundy = bounds[];
       jcrop_api = this;
       $preview.appendTo(jcrop_api.ui.holder);
     });
  //赋值
  function showCoords(c){
     var x=c.x;
     var y=c.y;
     var w=c.w;
     var h=c.h;
     $("#x1").val(parseInt(x));
     $("#y1").val(parseInt(y));
     $("#w").val(parseInt(w));
     $("#h").val(parseInt(h));
  if (parseInt(c.w) > ){
         var rx = xsize / c.w;
         var ry = ysize / c.h;
         $pimg.css({
           width: Math.round(rx * boundx) + 'px',
           height: Math.round(ry * boundy) + 'px',
           marginLeft: '-' + Math.round(rx * c.x) + 'px',
           marginTop: '-' + Math.round(ry * c.y) + 'px'
         });
       }
  }
 //更换图片设置
  function upimg(img){
      jcrop_api.setImage(img,function(){
      this.setOptions({
            bgOpacity:0.6,
            minSize: [, ],
              maxSize: [, ]
      });
      var bounds = this.getBounds();
      boundx = bounds[];
      $('#tw').val(boundx);
      this.setSelect(getRandom());
      });
  }
  //随机选择框
  function getRandom() {
      var dim = jcrop_api.getBounds();
      return [
        Math.round(Math.random() * dim[]),
        Math.round(Math.random() * dim[]),
        Math.round(Math.random() * dim[]),
        Math.round(Math.random() * dim[])
      ];
    };
 });

 File fromPic = new File(fileSavePath);
             BufferedImage image = ImageIO.read(fromPic);
             int imageWidth = image.getWidth();
             // 按比例缩放后 输出到 BufferedImage
             BufferedImage thumbnail = Thumbnails.of(fileSavePath)
                     .scale(Double.valueOf(request.getParameter("tw"))
                             / imageWidth)
                             .asBufferedImage();
                     // 截取图片路径，
                     fileSavePath = request.getSession().getServletContext()
                     .getRealPath("/upload")
                     + "/" + upLoadPath + newfilename + "_thum.jpg";
                     //生成截取图片,按照坐标
                     Thumbnails
                     .of(thumbnail)
                     .sourceRegion(
                             Integer.valueOf(request.getParameter("x")),
                             Integer.valueOf(request.getParameter("y")),
                             Integer.valueOf(request.getParameter("w")),
                             Integer.valueOf(request.getParameter("h")))
                     .size(Integer.valueOf(request.getParameter("w")),
                             Integer.valueOf(request.getParameter("h")))
                     .keepAspectRatio(false)
                     .toFile(fileSavePath);

在页面进行截取的时候，如果所操作的图片与原图大小不一致，在后台进行截取的时候就会出现偏差，

此处拿到原图后会与页面显示的图片大小进行比较，计算比例，进行比例缩放，在进行截取