【代码】JCrop头像剪辑预览+后端实现

头像上传的插件似乎要用到的时候非常少，查了下网上提供的插件，有些还是使用GPL协议的，果断弃之。

最终选用了JCrop来实现（补充下JCrop提供多种编辑方式和样式，使用MIT License)。

MIT License：

The MIT License Copyright ©2008 Kelly Hallman and Deep Liquid Group Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

头像上传的部分功能，只要是流程是这样：

1. 用户选择图片，上传至服务器后返回图片地址或其他参数返回给用户界面显示（上传的图片大小要做限制，如果图片大小符合要求但px即像素太大，也需要对图片进行一点比例的缩放处理，再返回）

2. 用户修改或者剪辑图片，根据需要剪辑图片大小和位置（可提供预览界面）

3. 保存图片（保存即将图片选取的坐标值传递至服务器，对图片做剪辑，并缩放至你显示给用户头像的大小）

前端效果一（选择图片）：

效果一代码：

   1: <form action="<%=request.getContextPath() %>/uploadImg.do"

   2:                                         name="imgForm1" enctype="multipart/form-data" method="POST">

   3:                                         <input type="file" name="imgFile" onchange="submit();" />

   4:                                     </form>

前端效果二（服务器返回后生成图片提供编辑）：

前端效果二代码：

   1: <script src="./scripts/jquery.min.js"></script>
   1:  
   2: <script src="./scripts/jquery.Jcrop.js">
   1: </script>
   2: <link rel="stylesheet" href="./css/jquery.Jcrop.css" type="text/css" />
   3: <%
   4: Object imgWO = request.getAttribute("imgWidth");
   5: int imgWidth = 0;
   6: if(null != imgWO) {
   7:     imgWidth = (Integer)imgWO;
   8: }
   9: Object imgHO = request.getAttribute("imgHeight");
  10: int imgHeight= 0;
  11: if(null != imgHO) {
  12:     imgHeight = (Integer)imgHO;
  13: }
  14: %>
  15: <script language="Javascript">
  16:  
  17:             // Remember to invoke within jQuery(window).load(...)
  18:             // If you don't, Jcrop may not initialize properly
  19:             jQuery(window).load(function(){
  20:  
  21:                 jQuery('#cropbox').Jcrop({
  22:                     setSelect: [ 100, 100, 200, 200 ],
  23:                     onChange: showCoords,
  24:                     onSelect: showPreview,
  25:                     aspectRatio: 1
  26:                 });
  27:             });
  28:  
  29:             // Our simple event handler, called from onChange and onSelect
  30:             // event handlers, as per the Jcrop invocation above
  31:             function showPreview(coords)
  32:             {
  33:                 var imgWidth = 300;
  34:                 var imgHeight = 300;
  35:                 var imgW = <%=imgWidth %>;
  36:                 var imgH = <%=imgHeight %>;
  37:                 if(imgW != null && imgW != 0) {
  38:                     imgWidth = imgW;
  39:                 }
  40:                 if(imgH != null && imgH != 0) {
  41:                     imgHeight = imgH;
  42:                 }
  43:             
  44:                 if (parseInt(coords.w) > 0)
  45:                 {
  46:                     var rx = 100 / coords.w;
  47:                     var ry = 100 / coords.h;
  48:  
  49:                     jQuery('#preview').css({
  50:                         width: Math.round(rx * imgWidth) + 'px',
  51:                         height: Math.round(ry * imgHeight) + 'px',
  52:                         marginLeft: '-' + Math.round(rx * coords.x) + 'px',
  53:                         marginTop: '-' + Math.round(ry * coords.y) + 'px'
  54:                     });
  55:                 }
  56:             }
  57:  
  58:             function showCoords(c)
  59:             {
  60:                 $('#x').val(c.x);
  61:                 $('#y').val(c.y);
  62:                 $('#x2').val(c.x2);
  63:                 $('#y2').val(c.y2);
  64:                 $('#w').val(c.w);
  65:                 $('#h').val(c.h);
  66:             };
  67:           
  68:           
  69:         
</script>

   2: <table width="800px">

   3:             <tr>

   4:                 <%
   1:  
   2:                 Object o = request.getAttribute("imgSrc");
   3:                 String imgSrc = "";
   4:                 if(null != o) {
   5:                     imgSrc = (String)o;
   6:                 }
   7:                 
   8:                 Object o1 = request.getAttribute("imgName");
   9:                 String imgName = "";
  10:                 if(null != o1) {
  11:                     imgName = (String)o1;
  12:                 }
  13:                 
%>

   5:                 <td width="400px">

   6:                 <div align="center">

   7:                 <form action="<%=request.getContextPath() %>/uploadImg.do"

   8:                     name="imgForm1" enctype="multipart/form-data" method="POST">

   9:                 <input type="file" name="imgFile" onchange="submit();" /></form>

  10:                 <img src="<%=imgSrc %>" id="cropbox" /></div>

  11:                 </td>

  12:                 <td width="400px">

  13:                 <form action="<%=request.getContextPath() %>/saveImg.do"

  14:                     name="imgForm" method="POST"><input type="hidden"

  15:                     name="imgName" id="imgName" value="<%=imgName %>" /> <label><input

  16:                     type="hidden" size="4" id="x" name="x" /></label> <label><input

  17:                     type="hidden" size="4" id="y" name="y" /></label> <label><input

  18:                     type="hidden" size="4" id="x2" name="x2" /></label> <label><input

  19:                     type="hidden" size="4" id="y2" name="y2" /></label> <label><input

  20:                     type="hidden" size="4" id="w" name="w" /></label> <label><input

  21:                     type="hidden" size="4" id="h" name="h" /></label>

  22:                 <div align="center">

  23:                 <div style="width:100px;height:100px;overflow:hidden;">

  24:                                             <img src="<%=imgSrc %>" id="preview" />

  25:                                         </div><br><br>

  26:                                         <input type="submit" value="保 存" name="submit"/>

  27:                                     </div>

  28:                                     </form> 

  29:                                 </td>

  30:                             </tr>

  31:                         </table>

前端效果三（保存后显示图片）：

后端代码（上传图片+保存图片+缩放图片处理），由于使用SpringMVC，所以这里保存的图片的代码非常简单，你也可以使用smartupload或者commonupload等插件来实现或自己重写：

   1: //上传图片，并返回给浏览器

   2: public ModelAndView uploadImg(HttpServletRequest request,

   3:         HttpServletResponse response) throws Exception {

   4:     ModelAndView mv = new ModelAndView("profileImg.jsp");

   5:     String sourcePath = request.getRealPath("") + "/upload/";

   6:     String serverPath = request.getRealPath("") + "/upload/";

   7:     serverPath = serverPath.replace("\\", "/");

   8:  

   9:     MultipartHttpServletRequest multipartRequest = (MultipartHttpServletRequest) request;

  10:     MultipartFile multipartFile = multipartRequest.getFile("imgFile");

  11:     File file = new File(sourcePath + multipartFile.getOriginalFilename());

  12:     multipartFile.transferTo(file);

  13:  

  14:     BufferedImage bi = ImageIO.read(file);

  15:     int w = bi.getWidth();

  16:     int h = bi.getHeight();

  17:     BufferedImage out = bi.getSubimage(0, 0, w, h);

  18:     out = resizeImage(out, BufferedImage.TYPE_INT_RGB, bi.getWidth(), bi.getHeight());

  19:     ImageIO.write(out, "jpg", file);

  20:     String imgSrc = "upload/" + multipartFile.getOriginalFilename();

  21:     mv.addObject("imgSrc", imgSrc);

  22:     mv.addObject("imgWidth", out.getWidth());

  23:     mv.addObject("imgHeight", out.getHeight());

  24:     mv.addObject("imgName", multipartFile.getOriginalFilename());

  25:     return mv;

  26: }

  27:  

  28: // 保存修剪后的头像

  29: public ModelAndView saveImg(HttpServletRequest request,

  30:         HttpServletResponse response) throws Exception {

  31:     ModelAndView mv = new ModelAndView("profileContent.jsp");

  32:     

  33:     String xStr = request.getParameter("x");

  34:     String yStr = request.getParameter("y");

  35:     String wStr = request.getParameter("w");

  36:     String hStr = request.getParameter("h");

  37:     int x = 0;

  38:     int y = 0;

  39:     int w = 300;

  40:     int h = 300;

  41:     if (null != xStr && !"".equals(xStr)) {

  42:         x = Integer.parseInt(xStr);

  43:     }

  44:  

  45:     if (null != yStr && !"".equals(yStr)) {

  46:         y = Integer.parseInt(yStr);

  47:     }

  48:     if (null != wStr && !"".equals(wStr)) {

  49:         w = Integer.parseInt(wStr);

  50:     } else {

  51:         w = 300;

  52:     }

  53:     if (null != hStr && !"".equals(hStr)) {

  54:         h = Integer.parseInt(hStr);

  55:     } else {

  56:         h = 300;

  57:     }

  58:  

  59:     String imgName = request.getParameter("imgName");

  60:       ServletContext context = getServletContext();

  61:       String  path = context.getRealPath("/") ;

  62:     String  path = request.getRealPath("/") ;

  63:     String sourcePath = path + "upload/";

  64:     String serverPath = path + "upload/" + imgName;

  65:     imgName = MD5.crypt(imgName);

  66:     String hashName = sourcePath + imgName + ".jpg";

  67:     BufferedImage bi = ImageIO.read(new File(serverPath));

  68:  

  69:     BufferedImage out = null;

  70:     if (w > 0 && h >0 && bi.getWidth() >= w && bi.getHeight() >= h) {

  71:         out = bi.getSubimage(x, y, w, h);

  72:     } else {

  73:         out = bi.getSubimage(0, 0, bi.getWidth(), bi.getHeight());

  74:     } 

  75:     

  76:     out = resizeImage(out, BufferedImage.TYPE_INT_RGB, 130, 130);

  77:     ImageIO.write(out, "jpg", new File(hashName));

  78:     response.setHeader("Pragma ", "No-cache ");

  79:     response.setHeader("Cache-Control ", "no-cache ");

  80:     response.setDateHeader("Expires ", 0);

  81:     request.getSession().setAttribute("imgSrc", "upload/" + imgName + ".jpg");

  82:  

  83:     return mv;

  84: }

  85:  

  86: //对图片大小进行缩放处理

  87: public BufferedImage resizeImage(BufferedImage originalImage,

  88:         int type, int width, int height) {

  89:     MathUtil mathUtil = new MathUtil();

  90:     Double rate = 0.0;

  91:     if (width < 300 && height < 300) {

  92:         BufferedImage resizedImage = new BufferedImage(width, height, type);

  93:         Graphics2D g = resizedImage.createGraphics();

  94:         g.drawImage(originalImage, 0, 0, width, height, null);

  95:         g.dispose();

  96:         return resizedImage;

  97:     } else {

  98:         rate = mathUtil.divide(new Double(height), new Double(300));

  99:         height = (int) mathUtil.divide(new Double(height), rate);

 100:         width = (int) mathUtil.divide(new Double(width), rate);

 101:     }

 102:     

 103:     BufferedImage resizedImage = new BufferedImage(width, height, type);

 104:     Graphics2D g = resizedImage.createGraphics();

 105:  

 106:     g.drawImage(originalImage, 0, 0, width, height, null);

 107:     g.dispose();

 108:  

 109:     return resizedImage;

 110: }

由于只是初稿，没有做逻辑和这种异常情况的判断，你可以根据你的需要自己增加。到这基本就完成了。

希望对你有帮助. 如有不足，敬请指出！

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