步骤如下：

(1)在html中定义1个form表单

<form id=”picForm” name=”picForm” action=”uploadPic.htm” enctype=”multipart/form-data” method=”post”>
    <table>
        <tr>
            <td>
                <label>图片：</label>
            </td>
            <td>
                <input id="picUpload" name="picUpload" type="file">
            </td>
        </tr>
        <tr>
            <td colspan=”2″>
            <input type="button" onclick="uploadPic();" value="上传">
            </td>
        </tr>
    </table>
</form>

(2)定义js函数

function uploadPic(){
    if($("#picUpload").val()==''){
        alert("please select picture first!");
        return;
    }
    var data = new FormData();
    data.append('file', document.picForm.picUpload.files[0]);
    $.ajax({
        type: "POST",
        url: "uploadPic.htm",
        processData:false,
        contentType:false,
        data: data,
        success: function (data) {
            var obj = jQuery.parseJSON(data);
            var result = obj.result;
            if(result !="1"){
                alert("Uploade file fail");
            }
            else{
                alert("Uploade file succeed");

            }

        }
    });
}

注意上面的document.picForm.picUpload.files[0]，这里，javascript是通过name属性来找元素的。

(3)服务器端配置

在spring的配置文件里加入以下内容。

<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
    <!-- one of the properties available; the maximum file size in bytes -->
    <property name="maxUploadSize" value="1000000"/>
</bean>

(4)服务器端代码

@Controller
public class MyController {

@RequestMapping("/uploadPic.htm")
@ResponseBody
public void uploadPic(ModelMap modelMap, HttpServletRequest req, HttpServletResponse res)
throws Exception {
      JSONObject json = new JSONObject();
      InputStream input = null;
      OutputStream output = null;
      try{
          MultipartHttpServletRequest multipartReq = (MultipartHttpServletRequest) req;
          MultipartFile rawFile = multipartReq.getFile("file");
          String rawFilename = rawFile.getOriginalFilename();
          String saveFileName = "d:\\"+rawFilename;
          input = rawFile.getInputStream();
          output = new BufferedOutputStream(new FileOutputStream(saveFileName));
          byte[] buffer = new byte[1024];
          int n = -1;
          while ((n = input.read(buffer)) != -1) {
              output.write(buffer, 0, n);
          }
          json.put("result", 1);
          res.setContentType("text/html;charset=utf-8");
          res.getWriter().write(json.toString());
      }
      catch(Exception e){
          json.put("result", 0);
          res.setContentType("text/html;charset=utf-8");
          res.getWriter().write(json.toString());
          return;
      }
      finally{
          input.close();
          output.close();
      }
   }
}