<form id="form" enctype="multipart/form-data">        upload image:        <input type="file" id="image_input" name="file" />        <a href="#" onclick="upload()">upload</a>    </form>    <div id="imgDiv"></div>

function upload() {        var imagePath = $("#image_input").val();        if (imagePath == "") {            alert("please upload image file");            return false;        }        var strExtension = imagePath.substr(imagePath.lastIndexOf(‘.‘) + 1);        if (strExtension != ‘jpg‘ && strExtension != ‘gif‘                && strExtension != ‘png‘ && strExtension != ‘bmp‘) {            alert("please upload file that is a image");            return false;        }        $("#form").ajaxSubmit({            type : ‘POST‘,            url : ‘upload/image.do‘,            success : function(data) {                alert("上传成功");                $("#imgDiv").empty();                $("#imgDiv").html(‘<img src="http://www.mamicode.com/‘+data+‘"/>‘);                $("#imgDiv").show();            },            error : function() {                alert("上传失败，请检查网络后重试");            }        });    }

package com.shop.controller;import java.io.File;import java.io.IOException;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestParam;import org.springframework.web.bind.annotation.ResponseBody;import org.springframework.web.multipart.MultipartFile;@Controller@RequestMapping("/upload/")public class ImageUploadController {    /**     * upload image and return the image url     *      * @return     * @throws IOException     * @throws IllegalStateException     */    @RequestMapping("image")    @ResponseBody    public String uploadImage(HttpServletRequest request,            HttpServletResponse response, HttpSession session,            @RequestParam(value = "file", required = true) MultipartFile file)            throws IllegalStateException, IOException {        String path = session.getServletContext().getRealPath("/upload");        System.out.println("real path: " + path);        String fileName = file.getOriginalFilename();        System.out.println("file name: " + fileName);        File targetFile = new File(path, fileName);        if (!targetFile.exists()) {            targetFile.mkdirs();        }        file.transferTo(targetFile);        String fileUrl = request.getContextPath() + "/upload/" + fileName;        return fileUrl;    }}