前台代码

上传图片按钮

<a href="javascript:void(0)" onclick="uploadPhoto()">选择图片</a>

隐藏的文件选择器

<input type="file" id="photoFile" style="display: none;" onchange="upload()">

图片预览

<img id="preview_photo" src="" width="200px" height="200px">

去除图片预览未选择时默认时的边框

<style>img[src=""],img:not([src]){opacity:0;}
</style>

JavaScript部分

<script>function uploadPhoto() {$("#photoFile").click();}/*** 上传图片*/function upload() {if ($("#photoFile").val() == '') {return;}var formData = new FormData();formData.append('photo', document.getElementById('photoFile').files[0]);$.ajax({url:"${pageContext.request.contextPath}/system/uploadPhoto",type:"post",data: formData,contentType: false,processData: false,success: function(data) {if (data.type == "success") {$("#preview_photo").attr("src", data.filepath+data.filename);$("#productImg").val(data.filename);} else {alert(data.msg);}},error:function(data) {alert("上传失败")}});}
</script>

后台代码

    /*** 图片上传* @param photo* @param request* @return*/@RequestMapping(value = "/uploadPhoto", method = RequestMethod.POST)@ResponseBodypublic Map<String, String> uploadPhoto(MultipartFile photo, HttpServletRequest request) {Map<String, String> ret = new HashMap<String, String>();if (photo == null) {ret.put("type", "error");ret.put("msg", "选择要上传的文件！");return ret;}if (photo.getSize() > 1024 * 1024 * 10) {ret.put("type", "error");ret.put("msg", "文件大小不能超过10M！");return ret;}//获取文件后缀String suffix = photo.getOriginalFilename().substring(photo.getOriginalFilename().lastIndexOf(".") + 1, photo.getOriginalFilename().length());if (!"jpg,jpeg,gif,png".toUpperCase().contains(suffix.toUpperCase())) {ret.put("type", "error");ret.put("msg", "请选择jpg,jpeg,gif,png格式的图片！");return ret;}//获取项目根目录加上图片目录 webapp/static/imgages/upload/String savePath = request.getSession().getServletContext().getRealPath("/") + "/static/images/upload/";File savePathFile = new File(savePath);if (!savePathFile.exists()) {//若不存在该目录，则创建目录savePathFile.mkdir();}String filename = new Date().getTime() + "." + suffix;try {//将文件保存指定目录photo.transferTo(new File(savePath + filename));} catch (Exception e) {ret.put("type", "error");ret.put("msg", "保存文件异常！");e.printStackTrace();return ret;}ret.put("type", "success");ret.put("msg", "上传图片成功！");ret.put("filepath", request.getSession().getServletContext().getContextPath() + "/static/images/upload/");ret.put("filename", filename);return ret;}