springMVC图片上传的处理方式详解

<dependency>　　<groupId>commons-io</groupId>　　<artifactId>commons-io</artifactId>　　<version>1.3.2</version></dependency><dependency>　　<groupId>commons-fileupload</groupId>　　<artifactId>commons-fileupload</artifactId>　　<version>1.2.1</version></dependency>

<a href="javascript:;" rel="external nofollow" class="a-upload">　　<input class="" type="file" name="file" id="file" required="required">上传</a>

.a-upload { padding: 4px 10px; height: 27px; line-height: 27px; position: relative; cursor: pointer; color: #888; background: #fafafa; border: 1px solid #ddd; border-radius: 4px; overflow: hidden;}.a-upload input { position: absolute; width: 100%; right: 0; top: 0; opacity: 0; filter: alpha(opacity=0); cursor: pointer}.a-upload:hover { color: #444; background: #eee; border-color: #ccc; text-decoration: none}

$('#file').on('change', function () { var $this = $(this); var formData = new FormData(); formData.append('file', $('#file')[0].files[0]); var fileName = $('#file')[0].files[0].name; var fileType = fileName.substring(fileName.lastIndexOf('.') + 1); var fileSize = $('#file')[0].files[0].size; if (fileType != 'jpg' && fileType != 'png' && fileType != 'gif') {  alert("请上传.jpg、.png、.gif格式的图片！");  return; } if (fileSize > 300 * 1024) {  alert("请上传大小小于300KB的图片！");  return; } $.ajax({  url: '/admin/upload',  type: 'POST',  data: formData,  cache: false,  processData: false,  contentType: false }).done(function (result) {  if (result != '') {   $this.closest('div').append('<div class="img-preview"><img src="' + result + '"/></div>');  } else {   alert("请上传.jpg、.png、.gif格式的图片！");  } }).fail(function () {  alert("图片上传失败！"); });});

 @RequestMapping(value = "admin/upload", method = RequestMethod.POST) @ResponseBody public String uploadFile(@RequestParam("file") MultipartFile file) {  try {   String filename = file.getOriginalFilename();   if (filename.endsWith("jpg") || filename.endsWith("png") || filename.endsWith("gif")) {    String prefix = filename.substring(filename.lastIndexOf("."));    String imgName = UUID.randomUUID().toString() + prefix;    String imgUri = writeToFileSystem(imgName, file.getBytes());    return imgUri;   }  } catch (Exception e) {   LOG.error("uploadFile failed:", e);  }  return null; }