form表单图片上传

1、前端页面

<div class="tkDiv" id="addLOGO" style="display:none;z-index:12;width:800px;height:auto;margin-left:-400px;margin-top: -160px">

	  		<div class="tk1_header" style="width:800px;height:40px;line-height:40px;background: #263552 !important;color: #ffffff !important;margin-left:-10px;margin-top:-10px;">
	  			<span style="font-size: 16px;margin-left:20px;color:#FFF" id="gn_title">添加主页图片</span>
	  			<a id="close_modal" style="width:30px;height:20px;background-size:20px;float: right;">×</a>
	  		</div>

	  		<div class="tk1" id="addZ" style="width:750px;height:200px;">
	  		<div class="tk1_content" id="registerDiv" style="width:750px;">
	  			<form id="imageForm" class="bs-docs-example form-horizontal" method="post" action="<%=path %>/webCenter.do" enctype="multipart/form-data">
	  			<input type="hidden" name="method" value="saveConferencesImage">
				<input type="hidden" id="imageId" name="imageId" value="-1">
		  			<table style="width:750px">
		  				<tr height="50px">
		  					<td align="right" width="150px" >
		  						图片名称
		  					</td>
		  					<td>
		  						<input id="imageName" class="form-control" name="imageName" type="text" style="margin-left:40px;display:inline-block;height:34px;"/>
		  					</td>
		  				</tr>
		  				<tr height="50px">
		  					<td align="right" width="150px" >
		  						上传图片
		  					</td>
		  					<td>
		  						<input id="imageFile"  name="imageFile" type="file" style="margin-left:40px;display:inline-block;height:34px;"/>
		  					</td>
		  				</tr>
		  			</table>
		  		</form>
	  		</div>
	  		<div style="border-top: 1px solid rgba(0, 0, 0, 0.1);text-align: center;">
	  			<input id="saveBtn" type="button" class="button" value="添　加" style="border-radius:0;width:260px;height:40px;margin:auto 50px;margin:20px; background: #263552 !important;color: #ffffff !important;"/>
	  		</div>
	  	</div>

　　2、js代码

$(function(){
		$("#saveBtn").click(function(){
			var imageName = $("#imageName").val();
			var imageFile = $("#imageFile").val();
			if(imageName == '' || imageName.length == 0){
				alert("请输入图片名称");
				return;
			}if(imageFile == '' || imageFile.length == 0){
				alert("请选择要上传的图片");
				return;
			}
			var formData = new FormData();
	            formData.append("imagePath", $("#imageFile")[0].files[0]);
			$.ajax({
				url:"<%=path%>/webCenter.do?uploadConImage",
				type:"post",
				data:formData,
				dataType:"json",
				// 告诉jQuery不要去处理发送的数据
	            processData: false,
	            // 告诉jQuery不要去设置Content-Type请求头
	            contentType: false,
	            beforeSend: function () {
	               console.log("正在进行，请稍候");
	            },
				success:function(data){
					if(data.state == 0){
						alert(data.msg)
					}else{
						$("#imageForm").submit();
					}
				}
			})
		})
}）

　　3、后台数据处理

　　① 第一步验证图片大小

//判断图片大小，不是这个大小的提示不能上传
@RequestMapping(params = "uploadConImage",method = RequestMethod.POST)
	public void uploadConImage(HttpServletRequest request,HttpServletResponse response){
		try{
			MultipartHttpServletRequest mRequest = (MultipartHttpServletRequest) request;
			MultipartFile mFile = mRequest.getFile("imagePath");
			InputStream is = mFile.getInputStream();//输入流
			BufferedImage bufferedImg = ImageIO.read(is);
			int width = bufferedImg.getWidth();//获取图片宽高
			int height = bufferedImg.getHeight();
			JSONObject json = new JSONObject();

			if(width != 500 && height != 300){
				float bili = (float)(new Float(height)/new Float(width));
				float   b   =   (float)(Math.round(bili*100))/100;
				if(b != new Float(0.45)){
					json.accumulate("state", 0);
					json.accumulate("msg", "请上传分辨率为500*300的图片或者长宽比为0.6的图片(高除以宽为0.6)");
				}else{
					json.accumulate("state", 1);
				}
			}else{
				json.accumulate("state", 1);
			}
			writeJson(response, json.toString());
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

　　② 在js里面用$("#imageForm").submit();提交form表单，上传图片。注意：用form表单上传图片时，在from表单上要添加  enctype="multipart/form-data"  属性。form表单看上面代码，下面是后台数据处理。

@RequestMapping(params = "method=saveConferencesImage",method = RequestMethod.POST)
	public void saveConferencesImage(int imageId,String imageName,HttpServletRequest request,HttpServletResponse response){
		try {
			HttpSession session  = this.getSession(request);
			Adminuser adminUser = session.getAttribute("centerAdminUser") == null?null:(Adminuser) session.getAttribute("centerAdminUser");
			if(adminUser == null){
				try {
					response.sendRedirect(request.getContextPath()+"/center/index.jsp");
				} catch (Exception e) {
					e.printStackTrace();
				}
			}else{
				String conId = request.getSession().getAttribute("conId") == null ? null: request.getSession().getAttribute("conId").toString();
				if (conId == null) {
					response.sendRedirect(request.getContextPath()+"/center/index.jsp");
				}
				Conferences conferences = webService.getConferencesById(Integer.parseInt(conId));
				ConferencesImage conferencesImage = null;
				if(imageId == -1){
					conferencesImage = new ConferencesImage();
				}else{
					conferencesImage = webService.getConferencesImageById(imageId);
				}
				conferencesImage.setConferencesId(Integer.parseInt(conId));
				conferencesImage.setImageName(imageName);
				int level = webService.getConferencesImageLevel(Integer.parseInt(conId));
				conferencesImage.setLevel(level);
				MultipartHttpServletRequest mRequest = (MultipartHttpServletRequest)request;
				MultipartFile mFile = mRequest.getFile("imageFile");
				String fileName= mFile.getOriginalFilename();//获取文件名
				fileName = fileName.substring(fileName.lastIndexOf("."),fileName.length());
				String newFileName = String.valueOf(System.currentTimeMillis())+"_mainPage"+fileName;
				String filePath = request.getSession().getServletContext().getRealPath("/");
				filePath = filePath + conferences.getAbbreviation()+"/images/mainPage/";
				File file = new File(filePath);
				if(!file.exists()){
					file.mkdirs();
				}
				File saveFile = new File(filePath+newFileName);
				mFile.transferTo(saveFile);
				conferencesImage.setImageUrl("/"+conferences.getAbbreviation()+"/images/mainPage/"+newFileName);
				webService.saveObject(conferencesImage);
				response.sendRedirect(request.getContextPath()+"/webCenter.do?getConferencesImage");
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
	}