首先要导入2个包(上传文件包和io的包)
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配置文件spring-servlet.xml文件中
<!-- 配置文件上传MultipartResolver -->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<property name="maxUploadSize" value="5000000"></property>
</bean>
如果id="multipartResolver"没传，就会报以下的错（小心小心）
Request processing failed; nested exception is java.lang.IllegalArgumentException: Expected MultipartHttpServletRequest: is a MultipartResolver configured?
添加文件的显示页面add.sjp
a、enctype="multipart/form-data"这句就是告诉，要添加文件，很重要
b、 attach：<input type="file" name="attach"><br/>
<form:form modelAttribute="user" method="post" enctype="multipart/form-data">
ID:<form:input path="id"/><br/>
userName:<form:input path="userName"/><form:errors path="userName"/><br/>
password:<form:input path="password"/><form:errors path="password"/><br/>
email:<form:input path="email"/><form:errors path="email"/><br/>
attach：<input type="file" name="attach"><br/>
<input type="submit" value="提交"/>
</form:form>
修改添加的方法
a、指定路径
b、上传文件，就要文件保存的目标位置
@RequestMapping(value="/add",method=RequestMethod.POST)
public String add(@Validated User user,BindingResult bindingResult,MultipartFile attach,HttpServletRequest request){
//上传文件就是要上传的路径所以就需要request对象
if(bindingResult.hasErrors()){
return "user/add";
}
//指定上传位置
String uploadFilePath = request.getSession().getServletContext().getRealPath("statics/upload");
System.out.println(uploadFilePath); System.out.println(attach.getOriginalFilename());//原始名
System.out.println(attach.getContentType());//类型
System.out.println(attach.getName());//页面表单控件name的值 if(!attach.isEmpty()){
try {
//"/" 更换成自动识别分隔符File.separator
File saveFile = new File(uploadFilePath+File.separator+attach.getOriginalFilename());
//第一个是拿到输入流，第二个参数是保存到哪里
FileUtils.copyInputStreamToFile(attach.getInputStream(), saveFile);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
//把user对象放进去key（id）
userList.put(user.getId(), user); // return "user/userlist";//返回到逻辑视图名
//（添加后，不能把添加过的数据展示出来）服务器端行为
return "redirect:/user/list";//客户端重新发送请求（把添加进去的展示出来）
}
多文件的上传
因为是多文件所以一定要加@RequestParam不加的话报如下异常
//Could not instantiate bean class [[Lorg.springframework.web.multipart.MultipartFile;]: No default constructor found;nested exception is java.lang
//不能实例化bean类[[Lorg.springframework.web.multipart。MultipartFile;]:没有默认构造函数发现,嵌套异常. lang。
//页面500
//文件上传（多文件）
@RequestMapping(value="/add",method=RequestMethod.POST)
public String add(@Validated User user,BindingResult bindingResult,@RequestParam("attachs") MultipartFile[] attachs,HttpServletRequest request){
//上传文件就是要上传的路径所以就需要request对象
if(bindingResult.hasErrors()){
return "user/add";
}
//指定上传位置
String uploadFilePath = request.getSession().getServletContext().getRealPath("statics/upload");
try {
for(MultipartFile attach:attachs){ if(!attach.isEmpty()){ //"/" 更换成自动识别File.separator
File saveFile = new File(uploadFilePath+File.separator+attach.getOriginalFilename());
//第一个是拿到输入流，第二个参数是保存到哪里
FileUtils.copyInputStreamToFile(attach.getInputStream(), saveFile);
}
}
}catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
//把user对象放进去key（id）
userList.put(user.getId(), user); // return "user/userlist";//返回到逻辑视图名
//（添加后，不能把添加过的数据展示出来）服务器端行为
return "redirect:/user/list";//客户端重新发送请求（把添加进去的展示出来）
}
因为多文件是一个数组，attach：<input type="file" name="attachs"><br/>
这边的name要是attachs，否则就找不到
<form:form modelAttribute="user" method="post" enctype="multipart/form-data">
ID:<form:input path="id"/><br/>
userName:<form:input path="userName"/><form:errors path="userName"/><br/>
password:<form:input path="password"/><form:errors path="password"/><br/>
email:<form:input path="email"/><form:errors path="email"/><br/>
attach：<input type="file" name="attachs"><br/>
attach1：<input type="file" name="attachs"><br/>
attach2：<input type="file" name="attachs"><br/>
<input type="submit" value="提交"/>
</form:form>