一、单个文件上传

1）jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<%
    pageContext.setAttribute("ctp", request.getContextPath());
%>

</head>
<body>
<!-- 
    文件上传
    1.写表单；：enctype="multipart/form-data"
    2.导入fileuplod包
    commons-fileupload-1.2.1.jar
    commons-io-2.0.jar
    3.javaweb.......
    3.现在用框架
    只需要在springmvc配置文件中，编写一个文件上传解析器MultiPartResolver九大组件之一
    4.文件上传请求处理写Controller
    
-->
<!-- action最好写全路径 -->
${msg }
<!-- 取一下model保存的提示信息 -->
    <form action="${ctp }/upload" method="post" enctype="multipart/form-data">
    用户头像：<input type="file" name="headerimg"/><br/>
    用户名：<input type="text" name="username"/><br/>
    <input type="submit"/>
    </form>
</body>
</html>

2）springmvc.xml

编写一个文件上传解析器MultiPartResolver九大组件之一，其余配置都是标配

<context:component-scan base-package="com.atguigu"></context:component-scan>
    
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/pages/"></property>
        <property name="suffix" value=".jsp"></property>
    </bean>

    
<!--     配置文件上传解析器MultiPartResolver接口，用CommonsMultipartResolver实现类  
        id必须是multipartResolver
-->
    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <property name="maxUploadSize" value="#{1024*1024*20}"></property>
        <property name="defaultEncoding" value="UTF-8"></property>
    </bean>
    
    
    <mvc:default-servlet-handler/>
    <mvc:annotation-driven ></mvc:annotation-driven>

3）Controller

@Controller
public class FileUploadController {
    @RequestMapping("/upload")
    public String upload(@RequestParam(value="username",required = false)String username,
            @RequestParam("headerimg")MultipartFile file,
            Model model) {
        
        System.out.println("上传文件的信息");
        System.out.println("文件的名字："+file.getName());//假名（jsp文件项的<name=“”>）
        System.out.println("文件的名字："+file.getOriginalFilename());//真名
        //文件保存
        try {
            file.transferTo(new File("G:\"+file.getOriginalFilename()));
            model.addAttribute("msg","文件上传成功了");
        } catch (Exception e) {
            // TODO Auto-generated catch block
            model.addAttribute("msg","文件上传失败了"+e.getMessage());
        }
        
        
        
        //懒得再写新的jsp了
        return "forward:/index.jsp";
    }
    
}

二、多个文件上传

1)jsp里多写几个<input type="file" name="headerimg"/><br/>

2)Controller

@Controller
public class FileUploadController {
    @RequestMapping("/upload")
    public String upload(@RequestParam(value="username",required = false)String username,
            @RequestParam("headerimg")MultipartFile[] file,
            Model model) {
            
            对MultipartFile[] file增强型for循环
            同上
        
    
        //懒得再写新的jsp了
        return "forward:/index.jsp";
    }
    
}