利用spring的CommonsMultipartResolver上传文件

1、CommonsMultipartResolver是spring里面提供的一个上传方式，效率我不知道，但是加入spring容器管理还是很不错的。

2、先看依赖包pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.troy</groupId>
  <artifactId>springfile</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>war</packaging>
  <dependencies>
      <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>3.2.8.RELEASE</version>
    </dependency>
    <dependency>
      <groupId>org.apache.commons</groupId>
      <artifactId>com.springsource.org.apache.commons.fileupload</artifactId>
      <version>1.2.1</version>
    </dependency>
    <dependency>
      <groupId>commons-io</groupId>
      <artifactId>commons-io</artifactId>
      <version>2.5</version>
    </dependency>
  </dependencies>
</project>

说明：因为上传文件的这一套东西都是apache提供的，在使用CommonsMultipartResolver上传文件时，需要用到相应的依赖包
3、web.xml配置

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">
  <display-name>iframe</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
      <servlet-name>springmvc</servlet-name>
      <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
      <init-param>
          <param-name>contextConfigLocation</param-name>
          <param-value>classpath:spring/spring-mvc.xml</param-value>
      </init-param>
      <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
      <servlet-name>springmvc</servlet-name>
      <url-pattern>/</url-pattern>
  </servlet-mapping>
  <filter>
      <filter-name>filterEncoding</filter-name>
      <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
      <init-param>
          <param-name>encoding</param-name>
          <param-value>UTF-8</param-value>
      </init-param>
      <init-param>
          <param-name>forceEncoding</param-name>
          <param-value>true</param-value>
      </init-param>
  </filter>
  <filter-mapping>
      <filter-name>filterEncoding</filter-name>
      <url-pattern>/</url-pattern>
  </filter-mapping>
  <servlet-mapping>
      <servlet-name>default</servlet-name>
      <url-pattern>*.js</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
      <servlet-name>default</servlet-name>
      <url-pattern>*.css</url-pattern>
  </servlet-mapping>
</web-app>

4.spring-mvc.xml配置

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:jdbc="http://www.springframework.org/schema/jdbc"
    xmlns:jee="http://www.springframework.org/schema/jee"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:util="http://www.springframework.org/schema/util"
    xmlns:jpa="http://www.springframework.org/schema/data/jpa"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd
        http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.2.xsd
        http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.2.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd
        http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa-1.3.xsd
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
        http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.2.xsd">

    <mvc:annotation-driven/>
    <context:component-scan base-package="com.troy"/>
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/page/"/>
        <property name="suffix" value=".jsp"/>
    </bean>
    <bean id="commonsMultipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <property name="defaultEncoding" value="utf-8"/>
    </bean>
</beans>

5、web端的代码（file.jsp）

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<%
    String path = request.getContextPath();
    String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<html>
<head>
<base href="<%=basePath%>">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
<script type="text/javascript" src="js/jquery-3.1.1.min.js"></script>
</head>
<body>
    <form action="file/upLoad" method="post" enctype="multipart/form-data">
        <input type="file" name="file"/>
        <input type="submit" value="上传"/>
    </form>
</body>
</html>

注意：上传的文件的input需要写入name并且唯一
6、java后台

@RequestMapping(value="/file")
@Controller
public class FileController {

    @RequestMapping(value="/init")
    public String init(){

        return "file";
    }

    @RequestMapping(value="/upLoad")
    @ResponseBody
    public void upLoad(HttpServletRequest request) throws Exception{

        //创建一个多分解的容器
        CommonsMultipartResolver cmr = new CommonsMultipartResolver(request.getSession().getServletContext());
        //设置编码
        cmr.setDefaultEncoding("utf-8");
        //判断是否有文件上传
        if(cmr.isMultipart(request)){
            //将request转换成多分解请求
            MultipartHttpServletRequest mhs = cmr.resolveMultipart(request);
            //根据input中存在的name来获取是否存在上传文件
            MultipartFile mf = mhs.getFile("file");#这里可以用getFiles("file")的方式来处理多个文件。返回的是一个list.然后一个一个处理就可以了
            //创建文件保存名
            File file = new File(mf.getOriginalFilename());
            //上传文件
            mf.transferTo(file);
        }
    }
}

7、效果，因为是相对路径，我直接打开项目

8、具体实现就到这里，效率问题，请百度。个人认为挺好用的