在SpringMVC框架下實(shí)現(xiàn)文件的上傳和下載示例

<?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" 
id="WebApp_ID" version="2.5">
 
   <!-- 配置SpringMVC的DispatcherServlet -->
  <servlet>
    <servlet-name>springDispatcherServlet</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:springmvc.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>

  <servlet-mapping>
    <servlet-name>springDispatcherServlet</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>
 
  <!-- 配置 HiddenHttpMethodFilter: 把 POST 請(qǐng)求轉(zhuǎn)為 DELETE、PUT 請(qǐng)求 -->
   <filter>
     <filter-name>HiddenHttpMethodFilter</filter-name>
     <filter-class>org.springframework.web.filter.HiddenHttpMethodFilter</filter-class>
   </filter>
   
   <filter-mapping>
     <filter-name>HiddenHttpMethodFilter</filter-name>
     <url-pattern>/*</url-pattern>
   </filter-mapping>
 
</web-app> 

<?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:mvc="http://www.springframework.org/schema/mvc"
  xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
    http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">
  
  <!-- 配置自動(dòng)掃描的包 -->
  <context:component-scan base-package="com.atguigu.springmvc"></context:component-scan>
  
  <!-- 配置視圖解析器 -->
  <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="prefix" value="/WEB-INF/views/"></property>
    <property name="suffix" value=".jsp"></property>
  </bean>
  
  <!-- 
    default-servlet-handler 將在 SpringMVC 上下文中定義一個(gè) DefaultServletHttpRequestHandler,
    它會(huì)對(duì)進(jìn)入 DispatcherServlet 的請(qǐng)求進(jìn)行篩查, 如果發(fā)現(xiàn)是沒有經(jīng)過映射的請(qǐng)求, 就將該請(qǐng)求交由 WEB 應(yīng)用服務(wù)器默認(rèn)的 
    Servlet 處理. 如果不是靜態(tài)資源的請(qǐng)求，才由 DispatcherServlet 繼續(xù)處理

    一般 WEB 應(yīng)用服務(wù)器默認(rèn)的 Servlet 的名稱都是 default.
    若所使用的 WEB 服務(wù)器的默認(rèn) Servlet 名稱不是 default，則需要通過 default-servlet-name 屬性顯式指定
    
  -->
  <mvc:default-servlet-handler/>
  
  <!-- 一般都會(huì)配置這個(gè) <mvc:annotation-driven ></mvc:annotation-driven>，
  由于。。。requestmapping請(qǐng)求實(shí)現(xiàn)不了，使用這個(gè)，會(huì)使requestmapping請(qǐng)求一定實(shí)現(xiàn)
  -->
  <mvc:annotation-driven ></mvc:annotation-driven> 
　　<!-- 配置 MultipartResolver ，即配置文件上傳的屬性-->
 　　<bean id="multipartResolver" 
　　　　class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
　　　　<!-- 默認(rèn)的字符編碼 -->
　　　　<property name="defaultEncoding" value="UTF-8"></property> 
　　　　<!-- 上傳文件的大小 ,最大上傳大小-->
　　　　<property name="maxUploadSize" value="1024000"></property>
 　　</bean>
 </beans> 

 @Controller
public class SpringMVCTest {
  
  @Autowired
  private EmployeeDao employeeDao;
  //實(shí)現(xiàn)文件的下載
  //需要說明的是文件的上傳和下載不需要其他配置
  @RequestMapping("testResponseEntity")
  public ResponseEntity<byte[]> testResponseEntity(HttpSession session) throws IOException{
    
    byte[] body=null;
    ServletContext servletContext=session.getServletContext();
    ///files/abc.txt：所要下載文件的地址
    InputStream in=servletContext.getResourceAsStream("/files/abc.txt");
    body=new byte[in.available()];
    in.read(body);
    
    HttpHeaders headers=new HttpHeaders();
    //響應(yīng)頭的名字和響應(yīng)頭的值
    headers.add("Content-Disposition", "attachment;filename=abc.txt");
    
    HttpStatus statusCode=HttpStatus.OK;
    
    ResponseEntity<byte[]> response=new ResponseEntity<byte[]>(body, headers, statusCode);
    return response;
  } 
　　//文件上傳，
 　　　　@RequestMapping("/testFileUpload")
 　　　　public String testFileUpload(@RequestParam("desc") String desc,
　　　　　　@RequestParam("file") MultipartFile file) throws IOException{

　　　　　　System.out.println("desc:"+desc);
　　　　　　System.out.println("OriginalFilename"+file.getOriginalFilename());
　　　　　　System.out.println("InputStream"+file.getInputStream());
　　　　　　return "success";
 　　}
 } 

<%@ 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">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
  
  <center> 
　　<!-- 文件上傳的表單 -->
 　　<form action="testFileUpload" method="post" enctype="multipart/form-data">
　　　　File:<input type="file" name="file"/>
　　　　Desc:<input type="text" name="desc"/>
　　　　<input type="submit" value="Submit"/>
 　　</form>
   <br><br>
  
  <!-- 文件的下載 -->
  <a href="testResponseEntity" rel="external nofollow" >Test ResponseEntity</a>
  
  </center>
  
</body>
</html> 

 <%@ 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">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
  
  <h4>Success page</h4>
  
</body>
</html>