MultipartResolver实现文件上传功能

转自：https://www.jb51.net/article/142736.htm

springMVC默认的解析器里面是没有加入对文件上传的解析的,，使用springmvc对文件上传的解析器来处理文件上传的时需要用springmvc提供的MultipartResolver的申明，又因为CommonsMultipartResolver实现了MultipartResolver接口，所以我们可以在springmvc配置文件中这样配置：

1 <bean id="multipartResolver"
2    class="org.springframework.web.multipart.commons.CommonsMultipartResolver"> 
3    <property name="defaultEncoding" value="utf-8" /> 
4    <property name="maxUploadSize" value="10485760000" /> 
5    <property name="maxInMemorySize" value="40960" /> 
6  </bean>

首先引入文件上传所需要的包,commons-logging-*.jar commons-io-*.jar commons-fileupload-*.jar

新建一个JSP页面.

 1 <%@ page language="java" contentType="text/html; charset=UTF-8" 
 2   pageEncoding="UTF-8"%> 
 3 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 
 4 <html> 
 5 <head> 
 6 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 
 7 <title>文件上传</title> 
 8 </head> 
 9 <body> 
10   <%--<form action="user/fileUpload" method="post" enctype="multipart/form-data">--%> 
11   <form action="user/fileUpload" method="post" enctype="multipart/form-data"> 
12     <input type="file" name="fileUpload" /> 
13     <input type="submit" value="上传" /> 
14   </form> 
15 </body> 
16 </html>

springmvc上传文件的形式有很多,这里我介绍两种.

第一种,看Controller

 1 package gd.hz.springmvc.controller; 
 2   
 3 import java.io.File; 
 4 import java.io.IOException; 
 5   
 6 import org.springframework.stereotype.Controller; 
 7 import org.springframework.web.bind.annotation.RequestMapping; 
 8 import org.springframework.web.bind.annotation.RequestMethod; 
 9 import org.springframework.web.bind.annotation.RequestParam; 
10 import org.springframework.web.multipart.commons.CommonsMultipartFile; 
11 import org.springframework.web.servlet.ModelAndView; 
12   
13 @Controller("userController") 
14 @RequestMapping("user") 
15 public class UserController { 
16   
17   // 处理文件上传一 
18   @RequestMapping(value = "fileUpload", method = RequestMethod.POST) 
19   public ModelAndView fileUpload( 
20       @RequestParam("fileUpload") CommonsMultipartFile file) { 
21     // 获取文件类型 
22     System.out.println(file.getContentType()); 
23     // 获取文件大小 
24     System.out.println(file.getSize()); 
25     // 获取文件名称 
26     System.out.println(file.getOriginalFilename()); 
27   
28     // 判断文件是否存在 
29     if (!file.isEmpty()) { 
30       String path = "D:/" + file.getOriginalFilename(); 
31       File localFile = new File(path); 
32       try { 
33         file.transferTo(localFile); 
34       } catch (IllegalStateException e) { 
35         e.printStackTrace(); 
36       } catch (IOException e) { 
37         e.printStackTrace(); 
38       } 
39     } 
40     return new ModelAndView("dataSuccess"); 
41   } 
42 }

类CommonsMultipartFile为我们提供了许多对文件处理的方法.例如文件大小,上传文件名称,文件类型,具体用法可以查看spring的文档.transferTo就是将文件输出到指定地方.

文件上传的第二种方法,这种方法比较常用:

 1 package gd.hz.springmvc.controller; 
 2   
 3 import java.io.File; 
 4 import java.io.IOException; 
 5 import java.util.Iterator; 
 6   
 7 import javax.servlet.http.HttpServletRequest; 
 8   
 9 import org.springframework.stereotype.Controller; 
10 import org.springframework.web.bind.annotation.RequestMapping; 
11 import org.springframework.web.bind.annotation.RequestMethod; 
12 import org.springframework.web.multipart.MultipartFile; 
13 import org.springframework.web.multipart.MultipartHttpServletRequest; 
14 import org.springframework.web.multipart.commons.CommonsMultipartResolver; 
15   
16 @Controller("userController") 
17 @RequestMapping("user") 
18 public class UserController { 
19   
20   // 处理文件上传二 
21   @RequestMapping(value = "fileUpload2", method = RequestMethod.POST) 
22   public String fileUpload2(HttpServletRequest request) 
23       throws IllegalStateException, IOException { 
24     // 设置上下方文 
25     CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver( 
26         request.getSession().getServletContext()); 
27   
28     // 检查form是否有enctype="multipart/form-data" 
29     if (multipartResolver.isMultipart(request)) { 
30       MultipartHttpServletRequest multiRequest = (MultipartHttpServletRequest) request; 
31   
32       Iterator<String> iter = multiRequest.getFileNames(); 
33       while (iter.hasNext()) { 
34   
35         // 由CommonsMultipartFile继承而来,拥有上面的方法. 
36         MultipartFile file = multiRequest.getFile(iter.next()); 
37         if (file != null) { 
38           String fileName = "demoUpload" + file.getOriginalFilename(); 
39           String path = "D:/" + fileName; 
40   
41           File localFile = new File(path); 
42           file.transferTo(localFile); 
43         } 
44   
45       } 
46     } 
47     return "dataSuccess"; 
48   } 
49 }

MultipartHttpServletRequest提供了更加灵活的方法,可以获取多个文件和文件名,可以遍历获得每个文件.