springmvc上传下载文件
1. 概述
本篇博客基于《springmvc注解项目开发流程》的代码，实现web前端的文件上传和下载功能。
主要参考包括：《SpringMVC学习（二）——快速搭建SpringMVC开发环境（注解方式）》
该博客源码托管地址：https://gitee.com/leo825/spring-framework-learning-example
2. 环境配置
2.1 pom.xml添加依赖
修改pom.xml里，添加上传文件依赖
<!-- 上传文件 -->
<dependency>
<groupId>commons-fileupload</groupId>
<artifactId>commons-fileupload</artifactId>
<version>1.3.3</version>
</dependency>
2.2 liwl-springmvc-servlet.xml配置bean
修改liwl-springmvc-servlet.xml修改
<!-- 上传文件 -->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<property name="defaultEncoding" value="utf-8"></property>
<property name="maxUploadSize" value="104857600"></property>
</bean>
3.文件上传
3.1 创建前端页面
创建一个前端jsp用于接受上传文件请求。在WEB-INF/views/目录下创建uploadpage.jsp，内容如下
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<body>
<form action="${pageContext.request.contextPath}/upload" enctype="multipart/form-data" method="post">
<input type="file" name="file" value="请选择需要上传的文件" /><br>
<input type="submit" value="提交">
</form>
</body>
</html>
创建上传成功后显示的页面uploadsuccess.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<body>
<p>
上传成功
</p>
</body>
</html>
3.2 创建后端代码
在controller目录下创建FileUploadController.java
package com.liwl.controller;
import java.io.File;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.servlet.ModelAndView;
@Controller
public class FileUploadController {
@RequestMapping(value = "/fileupload",method = RequestMethod.GET)
public ModelAndView liwanliang() throws ServletException,IOException{
ModelAndView modelAndView = new ModelAndView();
modelAndView.setViewName("uploadpage");
return modelAndView;
}
@RequestMapping(value = "/upload",method = RequestMethod.POST)
public String upload(@RequestParam(value = "file") MultipartFile multipartFile,HttpServletRequest request) throws IOException{
if (!multipartFile.isEmpty()){
String fileDirStr = request.getServletContext().getRealPath("/uploadFile");
String fileName = multipartFile.getOriginalFilename();
File fileDir = new File(fileDirStr);
if(!fileDir.exists()){
fileDir.mkdirs();
}
File filetmp = new File(fileDir, fileName);
multipartFile.transferTo(filetmp);
}
return "uploadsucces";
}
}
前端代码通过post请求，向/upload的URL发送了上传file的请求
后端接收该请求，创建/uploadFile目录，把文件放置在该目录下，并返回uploadsuccess的页面
访问:http://localhost:8080/liwl_springmvc_annotation/fileupload，开始上传文件，上传文件提交时，url是upload
上传成功以后，返回的是uploadsuccess的页面，返回的url是:http://localhost:8080/liwl_springmvc_annotation/upload
4. 下载文件
4.1 创建后端代码
修改FileUploadController.java，增加
package com.liwl.controller;
import java.io.File;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.io.FileUtils;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.servlet.ModelAndView;
@Controller
public class FileUploadController {
@RequestMapping(value = "/fileupload",method = RequestMethod.GET)
public ModelAndView liwanliang() throws ServletException,IOException{
ModelAndView modelAndView = new ModelAndView();
modelAndView.setViewName("uploadpage");
return modelAndView;
}
@RequestMapping(value = "/upload",method = RequestMethod.POST)
public ModelAndView upload(@RequestParam(value = "file") MultipartFile multipartFile,HttpServletRequest request) throws IOException{
ModelAndView modelAndView = new ModelAndView();
if (!multipartFile.isEmpty()){
String fileDirStr = request.getServletContext().getRealPath("/uploadFile");
String fileName = multipartFile.getOriginalFilename();
File fileDir = new File(fileDirStr);
if(!fileDir.exists()){
fileDir.mkdirs();
}
File filetmp = new File(fileDir, fileName);
multipartFile.transferTo(filetmp);
modelAndView.addObject("filename", ""+fileName);
modelAndView.setViewName("uploadsuccess");
} else {
modelAndView.setViewName("uploadfail");
}
return modelAndView;
}
@RequestMapping(value = "/download",method = RequestMethod.GET)
public void download(HttpServletRequest request,HttpServletResponse response,@RequestParam String filename) throws IOException{
String fileDirStr = request.getServletContext().getRealPath("/uploadFile");
File file = new File(fileDirStr, filename);
byte[] outByte = FileUtils.readFileToByteArray(file);
String downloadFilename = new String(file.getName().getBytes("utf-8"),"iso-8859-1");
response.setHeader("Content-Disposition", "attchement;filename="+downloadFilename);
response.getOutputStream().write(outByte);
response.getOutputStream().close();
}
}
4.2 创建前端代码
创建uploadsuccess.jsp，增加下载功能
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<body>
<p>
上传成功!文件名:${filename},<a href="${pageContext.request.contextPath}/download?filename=${requestScope.filename}">点击下载</a>
</p>
</body>
</html>
访问：http://localhost:8080/fileupload，出现上传文件界面。
上传文件成功后，会列出当前的文件名，以及下载后缀
上传成功!文件名:174890324_nb2-1-64.flv,点击下载
点击下载以后，就能够下载上传的flv文件。
