初学SpringMVC之文件上传和下载
pom.xml 文件导入 commons-fileupload 的 jar 包
<!-- 文件上传 -->
<dependency>
<groupId>commons-fileupload</groupId>
<artifactId>commons-fileupload</artifactId>
<version>1.5</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>4.0.1</version>
</dependency>index.jsp：
enctype="multipart/form-data"
浏览器会采用二进制流的方式来处理表单数据
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<meta charset="utf-8">
<title></title>
</head>
<body>
<form action="${pageContext.request.contextPath}/upload" enctype="multipart/form-data" method="post">
<input type="file" name="file"/>
<input type="submit" value="upload"/>
</form>
</body>
</html>Spring MVC 为文件上传提供了直接的支持
上传文件配置，固定写法
<!-- 文件上传配置 -->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<!-- 请求的编码格式，必须和JSP的pageEncoding属性一致，默认为ISO-8859-1 -->
<property name="defaultEncoding" value="utf-8"/>
<!-- 上传文件大小上限，单位为字节（10485760=10M） -->
<property name="maxUploadSize" value="10485760"/>
<property name="maxInMemorySize" value="40960"/>
</bean>方法一：通过 IO 流
package com.demo.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.commons.CommonsMultipartFile;
import javax.servlet.http.HttpServletRequest;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
@Controller
public class FileController {
//@RequestParam("file") 将 name=file 控件得到的文件封装成 CommonsMultipartFile 对象
@RequestMapping("/upload")
public String fileUpload(@RequestParam("file") CommonsMultipartFile file, HttpServletRequest request) throws IOException {
//获取文件名：file.getOriginalFilename()
String uploadFileName = file.getOriginalFilename();
//如果文件名为空，返回到首页
if("".equals(uploadFileName)){
return "redirect:/index.jsp";
}
System.out.println("上传文件名：" + uploadFileName);
//上传路径保存设置
String path = request.getSession().getServletContext().getRealPath("/upload");
//如果路径不存在，创建一个
File realPath = new File(path);
if(!realPath.exists()){
realPath.mkdir();
}
System.out.println("上传文件保存地址：" + realPath);
InputStream inputStream = file.getInputStream(); //文件输入流
FileOutputStream outputStream = new FileOutputStream(new File(realPath,uploadFileName)); //文件输出流
//读取写出
int len = 0;
byte[] buffer = new byte[1024];
while ((len = inputStream.read(buffer)) != -1){
outputStream.write(buffer,0,len);
outputStream.flush();
}
outputStream.close();
inputStream.close();
return "redirect:/index.jsp";
}
}
方法二：通过 file.transferTo 来保存上传的文件
package com.demo.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.commons.CommonsMultipartFile;
import javax.servlet.http.HttpServletRequest;
import java.io.File;
import java.io.IOException;
@Controller
public class FileController {
@RequestMapping("/upload")
public String fileUpload(@RequestParam("file") CommonsMultipartFile file,HttpServletRequest request) throws IOException {
//上传路径保存设置
String path = request.getSession().getServletContext().getRealPath("/upload");
File realPath = new File(path);
if(!realPath.exists()){
realPath.mkdir();
}
//上传文件地址
System.out.println("上传文件保存地址：" + realPath);
//通过 CommonsMultipartFile 方法直接写文件
file.transferTo(new File(realPath + "/" + file.getOriginalFilename()));
return "redirect:/index.jsp";
}
}可以看到目录生成，上传的文件将出现在文件夹
下载文件：
1.设置 response 响应头
2.读取文件 InputStream
3.写出文件 OutputStream
4.执行操作
5.关闭流，先开后关
package com.demo.controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.net.URLEncoder;
@RestController
public class FileController {
@RequestMapping(value = "/download")
public String download(HttpServletRequest request,HttpServletResponse response) throws Exception {
//要下载的文件地址
String path = request.getSession().getServletContext().getRealPath("/upload");
String fileName = ""; //填文件名
//1.设置 response 响应头
response.reset(); //设置页面不缓存，清空 buffer
response.setCharacterEncoding("UTF-8"); //字符编码
response.setContentType("multipart/form-data"); //二进制传输数据
//设置响应头
response.setHeader("Content-Disposition","attachment;fileName=" + URLEncoder.encode(fileName,"UTF-8"));
File file = new File(path, fileName);
//2.读取文件 输入流
InputStream input = new FileInputStream(file);
//3.写出文件 输出流
OutputStream output = response.getOutputStream();
byte[] buffer = new byte[1024];
int index = 0;
//4.执行 写出操作
while (index = input.read(buffer) != -1){
output.write(buffer,0,index);
output.flush();
}
//5.关闭流 先开后关
output.close();
input.close();
return null;
}
}原文地址：https://blog.csdn.net/m0_58838332/article/details/140529176
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