2020年11月25日：
文件上传
1） Spring MVC 为文件上传提供了直接的支持，这种支持是通过即插即用的 MultipartResolver实现的。
2） Spring 用 Jakarta Commons FileUpload 技术实现了一个 MultipartResolver 实现类：CommonsMultipartResolver
3） Spring MVC 上下文中默认没有装配 MultipartResovler，因此默认情况下不能处理文件的上传工作，如果想使用 Spring 的文件上传功能，需现在上下文中配置 MultipartResolver。
设置步骤：
1）导入jar包
commons-fileupload-1.2.1.jar
commons-io-2.0.jar
2）配置文件上传解析器，
<!--
处理文件，将客户端上传的File文件，处理为MultipartFile
注意：文件解析器的bean中id必须设置为multipartResolver
-->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<!-- 设置文件解析的编码，注意：一定要和页面的pageEncoding保持一致 -->
<property name="defaultEncoding" value="UTF-8"></property>
<!-- 设置最大上传文件大小， 注意不能写表达式，例如1024*1024，因为xml为纯文本存储，相当于都是字符串，不能处理表达式-->
<property name="maxUploadSize" value="88888888"></property>
</bean>
3）上传页面
<%@ 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>
<a href="down">下载图片</a>
<form action="up1" method="post" enctype="multipart/form-data">
头像：<input type="file" name="uploadFile" />
描述：<input type="text" name="desc" />
<input type="submit" value="上传1" />
</form>
<form action="up2" method="post" enctype="multipart/form-data">
头像：<input type="file" name="uploadFile" />
描述：<input type="text" name="desc" />
<input type="submit" value="上传2" />
</form>
</body>
</html>
4）控制器方法
package com.spring.controller;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.UUID;
import javax.servlet.http.HttpSession;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.multipart.MultipartFile;
@Controller
public class Download {
@RequestMapping("/down")
public ResponseEntity<byte[]> down(HttpSession session) throws IOException{
//获取下载文件的路径
String realPath = session.getServletContext().getRealPath("img");
String finalPath = realPath + File.separator + "2.jpg";
InputStream is = new FileInputStream(finalPath);
//available():获取输入流所读取的文件的最大字节数
byte[] b = new byte[is.available()];
is.read(b);
//设置请求头
HttpHeaders headers = new HttpHeaders();
headers.add("Content-Disposition", "attachment;filename=zzz.jpg");
//设置响应状态
HttpStatus statusCode = HttpStatus.OK;
ResponseEntity<byte[]> entity = new ResponseEntity<byte[]>(b, headers, statusCode);
return entity;
}
@RequestMapping(value="/up1", method=RequestMethod.POST)
//注意参数名称和表单name一致
public String up_old(String desc, MultipartFile uploadFile, HttpSession session) throws IOException {
//获取上传文件的名称
String fileName = uploadFile.getOriginalFilename();
//上传文件的保存路径
String path = session.getServletContext().getRealPath("photo") + File.separator + fileName;
//获取输入流
InputStream is = uploadFile.getInputStream();
//获取输出流
File file = new File(path);
OutputStream os = new FileOutputStream(file);
/*int i = 0;
while((i = is.read()) != -1) {
os.write(i);
}*/
int i = 0;
byte[] b = new byte[1024];
while((i = is.read(b)) != -1) {
os.write(b, 0, i);
}
os.close();
is.close();
return "success";
}
@RequestMapping(value="/up2", method=RequestMethod.POST)
public String up(String desc, MultipartFile uploadFile, HttpSession session) throws IOException {
//获取上传文件的名称
String fileName = uploadFile.getOriginalFilename();
String finalFileName = UUID.randomUUID() + fileName.substring(fileName.lastIndexOf("."));
String path = session.getServletContext().getRealPath("photo") + File.separator + finalFileName;
File file = new File(path);
uploadFile.transferTo(file);
return "success";
}
}