一、pom.xml配置 

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.4</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.yl</groupId>
    <artifactId>fileupload</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>fileupload</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

二、文件上传的配置 

# 文件上传的配置
# 是否开启文件上传功能，默认开启
spring.servlet.multipart.enabled=true
# 文件大小
spring.servlet.multipart.max-file-size=2MB
# 文件大小超过多少时就往缓存里面放
spring.servlet.multipart.file-size-threshold=3MB
# 文件保存的临时位置
spring.servlet.multipart.location=
# 最大的请求大小
spring.servlet.multipart.max-request-size=10MB
# 是否开启延迟解析
spring.servlet.multipart.resolve-lazily=falses

三、单个文件的上传

1.html页面 

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="/upload" method="post" enctype="multipart/form-data">
    <input type="file" name="file">
    <input type="submit" value="上传">
</form>
</body>
</html>

2.controller 

package com.yl.fileupload.controller;

import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;
import javax.servlet.http.HttpServletRequest;
import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.UUID;

/**
 * 单文件上传
 */
@RestController
public class FileUploadController {
    SimpleDateFormat sdf = new SimpleDateFormat("/yyyy/MM/dd/");

    @PostMapping("/upload")
    public String upload(MultipartFile file, HttpServletRequest request) {
        String s = sdf.format(new Date());
        String path = "D:\\fileUpload" + s;
        File folder = new File(path);
        if (!folder.exists()) {
            folder.mkdirs();
        }
        //旧文件名
        String oldName = file.getOriginalFilename();
        //新文件名
        String newName = UUID.randomUUID().toString() + oldName.substring(oldName.lastIndexOf("."));
        //上传文件
        try {
            file.transferTo(new File(folder,newName));
            String s1 = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort() + s + newName;
            return s1;
        } catch (IOException e) {
            e.printStackTrace();
        }
        return "";
    }
}

四、多文件上传

1.html页面 

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="/upload2" method="post" enctype="multipart/form-data">
    <input type="file" name="files" multiple>
    <input type="submit" value="上传">
</form>
</body>
</html>

2.controller 

package com.yl.fileupload.controller;

import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;
import javax.servlet.http.HttpServletRequest;
import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.UUID;

/**
 * 多文件上传
 */
@RestController
public class FileUploadController2 {
    SimpleDateFormat sdf = new SimpleDateFormat("/yyyy/MM/dd/");

    @PostMapping("/upload2")
    public String upload(MultipartFile[] files, HttpServletRequest request) {
        String realPath = request.getServletContext().getRealPath("/");
        String s = sdf.format(new Date());
        String path = realPath + s;
        File folder = new File(path);
        if (!folder.exists()) {
            folder.mkdirs();
        }
        try {
            String finalStr = "";
            for (MultipartFile multipartFile : files) {
                //旧文件名
                String oldName = multipartFile.getOriginalFilename();
                //新文件名
                String newName = UUID.randomUUID().toString() + oldName.substring(oldName.lastIndexOf("."));
                //上传文件
                multipartFile.transferTo(new File(folder,newName));
                String s1 = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort() + s + newName;
                finalStr += s1 + ";";
            }
            return finalStr;
        } catch (IOException e) {
            e.printStackTrace();
        }
        return "";
    }
}