SpringBoot2.x实现文件上传与下载

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1，配置pom文件

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.itpengwei</groupId>
    <artifactId>springboot-test</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>springboot-test</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!-- thymeleaf模板插件 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</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>

2，配置文件(application.yml)

server:
  port: 8080
spring:
  thymeleaf:
    cache: false
  servlet:
    multipart:
      max-file-size: 5Mb
      max-request-size: 10Mb

3,Controller

package com.itpengwei.springboottest.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletResponse;
import java.io.*;

/**
 * 文件上传,下载类
 */
@Controller
public class FileUploadController {
    /**
     * 文件上传
     *
     * @param file
     * @return
     */
    @PostMapping(value = "/fileUpload")
    @ResponseBody
    public String fileUpload(@RequestParam("fileName") MultipartFile file) {
        if (file.isEmpty()) {
            return "请选择一个文上传";
        }
        String filename = file.getOriginalFilename();
        long fileSize = file.getSize();
        System.out.println("文件名称" + filename + "-------文件大小" + fileSize);
        String path = "F:/test";
        File dest = new File(path + "/" + filename);
        if (!dest.getParentFile().exists()) {
            //父目录不存在就创建一个
            dest.getParentFile().mkdir();
        }
        //保存文件
        try {
            file.transferTo(dest);
            return "文件上传成功";
        } catch (IOException e) {
            e.printStackTrace();
            return "文件上传失败";
        }
    }

    /**
     * 文件下载
     *
     * @param response
     * @return
     */
    @RequestMapping(value = "/fileDownload")
    @ResponseBody
    public String download(HttpServletResponse response) {
        String fileName = "Cloud总结.docx";
        String filepath = "F:/test";
        File file = new File(filepath + "/" + fileName);
        byte[] buff = new byte[1024];
        BufferedInputStream bis = null;
        OutputStream os = null;
        try {
            os = response.getOutputStream();
            bis = new BufferedInputStream(new FileInputStream(file));
            int i = bis.read(buff);
            while (i != -1) {
                os.write(buff, 0, buff.length);
                os.flush();
                i = bis.read(buff);
            }
        } catch (IOException e) {
            e.printStackTrace();
            return "文件上传失败";
        } finally {
            if (bis != null) {
                try {
                    bis.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return "文件上传成功";
    }
}

4，启动项目，就实现了文件上传与下载