springBoot实现文件上传-下载

时间：2020-10-26 15:53:09 阅读：37 评论：0 收藏：0 [点我收藏+]

前言

作为一名java程序员，或多或少都会使用到文件的上传和下载。

比如图片文件，excel文件等。所以，能快捷的实现对文件的上传和下载，或者有一个自己的模板，是一件很方便的事情。

今天就带领大家使用springboot来搭建文件的上传和下载的模板。其他不多说，直接上代码！！！

一、创建一个spring boot项目

1.1 开发工具 idea

1.2 jdk 1.8

1.3 具体项目搭建流程可以阅读我的另一篇博客（创建spring boot项目）

1.4 整体结构

技术分享图片

二、搭建spring boot开发环境

2.1 添加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 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>2.3.4.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <groupId>com.liyh</groupId>
    <artifactId>springboot_file_upload_download</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>
    <name>springboot_file_upload_download</name>
    <description>Demo project for Spring Boot</description>

    <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-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

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

        <dependency>
            <groupId>net.sourceforge.nekohtml</groupId>
            <artifactId>nekohtml</artifactId>
            <version>1.9.15</version>
        </dependency>
    </dependencies>

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

</project>

2.2 配置application.yml文件

# 配置端口
server:
  port: 8085

# 去除thymeleaf的html严格校验
spring:
  thymeleaf:
    mode: LEGACYHTML5
    # 取消模板文件缓存
    cache: false

  #设定thymeleaf文件路径 默认为src/main/resources/templates
  freemarker:
    template-loader-path: classpath:/templates

  #设定静态文件路径，js,css等
  mvc:
    static-path-pattern: /static/**

  servlet:
    multipart:
      # 设置单个文件大小
      max-file-size: 200MB
      # 设置单次请求文件的总大小
      max-request-size: 200MB

2.3 编写摸板文件

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<p>单文件上传</p>
<form action="upload" method="POST" enctype="multipart/form-data">
    文件：<input type="file" name="file"/>
    <input type="submit"/>
</form>
<hr/>
<p>文件下载</p>
<a href="download">下载文件</a>
<hr/>
<p>多文件上传</p>
<form method="POST" enctype="multipart/form-data" action="batch">
    <p>文件1：<input type="file" name="file"/></p>
    <p>文件2：<input type="file" name="file"/></p>
    <p><input type="submit" value="上传"/></p>
</form>
</body>
</html>

2.4 创建IndexController，FileController

package com.liyh.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

/**
 * @Author: liyh
 * @Date: 2020/10/12 12:33
 */

@Controller
public class IndexController {

    @RequestMapping("/")
    public String index()
    {
        return "index";
    }
}

package com.liyh.controller;

import com.liyh.utils.FileUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.multipart.MultipartHttpServletRequest;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.util.List;

/**
 * @Author: liyh
 * @Date: 2020/10/12 11:58
 */

@RestController
public class FileController {
    private static final Logger log = LoggerFactory.getLogger(FileController.class);

    @RequestMapping(value = "/upload")
    public String upload(@RequestParam("file") MultipartFile file) {
        try {
            if (file.isEmpty()) {
                return "文件为空";
            }
            // 获取大小
            long size = file.getSize();
            log.info("文件大小： " + size);
            // 判断上传文件大小
            if (!FileUtils.checkFileSize(file,50,"M")) {
                log.error("上传文件规定小于50MB");
                return "上传文件规定小于50MB";
            }
            // 获取文件名
            String fileName = file.getOriginalFilename();
            log.info("上传的文件名为：" + fileName);
            // 获取文件的后缀名
            String suffixName = fileName.substring(fileName.lastIndexOf("."));
            log.info("文件的后缀名为：" + suffixName);
            // 设置文件存储路径
            String filePath = "C:/software/file/";
            String path = filePath + fileName;
            File dest = new File(path);
            // 检测是否存在目录
            if (!dest.getParentFile().exists()) {
                dest.getParentFile().mkdirs();// 新建文件夹
            }
            file.transferTo(dest);// 文件写入
            return "上传成功";
        } catch (IllegalStateException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return "上传失败";
    }

    @PostMapping("/batch")
    public String handleFileUpload(HttpServletRequest request) {
        List<MultipartFile> files = ((MultipartHttpServletRequest) request).getFiles("file");
        MultipartFile file = null;
        BufferedOutputStream stream = null;
        for (int i = 0; i < files.size(); ++i) {
            file = files.get(i);
            String filePath = "C:/software/file/";
            if (!file.isEmpty()) {
                try {
                    byte[] bytes = file.getBytes();
                    stream = new BufferedOutputStream(new FileOutputStream(
                            new File(filePath + file.getOriginalFilename())));//设置文件路径及名字
                    stream.write(bytes);// 写入
                    stream.close();
                } catch (Exception e) {
                    stream = null;
                    return "第 " + i + " 个文件上传失败 ==> "
                            + e.getMessage();
                }
            } else {
                return "第 " + i
                        + " 个文件上传失败因为文件为空";
            }
        }
        return "上传成功";
    }

    @GetMapping("/download")
    public String downloadFile(HttpServletRequest request, HttpServletResponse response) {
        String fileName = "timg.jpg";// 文件名
        if (fileName != null) {
            //设置文件路径
            //File file = new File(realPath , fileName);
            File file = new File("C:/software/file/timg.jpg");
            if (file.exists()) {
                response.setContentType("application/force-download");// 设置强制下载不打开
                response.addHeader("Content-Disposition", "attachment;fileName=" + fileName);// 设置文件名
                byte[] buffer = new byte[1024];
                FileInputStream fis = null;
                BufferedInputStream bis = null;
                try {
                    fis = new FileInputStream(file);
                    bis = new BufferedInputStream(fis);
                    OutputStream os = response.getOutputStream();
                    int i = bis.read(buffer);
                    while (i != -1) {
                        os.write(buffer, 0, i);
                        i = bis.read(buffer);
                    }
                    return "下载成功";
                } catch (Exception e) {
                    e.printStackTrace();
                } finally {
                    if (bis != null) {
                        try {
                            bis.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                    if (fis != null) {
                        try {
                            fis.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }
            }
        }
        return "下载失败";
    }
}

2.4 判断文件大小的工具类FileUtils

package com.liyh.utils;

import org.springframework.web.multipart.MultipartFile;

/**
 * @Author: liyh
 * @Date: 2020/10/12 14:54
 */
public class FileUtils {
    /**
     * 判断文件大小
     *
     * @param file
     *            文件
     * @param size
     *            限制大小
     * @param unit
     *            限制单位（B,K,M,G）
     * @return
     */
    public static boolean checkFileSize(MultipartFile file, int size, String unit) {
        long len = file.getSize();
        double fileSize = 0;
        if ("B".equals(unit.toUpperCase())) {
            fileSize = (double) len;
        } else if ("K".equals(unit.toUpperCase())) {
            fileSize = (double) len / 1024;
        } else if ("M".equals(unit.toUpperCase())) {
            fileSize = (double) len / 1048576;
        } else if ("G".equals(unit.toUpperCase())) {
            fileSize = (double) len / 1073741824;
        }
        if (fileSize > size) {
            return false;
        }
        return true;
    }
}