springBoot實現文件上傳-下載

本文轉載自查看原文 2020-10-26 14:29 3112 Java/ java/ file/ SpringBoot

前言

作為一名java程序員，或多或少都會使用到文件的上傳和下載。

比如圖片文件，excel文件等。所以，能快捷的實現對文件的上傳和下載，或者有一個自己的模板，是一件很方便的事情。

今天就帶領大家使用springboot來搭建文件的上傳和下載的模板。其他不多說，直接上代碼！！！

一、創建一個spring boot項目

1.1 開發工具 idea

1.2 jdk 1.8

1.3 具體項目搭建流程可以閱讀我的另一篇博客（創建spring boot項目）

1.4 整體結構

二、搭建spring boot開發環境

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嚴格校驗
spring:
  thymeleaf:
    mode: LEGACYHTML5
    # 取消模板文件緩存
    cache: false

  #設定thymeleaf文件路徑 默認為src/main/resources/templates
  freemarker:
    template-loader-path: classpath:/templates

  #設定靜態文件路徑，js,css等
  mvc:
    static-path-pattern: /static/**

  servlet:
    multipart:
      # 設置單個文件大小
      max-file-size: 200MB
      # 設置單次請求文件的總大小
      max-request-size: 200MB

2.3 編寫摸板文件

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<p>單文件上傳</p>
<form action="upload" method="POST" enctype="multipart/form-data">
    文件：<input type="file" name="file"/>
    <input type="submit"/>
</form>
<hr/>
<p>文件下載</p>
<a href="download">下載文件</a>
<hr/>
<p>多文件上傳</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="上傳"/></p>
</form>
</body>
</html>

2.4 創建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 "文件為空";
            }
            // 獲取大小
            long size = file.getSize();
            log.info("文件大小： " + size);
            // 判斷上傳文件大小
            if (!FileUtils.checkFileSize(file,50,"M")) {
                log.error("上傳文件規定小於50MB");
                return "上傳文件規定小於50MB";
            }
            // 獲取文件名
            String fileName = file.getOriginalFilename();
            log.info("上傳的文件名為：" + fileName);
            // 獲取文件的后綴名
            String suffixName = fileName.substring(fileName.lastIndexOf("."));
            log.info("文件的后綴名為：" + suffixName);
            // 設置文件存儲路徑
            String filePath = "C:/software/file/";
            String path = filePath + fileName;
            File dest = new File(path);
            // 檢測是否存在目錄
            if (!dest.getParentFile().exists()) {
                dest.getParentFile().mkdirs();// 新建文件夾
            }
            file.transferTo(dest);// 文件寫入
            return "上傳成功";
        } catch (IllegalStateException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return "上傳失敗";
    }

    @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())));//設置文件路徑及名字
                    stream.write(bytes);// 寫入
                    stream.close();
                } catch (Exception e) {
                    stream = null;
                    return "第 " + i + " 個文件上傳失敗 ==> "
                            + e.getMessage();
                }
            } else {
                return "第 " + i
                        + " 個文件上傳失敗因為文件為空";
            }
        }
        return "上傳成功";
    }

    @GetMapping("/download")
    public String downloadFile(HttpServletRequest request, HttpServletResponse response) {
        String fileName = "timg.jpg";// 文件名
        String result = FileUtils.downloadFiles(request, response, fileName);
        if (request == null) {
            return null;
        }
        return result;
    }
}

2.4 判斷文件大小的工具類FileUtils

package com.liyh.utils;

import org.springframework.core.io.ClassPathResource;
import org.springframework.util.StringUtils;
import org.springframework.web.multipart.MultipartFile;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;

/**
 * @Author: liyh
 * @Date: 2020/11/4 16:10
 */

public class FileUtils {

    /**
     * 下載文件
     * @param request
     * @param response
     * @param fileName
     * @return
     * @throws IOException
     */
    public static String downloadFiles(HttpServletRequest request, HttpServletResponse response, String fileName){

        if (StringUtils.isEmpty(fileName)) {
            return "文件名稱為空";
        }

        //設置文件路徑
        ClassPathResource classPathResource = new ClassPathResource("templates/" + fileName);
        File file = null;
        try {
            file = classPathResource.getFile();
        } catch (IOException e) {
            e.printStackTrace();
            return "文件不存在";
        }

        response.setHeader("content-type", "application/octet-stream");
        // 設置強制下載不打開
        response.setContentType("application/force-download");
        // 設置文件名
        response.addHeader("Content-Disposition", "attachment;fileName=" + fileName);

        byte[] buffer = new byte[1024];
        InputStream 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);
            }
        } 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 "文件下載成功";
    }

    /**
     * 判斷文件大小
     *
     * @param file  文件
     * @param size  限制大小
     * @param unit  限制單位（B,K,M,G）
     * @return
     */
    public static boolean checkFileSize(MultipartFile file, int size, String unit) {
        if (file.isEmpty() || StringUtils.isEmpty(size) || StringUtils.isEmpty(unit)) {
            return false;
        }
        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;
    }
}