Java SpringBoot实现文件上传下载

逃离我推掉我的手 2022-09-05 12:57 350阅读 0赞

### Java SpringBoot实现文件上传下载 ###

*  1. 业务概述
 *  2. 环境准备
 *  3. 实现验证
 *   *  3.1 文件对象 UploadFile
     *  3.2 文件上传接口 FileStorageService
     *  3.3 文件上传实现类 FileStorageServiceImpl
     *  3.4 文件上传初始化配置 FileUploadConfiguration
     *  3.5 文件控制器 FileUploadController
     *  3.6 统一结果集 Response
     *  3.7 配置文件 application.yml
     *  3.8 全局异常处理 FileUploadExceptionAdvice
 *  4. 验证

# 1. 业务概述 #

业务开发中文件上传与下载在Web应用中是一个比较常见的功能。通常采用两张方式：  
1.上传至自定义的文件服务器。  
2.上传至云服务器，例如阿里云OSS，AWS等  
阿里云OSS：[https://help.aliyun.com/product/31815.html?spm=a2c4g.750001.list.24.7a184c07xKtHUD][https_help.aliyun.com_product_31815.html_spm_a2c4g.750001.list.24.7a184c07xKtHUD]  
AWS S3：[https://aws.amazon.com/cn/s3/][https_aws.amazon.com_cn_s3]

云服务相关文档很详细就不在介绍，本文主要是springboot实现文件的上传下载功能。

# 2. 环境准备 #

JDK: Java 1.8  
Framework: Spring Boot 2.5.0(Only Using Spring Web MVC)  
Maven: Maven 3.5.0+  
IDE: IntelliJ IDEA 2019.2  
springfox-swagger2 2.6.1

# 3. 实现验证 #

工程目录结构说明如下：
    
    config/FileUploadConfiguration.java: 常规组件，主要在重启应用时清理历史文件；
    controller/FileUploadController.java: 主要的控制器，负责处理文件的上传，下载，浏览等请求；
    exception/FileUploadExceptionAdvice.java: 全局的异常处理类，提供用户友好的异常提示信息；
    service/FileStorageService.java: 文件上传接口类，提供存储地址初始化，保存文件，加载文件，清理文件等操作；
    service/impl/FileStorageServiceImpl.java: 文件上传接口实现类；
    valueobject/UploadFile.java: 封装了文件名和存储地址的POJO类；
    valueobject/Message.java: 请求/响应的消息对象；
    resources/application.yml: 项目配置文件，主要配置了文件上传大小限制；
    pom.xml:Maven依赖配置文件。

## 3.1 文件对象 UploadFile ##

package com.example.category.entity;
    
    import lombok.AllArgsConstructor;
    import lombok.Data;
    import lombok.NoArgsConstructor;
    
    /** * 文件对象 * * @author zrj * @since 2021/8/17 **/
    @Data
    @NoArgsConstructor
    @AllArgsConstructor
    public class UploadFile { 
        private String fileName;
        private String url;
    }

## 3.2 文件上传接口 FileStorageService ##

package com.example.category.service;
    
    import org.springframework.core.io.Resource;
    import org.springframework.web.multipart.MultipartFile;
    
    import java.nio.file.Path;
    import java.util.stream.Stream;
    
    /** * 文件上传接口 * * @author zrj * @since 2021/8/17 **/
    public interface FileStorageService { 
        /** * 文件初始化 */
        void init();
    
        /** * 文件上传 */
        void fileUpload(MultipartFile multipartFile);
    
        /** * 文件下载 */
        Resource load(String filename);
    
        /** * 文件加载 */
        Stream<Path> load();
    
        /** * 文件全部删除 */
        void clear();
    
        /** * 文件删除 */
        void fileDeleted(String fileName);
    }

## 3.3 文件上传实现类 FileStorageServiceImpl ##

package com.example.category.service.impl;
    
    import com.example.category.service.FileStorageService;
    import lombok.extern.slf4j.Slf4j;
    import org.springframework.core.io.UrlResource;
    import org.springframework.stereotype.Service;
    import org.springframework.util.FileSystemUtils;
    import org.springframework.web.multipart.MultipartFile;
    import org.springframework.core.io.Resource;
    
    import java.io.File;
    import java.io.IOException;
    import java.net.MalformedURLException;
    import java.nio.file.Files;
    import java.nio.file.Path;
    import java.nio.file.Paths;
    import java.util.stream.Stream;
    
    /** * 文件上传实现类 * * @author zrj * @since 2021/8/17 **/
    @Slf4j
    @Service("fileStorageService")
    public class FileStorageServiceImpl implements FileStorageService { 
        private final Path path = Paths.get("fileStorage");
    
        @Override
        public void init() { 
            log.info("文件管理初始化...path=" + path);
            try { 
                boolean exists = new File(path.toUri()).exists();
                if (!exists) { 
                    log.info("文件路径不存在创建");
                    Files.createDirectory(path);
                }
            } catch (IOException e) { 
                throw new RuntimeException("Could not initialize folder for upload!");
            }
        }
    
        @Override
        public void fileUpload(MultipartFile multipartFile) { 
            log.info("文件上传...path=" + path);
            try { 
                Files.copy(multipartFile.getInputStream(), this.path.resolve(multipartFile.getOriginalFilename()));
            } catch (IOException e) { 
                throw new RuntimeException("Could not store the file. Error:" + e.getMessage());
            }
        }
    
        @Override
        public Resource load(String filename) { 
            log.info("文件下载...path=" + path);
    
            Path file = path.resolve(filename);
            try { 
                Resource resource = new UrlResource(file.toUri());
                if (resource.exists() || resource.isReadable()) { 
                    return resource;
                } else { 
                    throw new RuntimeException("Could not read the file.");
                }
            } catch (MalformedURLException e) { 
                throw new RuntimeException("Error:" + e.getMessage());
            }
        }
    
        @Override
        public Stream<Path> load() { 
            log.info("文件下载...path=" + path);
            try { 
                return Files.walk(this.path, 1)
                        .filter(path -> !path.equals(this.path))
                        .map(this.path::relativize);
            } catch (IOException e) { 
                throw new RuntimeException("Could not load the files.");
            }
        }
    
        @Override
        public void clear() { 
            log.info("文件clear...path=" + path);
            if (false) { 
                FileSystemUtils.deleteRecursively(path.toFile());
            }
        }
    
        @Override
        public void fileDeleted(String fileName) { 
            log.info("文件删除...fileName=" + fileName);
        }
    }

## 3.4 文件上传初始化配置 FileUploadConfiguration ##

package com.example.category.config;
    
    import com.example.category.service.FileStorageService;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.boot.CommandLineRunner;
    import org.springframework.stereotype.Service;
    
    /** * 文件上传初始化配置 * * @author zrj * @since 2021/8/17 **/
    @Service
    public class FileUploadConfiguration implements CommandLineRunner { 
    
        @Autowired
        FileStorageService fileStorageService;
    
        @Override
        public void run(String... args) throws Exception { 
            fileStorageService.clear();
            fileStorageService.init();
        }
    }

## 3.5 文件控制器 FileUploadController ##

## 3.6 统一结果集 Response ##

package com.example.category.controller;
    
    import com.example.category.entity.Response;
    import com.example.category.entity.UploadFile;
    import com.example.category.service.FileStorageService;
    import io.swagger.annotations.Api;
    import io.swagger.annotations.ApiOperation;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.core.io.Resource;
    import org.springframework.http.HttpHeaders;
    import org.springframework.http.ResponseEntity;
    import org.springframework.web.bind.annotation.*;
    import org.springframework.web.multipart.MultipartFile;
    import org.springframework.web.servlet.mvc.method.annotation.MvcUriComponentsBuilder;
    
    import java.util.List;
    import java.util.stream.Collectors;
    
    /** * 文件控制器 * * @author zrj * @since 2021/8/17 **/
    @RestController
    @RequestMapping("/file")
    @Api(tags = "文件管理", description = "文件上传")
    public class FileUploadController { 
        @Autowired
        FileStorageService fileStorageService;
    
        /** * 文件上传 */
        @PostMapping("/fileUpload")
        @ApiOperation(value = "文件上传", httpMethod = "POST")
        public Response<String> fileUpload(@RequestParam("file") MultipartFile file) { 
            try { 
                fileStorageService.fileUpload(file);
                return Response.success("fileUpload success", file.getOriginalFilename());
            } catch (Exception e) { 
                return Response.success("fileUpload failed", file.getOriginalFilename());
            }
        }
    
        /** * 文件列表 */
        @GetMapping("/fileList")
        @ApiOperation(value = "文件列表", httpMethod = "GET")
        public Response<List<UploadFile>> fileList() { 
            List<UploadFile> fileList = fileStorageService.load()
                    .map(path -> { 
                        String fileName = path.getFileName().toString();
                        String url = MvcUriComponentsBuilder
                                .fromMethodName(FileUploadController.class, "getFile", path.getFileName().toString())
                                .build().toString();
                        return new UploadFile(fileName, url);
                    }).collect(Collectors.toList());
    
            return Response.success("fileList success", fileList);
        }
    
        /** * 文件下载 * {filename:.+}：正则表达式匹配, 语法: {varName:regex} 前面是变量名，后面是表达式。 * 匹配出现过一次或多次.的字符串 如: "hello.png" */
        @GetMapping("/files/{filename:.+}")
        @ApiOperation(value = "文件下载", httpMethod = "GET")
        public ResponseEntity<Resource> getFile(@PathVariable("filename") String filename) { 
            // 根据文件名读取文件
            Resource file = fileStorageService.load(filename);
    
            // @ResponseBody 用于直接返回结果(自动装配)
            // ResponseEntity 可以定义返回的 HttpHeaders 和 HttpStatus (手动装配)
            // ResponseEntity.ok 相当于设置 HttpStatus.OK (200)
            // CONTENT_DISPOSITION 该 标志将通知浏览器启动下载
            return ResponseEntity.ok()
                    .header(HttpHeaders.CONTENT_DISPOSITION, "attachment;filename=\"" + file.getFilename() + "\"")
                    .body(file);
        }
    
        /** * 文件删除 */
        @PostMapping("/fileDeleted")
        @ApiOperation(value = "文件删除", httpMethod = "POST")
        public Response<String> fileDeleted(@RequestParam("fileName") String fileName) { 
            try { 
                fileStorageService.fileDeleted(fileName);
                return Response.success("fileDeleted success", fileName);
            } catch (Exception e) { 
                return Response.success("fileDeleted failed", fileName);
            }
        }
    }

## 3.7 配置文件 application.yml ##

spring.servlet.multipart.max-request-size=50MB: 单次请求所能上传文件的总文件大小
    spring.servlet.multipart.max-file-size=50MB：单个文件所能上传的文件大小

## 3.8 全局异常处理 FileUploadExceptionAdvice ##

package com.example.category.exception;
    
    import com.example.category.entity.Message;
    import org.springframework.http.ResponseEntity;
    import org.springframework.web.bind.annotation.ControllerAdvice;
    import org.springframework.web.bind.annotation.ExceptionHandler;
    import org.springframework.web.multipart.MaxUploadSizeExceededException;
    import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler;
    
    import javax.naming.SizeLimitExceededException;
    
    /** * @author zrj * @since 2021/8/17 **/
    @ControllerAdvice
    public class FileUploadExceptionAdvice extends ResponseEntityExceptionHandler { 
    
        @ExceptionHandler(SizeLimitExceededException.class)
        public ResponseEntity<Message> handleMaxUploadSizeExceededException(MaxUploadSizeExceededException e) { 
            return ResponseEntity.badRequest().body(new Message("Upload file too large."));
        }
    }

# 4. 验证 #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzM3NTgzNjU1_size_16_color_FFFFFF_t_70]

[https_help.aliyun.com_product_31815.html_spm_a2c4g.750001.list.24.7a184c07xKtHUD]: https://help.aliyun.com/product/31815.html?spm=a2c4g.750001.list.24.7a184c07xKtHUD
[https_aws.amazon.com_cn_s3]: https://aws.amazon.com/cn/s3/
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzM3NTgzNjU1_size_16_color_FFFFFF_t_70]: /images/20220829/f9337bfcff554232bcd5e7bec5e960cb.png