SpringBoot 文件上传和下载

红太狼 2022-05-28 06:24 378阅读 0赞

本篇文章介绍SpringBoot的上传和下载。

# 一、创建SpringBoot工程，添加依赖 #

compile("org.springframework.boot:spring-boot-starter-web")
        compile("org.springframework.boot:spring-boot-starter-thymeleaf")

# 工程目录为： #

![20180330223547907][]

Application.java 启动类

package hello;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.boot.context.properties.EnableConfigurationProperties;
    
    @SpringBootApplication
    public class Application {
    
        public static void main(String[] args) {
            SpringApplication.run(Application.class, args);
        }
    
    }

# 二、创建测试页面 #

在resources/templates目录下新建uploadForm.html

<html xmlns:th="http://www.thymeleaf.org">
    <body>
    
    	<div th:if="${message}">
    		<h2 th:text="${message}"/>
    	</div>
    
    	<div>
    		<form method="POST" enctype="multipart/form-data" action="/">
    			<table>
    				<tr><td>File to upload:</td><td><input type="file" name="file" /></td></tr>
    				<tr><td></td><td><input type="submit" value="Upload" /></td></tr>
    			</table>
    		</form>
    	</div>
    
    	<div>
    		<ul>
    			<li th:each="file : ${files}">
    				<a th:href="${file}" th:text="${file}" />
    			</li>
    		</ul>
    	</div>
    
    </body>
    </html>

# 三、新建StorageService服务 #

StorageService接口

package hello.storage;
    
    import org.springframework.core.io.Resource;
    import org.springframework.web.multipart.MultipartFile;
    
    import java.nio.file.Path;
    import java.util.stream.Stream;
    
    public interface StorageService {
    
        void init();
    
        void store(MultipartFile file);
    
        Stream<Path> loadAll();
    
        Path load(String filename);
    
        Resource loadAsResource(String filename);
    
        void deleteAll();
    
    }

StorageService实现

package hello.storage;
    
    import org.springframework.core.io.Resource;
    import org.springframework.core.io.UrlResource;
    import org.springframework.stereotype.Service;
    import org.springframework.util.FileSystemUtils;
    import org.springframework.util.StringUtils;
    import org.springframework.web.multipart.MultipartFile;
    
    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.nio.file.StandardCopyOption;
    import java.util.function.Predicate;
    import java.util.stream.Stream;
    
    @Service
    public class FileSystemStorageService implements StorageService
    {
    
        private final Path rootLocation = Paths.get("upload-dir");
    
    
        /**
         * 保存文件
         *
         * @param file 文件
         */
        @Override
        public void store(MultipartFile file)
        {
            String filename = StringUtils.cleanPath(file.getOriginalFilename());
            try
            {
                if (file.isEmpty())
                {
                    throw new StorageException("Failed to store empty file " + filename);
                }
                if (filename.contains(".."))
                {
                    // This is a security check
                    throw new StorageException("Cannot store file with relative path outside current directory " + filename);
                }
                Files.copy(file.getInputStream(), this.rootLocation.resolve(filename), StandardCopyOption.REPLACE_EXISTING);
            }
            catch (IOException e)
            {
                throw new StorageException("Failed to store file " + filename, e);
            }
        }
    
        /**
         * 列出upload-dir下面所有文件
         * @return
         */
        @Override
        public Stream<Path> loadAll()
        {
            try
            {
                return Files.walk(this.rootLocation, 1)  //path -> !path.equals(this.rootLocation)
                        .filter(new Predicate<Path>()
                        {
                            @Override
                            public boolean test(Path path)
                            {
                                return !path.equals(rootLocation);
                            }
                        });
            }
            catch (IOException e)
            {
                throw new StorageException("Failed to read stored files", e);
            }
    
        }
    
        @Override
        public Path load(String filename)
        {
            return rootLocation.resolve(filename);
        }
    
        /**
         * 获取文件资源
         * @param filename 文件名
         * @return Resource
         */
        @Override
        public Resource loadAsResource(String filename)
        {
            try
            {
                Path file = load(filename);
                Resource resource = new UrlResource(file.toUri());
                if (resource.exists() || resource.isReadable())
                {
                    return resource;
                }
                else
                {
                    throw new StorageFileNotFoundException("Could not read file: " + filename);
    
                }
            }
            catch (MalformedURLException e)
            {
                throw new StorageFileNotFoundException("Could not read file: " + filename, e);
            }
        }
    
        /**
         * 删除upload-dir目录所有文件
         */
        @Override
        public void deleteAll()
        {
            FileSystemUtils.deleteRecursively(rootLocation.toFile());
        }
    
        /**
         * 初始化
         */
        @Override
        public void init()
        {
            try
            {
                Files.createDirectories(rootLocation);
            }
            catch (IOException e)
            {
                throw new StorageException("Could not initialize storage", e);
            }
        }
    }

StorageException.java

package hello.storage;
    
    public class StorageException extends RuntimeException {
    
        public StorageException(String message) {
            super(message);
        }
    
        public StorageException(String message, Throwable cause) {
            super(message, cause);
        }
    }

StorageFileNotFoundException.java

package hello.storage;
    
    public class StorageFileNotFoundException extends StorageException {
    
        public StorageFileNotFoundException(String message) {
            super(message);
        }
    
        public StorageFileNotFoundException(String message, Throwable cause) {
            super(message, cause);
        }
    }

# 四、Controller创建 #

将上传的文件，放到工程的upload-dir目录，默认在界面上列出可以下载的文件。

listUploadedFiles函数，会列出当前目录下的所有文件

serveFile下载文件

handleFileUpload上传文件

package hello;
    
    import java.io.IOException;
    import java.util.stream.Collectors;
    
    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.stereotype.Controller;
    import org.springframework.ui.Model;
    import org.springframework.web.bind.annotation.ExceptionHandler;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.PathVariable;
    import org.springframework.web.bind.annotation.PostMapping;
    import org.springframework.web.bind.annotation.RequestParam;
    import org.springframework.web.bind.annotation.ResponseBody;
    import org.springframework.web.multipart.MultipartFile;
    import org.springframework.web.servlet.mvc.method.annotation.MvcUriComponentsBuilder;
    import org.springframework.web.servlet.mvc.support.RedirectAttributes;
    
    import hello.storage.StorageFileNotFoundException;
    import hello.storage.StorageService;
    
    @Controller
    public class FileUploadController {
    
        private final StorageService storageService;
    
        @Autowired
        public FileUploadController(StorageService storageService) {
            this.storageService = storageService;
        }
    
        @GetMapping("/")
        public String listUploadedFiles(Model model) throws IOException {
    
            model.addAttribute("files", storageService.loadAll().map(
                    path -> MvcUriComponentsBuilder.fromMethodName(FileUploadController.class,
                            "serveFile", path.getFileName().toString()).build().toString())
                    .collect(Collectors.toList()));
    
            return "uploadForm";
        }
    
        @GetMapping("/files/{filename:.+}")
        @ResponseBody
        public ResponseEntity<Resource> serveFile(@PathVariable String filename) {
    
            Resource file = storageService.loadAsResource(filename);
            return ResponseEntity.ok().header(HttpHeaders.CONTENT_DISPOSITION,
                    "attachment; filename=\"" + file.getFilename() + "\"").body(file);
        }
    
        @PostMapping("/")
        public String handleFileUpload(@RequestParam("file") MultipartFile file,
                RedirectAttributes redirectAttributes) {
    
            storageService.store(file);
            redirectAttributes.addFlashAttribute("message",
                    "You successfully uploaded " + file.getOriginalFilename() + "!");
    
            return "redirect:/";
        }
    
        @ExceptionHandler(StorageFileNotFoundException.class)
        public ResponseEntity<?> handleStorageFileNotFound(StorageFileNotFoundException exc) {
            return ResponseEntity.notFound().build();
        }
    
    }

**源码下载：**[https://github.com/HelloKittyNII/SpringBoot/tree/master/SpringBootUploadAndDownload][https_github.com_HelloKittyNII_SpringBoot_tree_master_SpringBootUploadAndDownload]

[20180330223547907]: /images/20220528/5bbe0af369f9425cb6aecfb014ecce31.png
[https_github.com_HelloKittyNII_SpringBoot_tree_master_SpringBootUploadAndDownload]: https://github.com/HelloKittyNII/SpringBoot/tree/master/SpringBootUploadAndDownload