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SpringBoot 文件上传和下载

程序员文章站 2022-06-02 14:11:23
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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:

SpringBoot 文件上传和下载

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

相关标签: SpringBoot