[原创]5.Spring文件上传

实现效果:

创建可以接收HTTP multi-part 文件上传的服务器应用程序.

项目结构

└── src

    └── main

        └── java

            └── hello

pom.xml



    4.0.0

    org.springframework
    gs-uploading-files
    0.1.0

    
        org.springframework.boot
        spring-boot-starter-parent
        2.1.6.RELEASE
    

    
        1.8
    


    
        
            org.springframework.boot
            spring-boot-starter-web
        
        
            org.springframework.boot
            spring-boot-starter-thymeleaf
        

        
            org.springframework.boot
            spring-boot-starter-test
            test
        
    

    
        
            
                org.springframework.boot
                spring-boot-maven-plugin

1.创建一个应用类

要启动Spring Boot MVC应用程序，首先需要一个启动器; 这里，spring-boot-starter-thymeleaf和spring-boot-starter-web已经被添加为依赖项。要使用Servlet容器上传文件，需要注册一个MultipartConfigElement类（在web.xml中为）。 Spring Boot会自动配置！
src/main/java/hello/Application.java

package hello;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

}

作为Spring MVC自动配置的一部分，Spring Boot将创建一个MultipartConfigElement类型 bean，并为文件上传做好准备。

2.创建一个文件上传的controller

程序初始化时候已经导入一些类来处理存储和加载上传的磁盘文件; 它们都位于hello.storage包中。将在FileUploadController中使用它们。
src/main/java/hello/FileUploadController.java

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 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();
    }

}

用@Controller注释，使Spring MVC可以选择并查找路由。每个方法都使用@GetMapping或@PostMapping进行标记，将路径和HTTP操作绑定到特定的Controller。

GET /请求,从StorageService中获取当前上载文件列表，并将其加载到Thymeleaf模板中。它使用MvcUriComponentsBuilder计算出资源的真实链接.
GET / files / {filename} 请求,加载资源（如果存在）并用“Content-Disposition”作为响应头,将其发送到浏览器进行下载.
POST /请求,用来处理多部分消息文件并将其提供给Storage Service进行保存

在实际生产环境中，有可能将文件存储在临时位置，数据库或Mongo的GridFS之类的NoSQL存储中。最好不要使用content加载应用程序的文件系统。
需要为控制器提供StorageService接口以与存储层（例如文件系统）进行交互。接口是这样的：
src/main/java/hello/storage/StorageService.java

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 loadAll();

    Path load(String filename);

    Resource loadAsResource(String filename);

    void deleteAll();

}

下面提供一个简单的接口实现代码:

package hello.storage;

import java.io.IOException;
import java.io.InputStream;
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.stream.Stream;

import org.springframework.beans.factory.annotation.Autowired;
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;

@Service
public class FileSystemStorageService implements StorageService {

    private final Path rootLocation;

    @Autowired
    public FileSystemStorageService(StorageProperties properties) {
        this.rootLocation = Paths.get(properties.getLocation());
    }

    @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);
            }
            try (InputStream inputStream = file.getInputStream()) {
                Files.copy(inputStream, this.rootLocation.resolve(filename),
                    StandardCopyOption.REPLACE_EXISTING);
            }
        }
        catch (IOException e) {
            throw new StorageException("Failed to store file " + filename, e);
        }
    }

    @Override
    public Stream loadAll() {
        try {
            return Files.walk(this.rootLocation, 1)
                .filter(path -> !path.equals(this.rootLocation))
                .map(this.rootLocation::relativize);
        }
        catch (IOException e) {
            throw new StorageException("Failed to read stored files", e);
        }

    }

    @Override
    public Path load(String filename) {
        return rootLocation.resolve(filename);
    }

    @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);
        }
    }

    @Override
    public void deleteAll() {
        FileSystemUtils.deleteRecursively(rootLocation.toFile());
    }

    @Override
    public void init() {
        try {
            Files.createDirectories(rootLocation);
        }
        catch (IOException e) {
            throw new StorageException("Could not initialize storage", e);
        }
    }
}

3.创建HTML 模板

src/main/resources/templates/uploadForm.html




    
        
    

    
        
            
                File to upload:

模板分三部分:

顶部是判断message变量存在则显示.
中间是允许用户上传文件的form
底部是从后台获取的文件列表list

4.调整文件上载限制

配置文件上传时，设置文件大小限制通常很有用。想象一下尝试使用Spring Boot处理5GB文件上传会发生什么，可以使用一些属性设置调整其自动配置的MultipartConfigElement。
添加新的属性到application.properties文件中:
src/main/resources/application.properties

spring.servlet.multipart.max-file-size=128KB
spring.servlet.multipart.max-request-size=128KB

总共上传文件大小不超过128K
单个form表单提交的文件大小不超过128K

5.修改启动类

src/main/java/hello/Application.java

package hello;

import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;

import hello.storage.StorageProperties;
import hello.storage.StorageService;

@SpringBootApplication
@EnableConfigurationProperties(StorageProperties.class)
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

    @Bean
    CommandLineRunner init(StorageService storageService) {
        return (args) -> {
            storageService.deleteAll();
            storageService.init();
        };
    }
}

CommandLineRunner 初始化回调函数.

建立一个可执行的 JAR

利用maven打包war或者jar运行,这里不做介绍.
java -jar target/gs-uploading-files-0.1.0.jar

测试

启动web服务,访问http://localhost:8080/
,选择一个文件上传,上传成功后会看到类似下方信息:

You successfully uploaded !

测试方法2:

还可以用MockMvc测试应用,而无需启动Servlet 容器.
写一个测试类:
src/test/java/hello/FileUploadTests.java

package hello;

import java.nio.file.Paths;
import java.util.stream.Stream;

import org.hamcrest.Matchers;
import org.junit.Test;
import org.junit.runner.RunWith;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.mock.mockito.MockBean;
import org.springframework.mock.web.MockMultipartFile;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.test.web.servlet.MockMvc;

import static org.mockito.BDDMockito.given;
import static org.mockito.BDDMockito.then;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.fileUpload;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.header;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.model;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;

import hello.storage.StorageFileNotFoundException;
import hello.storage.StorageService;

@RunWith(SpringRunner.class)
@AutoConfigureMockMvc
@SpringBootTest
public class FileUploadTests {

    @Autowired
    private MockMvc mvc;

    @MockBean
    private StorageService storageService;

    @Test
    public void shouldListAllFiles() throws Exception {
        given(this.storageService.loadAll())
                .willReturn(Stream.of(Paths.get("first.txt"), Paths.get("second.txt")));

        this.mvc.perform(get("/")).andExpect(status().isOk())
                .andExpect(model().attribute("files",
                        Matchers.contains("http://localhost/files/first.txt",
                                "http://localhost/files/second.txt")));
    }

    @Test
    public void shouldSaveUploadedFile() throws Exception {
        MockMultipartFile multipartFile = new MockMultipartFile("file", "test.txt",
                "text/plain", "Spring Framework".getBytes());
        this.mvc.perform(fileUpload("/").file(multipartFile))
                .andExpect(status().isFound())
                .andExpect(header().string("Location", "/"));

        then(this.storageService).should().store(multipartFile);
    }

    @SuppressWarnings("unchecked")
    @Test
    public void should404WhenMissingFile() throws Exception {
        given(this.storageService.loadAsResource("test.txt"))
                .willThrow(StorageFileNotFoundException.class);

        this.mvc.perform(get("/files/test.txt")).andExpect(status().isNotFound());
    }

}

用MockMultipartFile测试文件上传

也可以用下面方法测试:

package hello;

import org.junit.Test;
import org.junit.runner.RunWith;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.mock.mockito.MockBean;
import org.springframework.boot.test.web.client.TestRestTemplate;
import org.springframework.boot.web.server.LocalServerPort;
import org.springframework.core.io.ClassPathResource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.web.multipart.MultipartFile;

import static org.assertj.core.api.Assertions.assertThat;
import static org.mockito.BDDMockito.given;
import static org.mockito.BDDMockito.then;
import static org.mockito.Matchers.any;

import hello.storage.StorageService;

@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
public class FileUploadIntegrationTests {

    @Autowired
    private TestRestTemplate restTemplate;

    @MockBean
    private StorageService storageService;

    @LocalServerPort
    private int port;

    @Test
    public void shouldUploadFile() throws Exception {
        ClassPathResource resource = new ClassPathResource("testupload.txt", getClass());

        MultiValueMap map = new LinkedMultiValueMap();
        map.add("file", resource);
        ResponseEntity response = this.restTemplate.postForEntity("/", map,
                String.class);

        assertThat(response.getStatusCode()).isEqualByComparingTo(HttpStatus.FOUND);
        assertThat(response.getHeaders().getLocation().toString())
                .startsWith("http://localhost:" + this.port + "/");
        then(storageService).should().store(any(MultipartFile.class));
    }

    @Test
    public void shouldDownloadFile() throws Exception {
        ClassPathResource resource = new ClassPathResource("testupload.txt", getClass());
        given(this.storageService.loadAsResource("testupload.txt")).willReturn(resource);

        ResponseEntity response = this.restTemplate
                .getForEntity("/files/{filename}", String.class, "testupload.txt");

        assertThat(response.getStatusCodeValue()).isEqualTo(200);
        assertThat(response.getHeaders().getFirst(HttpHeaders.CONTENT_DISPOSITION))
                .isEqualTo("attachment; filename=\"testupload.txt\"");
        assertThat(response.getBody()).isEqualTo("Spring Framework");
    }

}

用Spring处理文件上传.