Feign實現檔案上傳下載

Feign框架對於檔案上傳訊息體格式並沒有做原生支援，需要整合模組feign-form來實現。

獨立使用Feign

新增模組依賴：

<!-- Feign框架核心 -->
<dependency>
    <groupId>io.github.openfeign</groupId>
    <artifactId>feign-core</artifactId>
    <version>11.1</version>
</dependency>
<!-- 支援表單格式，檔案上傳格式 -->
<dependency>
    <groupId>io.github.openfeign.form</groupId>
    <artifactId>feign-form</artifactId>
    <version>3.8.0</version>
</dependency>
<!-- 檔案操作工具類 -->
<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.11.0</version>
</dependency>

上傳檔案

定義介面：

public interface FileUploadAPI {
    // 上傳檔案：引數為單個檔案物件
    @RequestLine("POST /test/upload/single")
    @Headers("Content-Type: multipart/form-data")
    String upload(@Param("file") File file);

    // 上傳檔案：引數文多個檔案物件
    @RequestLine("POST /test/upload/batch")
    @Headers("Content-Type: multipart/form-data")
    String upload(@Param("files") File[] files);

    // 上傳檔案：引數文多個檔案物件
    @RequestLine("POST /test/upload/batch")
    @Headers("Content-Type: multipart/form-data")
    String upload(@Param("files") List<File> files);

    // 上傳檔案：引數為檔案位元組陣列（這種方式在服務端無法獲取檔名，不要使用）
    @RequestLine("POST /test/upload/single")
    @Headers("Content-Type: multipart/form-data")
    String upload(@Param("file") byte[] bytes);

    // 上傳檔案：引數為FormData物件
    @RequestLine("POST /test/upload/single")
    @Headers("Content-Type: multipart/form-data")
    String upload(@Param("file") FormData photo);

    // 上傳檔案：引數為POJO物件
    @RequestLine("POST /test/upload/single")
    @Headers("Content-Type: multipart/form-data")
    String upload(@Param("file") MyFile myFile);

    class MyFile {
        @FormProperty("is_public")
        Boolean isPublic;
        File file;

        public Boolean getPublic() {
            return isPublic;
        }

        public void setPublic(Boolean aPublic) {
            isPublic = aPublic;
        }

        public File getFile() {
            return file;
        }

        public void setFile(File file) {
            this.file = file;
        }
    }
}

呼叫介面：

FileAPI fileAPI = Feign.builder()
        .encoder(new FormEncoder()) // 必須明確設定請求引數編碼器
        .logger(new Slf4jLogger())
        .logLevel(Logger.Level.FULL)
        .target(FileAPI.class, "http://localhost:8080");
File file1 = new File("C:\\Users\\xxx\\Downloads\\test1.jpg");
File file2 = new File("C:\\Users\\xxx\\Downloads\\test2.jpg");

// 上傳檔案1：引數為檔案物件
fileAPI.upload(file1);

// 上傳檔案2：引數為位元組陣列（注意：在服務端無法獲取到檔名）
byte[] bytes = FileUtils.readFileToByteArray(file1);
fileAPI.upload(bytes);

// 上傳檔案3：引數為FormData物件
byte[] bytes = FileUtils.readFileToByteArray(file1);
FormData formData = new FormData("image/jpg", "test1.jpg", bytes);
String result = fileAPI.upload(formData);

// 上傳檔案4：引數為POJO物件
FileAPI.MyFile myFile = new FileAPI.MyFile();
myFile.setPublic(true);
myFile.setFile(file1);
fileAPI.upload(myFile);

// 上傳檔案：引數為多個檔案
fileAPI.upload(new File[]{file1, file2});
fileAPI.upload(Arrays.asList(new File[]{file1, file2}));

下載檔案

定義介面：

public interface FileDownloadAPI {
    // 下載檔案
    @RequestLine("GET /test/download/file")
    Response download(@QueryMap Map<String, Object> queryMap);
}

呼叫介面：

// 下載檔案時返回值為Response物件，不需要設定解碼器
FileAPI fileAPI = Feign.builder()
                .logger(new Slf4jLogger())
                .logLevel(Logger.Level.FULL)
                .target(FileAPI.class, "http://localhost:8080");
String fileName = "test.jpg";
Map<String, Object> queryMap = new HashMap<>();
queryMap.put("fileName", fileName);
Response response = fileAPI.download(queryMap);
if (response.status() == 200) {
    File downloadFile = new File("D:\\Downloads\\", fileName);
    FileUtils.copyInputStreamToFile(response.body().asInputStream(), downloadFile);
}

使用Spring Cloud Feign

在Spring框架中使用Feign實現檔案上傳時需要依賴feign-form和feign-form-spring，這2個模組已經在“Spring Cloud Feign”中自帶了，只需要新增spring-cloud-starter-openfeign依賴即可。

<!-- 整合Spring和Feign，包含了模組feign-form和feign-form-spring -->
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-openfeign</artifactId>
    <version>3.0.2</version>
</dependency>

<!-- 檔案操作工具類 -->
<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.11.0</version>
</dependency>

上傳檔案

定義介面及配置：

@FeignClient(value = "FileAPI", url = "http://localhost:8080", configuration = FileUploadAPI.FileUploadAPIConfiguration.class)
public interface FileUploadAPI {

    /**
     * 上傳單個檔案
     * @param file
     * @return
     */
    @RequestMapping(value = "/test/upload/single", method = RequestMethod.POST, headers = "Content-Type=multipart/form-data")
    String upload(@RequestPart("file") MultipartFile file);

    /**
     * 上傳多個檔案
     * @param files
     * @return
     */
    @RequestMapping(value = "/test/upload/batch", method = RequestMethod.POST, headers = "Content-Type=multipart/form-data")
    String upload(@RequestPart("files") List<MultipartFile> files);

    class FileUploadAPIConfiguration {
        @Autowired
        private ObjectFactory<HttpMessageConverters> messageConverters;

        @Bean
        public Encoder feignEncoder () {
            return new SpringFormEncoder(new SpringEncoder(messageConverters));
        }

        @Bean
        public Logger feignLogger() {
            return new Slf4jLogger();
        }

        @Bean
        public Logger.Level feignLoggerLevel() {
            return Logger.Level.FULL;
        }
    }
}

呼叫介面：

// 上傳單個檔案
File file = new File("C:\\Users\\xxx\\Downloads\\test1.jpg");
FileInputStream fis = new FileInputStream(file);
MockMultipartFile mockMultipartFile = new MockMultipartFile("file", file.getName(), "image/jpg", fis);
this.fileUploadAPI.upload(mockMultipartFile);
fis.close();

// 上傳多個檔案
File file1 = new File("C:\\Users\\xxx\\Downloads\\test1.jpg");
File file2 = new File("C:\\Users\\xxx\\Downloads\\test2.jpg");
FileInputStream fis1 = new FileInputStream(file1);
FileInputStream fis2 = new FileInputStream(file2);
MockMultipartFile f1 = new MockMultipartFile("files", file1.getName(), "image/jpg", fis1);
MockMultipartFile f2 = new MockMultipartFile("files", file2.getName(), "image/jpg", fis2);
this.fileUploadAPI.upload(Arrays.asList(new MockMultipartFile[]{f1, f2}));
fis1.close();
fis2.close();

下載檔案

定義介面：

@FeignClient(value = "FileDownloadAPI", url = "http://localhost:8080", configuration = FileDownloadAPI.FileDownloadAPIConfiguration.class)
public interface FileDownloadAPI {

    /**
     * 下載檔案
     * @param fileName 檔名
     * @return
     */
    @RequestMapping(value = "/test/download/file", method = RequestMethod.GET)
    Response download(@RequestParam("fileName") String fileName);

    // 下載檔案時返回值為Response物件，不需要設定解碼器
    class FileDownloadAPIConfiguration {
        @Bean
        public Logger feignLogger() {
            return new Slf4jLogger();
        }

        @Bean
        public Logger.Level feignLoggerLevel() {
            return Logger.Level.FULL;
        }
    }
}

呼叫介面：

String fileName = "test.jpg";
Response response = this.fileDownloadAPI.download(fileName);
File destFile = new File("D:\\Downloads\\", fileName);
// 使用org.apache.commons.io.FileUtils工具類將輸入流中的內容轉存到檔案
FileUtils.copyInputStreamToFile(response.body().asInputStream(), destFile);

總結

1.Feign框架需要整合模組feign-form才能支援檔案上傳的訊息體格式。
2.不論是獨立使用Feign，還是使用Spring Cloud Feign，下載檔案時的返回值都必須為feign.Response型別。