由于ResourceConfig不需要参数构造函数，Dropwizard文件上传测试失败

Question

我在Dropwizard中实现了一个文件上传REST端点。我是新来的，我只是试着学习。

@Path("/files")
@Produces(MediaType.APPLICATION_JSON)
public class FileUploadResource {

    private final MyAppWebConfiguration configuration;
    private static final Logger logger = LoggerFactory.getLogger(FileUploadResource.class);

    public FileUploadResource(MyAppWebConfiguration configuration) {
        this.configuration = configuration;
    }

    @POST
    @Consumes(MediaType.MULTIPART_FORM_DATA)
    public Response uploadFile(
            @FormDataParam("file") InputStream uploadedInputStream,
            @FormDataParam("file") FormDataContentDisposition fileDetail) throws IOException {

        logger.info("Request to upload the file ", fileDetail.getFileName());
        final String uploadedFileLocation = configuration.getCsvUploadPath();
        final String fileName = fileDetail.getFileName();
        writeToFile(uploadedInputStream, uploadedFileLocation, fileName);
        return Response.ok("File " + fileName + " is uploaded to the location " + uploadedFileLocation).build();
    }

    // save uploaded file to new location
    protected void writeToFile(InputStream uploadedInputStream, String uploadedFileLocation, String fileName) throws IOException {
        logger.info("Writing {} to {}", fileName, uploadedFileLocation);
        final java.nio.file.Path outputPath = FileSystems.getDefault().getPath(uploadedFileLocation, fileName);
        Files.copy(uploadedInputStream, outputPath, StandardCopyOption.REPLACE_EXISTING);
        logger.info("Uploaded {} to the location {}", fileName, uploadedFileLocation);
    }

代码工作正常，能够上传文件。我正在尝试使用以下基于https://gist.github.com/psamsotha/218c6bbeb6164bac7cbc的代码来测试它：

public class FileUploadResourceTest extends JerseyTest {

    private final static MyAppWebConfiguration mockConfiguration = mock(MyAppWebConfiguration.class);

    @Override
    public ResourceConfig configure() {
        return new ResourceConfig(FileUploadResource.class)
                .register(MultiPartFeature.class)
                .register(new LoggingFilter(Logger.getAnonymousLogger(), true));
    }

    @Override
    public void configureClient(ClientConfig config) {
        config.register(MultiPartFeature.class);
    }

    @Test
    public void test() {
        FileDataBodyPart filePart = new FileDataBodyPart("file", new File("/Users/rocky/Downloads/test.csv"));
        filePart.setContentDisposition(FormDataContentDisposition.name("file").fileName("/Users/rocky/Downloads/test.csv").build());

        MultiPart multiPart = new FormDataMultiPart()
                .bodyPart(filePart);
        Response response = target("/files").request()
                .post(Entity.entity(multiPart, MediaType.MULTIPART_FORM_DATA_TYPE));
        assertThat(response.getStatus()).isEqualTo(Response.Status.OK.getStatusCode());
        response.close();
    }

此测试失败，出现以下错误：

WARNING: The following warnings have been detected: WARNING: HK2 service reification failed for [com.my.app.resources.FileUploadResource] with an exception:
MultiException stack 1 of 2
java.lang.NoSuchMethodException: Could not find a suitable constructor in com.my.app.resources.FileUploadResource class.
    at org.glassfish.jersey.internal.inject.JerseyClassAnalyzer.getConstructor(JerseyClassAnalyzer.java:192)
    at org.jvnet.hk2.internal.Utilities.getConstructor(Utilities.java:178)
    at org.jvnet.hk2.internal.ClazzCreator.initialize(ClazzCreator.java:128)
    at org.jvnet.hk2.internal.ClazzCreator.initialize(ClazzCreator.java:179)

我在FileUploadResource中没有任何参数构造函数，但是new ResourceConfig(FileUploadResource.class)需要一个无参数构造函数。如何在这里传递关于一个参数构造函数的信息？

这里的任何帮助都将是非常感谢的。此外，请随时建议关于代码和测试的任何其他最佳实践，以便我能够改进它们。

在此之前，非常感谢您。

Answer 1

将资源注册为类时

new ResourceConfig(FileUploadResource.class)

你是在告诉泽西去创造它。但是它不知道如何创建它，因为只有一个构造函数可以接受配置对象，而泽西岛对此一无所知。相反，您应该注册为一个对象。与注册Dropwizard (env.jersey().register(...))的方式相同。

new ResourceConfig().regster(new FileUploadResource(mockConfiguration))
    ...

顺便提一下，对于Dropwizard，我们不需要显式地使用JerseyTest。Dropwizard附带了一个JUnit规则，它显式地运行自己的JerseyTest，我们可以使用该规则配置它。参见本期，在这里我发布了一个完整的示例。