Spring测试中的NullPointerException with Service，尽管参数已经有一个值

Question

我想在服务类中测试一个方法，但是如果（！uploadFolder.endswith（“/”））uploadFolder+=“/”行中有NullPointerException,尽管uploadFolder已经有一个有效值。测试类中uploadFolder的模拟值取自Application.yml文件。MockMultipartFile也成功创建，其中包含内容。

服务类别：

@Service
public class UploadService {
  private static File uploadedDocument;

  @Value("${directory.upload}")
  private String uploadFolder;

  public ResponseEntity saveFile(MultipartFile file) {
    if (!uploadFolder.endsWith( "/" )) uploadFolder += "/";
    try {
        File saveDir = new File( uploadFolder );

        if (!saveDir.exists()) {
            if (!saveDir.mkdirs())
                return ResponseEntity.status( HttpStatus.FORBIDDEN ).body( "No permission to write." );
        }
        byte bytes[] = file.getBytes();
        Path path = Paths.get( uploadFolder + file.getOriginalFilename() );
        Files.write( path, bytes );
        File myFile = new File( uploadFolder, file.getOriginalFilename() );

        uploadedDocument = myFile;

        return ResponseEntity.status( 200 ).build();

    } catch (IOException e) {
        e.printStackTrace();
    }

    return ResponseEntity.status( 500 ).build();
}

测试类：

@RunWith(SpringRunner.class)
@SpringBootTest
@TestPropertySource("classpath:application.yml")
@ActiveProfiles("test")
public class UploadServiceTest {

  private UploadService uploadService;

  @Value("${directory.upload}")
  private String uploadFolder;

  @Before
  public void before() {
    uploadService = new UploadService();
    System.out.println( uploadFolder );
  }

  @Test
  public void testSaveFile() throws Exception {
    byte[] content = Files.readAllBytes( Paths.get( uploadFolder + "\\test.txt" ) );
    MockMultipartFile mockMultipartFile = new MockMultipartFile( "document", content );
    ResponseEntity response = uploadService.saveFile( mockMultipartFile );
    Assert.assertEquals( response, new ResponseEntity( HttpStatus.ACCEPTED ) );
  }

}

Answer 1

您的UploadFolder变量仅加载在测试类中。这就是为什么要得到NullPointerException。如果执行测试，则uploadservice中的uploadfolder仍然为空。

只要可能，我都不会在测试中使用spring上下文。在您的示例中，可以将测试作为普通的junit测试运行，并使用Spring中的ReflectionTestUtils类设置UploadService的UploadFolder变量。在测试类的before-method中添加以下行：

RectionTestUtils.setField(uploadService, "uploadFolder", "your_folder_path");

参见ReflectionTestUtils类的JavaDoc：JavaDoc：ReflectionTestUtils.SetField（java.lang.Object,java.lang.String,java.lang.Object）