Java MultipartFile#getContentType在Spring的集成测试期间返回null

我有以下文件：

ImageForm.java:

public class ImageForm {
  @FileNotEmpty
  private MultipartFile file;
  // other code ...
}

@Controller
@RequestMapping("/admin/galleries")
public class GalleryController {
@PostMapping("/{id}/image/create")
  public ModelAndView createImage(@PathVariable("id") long galleryId, @Valid ImageForm imageForm, BindingResult bindingResult, RedirectAttributes redirectAttributes) {
    // other code ...
    System.out.println(imageForm.getFile().getContentType()); // Prints: null
    // other code ...
  }
}

@SqlGroup({
     @Sql("classpath:test-schema.sql"),
     @Sql("classpath:test-gallery-data.sql"),
     @Sql("classpath:test-image-data.sql")
})
public class GalleryControllerIT extends SetupControllerIT {
    @Test
    public void createImage_POSTHttpMethod_ImageIsCreated() throws Exception {
        Path path = Paths.get(getClass().getClassLoader().getResource("test-image.png").toURI());
        byte[] image = Files.readAllBytes(path);

        mvc.perform(
            multipart("/admin/galleries/1/image/create")
                .file("file", image) // TODO: ImageForm.file.contentType is null.
                .with(csrf())
        ).andExpect(status().isFound());

        assertThat(imageRepository.count(), is(5L));
    }
}

GalleryController.java:

public class ImageForm {
  @FileNotEmpty
  private MultipartFile file;
  // other code ...
}

@Controller
@RequestMapping("/admin/galleries")
public class GalleryController {
@PostMapping("/{id}/image/create")
  public ModelAndView createImage(@PathVariable("id") long galleryId, @Valid ImageForm imageForm, BindingResult bindingResult, RedirectAttributes redirectAttributes) {
    // other code ...
    System.out.println(imageForm.getFile().getContentType()); // Prints: null
    // other code ...
  }
}

@SqlGroup({
     @Sql("classpath:test-schema.sql"),
     @Sql("classpath:test-gallery-data.sql"),
     @Sql("classpath:test-image-data.sql")
})
public class GalleryControllerIT extends SetupControllerIT {
    @Test
    public void createImage_POSTHttpMethod_ImageIsCreated() throws Exception {
        Path path = Paths.get(getClass().getClassLoader().getResource("test-image.png").toURI());
        byte[] image = Files.readAllBytes(path);

        mvc.perform(
            multipart("/admin/galleries/1/image/create")
                .file("file", image) // TODO: ImageForm.file.contentType is null.
                .with(csrf())
        ).andExpect(status().isFound());

        assertThat(imageRepository.count(), is(5L));
    }
}

GalleryControllerIT.java:

public class ImageForm {
  @FileNotEmpty
  private MultipartFile file;
  // other code ...
}

@Controller
@RequestMapping("/admin/galleries")
public class GalleryController {
@PostMapping("/{id}/image/create")
  public ModelAndView createImage(@PathVariable("id") long galleryId, @Valid ImageForm imageForm, BindingResult bindingResult, RedirectAttributes redirectAttributes) {
    // other code ...
    System.out.println(imageForm.getFile().getContentType()); // Prints: null
    // other code ...
  }
}

@SqlGroup({
     @Sql("classpath:test-schema.sql"),
     @Sql("classpath:test-gallery-data.sql"),
     @Sql("classpath:test-image-data.sql")
})
public class GalleryControllerIT extends SetupControllerIT {
    @Test
    public void createImage_POSTHttpMethod_ImageIsCreated() throws Exception {
        Path path = Paths.get(getClass().getClassLoader().getResource("test-image.png").toURI());
        byte[] image = Files.readAllBytes(path);

        mvc.perform(
            multipart("/admin/galleries/1/image/create")
                .file("file", image) // TODO: ImageForm.file.contentType is null.
                .with(csrf())
        ).andExpect(status().isFound());

        assertThat(imageRepository.count(), is(5L));
    }
}

在测试

GallerControllerIT#createImage_POSTHttpMethod_Images已创建

我设置了一个文件

测试将文件发送到GalleryController#createImage并映射它 到

ImageForm#file

属性

ImageForm#file

的类型为

MultipartFile

，其方法为

getContentType

方法

MultipartFile#getContentType

返回

null

---

问题是，

MultipartFile#getContentType

为什么返回null？在测试之外时，它可以正常工作。

有关完整数据，您应该调用

.file(new MockMultipartFile("image", "some_name", MediaType.MULTIPART_FORM_DATA_VALUE, image))

因为在你的例子中，如果你调用

.file（“file”，image）

他们调用构造函数的短版本

MockMultipartFile

，而不使用内容类型

---

MockMvc

尝试不创建或声明一些附加值或参数，如果您没有声明它们的值或参数。

谢谢，这就是问题所在。