spring boot setContentType不起作用

Question

我试图在spring-boot上返回一个图像(1.2.2)
我应该如何设置内容类型？以下不适用于我(意味着响应标头根本不包含'content-type'标头):

    @RequestMapping(value = "/files2/{file_name:.+}", method = RequestMethod.GET)
public ResponseEntity<InputStreamResource> getFile2(final HttpServletResponse response) throws IOException {
    InputStream is = //someInputStream...
    org.apache.commons.io.IOUtils.copy(is, response.getOutputStream());
    response.setContentType("image/jpeg");
    InputStreamResource inputStreamR = new InputStreamResource(is);
    return new ResponseEntity<>(inputStreamR, HttpStatus.OK);
}

@RequestMapping(value = "/files3/{file_name:.+}", method = RequestMethod.GET)
public HttpEntity<byte[]> getFile3() throws IOException {
    InputStream is = //someInputStream...
    HttpHeaders headers = new HttpHeaders();
    headers.setContentType(MediaType.IMAGE_JPEG);
    return new HttpEntity<>(IOUtils.toByteArray(is), headers);
}

Answer 1

首先,@ResponseBody除了在类级而不是仅@RequestMapping使用注释之外,您还需要应用注释.另外,尝试例如的元素@RestController@Controllerproduces@RequestMapping

@RequestMapping(value = "/files2/{file_name:.+}", method = RequestMethod.GET, produces = {MediaType.IMAGE_JPEG_VALUE})

这应该"缩小主映射"并确保设置正确的内容类型.请参阅文档:http://docs.spring.io/spring/docs/current/spring-framework-reference/htmlsingle/#mvc-ann-requestmapping-produces

Answer 2

明白了...必须添加ByteArrayHttpMessageConverter到WebConfiguration类中：

@Configuration
@EnableWebMvc
@ComponentScan
public class WebConfiguration extends WebMvcConfigurerAdapter {

@Override
public void configureMessageConverters(List<HttpMessageConverter<?>> httpMessageConverters) {
    httpMessageConverters.add(new ByteArrayHttpMessageConverter());
}
}

然后我的第二次尝试（getFile3()）工作正常