spring 启动 setContentType 不工作

Question

我正在尝试 return spring-boot (1.2.2)
上的图像我应该如何设置content-type？以下都不适合我（意味着响应 header 根本不包含 'content-type' header）：

    @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，除了 @RequestMapping 之外，您还需要应用 @ResponseBody 注释，除非您在 class 级别使用 @RestController 而不是 @Controller。另外，尝试 @RequestMapping 的 produces 元素，例如

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

这应该 'narrow the primary mapping' 并确保设置了正确的内容类型。请参阅文档：http://docs.spring.io/spring/docs/current/spring-framework-reference/htmlsingle/#mvc-ann-requestmapping-produces

Answer 2

知道了...必须将 ByteArrayHttpMessageConverter 添加到 WebConfiguration class:

@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

spring 启动 setContentType 不工作

spring boot setContentType is not working

spring

content-type

spring-boot