如何在spring集成（DSL）中公开“内容配置”？

Question

下载文件时，我会将“内容配置”添加到我的responseHeader中，但它不起作用。

响应不会有任何添加的属性。

    @Bean
    public ExpressionParser fileParser() {
        return new SpelExpressionParser();
    }

    @Bean
    public HeaderMapper<HttpHeaders> fileHeaderMapper() {
        return new DefaultHttpHeaderMapper();
    }

@Bean
    public IntegrationFlow httpGetFileDownload() {
        return IntegrationFlows.from(
                Http.inboundGateway("/api/files/download/{id}")
                        .requestMapping(r -> r.methods(HttpMethod.GET))
                        .statusCodeExpression(fileParser().parseExpression("T(org.springframework.http.HttpStatus).BAD_REQUEST"))
                        .payloadExpression(fileParser().parseExpression("#pathVariables.id"))
                        .crossOrigin(cors -> cors.origin("*").exposedHeaders("Content-Disposition", "content-disposition"))
                        .headerMapper(fileHeaderMapper())
                )
                .channel("http.file.download.channel")
                .handle("fileEndpoint", "download")
                .get();
    }



public Message<?> download(Message<Long> msg){
...

return MessageBuilder
                    .withPayload(resource)
                    .copyHeaders(msg.getHeaders())
                    .setHeader(STATUSCODE_HEADER, HttpStatus.OK)
                    .setHeader(HttpHeaders.CONTENT_DISPOSITION,"attachment;filename=" + file.getName())
                    .setHeader(HttpHeaders.CONTENT_TYPE, mimeType)
                    .setHeader(HttpHeaders.CONTENT_LENGTH, (int)file.length())
                    .build();
}

我得到的：

cache-control："no-cache， no-store， max-age=0， oble-revaltify"
content-type："Application/json"
过期："0"
pragma："no-cache"

Answer 1

您的问题是DefaultHttpHeaderMapper默认为空。我认为可能是时候将ctor设为已弃用以不允许从最终应用程序使用它。或者进行一些验证以拒绝只是空的（未配置）DefaultHttpHeaderMapper...

同样令人困惑的是，使用返回新的DefaultHttpHeaderMapper（）有什么意义 如果您没有自定义它。HttpRequestHandlingMessagingGateway中有一个默认值：

private HeaderMapper<HttpHeaders> headerMapper = DefaultHttpHeaderMapper.inboundMapper();

为了解决您的问题，您肯定需要使用这个inboundMapper（）factory方法，它可以实现以下功能：

/**
 * Factory method for creating a basic inbound mapper instance.
 * This will map all standard HTTP request headers when receiving an HTTP request,
 * and it will map all standard HTTP response headers when sending an HTTP response.
 * @return The default inbound mapper.
 */
public static DefaultHttpHeaderMapper inboundMapper() {
    DefaultHttpHeaderMapper mapper = new DefaultHttpHeaderMapper();
    setupDefaultInboundMapper(mapper);
    return mapper;
}

setupDefaultInboundMapper（）非常重要：它为我们带来了一组从请求映射到响应的头。