在Spring Integration 4.2中逃脱了application/json响应的问题 [英] Issue with application/json reponse being escaped in Spring Integration 4.2

问题描述

在Spring Integration 4.2.1.RELEASE中创建HTTP代理.环境正在使用最新的2.0.0.RELEASE平台BOM，其中包括运行在Tomcat7上的spring-webmvc层.

Creating an HTTP proxy in Spring Integration 4.2.1.RELEASE. Environment is using the latest 2.0.0.RELEASE platform BOM, including a spring-webmvc layer - running on Tomcat7.

调用是应用程序/json"，通过Web层传递到另一个REST服务器端点(setupUrl方法重写URL).该代码成功调用了外部服务器，获得了良好的响应，然后在响应返回给调用者之前对其进行了处理.

Calls are "application/json", passed through the web layer to a different REST server endpoint (the setupUrl method rewrites the URL). The code successfully calls the external server, gets good response, then mangles the response before it returns to the caller.

@Bean
    public IntegrationFlow httpProxyFlow()  {
        return IntegrationFlows
            .from((MessagingGateways g) ->
                    g.httpGateway("/my-service/**")
                            .messageConverters(new MappingJackson2HttpMessageConverter())
                        .payloadFunction(httpEntity ->
                                ((ServletRequestAttributes) RequestContextHolder.currentRequestAttributes())
                                        .getRequest()
                                        .getQueryString())
                        .requestPayloadType(String.class))
                        .handleWithAdapter(a ->
                                a.httpGateway(this::setupUrl)
                                        .httpMethodFunction(this::getMethodFunction)
                                        .errorHandler(new PassThroughErrorHandler())
                                        .encodeUri(false)
                                        .expectedResponseType(String.class)
                        ).get();
    }

直接调用REST端点的调用会返回

The call directly to the REST endpoint returns

{会员":测试"，生产者":"TST"，产品" ...

{"affiliate":"test","producer":"TST","products"...

通过Spring Integration进行的调用返回

While the call through Spring Integration returns

"{\"会员\:\"测试\，\"生产者\:\" TST \，\"产品\:[{\"

"{\"affiliate\":\"test\",\"producer\":\"TST\",\"products\":[{\"

尝试了将StringHttpMessageConverter添加到出站适配器的许多组合.混淆编码(UTF-8而不是ISO-8859-1).响应字符串有些混乱，似乎在我可以告诉它之前，它就离Spring Integration很近了. Integration上次接触它的时间是HttpRequestHandlingMessagingGateway.handleRequest()第117行.在该响应对象中，它看起来仍然正确.

Tried a lot of combinations of adding StringHttpMessageConverter to the outbound adapter. Messing with the encodings (UTF-8 rather than ISO-8859-1). Something is messing with the response string, and it seems to be AFTER it leaves Spring Integration as near as I can tell. The last time Integration touches it is HttpRequestHandlingMessagingGateway.handleRequest() line 117. It still looks correct in the response object there.

spring-mvc可能确实存在问题，这是我在调试中首先看到错误的字符串.

It's possible the issue is really with spring-mvc, that is the first place I see the mangled string in debugging.

推荐答案

最好的猜测是accept(入站)或content-type(出站)存在一些问题.

Best guess is some problem with the accept (inbound) or content-type (outbound).

我只是这样更改了http示例...

I just changed the http sample like so...

<int-http:inbound-gateway request-channel="proxyChannel"
                            reply-channel="reply"
                            path="/receiveGateway"
                            supported-methods="POST"/>

<int:channel id="reply" />

<int-http:outbound-gateway request-channel="proxyChannel"
                reply-channel="reply"
                expected-response-type="java.lang.String"
                url="http://localhost:8080/http/receiveGateway2"/>

<int-http:inbound-gateway request-channel="receiveChannel"
                            path="/receiveGateway2"
                            supported-methods="POST"/>

<int:channel id="receiveChannel"/>

<int:chain input-channel="receiveChannel">
    <int:header-filter header-names="content-type" />
    <int:service-activator expression='{"foo" : "bar"}'/>
</int:chain>

返回到第一个网关的有效负载是类型String；它适用于text/plain或application/json的入站accept.

The payload being returned to the first gateway is type String; it works for me with an inbound accept of text/plain or application/json.

由于StringHttpMessageConverter在列表中的JSON消息转换器之前，并且有效负载为String，因此选择它是因为类型为String并且该转换器可以处理*/* accept，因此没有双重JSON编码.

Since the StringHttpMessageConverter is ahead of the JSON message converter in the list, and the payload is a String, it is chosen because the type is String and that converter can handle */* accept, so there's no double JSON encoding.

{"foo":"bar"}.

如果无法通过DEBUG日志记录和/或调试器解决问题，则可以尝试仅使用StringHttpMessageConverter重新配置入站网关.

If you can't figure it out with DEBUG logging and/or the debugger, you could try reconfiguring the inbound gateway with just a StringHttpMessageConverter.

在HttpRequestHandlingMessagingGateway的第151行(当前版本)处设置一个断点，以查看正在选择哪个出站消息转换器.

Set a breakpoint at line 151 (current release) in HttpRequestHandlingMessagingGateway to see which outbound message converter is being selected.

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