如果你没有指定 expected-response-type 在您的网关中,默认行为是响应消息仅包含状态代码(expected-response-type为null)。尝试设置 expected-response-type="java.lang.String" :
expected-response-type
expected-response-type="java.lang.String"
<int-http:outbound-gateway url="#{appProperties['rootUrl']}" http-method="#{appProperties['myMethod']}" expected-response-type="java.lang.String" request-channel="myRequestChannel" reply-channel="myResponseChannel" />