Http Outbound Gateway动态填充URL报错问题求助

Let's tackle both of your errors one by one, with clear fixes you can apply immediately:

1. Fixing "Could not resolve placeholder 'UrlVariable' in string value" #

Root Cause #

You confused Spring property placeholders ( ${...} ) with Spring Integration URI variables ( {...} ). The ${UrlVariable} syntax tells Spring to look for a static property named UrlVariable in your configuration files (like application.properties), but you actually want to dynamically populate the URL from a message header.

Correct Configuration #

Update your <http:outbound-gateway> to use URI variable syntax instead of property placeholders, and align the variable name with your header:

<http:outbound-gateway 
    mapped-request-headers="Accept*, Content-Type, X-*, HTTP_REQUEST_HEADERS" 
    request-channel="create_order_outbound_gateway_with_json_POST" 
    reply-channel="print_payload" 
    url="{postURL}" <!-- Use URI variable syntax here -->
    http-method="POST" 
    expected-response-type="java.lang.String" 
    charset="UTF-8" 
    request-factory="httpRequestFactory">
    <http:uri-variable name="postURL" expression="headers['postURL']"/> <!-- Match the variable name in url -->
</http:outbound-gateway>

This tells Spring Integration to replace {postURL} with the value of the postURL header from your message, instead of trying to resolve it as a static configuration property.

2. Fixing "Invalid use of BasicClientConnManager: connection still allocated" #

Root Cause #

BasicClientConnectionManager is a single-threaded connection manager—it only allows one active connection at a time. If you have concurrent requests or connections aren't properly released (e.g., due to unhandled exceptions), you'll hit this error.

Correct Configuration #

Replace BasicClientConnectionManager with PoolingHttpClientConnectionManager, which supports concurrent connections. Here's how to configure it in XML:

First, define the pooling connection manager and HTTP client:

<bean id="poolingConnManager" class="org.apache.http.impl.conn.PoolingHttpClientConnectionManager">
    <property name="maxTotal" value="100"/> <!-- Adjust based on your concurrency needs -->
    <property name="defaultMaxPerRoute" value="20"/>
</bean>

<bean id="httpClient" class="org.apache.http.impl.client.HttpClientBuilder" factory-method="create">
    <property name="connectionManager" ref="poolingConnManager"/>
</bean>

Then update your httpRequestFactory to use this pooled client:

<bean id="httpRequestFactory" class="org.springframework.http.client.HttpComponentsClientHttpRequestFactory">
    <constructor-arg ref="httpClient"/>
    <!-- Optional: Set connection/read timeouts -->
    <property name="connectTimeout" value="5000"/>
    <property name="readTimeout" value="10000"/>
</bean>

This setup allows multiple concurrent connections and properly manages connection lifecycle, eliminating the "connection still allocated" error.

Full Modified Configuration Snippet #

Putting it all together, your relevant config should look like this:

<int:header-enricher input-channel="jmsInboundChannel_POST" output-channel="outbound_gateway_channel_POST">
    <int:header name="postURL" expression="payload.getUrl()"/>
    <int:header name="Accept-Language" value="en_GB"/>
    <int:header name="X-Source-CountryCode" value="GB"/>
    <int:header name="X-Source-Operator" value="Enterprise"/>
    <int:header name="X-Source-Division" value="OrderManagement"/>
    <int:header name="X-Source-System" value="${sapwebservices.http.header.source.system}"/>
    <int:header name="X-Source-Timestamp" expression="new java.text.SimpleDateFormat('yyyy-MM-dd HH:mm:ss').format(new java.util.Date())"/>
    <int:header name="Accept" value="application/json"/>
    <int:header name="Content-Type" value="application/json;charset=UTF-8"/>
</int:header-enricher>

<int:object-to-json-transformer input-channel="outbound_gateway_channel_POST" output-channel="create_order_outbound_gateway_with_json_POST" object-mapper="nonNullObjectMapper"/>

<!-- New Pooled Connection Manager Setup -->
<bean id="poolingConnManager" class="org.apache.http.impl.conn.PoolingHttpClientConnectionManager">
    <property name="maxTotal" value="100"/>
    <property name="defaultMaxPerRoute" value="20"/>
</bean>

<bean id="httpClient" class="org.apache.http.impl.client.HttpClientBuilder" factory-method="create">
    <property name="connectionManager" ref="poolingConnManager"/>
</bean>

<bean id="httpRequestFactory" class="org.springframework.http.client.HttpComponentsClientHttpRequestFactory">
    <constructor-arg ref="httpClient"/>
    <property name="connectTimeout" value="5000"/>
    <property name="readTimeout" value="10000"/>
</bean>

<!-- Fixed Outbound Gateway -->
<http:outbound-gateway 
    mapped-request-headers="Accept*, Content-Type, X-*, HTTP_REQUEST_HEADERS" 
    request-channel="create_order_outbound_gateway_with_json_POST" 
    reply-channel="print_payload" 
    url="{postURL}" 
    http-method="POST" 
    expected-response-type="java.lang.String" 
    charset="UTF-8" 
    request-factory="httpRequestFactory">
    <http:uri-variable name="postURL" expression="headers['postURL']"/>
</http:outbound-gateway>

内容的提问来源于stack exchange，提问作者rowen