Question

我在我的应用程序中发现了一个配置问题，该问题应该尝试向第三方服务发送请求并等待响应。请求和响应的内容类型是json。

我发现的问题是在MessagingGatewaySupport类中我发现应该是PollableChannel的回复通道的期望，但我需要使用DirectChannel而不是Pollable：

protected Object receive() {
this.initializeIfNecessary();
MessageChannel replyChannel = getReplyChannel();
Assert.state(replyChannel != null && (replyChannel instanceof PollableChannel),
        "receive is not supported, because no pollable reply channel has been configured");
return this.messagingTemplate.receiveAndConvert(replyChannel, null);
}

我真的认为我的配置错误如下：

<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:jee="http://www.springframework.org/schema/jee" xmlns:int="http://www.springframework.org/schema/integration" xmlns:int-http="http://www.springframework.org/schema/integration/http" xsi:schemaLocation="http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-4.3.xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd http://www.springframework.org/schema/integration/http http://www.springframework.org/schema/integration/http/spring-integration-http-4.3.xsd http://www.springframework.org/schema/integration http://www.springframework.org/schema/integration/spring-integration-4.3.xsd">

<jee:jndi-lookup id="repositoryUrl" jndi-name="repositoryUrl"/>
<jee:jndi-lookup id="wsMaxTotalConnections" jndi-name="wsMaxTotalConnections" default-value="50"/>
<jee:jndi-lookup id="wsMaxPerRoute" jndi-name="wsDefaultMaxPerRoute" default-value="50"/>
<jee:jndi-lookup id="wsConnectionTimeout" jndi-name="wsDefaultConnectionTimeout" default-value="10000"/>
<jee:jndi-lookup id="wsReadTimeout" jndi-name="wsDefaultReadTimeout" default-value="5000"/>

<int:gateway id="requestGateway" service-interface="com.example.Repository" default-request-channel="requestChannel" 
    default-reply-channel="responseChannel"/>

<int:channel id="requestChannel"/>
<int:channel id="responseChannel"/>

<int-http:outbound-gateway request-channel="requestChannel" url="#{repositoryUrl}" http-method="POST" expected-response-type="java.lang.String"
    request-factory="httpComponentsClientHttpRequestFactory" message-converters="jsonMessageConverter"/>

<bean id="jsonMessageConverter" class="com.example.JsonMessageConverter">
    <constructor-arg>
        <bean class="com.example.DataType"/>
    </constructor-arg>
</bean>

<bean id="httpComponentsClientHttpRequestFactory" class="com.example.ApplicationHttpComponentsClientHttpRequestFactory">
    <property name="maxTotalConnections" ref="wsMaxTotalConnections"/>
    <property name="defaultMaxPerRoute" ref="wsMaxPerRoute"/>
    <property name="connectionTimeout" ref="wsConnectionTimeout"/>
    <property name="readTimeout" ref="wsReadTimeout"/>
</bean>

JsonMessageConverter类：

public class JsonMessageConverter implements HttpMessageConverter<Object> {
private static final Logger logger = LoggerFactory.getLogger(JsonMessageConverter.class);

private Object clazz;

private List<MediaType> supportedMediaTypes = Collections.emptyList();

public Object getClazz()
{
    return clazz;
}

public void setClazz(Object clazz)
{
    this.clazz = clazz;
}

public JsonMessageConverter(Object clazz)
{
    this.clazz = clazz;
}

@Override
public boolean canRead(Class<?> clazz, MediaType mediaType)
{
    return this.clazz.getClass().equals(clazz);
}

@Override
public boolean canWrite(Class<?> clazz, MediaType mediaType)
{
    return false;
}

@Override
public List<MediaType> getSupportedMediaTypes()
{
    return supportedMediaTypes;
}

@Override
public Object read(Class<? extends Object> clazz, HttpInputMessage inputMessage) throws IOException, HttpMessageNotReadableException
{
    Object response = new Object();

    logger.trace("Received message in :{} ", inputMessage.getBody().toString());

    try
    {
        Gson gson = new Gson();
        String inputStreamString = inputMessage.getBody().toString();

        response = gson.fromJson(inputStreamString, this.clazz.getClass());
    }
    catch (Exception e)
    {
        throw new HttpMessageConversionException("Failed to convert response to: " + clazz, e);
    }

    logger.trace("Received message out :{} ", response);

    return response;

}

@Override
public void write(Object t, MediaType contentType, HttpOutputMessage outputMessage) throws IOException, HttpMessageNotWritableException
{
    Gson gson = new Gson();

    logger.trace("Sent message in :{} ", t);

    String json = gson.toJson(t);

    outputMessage.getBody().write(json.getBytes());

    logger.trace("Sent message out :{} ", json);
}

}

例外的相关部分：

java.lang.IllegalStateException: receive is not supported, because no pollable reply channel has been configured
at org.springframework.util.Assert.state(Assert.java:392)
at org.springframework.integration.gateway.MessagingGatewaySupport.receive(MessagingGatewaySupport.java:391)
at org.springframework.integration.gateway.GatewayProxyFactoryBean.invokeGatewayMethod(GatewayProxyFactoryBean.java:468)
at org.springframework.integration.gateway.GatewayProxyFactoryBean.doInvoke(GatewayProxyFactoryBean.java:429)
at org.springframework.integration.gateway.GatewayProxyFactoryBean.invoke(GatewayProxyFactoryBean.java:420)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213)
at com.sun.proxy.$Proxy28.getSoccerSeasons(Unknown Source)
at com.example.ServiceImpl.getData(ServiceImpl.java:26)

Spring Integration的版本是4.3.6。有人能帮助我吗？我尝试了很多例子，但我没有找到任何合适的例子。

提前感谢您的帮助。

Answer 1

您需要显示com.example.Repository界面。

看起来你正在调用的方法没有参数。您需要发送一些内容才能收到回复。

请参阅the documentation about gateway methods with no parameters。

在Gateway接口上调用没有任何参数的方法时，默认行为是从PollableChannel接收消息。

有时，您可能希望触发无参数方法，以便您实际上可以与下游不需要用户提供的参数的其他组件进行交互，例如：触发无参数SQL调用或存储过程。

为了实现发送和接收语义，您必须提供有效负载。为了生成有效载荷，......

Spring http出站网关希望使用PollableChannel而不是DirectChannel

1 个答案: