Java 驼峰聚合策略生成空体消息
我目前有以下骆驼路线:Java 驼峰聚合策略生成空体消息,java,nullpointerexception,apache-camel,aggregate,enterprise-integration,Java,Nullpointerexception,Apache Camel,Aggregate,Enterprise Integration,我目前有以下骆驼路线: <camelContext id="my-camel-context" xmlns="http://camel.apache.org/schema/spring"> <propertyPlaceholder id="envProps" location="classpath:myapp.properties" /> <route id="my-camel-route"> <from uri="{{
<camelContext id="my-camel-context" xmlns="http://camel.apache.org/schema/spring">
<propertyPlaceholder id="envProps" location="classpath:myapp.properties" />
<route id="my-camel-route">
<from uri="{{start.uri}}"/>
<setHeader headerName="id">
<constant>1</constant>
</setHeader>
<to uri="bean:preProcessor?method=process" />
<aggregate strategyRef="myAggregationStrategy" completionSize="1">
<correlationExpression>
<simple>${header.id} == 1</simple>
</correlationExpression>
<to uri="bean:postProcessor?method=process" />
</aggregate>
<to uri="bean:mailer?method=process" />
</route>
</camelContext>
<bean id="myAggregationStrategy" class="com.me.myapp.MyAggregationStrategy" />
<bean id="postProcessor" class="com.me.myapp.PostProcessor" />
<bean id="mailer" class="com.me.myapp.Mailer" />
还有我的后处理器bean:
public class PostProcessor implement Processor {
@Override
public void process(Exchange exchange) {
try {
System.out.println("In PostProcessor...");
AppPayload payload = (AppPayload)exchange.getIn().getBody();
System.out.println("\t...payload acquired...");
if(payload == null)
System.out.println("Payload is NULL.");
} catch(Throwable throwable) {
System.out.println(ExceptionUtils.getFullStackTrace(throwable));
}
}
}
当我运行这段代码时,我会看到来自预处理器
bean的日志消息,表明它正在正确执行。我还看到,MyAggregationStrategy
正确地“聚合”了消息,然后在第一条消息到达后让它传递给后处理器(同样,因为completionSize=1
)。但是,我在后处理器中得到以下输出:
In PostProcessor...
...payload acquired...
Payload is NULL.
有人知道为什么有效负载
会为空吗?它不应该在MyAggregationStrategy
中初始化吗?!?我很高兴发布更多代码,但我相信这是因为我错误地使用了AggregationStrategy
API。我相信您会对aggregatingExchange
和incomingExchange
感到困惑。你能试试这个吗
public class MyAggregationStrategy implements AggregationStrategy {
@Override
public Exchange aggregate(Exchange aggregatingExchange, Exchange incomingExchange) {
AppPayload payload = null;
if(aggregatingExchange == null) {
payload = new AppPayload(); // This should prevent it from being NULL below in PostProcessor...
} else {
payload = (AppPayload)aggregatingExchange.getIn().getBody();
}
payload.setCargo((Order)incomingExchange.getIn().getBody());
if(aggregatingExchange == null) {
incomingExchange.getIn().setBody(payload);
return incomingExchange;
} else {
return aggregatingExchange;
}
}
}
添加@hveiga已经提到的内容。
我有一个类似的问题,我通过在邮件中添加标题来解决。
然而,在您的例子中,我看到您没有使用splitter,并且已经定义了一个头。从克劳斯·伊布森那里得到的一条信息是,第一次交换的时间是空的,我们需要检查空对象
请参阅此以了解更多解释-
在此处跟踪完整的解释-
public class MyAggregationStrategy implements AggregationStrategy {
@Override
public Exchange aggregate(Exchange aggregatingExchange, Exchange incomingExchange) {
AppPayload payload = null;
if(aggregatingExchange == null) {
payload = new AppPayload(); // This should prevent it from being NULL below in PostProcessor...
} else {
payload = (AppPayload)aggregatingExchange.getIn().getBody();
}
payload.setCargo((Order)incomingExchange.getIn().getBody());
if(aggregatingExchange == null) {
incomingExchange.getIn().setBody(payload);
return incomingExchange;
} else {
return aggregatingExchange;
}
}
}