Question

如何在Spring DSL中实现以下谓词示例given：

Predicate isWidget = header("type").isEqualTo("widget");

from("jms:queue:order")
   .choice()
      .when(isWidget).to("bean:widgetOrder")
      .when(isWombat).to("bean:wombatOrder")
   .otherwise()
      .to("bean:miscOrder")
   .end();

Answer 1

所需的简单元素（见accepted answer）是

<simple>${header.type} == 'widget'</simple>

注意字段表达式如何被$ {}包围，后跟OGNL语法进行比较，这不是字段表达式本身的一部分。

Answer 2

像这样：

<route>
  <from uri="jms:queue:order"/>
  <choice>
    <when>
       <simple>${header.type} == 'widget'</simple>
       <to uri="bean:widgetOrder"/>
    </when>
    <when>
      <simple>${header.type} == 'wombat'</simple>
      <to uri="bean:wombatOrder"/>
    </when>
    <otherwise>
      <to uri="bean:miscOrder"/>
    </otherwise>
  </choice>
</route>

Answer 3

如果目标是在Spring XML DSL中使用谓词，那么这会更合适-

<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:camel="http://camel.apache.org/schema/spring"
xsi:schemaLocation="
            http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
            http://camel.apache.org/schema/spring http://camel.apache.org/schema/spring/camel-spring.xsd">

<camel:camelContext trace="true">
    <camel:route>
        <camel:from uri="jms:queue:order" />
        <camel:filter>
            <camel:method ref="myPredicate" />
            <to uri="bean:widgetOrder"/>
        </camel:filter>
    </camel:route>
</camel:camelContext>

<bean id="myPredicate" class="MyPredicate"/>
</beans>

xml DSL中的Camel谓词示例

3 个答案: