java - Apache Camel 和 Spring 的类型转换问题

Question

我正在尝试将我的 Camel Spring(Camel 2.20.2；Spring 4.3.14)配置外部化为 application.properties属性文件。该属性文件包含以下内容:

net.sender1.port = 47000
net.sender1.address = 127.255.255.255

application.properties文件位于src/main/resources内并由 maven-shade-plugin 复制到目标 jar。

我的 Camel 上下文如下所示:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="..." xmlns:xsi="..." xmlns:camel="..." xsi:schemaLocation="...">
  <bean id="udpSender1" class="com.foo.MyUDPSender">
    <constructor-arg type="java.lang.String" value="${net.sender1.address}" />
    <constructor-arg type="java.lang.Integer" value="${net.sender1.port}" />
  </bean>

  <camelContext xmlns="http://camel.apache.org/schema/spring">
    ...
  </camelContext>
</beans>

当我启动应用程序时，出现以下错误:

WARN | 2018-02-23 09:50:25,324 | [main]  ClassPathXmlApplicationContext.refresh  - Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'udpSender1' defined in class path resource [META-INF/spring/camel-context.xml]: Unsatisfied dependency expressed through constructor parameter 1: Could not convert argument value of type [java.lang.String] to required type [java.lang.Integer]: Failed to convert value of type 'java.lang.String' to required type 'java.lang.Integer'; nested exception is java.lang.NumberFormatException: For input string: "${net.sender1.port}"org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'udpSender1' defined in class path resource [META-INF/spring/camel-context.xml]: Unsatisfied dependency expressed through constructor parameter 1: Could not convert argument value of type [java.lang.String] to required type [java.lang.Integer]: Failed to convert value of type 'java.lang.String' to required type 'java.lang.Integer'; nested exception is java.lang.NumberFormatException: For input string: "${net.sender1.port}"    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:723)    at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:189)    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1193)    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1095)    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:513)    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761)    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867)    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543)    at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:139)    at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:93)    at org.apache.camel.spring.Main.createDefaultApplicationContext(Main.java:222)    at org.apache.camel.spring.Main.doStart(Main.java:154)    at org.apache.camel.support.ServiceSupport.start(ServiceSupport.java:61)    at com.foo.Server.main(Server.java:19)

看来address属性被正确解析，因为它是一个字符串。这意味着应用程序可以找到属性文件。

有没有办法在属性或 spring xml 中显式定义类型？

Answer 1

事实上，您的应用程序找不到您的属性文件。它试图将字符串文字“${net.sender1.port}”转换为整数，这就是您收到 NumberFormatException 的原因。

您需要指定一个PropertyPlaceholder才能读取外部属性文件。

<bean class="org.apache.camel.spring.spi.BridgePropertyPlaceholderConfigurer" id="bridgePropertyPlaceholder">
    <property name="location" value="classpath:application.properties"/>
</bean>

如果您将上述内容添加到您的应用程序中，它至少应该能够读取实际属性。