Apache Camel提供了和Spring的集成,通过Spring容器(ApplicationContext)来管理Camel的CamelContext,这样的话,就不需要写代码来控制CamelContext的初始化,启动和停止了.Camel会随着Spring的启动而启动起来.

本文将Apache Camel框架入门示例(http://blog.csdn.net/kkdelta/article/details/7231640)中的例子集成到Spring中,下面简单介绍一下集成的基本步骤.

1,新建一个Eclipse工程,将Spring3的jar包,和Camel的jar包配置到工程的classpath.

2,Route类要继承RouteBuilde,如下

public class FileProcessWithCamelSpring extends RouteBuilder {
    @Override
    public void configure() throws Exception {
        FileConvertProcessor processor = new FileConvertProcessor(); 
        from("file:d:/temp/inbox?delay=30000").process(processor).to("file:d:/temp/outbox");        
    }
}

3,Processor仍然和和入门示例的代码相同.

public class FileConvertProcessor implements Processor{
    @Override
    public void process(Exchange exchange) throws Exception {    
        try {
            InputStream body = exchange.getIn().getBody(InputStream.class);
            BufferedReader in = new BufferedReader(new InputStreamReader(body));
            StringBuffer strbf = new StringBuffer("");
            String str = null;
            str = in.readLine();
            while (str != null) {                
                System.out.println(str);
                strbf.append(str + " ");
                str = in.readLine();                
            }
            exchange.getOut().setHeader(Exchange.FILE_NAME, "converted.txt");
            // set the output to the file
            exchange.getOut().setBody(strbf.toString());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

4,创建一个Spring的配置文件如下:注意要将camel的xmlns加入文件中

<?xml version="1.0" encoding="UTF-8"?>
<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-3.0.xsd
    http://camel.apache.org/schema/spring http://camel.apache.org/schema/spring/camel-spring.xsd"
    default-autowire="byName"  default-init-method="init">
    <camelContext id="testCamelContext" xmlns="http://camel.apache.org/schema/spring">
        <package>com.test.camel</package>
    </camelContext>    
</beans>

5,启动Spring容器,Camel会自动启动,不用像入门示例那样CamelContext context = new DefaultCamelContext(), context.addRoutes(..); context.start();

ApplicationContext ac = new ClassPathXmlApplicationContext("config/cameltest.xml");
while (true) {
Thread.sleep(2000);
}

可见,Camel可以很容易的和Spring集成.

Camel还提供了"Spring DSL"来在XML中配置Route规则,不需要用JAVA类(如上面的FileProcessWithCamelSpring )来实现route.

<?xml version="1.0" encoding="UTF-8"?>
<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-3.0.xsd
    http://camel.apache.org/schema/spring http://camel.apache.org/schema/spring/camel-spring.xsd"
    default-autowire="byName"  default-init-method="init">
    <bean id="fileConverter" class="com.test.camel.FileConvertProcessor"/>
    <camelContext id="testCamelContext" xmlns="http://camel.apache.org/schema/spring">
        <route>
            <from uri="file:d:/temp/inbox?delay=30000"/>
            <process ref="fileConverter"/>
            <to uri="file:d:/temp/outbox"/>
        </route>
    </camelContext>
</beans>

与第五步一样启动Spring容器,Camel会每隔30秒轮询一下看d:/temp/inbox是否有文件,有的话则进行处理.