Camel 组件之 Timer

http://www.xeclipse.com/?p=1053

Timer是常用的定时组件，下面简单讲解一下这个组件的基础用法。

作用：定时产生一条Message。

注意：这个组件仅仅能用作consumer，不能用作producer。简单地说，就是只能放在from()里面，不能放在to()里面。

Timer用法

1	`timer:name[?options]`

非常简单，需要一个名字，以及必要的参数：

Name	Default Value	Description
time	null	A java.util.Date the first event should be generated. If using the URI, the pattern expected is: yyyy-MM-dd HH:mm:ss or yyyy-MM-dd'T'HH:mm:ss.
pattern	null	Allows you to specify a custom Date pattern to use for setting the time option using URI syntax.
period	1000	If greater than 0, generate periodic events every period milliseconds.
delay	0	The number of milliseconds to wait before the first event is generated. Should not be used in conjunction with the time option.
fixedRate	false	Events take place at approximately regular intervals, separated by the specified period.
daemon	true	Specifies whether or not the thread associated with the timer endpoint runs as a daemon.
repeatCount	0	Camel 2.8: Specifies a maximum limit of number of fires. So if you set it to 1, the timer will only fire once. If you set it to 5, it will only fire five times. A value of zero or negative means fire forever.

Timer产生的Message，带着特定的Properties，这些Properties分别为：

Name	Type	Description
Exchange.TIMER_NAME	String	The value of the name option.
Exchange.TIMER_TIME	Date	The value of the time option.
Exchange.TIMER_PERIOD	long	The value of the period option.
Exchange.TIMER_FIRED_TIME	Date	The time when the consumer fired.
Exchange.TIMER_COUNTER	Long	Camel 2.8: The current fire counter. Starts from 1.

同时Message也有一个Header：

Name	Type	Description
Exchange.TIMER_FIRED_TIME	java.util.Date	The time when the consumer fired

Timer示例

import org.apache.camel.CamelContext;

import org.apache.camel.builder.RouteBuilder;

import org.apache.camel.impl.DefaultCamelContext;

/**

* A Camel Router

*/

public class TimerRouteBuilder extends RouteBuilder {

/**

* A main() so we can easily run these routing rules in our IDE

*/

public static void main(String... args) throws Exception {

CamelContext camelContext = new DefaultCamelContext();

camelContext.addRoutes(new TimerRouteBuilder());

camelContext.start();

Thread.sleep(100000000);

}

/**

* Lets configure the Camel routing rules using Java code...

*/

public void configure() {

from("timer://myTimer?period=2000").setBody()

.simple("Current time is ${header.firedTime}").to("log:out");

}

每隔2秒钟，产生一条Message，并将消息的内容设为Timer触发的时间：

[ main] 12 Feb 10 14:41:16,985 DefaultCamelContext INFO Apache Camel 2.8.0 (CamelContext: camel-1) is starting

[ main] 12 Feb 10 14:41:16,985 DefaultCamelContext INFO JMX enabled. Using ManagedManagementStrategy.

[ main] 12 Feb 10 14:41:17,315 AnnotationTypeConverterLoader INFO Found 3 packages with 14 @Converter classes to load

[ main] 12 Feb 10 14:41:17,355 DefaultTypeConverter INFO Loaded 153 core type converters (total 153 type converters)

[ main] 12 Feb 10 14:41:17,375 AnnotationTypeConverterLoader INFO Loaded 4 @Converter classes

[ main] 12 Feb 10 14:41:17,395 DefaultTypeConverter INFO Loaded additional 22 type converters (total 175 type converters) in 0.040 seconds

[ main] 12 Feb 10 14:41:17,805 DefaultCamelContext INFO Route: route1 started and consuming from: Endpoint[timer://myTimer?period=2000]

[ main] 12 Feb 10 14:41:17,805 DefaultCamelContext INFO Total 1 routes, of which 1 is started.

[ main] 12 Feb 10 14:41:17,805 DefaultCamelContext INFO Apache Camel 2.8.0 (CamelContext: camel-1) started in 0.820 seconds

[ myTimer] 12 Feb 10 14:41:17,846

out                            INFO  Exchange[ExchangePattern:InOnly, BodyType:String, Body:Current time is Fri Feb

10 14:41:17 CST 2012]

[ myTimer] 12 Feb 10 14:41:19,806

out                            INFO  Exchange[ExchangePattern:InOnly, BodyType:String, Body:Current time is Fri Feb

10 14:41:19 CST 2012]

[ myTimer] 12 Feb 10 14:41:21,807

out                            INFO  Exchange[ExchangePattern:InOnly, BodyType:String, Body:Current time is Fri Feb

10 14:41:21 CST 2012]

[ myTimer] 12 Feb 10 14:41:23,808

out                            INFO  Exchange[ExchangePattern:InOnly, BodyType:String, Body:Current time is Fri Feb

10 14:41:23 CST 2012]

[ myTimer] 12 Feb 10 14:41:25,809

out                            INFO  Exchange[ExchangePattern:InOnly, BodyType:String, Body:Current time is Fri Feb

10 14:41:25 CST 2012]