(1). 概述
前面对Spring StateMachine进行了源码分析, 总体来说:Spring StateMachine是一个有状态的状态机, 而我期望的是一个更轻一些的状态机,同过度娘了解到:COLA,所以,特意把COLA的源码拉下来,先进行一个简单的入门,然后,再深入源码.
(2). 添加依赖包
<dependency>
<groupId>com.alibaba.cola</groupId>
<artifactId>cola-component-statemachine</artifactId>
<version>4.4.0-SNAPSHOT</version>
</dependency>
(3). COLA简单案例
package com.alibaba.cola.test;
import com.alibaba.cola.statemachine.Action;
import com.alibaba.cola.statemachine.Condition;
import com.alibaba.cola.statemachine.StateMachine;
import com.alibaba.cola.statemachine.StateMachineFactory;
import com.alibaba.cola.statemachine.builder.StateMachineBuilder;
import com.alibaba.cola.statemachine.builder.StateMachineBuilderFactory;
import org.junit.Assert;
import org.junit.Test;
public class StateMachineTest {
// 1. 定义状态机的唯一名称
static String MACHINE_ID = "TestStateMachine";
// 2. 定义所有的状态
static enum States {
STATE1, STATE2, STATE3, STATE4
}
// 3. 定义所有的事件
static enum Events {
EVENT1, EVENT2, EVENT3, EVENT4, INTERNAL_EVENT
}
// 4. 可以传递一个上下文
static class Context{
String operator = "frank";
String entityId = "123465";
}
// 5. 自定义检查条件
private Condition<Context> checkCondition() {
return new Condition<Context>() {
@Override
public boolean isSatisfied(Context context) {
System.out.println("Check condition : "+context);
return true;
}
};
} // end checkCondition
// 6. 定义符合触发事件时执行的动作.
private Action<States, Events, Context> doAction() {
return (from, to, event, ctx)->{
System.out.println(ctx.operator+" is operating "+ctx.entityId+" from:"+from+" to:"+to+" on:"+event);
};
} // end doAction
// **********************************************************************
// 7. 开始编排Source与Target和Event
// **********************************************************************
@Test
public void testExternalNormal(){
StateMachineBuilder<States, Events, Context> builder = StateMachineBuilderFactory.create();
builder.externalTransition()
.from(States.STATE1)
.to(States.STATE2)
.on(Events.EVENT1)
.when(checkCondition())
.perform(doAction());
StateMachine<States, Events, Context> stateMachine = builder.build(MACHINE_ID);
// 8. 触发事件(需要注意:此处要带上事件的Source状态)
States target = stateMachine.fireEvent(States.STATE1, Events.EVENT1, new Context());
Assert.assertEquals(States.STATE2, target);
} // end testExternalNormal
}
(4). 运行结果
Check condition : com.alibaba.cola.test.StateMachineTest$Context@2cfb4a64
frank is operating 123465 from:STATE1 to:STATE2 on:EVENT1
(5). 总结
这个案例是官网的,通过运行,大概能知道COLA的大体原理,与Spring StateMachine不同的点在于,触发事件时,是需要带上源始状态的,也不需要配置初始状态.
