一个java状态机样例的代码

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      在UML当中有状态机视图，这个状态机可以用于自动售货机，自动售票机等等场景，下面是用java代码模拟的一个状态机：

1.状态机接口

package stateMachine;/** * 状态机接口 * @author seacean * @date 2013-8-29 */public interface State {/** * 投入硬币 */void insertQuarter();    /**     * 根据摇动情况，处理摇动结果，返回处理结果，释放糖果     */void ejectQuarter();    /**     * 转动摇柄     */void turnCrank();    /**     * 机器放出糖果，处理机器内部状态，返回初始可投币状态     */void dispense();}

2.带有状态机的机器

package stateMachine;/** * 机器类，包含多种状态，处理流程 * @author seacean * @date 2013-8-29 */public class Machine {//机器本身包含所有的状态机private State soldOutState;private State noQuarterState;private State hasQuarterState;private State soldState;private State state; //机器的当前状态private int count = 0;//机器中当前糖果的数量    /**     * 初始化机器，引入所有的状态机，初始化糖果数量，初始化机器状态     * @param count     */public Machine(int count) {this.soldOutState = new SoldOutState(this);this.noQuarterState = new NoQuarterState(this);this.hasQuarterState = new HasQuarterState(this);this.soldState = new SoldState(this);this.count = count;if (this.count > 0) {this.state = noQuarterState;}}    /**     * 释放糖果时的内部处理程序     */public void releaseBall() {System.out.println("a gumball comes rolling out the solt...");if (count > 0) {count -= 1;}}    public void insertQuerter() {state.insertQuarter();//加入硬币}public void ejectQuarter() {state.ejectQuarter();}public void turnCrank() {state.turnCrank();state.dispense();}public State getSoldOutState() {return soldOutState;}public State getNoQuarterState() {return noQuarterState;}public State getHasQuarterState() {return hasQuarterState;}public State getSoldState() {return soldState;}public State getState() {return state;}public int getCount() {return count;}public void setState(State state) {this.state = state;}}

3.下面是状态机的一些实现类

package stateMachine;/** * 机器处于没有投硬币的状态 * @author seacean * @date 2013-8-29 */public class NoQuarterState implements State {private Machine machine;public NoQuarterState(Machine machine) {this.machine = machine;}@Overridepublic void insertQuarter() {System.out.println("please insert a quarter!");machine.setState(machine.getHasQuarterState());}@Overridepublic void ejectQuarter() {System.out.println("please insert a quarter!");}@Overridepublic void turnCrank() {System.out.println("please insert a quarter!");}@Overridepublic void dispense() {System.out.println("please insert a quarter!");}}

package stateMachine;/** * 机器处于有硬币，有糖果，没有摇动的状态 * @author seacean * @date 2013-8-29 */public class HasQuarterState implements State {    private Machine machine;        public HasQuarterState(Machine machine){    this.machine=machine;    }@Overridepublic void insertQuarter() {System.out.println("You can not insert another quarter!");}@Overridepublic void ejectQuarter() {System.out.println("Quarter returned!");machine.setState(machine.getNoQuarterState());}@Overridepublic void turnCrank() {System.out.println("You turned ... ");        machine.setState(machine.getSoldState());}@Overridepublic void dispense() {System.out.println("No gumball dispensed!");}}

package stateMachine;/** * 机器正在出售糖果的状态 *  * @author seacean * @date 2013-8-29 */public class SoldState implements State {private Machine machine;public SoldState(Machine machine) {this.machine = machine;}@Overridepublic void insertQuarter() {System.out.println("please wait,we are already giving you a gumball!");}@Overridepublic void ejectQuarter() {System.out.println("Sorry, you have turned the crank!");}@Overridepublic void turnCrank() {System.out.println("Turning twice does not get you another gumball!");}@Overridepublic void dispense() {machine.releaseBall();if (machine.getCount() > 0) {machine.setState(machine.getNoQuarterState());} else {System.out.println("Out of Gumballs!");machine.setState(machine.getSoldOutState());}}}

package stateMachine;/** * 机器处于无糖果状态 * @author seacean * @date 2013-8-29 */public class SoldOutState implements State {    private Machine machine;public SoldOutState(Machine machine) {this.machine=machine;}@Overridepublic void insertQuarter() {System.out.println("Sorry, there is no gumball in the machine!");}@Overridepublic void ejectQuarter() {System.out.println("Sorry, there is no gumball in sold!");}@Overridepublic void turnCrank() {System.out.println("Sorry, there is no gumball!Turn is no meaning.");machine.setState(machine.getNoQuarterState());}@Overridepublic void dispense() {System.out.println("Sorry, there is no gumball!");}}

4.下面是测试类

package stateMachine;//测试类public class StateMachineTest {public static void main(String[] args) {         Machine machine=new Machine(10);         for(int i=0;i<11;i++){         System.out.println(machine);         machine.insertQuerter();         machine.turnCrank();         }}}