把过于复杂的条件判断转移到不同状态的一系列类之中,使逻辑简化.
当一个对象的行为取决于它的状态,并且它必须在运行时刻根据状态改变它的行为时,就可以使用状态模式.
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| package state;
public abstract class State {
public abstract void handle(Context context);
}
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| package state;
public class Morning extends State {
public void handle(Context context) {
System.out.println("精神饱满");
context.setCurrent(new Noon());
context.work();
}
}
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| package state;
public class Noon extends State {
public void handle(Context context) {
System.out.println("累了");
context.setCurrent(new Afternoon());
context.work();
}
}
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| package state;
public class Afternoon extends State {
public void handle(Context context) {
System.out.println("高高兴兴下班去");
}
}
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| package state;
public class Context {
private State current;
public Context() {
current = new Morning();
}
public void work() {
current.handle(this);
}
public State getCurrent() {
return current;
}
public void setCurrent(State current) {
this.current = current;
}
}
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| package state;
public class Main {
public static void main(String[] args) {
Context context = new Context();
context.work();
context.setCurrent(new Noon());
context.work();
}
}
|
