状态机
场景
行为根据状态改变
代码
实现方案1
环境类控制状态转移
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| interface State{
void action();
}
class StateA implements State {
public void action() {
}
}
class StateB implements State {
public void action() {
}
}
class Context {
private State state;
private int value;
public void setState(State state) {
this.state = state;
}
public State getState() {
return state;
}
public void request() {
state.action();
checkState();
}
private void checkState() {
if(value = 0) {
this.setState(new StateA());
}else if(value = 1) {
this.setState(new StateB();
}
}
}
|
实现方案2
状态内控制状态转移，状态之间有依赖
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| interface State{
void action(Context context);
}
class StateA implements State {
public void action(Context context) {
context.setState(new StateB());
}
}
class StateB implements State {
public void action(Context context) {
context.setState(new StateA());
}
}
class Context {
private State state;
public void setState(State state) {
this.state = state;
}
public State getState() {
return state;
}
public void request() {
state.action(this);
}
}
|
优缺点
- 避免了在多个方法内大量if-else判断各种状态
- 状态可扩展性强
- 增加了类个数，复杂度上升
应用
