狀態(tài)模式（State）完箩，當(dāng)一個對象的內(nèi)在狀態(tài)改變時允許改變其行為飞蹂，這個對象看起來像是改變了其類柄延。代替大量if else if判斷分支條件悲雳。
PS：其實就通過子類的各種繼承來進行邏輯轉(zhuǎn)換挎峦，通過定義新的子類可以很容易地增加新的狀態(tài)和轉(zhuǎn)換。
當(dāng)一個對象的行為取決于它的狀態(tài)合瓢，并且它必須在運行時刻根據(jù)狀態(tài)改變它的行為時坦胶，就可以考慮使用狀態(tài)模式

主方法

public class main {
    public static void main(String[] args) {
        Work emergencyProjects = new Work();
        emergencyProjects.setHour(9);
        emergencyProjects.writeProgram();
        emergencyProjects.setHour(10);
        emergencyProjects.writeProgram();
        emergencyProjects.setHour(12);
        emergencyProjects.writeProgram();
        emergencyProjects.setHour(13);
        emergencyProjects.writeProgram();
        emergencyProjects.setHour(14);
        emergencyProjects.writeProgram();
        emergencyProjects.setHour(17);

        emergencyProjects.setFinish(true);
//        emergencyProjects.setFinish(false);

        emergencyProjects.writeProgram();
        emergencyProjects.setHour(19);
        emergencyProjects.writeProgram();
        emergencyProjects.setHour(22);
        emergencyProjects.writeProgram();
    }
}

狀態(tài)抽象類

/**
 * 抽象狀態(tài)類
 */
public abstract class State {
    public abstract void writeProgram(Work work);
}

工作類

/**
 * 工作類
 */
public class Work {
    public Work() {
        current = new ForenoonState();
    }

    private State current;
    private int hour;//時間屬性，狀態(tài)轉(zhuǎn)換的依據(jù)
    private boolean finish = false;//工作任務(wù)是否完成的標志位

    public void writeProgram() {
        current.writeProgram(this);
    }

    public State getCurrent() {
        return current;
    }

    public void setCurrent(State current) {
        this.current = current;
    }

    public int getHour() {
        return hour;
    }

    public void setHour(int hour) {
        this.hour = hour;
    }

    public boolean isFinish() {
        return finish;
    }

    public void setFinish(boolean finish) {
        this.finish = finish;
    }
}

多種狀態(tài)類

public class ForenoonState extends State {
    public void writeProgram(Work work) {
        if (work.getHour() < 12) {
            System.out.println(String.format("當(dāng)前時間：{%d}點 上午工作晴楔，精神百倍", work.getHour()));
        } else {
            work.setCurrent(new NoonState());
            work.writeProgram();
        }
    }
}

public class NoonState extends State {
    public void writeProgram(Work work) {
        if (work.getHour() < 13) {
            System.out.println(String.format("當(dāng)前時間：{%d}點 餓了顿苇，午飯；犯困税弃，午休纪岁。", work.getHour()));
        } else {
            work.setCurrent(new AfternoonState());
            work.writeProgram();
        }
    }
}

public class AfternoonState extends State {
    public void writeProgram(Work work) {
        if (work.getHour() < 17) {
            System.out.println(String.format("當(dāng)前時間：{%d}點 下午狀態(tài)還不錯，繼續(xù)努力", work.getHour()));
        } else {
            work.setCurrent(new EveningState());
            work.writeProgram();
        }
    }
}

/**
 * 加個finish判斷则果，如果任務(wù)完成即下班
 */
public class EveningState extends State {
    public void writeProgram(Work work) {
        if (work.isFinish()) {//如果工作完成了就調(diào)用下班休息類
            work.setCurrent(new RestState());
            work.writeProgram();
        } else {
            if (work.getHour() < 21) {
                System.out.println(String.format("當(dāng)前時間：{%d}點 加班哦幔翰，疲累之極", work.getHour()));
            } else {
                work.setCurrent(new SleepingState());//工作未完成
                work.writeProgram();
            }
        }
    }
}

public class RestState extends State {
    public void writeProgram(Work work) {
        System.out.println(String.format("當(dāng)前時間：{%d}點 下班回家了", work.getHour()));
    }
}

public class SleepingState extends State {
    public void writeProgram(Work work) {
        System.out.println(String.format("當(dāng)前時間：{%d}點 不行了漩氨，睡著了", work.getHour()));
    }
}