場景
騰訊最近有一款手機游戲特別火：王者榮耀。小編是游戲小白，只知道有這么個游戲。但是，聽別人說玩游戲下次再進來游戲，進來的是上一個關卡。
包括，我們看視頻的時候也是，一個視頻看到一半的時候，退出軟件或關閉瀏覽器。再次進來的時候是近類似于上次觀看的點。
實現視頻恢復到上次觀看場景。
分析
備忘點包含：視頻id，用戶名id，最新片段時間點
視頻進程：watch方法,reset方法，backup方法
代碼
public class Main {
public static void main(String[] args) {
BackupManager manager = new BackupManager();
PersonTV personTV = new PersonTV("tvid", "userid", 100*60);
Watcher watcher = new Watcher();
watcher.setBackupManager(manager);
watcher.setPersonTV(personTV);
watcher.watchTV();
try {
Thread.sleep(57*1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
watcher.interupte();
watcher.watchTV();
}
}
//這里是簡單的內存存儲，真實情況會用redis或數據庫等其他存儲方式存儲
public class BackupManager {
private Map<String,Map<String, TVBackup>> backupMap = new HashMap<String, Map<String, TVBackup>>();
public void backup(TVBackup backup) {
Map<String, TVBackup> backupUserMap = backupMap.get(backup.getUserId());
if(backupUserMap==null) {
backupUserMap = new HashMap<String, TVBackup>();
backupMap.put(backup.getUserId(), backupUserMap);
}
backupUserMap.put(backup.getTvId(), backup);
}
public TVBackup get(String userId, String tvid) {
Map<String, TVBackup> backupUserMap = backupMap.get(userId);
if(backupUserMap == null) {
return null;
}
return backupUserMap.get(tvid);
}
}
//get set 篇幅長，省略
public class PersonTV {
private String tvid;
private String userid;
private long currentTime;
private long totalTime;
public PersonTV(String tvid, String userid, long totalTime) {
this.tvid = tvid;
this.userid = userid;
this.totalTime = totalTime;
}
}
//get set 篇幅長，省略
public class TVBackup {
private String tvId;
private String userId;
private long time;
public TVBackup(String tvId, String userId, long time) {
this.tvId = tvId;
this.userId = userId;
this.time = time;
}
}
public class Watcher {
private static final long backupTime = 1000l;
private BackupManager manager;
private PersonTV personTV;
private Timer timer;
private void saveTVState(PersonTV person) {
TVBackup backUp = new TVBackup(person.getTvid(), person.getUserid(), person.getCurrentTime());
manager.backup(backUp);
}
private void recoveryTVState() {
TVBackup backup = manager.get(personTV.getUserid(), personTV.getTvid());
if(backup == null) {
return;
}
personTV.setCurrentTime(backup.getTime());
}
public void setPersonTV(PersonTV personTV) {
this.personTV = personTV;
}
public void watchTV() {
this.timer = new Timer();
final Timer timer = this.timer;
final PersonTV tv = personTV;
recoveryTVState();
System.out.println("我們看到第"+personTV.getCurrentTime()+"秒了");
timer.schedule(new TimerTask(){
/**
* The action to be performed by this timer task.
*/
public void run() {
long currentTime = tv.getCurrentTime();
long totalTime = tv.getTotalTime();
currentTime++;
if (currentTime > totalTime){
timer.cancel();
}
System.out.println("我們看到第"+currentTime+"秒了");
tv.setCurrentTime(currentTime);
if(currentTime%30== 0) {
saveTVState(personTV);
}
}
}, 0, 1000);
}
public void interupte(){
timer.cancel();
}
public void setBackupManager(BackupManager manager) {
this.manager = manager;
}
}
定義
在不破壞封裝性的前提下，捕獲一個對象的內部狀態，并在該對象之外保存這個狀態。這樣以后就可將該對象恢復到原先保存的狀態
類圖
屏幕快照 2017-08-18 下午11.54.20.png
場景
電梯是現在樓房的業主必不可少的工具，因為沒有就得用爬的上20樓。哈哈，累死人了！！今天就是要實現人按電梯，上電梯，電梯到站的場景。
代碼
public abstract class ElevatorState {
protected Elevator elevator;
public void setElevator(Elevator elevator) {
this.elevator = elevator;
}
public abstract void open();
public abstract void close();
public abstract void run();
public abstract void stop();
}
public class OpenningElvatorState extends ElevatorState {
public void open() {
System.out.println("電梯開啟了");
}
public void close() {
super.elevator.setState(Elevator.closingElvatorState);
super.elevator.close();
}
public void run() {
//nothing
}
public void stop() {
//nothing
}
}
public class RunningElevatorState extends ElevatorState {
public void open() {
//nothing
}
public void close() {
//nothing
}
public void run() {
System.out.println("電梯開始跑咯");
}
public void stop() {
super.elevator.setState(Elevator.stoppingElvatorState);
super.elevator.stop();
}
}
public class StoppingElevatorState extends ElevatorState {
public void open() {
super.elevator.setState(Elevator.openningElvatorState);
super.elevator.open();
}
public void close() {
//nothing
}
public void run() {
super.elevator.setState(Elevator.runningElvatorState);
super.elevator.run();
}
public void stop() {
System.out.println("電梯停了");
}
}
public class ClosingElevatorState extends ElevatorState {
public void open() {
super.elevator.setState(Elevator.openningElvatorState);
super.elevator.open();
}
public void close() {
System.out.println("電梯門關閉了");
}
public void run() {
super.elevator.setState(Elevator.runningElvatorState);
super.elevator.run();
}
public void stop() {
//nothing
}
}
public class Elevator {
public final static ElevatorState openningElvatorState = new OpenningElvatorState();
public final static ElevatorState closingElvatorState = new ClosingElevatorState();
public final static ElevatorState stoppingElvatorState = new StoppingElevatorState();
public final static ElevatorState runningElvatorState = new RunningElevatorState();
private ElevatorState state;
public void open(){
state.open();
}
public void close(){
state.close();
}
public void run(){
state.run();
}
public void stop(){
state.stop();
}
public void setState(ElevatorState state) {
this.state = state;
this.state.setElevator(this);
}
}
public class Test {
public static void main(String[] args) {
Elevator elevator = new Elevator();
elevator.setState(new StoppingElevatorState());
elevator.run();
elevator.stop();
elevator.open();
elevator.close();
elevator.run();
elevator.stop();
}
}
定義
當一個對象的內在狀態改變時允許改變其行為，這個對象看起來像是改變了其類。
類圖
屏幕快照 2017-08-18 下午11.54.32.png
