Markdown版本笔记	我的GitHub首页	我的博客	我的微信	我的邮箱
MyAndroidBlogs	baiqiantao	baiqiantao	bqt20094	baiqiantao@sina.com

目录
常用库
首先写一个最简单的观察者模式
我们再对比下用 rx 写的观察者模式
简化代码
介绍一个操作符：map
对于 map 的更多用法
对 rx 设计理念的理解

implementation 'io.reactivex.rxjava2:rxandroid:2.0.2'
implementation 'io.reactivex.rxjava2:rxjava:2.x.x'implementation 'com.jakewharton.rxrelay2:rxrelay:2.0.0'implementation "com.github.akarnokd:rxjava2-extensions:0.16.0"implementation "com.squareup.retrofit2:retrofit:2.0.0"
implementation "com.squareup.retrofit2:converter-gson:2.0.0"
implementation "com.squareup.okhttp3:okhttp:3.7.0"
implementation "com.squareup.okhttp3:okhttp-urlconnection:3.0.1"
implementation 'com.jakewharton.retrofit:retrofit2-rxjava2-adapter:1.0.0'implementation 'top.zibin:Luban:1.1.8'
implementation 'com.github.tbruyelle:rxpermissions:0.10.2'
implementation 'com.jakewharton.rxbinding2:rxbinding:2.1.1'
implementation 'com.trello.rxlifecycle2:rxlifecycle-components:2.2.2'

interface Watcher {  void update(String str);
}  

interface Watched {  void addWatcher(Watcher watcher);  void removeWatcher(Watcher watcher);  void notifyWatchers(String str);
}  

class ConcreteWatcher implements Watcher {  @Override  public void update(String str) {  Log.i("bqt", "观察者收到被观察者的消息：" + str);  }
}  

class ConcreteWatched implements Watched {  private List<Watcher> list = new ArrayList<>();  @Override  public void addWatcher(Watcher watcher) {  if (list.contains(watcher)) {  Log.i("bqt", "失败，被观察者已经注册过此观察者");  } else {  Log.i("bqt", "成功，被观察者成功注册了此观察者");  list.add(watcher);  }  }  @Override  public void removeWatcher(Watcher watcher) {  if (list.contains(watcher)) {  boolean success = list.remove(watcher);  Log.i("bqt", "此观察者解除注册观察者结果：" + (success ? "成功" : "失败"));  } else {  Log.i("bqt", "失败，此观察者并未注册到被观察者");  }  }  @Override  public void notifyWatchers(String str) {  for (Watcher watcher : list) {  watcher.update(str);  }  }
}  

private Watcher watcher;
private Watched watched;
...
watcher = new ConcreteWatcher();
watched = new ConcreteWatched();
...
watched.addWatcher(watcher);
watched.notifyWatchers("救命啊");
watched.removeWatcher(watcher);  

Observable<String> observable = Observable.create(new ObservableOnSubscribe<String>() {  @Override  public void subscribe(ObservableEmitter<String> emitter) {  emitter.onNext("救命啊-------isDisposed=" + emitter.isDisposed());//false  if (new Random().nextBoolean()) emitter.onComplete(); //发送onComplete  else emitter.onError(new Throwable("发送onError")); //发送onComplete或onError事件后就取消注册了  Log.i("bqt", "调用 onComplete 或 onError 后 isDisposed=" + emitter.isDisposed());//true  }
});  

Observer<String> observer = new Observer<String>() {  @Override  public void onSubscribe(Disposable d) {  Log.i("bqt", "成功订阅-------isDisposed=" + d.isDisposed());//false  }  @Override  public void onNext(String s) {  Log.i("bqt", "【观察者接收到了事件】onNext:" + s);  }  @Override  public void onError(Throwable e) {  Log.i("bqt", "对Error事件作出响应:" + e.getMessage());  }  @Override  public void onComplete() {  Log.i("bqt", "对Complete事件作出响应");  }
};  

observable.subscribe(observer);//被观察者注册观察者  

Observable<String> observable = Observable.just("救命啊");  

new Consumer<String>() {  @Override  public void accept(String s) throws Exception {  Log.i("bqt", "【观察者收到被观察者的消息】onNext:" + s);  }
};  

public final Disposable subscribe(Consumer<? super T> onNext)
public final Disposable subscribe(Consumer<? super T> onNext, Consumer<? super Throwable> onError)
public final Disposable subscribe(Consumer<? super T> onNext, Consumer<? super Throwable> onError, Action onComplete)  

Observable.just("救命啊").subscribe(new Consumer<String>() {  @Override  public void accept(String s) throws Exception {  Log.i("bqt", "【观察者收到被观察者的消息】onNext:" + s);  }
});  

Observable.just("救命啊")  .subscribe(s -> Log.i("bqt", "【观察者收到被观察者的消息】onNext:" + s));  

Observable.just("救命啊", 1, true, 1.5f)  .subscribe(s -> "【观察者收到被观察者的消息】onNext:" + s));  

Observable.just("Hello, world! -包青天").subscribe(s -> System.out.println(s));  

Observable.just("Hello, world!")  .subscribe(s -> System.out.println(s + " -包青天"));  

Observable.just("Hello, world!")  .map(new Function<String, String>() {  @Override  public String apply(String s) throws Exception {  return s + " -包青天";  }  })  .subscribe(s -> System.out.println(s));  

Observable.just("Hello, world!")  .map(s -> s + " -包青天")  .subscribe(s -> System.out.println(s));  

Observable.just("Hello, world!")  .map(s -> s.hashCode())  .subscribe(i -> System.out.println(Integer.toString(i)));  

Observable.just("Hello, world!")  .map(s -> s.hashCode())  .map(i -> Integer.toString(i))  .subscribe(s -> System.out.println(s));  

Observable.just(System.currentTimeMillis())  .map(time -> time + 1000 * 60 * 60)//改变时间的值  .map(time -> new SimpleDateFormat("HH:mm:ss", Locale.getDefault()).format(new Date(time)))  .subscribe(string -> Log.i("bqt", string));