安卓RxJava第四弹之 应用场景

一.注册的时候所有输入信息（邮箱、密码、电话号码等）合法才点亮注册按钮。

Observable<CharSequence> _emailChangeObservable = RxTextView.textChanges(_email).skip(1);Observable<CharSequence> _passwordChangeObservable = RxTextView.textChanges(_password).skip(1);Observable<CharSequence>   _numberChangeObservable = RxTextView.textChanges(_number).skip(1);Observable.combineLatest(_emailChangeObservable,              _passwordChangeObservable,              _numberChangeObservable,              new Func3<CharSequence, CharSequence, CharSequence, Boolean>() {                  @Override                  public Boolean call(CharSequence newEmail,                                      CharSequence newPassword,                                      CharSequence newNumber) {                      Log.d("xiayong",newEmail+" "+newPassword+" "+newNumber);                      boolean emailValid = !isEmpty(newEmail) &&                                           EMAIL_ADDRESS.matcher(newEmail).matches();                      if (!emailValid) {                          _email.setError("Invalid Email!");                      }                      boolean passValid = !isEmpty(newPassword) && newPassword.length() > 8;                      if (!passValid) {                          _password.setError("Invalid Password!");                      }                      boolean numValid = !isEmpty(newNumber);                      if (numValid) {                          int num = Integer.parseInt(newNumber.toString());                          numValid = num > 0 && num <= 100;                      }                      if (!numValid) {                          _number.setError("Invalid Number!");                      }                      return emailValid && passValid && numValid;                  }              })//              .subscribe(new Observer<Boolean>() {                  @Override                  public void onCompleted() {                      log.d("completed");                  }                  @Override                  public void onError(Throwable e) {                     log.d("Error");                  }                  @Override                  public void onNext(Boolean formValid) {                     _btnValidIndicator.setEnabled(formValid);                    }              });

二.Scheduler线程切换

Observable.just(1, 2, 3, 4)            .subscribeOn(Schedulers.io()) // 指定 subscribe() 发生在 IO 线程            .observeOn(AndroidSchedulers.mainThread()) // 指定 Subscriber 的回调发生在主线程            .subscribe(new Action1<Integer>() {        @Override        public void call(Integer number) {            Log.d(tag, "number:" + number);        }    });

三.使用debounce做textSearch

用简单的话讲就是当N个结点发生的时间太靠近（即发生的时间差小于设定的值T），debounce就会自动过滤掉前N-1个结点。

比如在做百度地址联想的时候，可以使用debounce减少频繁的网络请求。避免每输入（删除）一个字就做一次联想

RxTextView.textChangeEvents(inputEditText)      .debounce(400, TimeUnit.MILLISECONDS)       .observeOn(AndroidSchedulers.mainThread())      .subscribe(new Observer<TextViewTextChangeEvent>() {    @Override    public void onCompleted() {        log.d("onComplete");    }    @Override    public void onError(Throwable e) {        log.d("Error");    }    @Override    public void onNext(TextViewTextChangeEvent onTextChangeEvent) {        log.d(format("Searching for %s", onTextChangeEvent.text().toString()));    }});

四.使用merge合并两个数据源。

Observable.merge(getDataFromFile(), getDataFromNet())              .observeOn(AndroidSchedulers.mainThread())              .subscribe(new Subscriber<String>() {                  @Override                  public void onCompleted() {                      log.d("done loading all data");                  }                  @Override                  public void onError(Throwable e) {                      log.d("error");                  }                  @Override                  public void onNext(String data) {                      log.d("all merged data will pass here one by one!")              });

五.使用concat和first做缓存

依次检查memory、disk和network中是否存在数据，任何一步一旦发现数据后面的操作都不执行。

Observable<String> memory = Observable.create(new Observable.OnSubscribe<String>() {    @Override    public void call(Subscriber<? super String> subscriber) {        if (memoryCache != null) {            subscriber.onNext(memoryCache);        } else {            subscriber.onCompleted();        }    }});Observable<String> disk = Observable.create(new Observable.OnSubscribe<String>() {    @Override    public void call(Subscriber<? super String> subscriber) {        String cachePref = rxPreferences.getString("cache").get();        if (!TextUtils.isEmpty(cachePref)) {            subscriber.onNext(cachePref);        } else {            subscriber.onCompleted();        }    }});Observable<String> network = Observable.just("network");//依次检查memory、disk、networkObservable.concat(memory, disk, network).first().subscribeOn(Schedulers.newThread()).subscribe(s -> {    memoryCache = "memory";    System.out.println("--------------subscribe: " + s);});

三级缓存的完整代码在github: https://github.com/Chaoba/RxImageloader

六.使用timer做定时操作。当有“x秒后执行y操作”类似的需求的时候，想到使用timer

Observable.timer(2, TimeUnit.SECONDS)              .subscribe(new Observer<Long>() {                  @Override                  public void onCompleted() {                      log.d ("completed");                  }                  @Override                  public void onError(Throwable e) {                      log.e("error");                  }                  @Override                  public void onNext(Long number) {                      log.d ("hello world");                  }              });

七.使用interval做周期性操作。当有“每隔xx秒后执行yy操作”类似的需求的时候，想到使用interval

例如：每隔2秒输出日志“helloworld”。

     Observable.interval(2, TimeUnit.SECONDS)              .subscribe(new Observer<Long>() {                  @Override                  public void onCompleted() {                     log.d ("completed");                  }                  @Override                  public void onError(Throwable e) {                     log.e("error");                  }                  @Override                  public void onNext(Long number) {                     log.d ("hello world");                  }              });

八.使用throttleFirst防止按钮重复点击

RxView.clicks(button)              .throttleFirst(1, TimeUnit.SECONDS)              .subscribe(new Observer<Object>() {                  @Override                  public void onCompleted() {                        log.d ("completed");                  }                  @Override                  public void onError(Throwable e) {                        log.e("error");                  }                  @Override                  public void onNext(Object o) {                       log.d("button clicked");                  }              });

九.使用schedulePeriodically做轮询请求

Observable.create(new Observable.OnSubscribe<String>() {            @Override            public void call(final Subscriber<? super String> observer) {                Schedulers.newThread().createWorker()                      .schedulePeriodically(new Action0() {                          @Override                          public void call() {                              observer.onNext(doNetworkCallAndGetStringResult());                          }                      }, INITIAL_DELAY, POLLING_INTERVAL, TimeUnit.MILLISECONDS);            }        }).subscribe(new Action1<String>() {            @Override            public void call(String s) {                log.d("polling….”));            }        })

十.RxJava进行数组、list的遍历

        String[] names = {"Tom", "Lily", "Alisa", "Sheldon", "Bill"};        Observable                .from(names)                .subscribe(new Action1<String>() {                    @Override                    public void call(String name) {                        log.d(name);                    }                });

十一.解决嵌套回调（callback hell）问题

NetworkService.getToken("username", "password")    .flatMap(s -> NetworkService.getMessage(s))    .subscribe(s -> {        System.out.println("message: " + s);})

十二.响应式的界面

SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this);RxSharedPreferences rxPreferences = RxSharedPreferences.create(preferences);Preference<Boolean> checked = rxPreferences.getBoolean("checked", true);CheckBox checkBox = (CheckBox) findViewById(R.id.cb_test);RxCompoundButton.checkedChanges(checkBox)        .subscribe(checked.asAction());