RxJava多种常用场景使用方法

一、Scheduler线程切换这种场景经常会在“后台线程取数据，主线程展示”的模式中看见[html] view plaincopyObservable.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); } }); 二、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[html] view plaincopyRxTextView.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())); } });

三、Retrofit结合RxJava做网络请求框架

这里不作详解，具体的介绍可以看扔物线的这篇文章，对RxJava的入门者有很大的启发。其中也讲到了RxJava和Retrofit如何结合来实现更简洁的代码

四、RxJava代替EventBus进行数据传递：RxBus

注意：RxBus并不是一个库，而是一种模式，是使用了RxJava的思想来达到EventBus的数据传递效果。这篇文章把RxBus讲的比较详细。

五、使用combineLatest合并最近N个结点

例如：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。

[html] view plaincopyObservable<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);                      }                });  

六、使用merge合并两个数据源。例如一组数据来自网络，一组数据来自文件，需要合并两组数据一起展示。[html] view plaincopyObservable.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!") }); 七、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。[html] view plaincopyObservable<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、network Observable.concat(memory, disk, network) .first() .subscribeOn(Schedulers.newThread()) .subscribe(s -> { memoryCache = "memory"; System.out.println("--------------subscribe: " + s); }); 八、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例如：2秒后输出日志“hello world”，然后结束。[html] view plaincopyObservable.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"); } }); 九、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”。[html] view plaincopyObservable.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"); } }); 十、使用throttleFirst防止按钮重复点击ps：debounce也能达到同样的效果[html] view plaincopyRxView.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"); } }); 十一、使用schedulePeriodically做轮询请求[html] view plaincopyObservable.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….”)); } }) 十二、RxJava进行数组、list的遍历[html] view plaincopyString[] names = {"Tom", "Lily", "Alisa", "Sheldon", "Bill"}; Observable .from(names) .subscribe(new Action1<String>() { @Override public void call(String name) { log.d(name); } }); 十三、解决嵌套回调（callback hell）问题[html] view plaincopyNetworkService.getToken("username", "password") .flatMap(s -> NetworkService.getMessage(s)) .subscribe(s -> { System.out.println("message: " + s); }) 十四、响应式的界面比如勾选了某个checkbox，自动更新对应的preference[html] view plaincopySharedPreferences 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());