RxJava使用场景小结

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>() {@Overridepublic 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>() {@Overridepublic void onCompleted() {log.d("onComplete");}@Overridepublic void onError(Throwable e) {log.d("Error");}@Overridepublic 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>() {@Overridepublic 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>() {@Overridepublic void onCompleted() {log.d("completed");}@Overridepublic void onError(Throwable e) {log.d("Error");}@Overridepublic 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>() {@Overridepublic void onCompleted() {log.d("done loading all data");}@Overridepublic void onError(Throwable e) {log.d("error");}@Overridepublic 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>() {@Overridepublic void call(Subscriber<? super String> subscriber) {if (memoryCache != null) {subscriber.onNext(memoryCache);} else {subscriber.onCompleted();}}});Observable<String> disk = Observable.create(new Observable.OnSubscribe<String>() {@Overridepublic 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);});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>() {@Overridepublic void onCompleted() {log.d ("completed");}@Overridepublic void onError(Throwable e) {log.e("error");}@Overridepublic 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>() {@Overridepublic void onCompleted() {log.d ("completed");}@Overridepublic void onError(Throwable e) {log.e("error");}@Overridepublic 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>() {@Overridepublic void onCompleted() {log.d ("completed");}@Overridepublic void onError(Throwable e) {log.e("error");}@Overridepublic 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>() {@Overridepublic void call(final Subscriber<? super String> observer) {Schedulers.newThread().createWorker().schedulePeriodically(new Action0() {@Overridepublic void call() {observer.onNext(doNetworkCallAndGetStringResult());}}, INITIAL_DELAY, POLLING_INTERVAL, TimeUnit.MILLISECONDS);}}).subscribe(new Action1<String>() {@Overridepublic 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>() {@Overridepublic 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());最后，由于个人能力有限，文章难免有疏漏之处，如果您有任何疑议，请让我知道，谢谢！本文所有的例子已经上传到github上致谢：这篇文章的绝大多数例子是从这里总结的，还有部分例子来自这里。对作者的无私贡献表示感谢！