希望是最全的RxJava2使用场景小结
2017-07-12 本文已影响206人
liuhuiAndroid
- 因为之前是看可能是东半球最全的RxJava使用场景小结来学习RxJava的，由于升级2.0版本部分API已经替换。所以打算仿写一个。
个人所有的关于RxJava2的Sample都放在RxJava2-Android-Samples
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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
subscribeOn指定Observable线程
observeOn指定Observer线程
subscribeOn()改变调用它之前代码的线程，多次调用subscribeOn()却只有第一个起作用
subscribeOn 作用于该操作符之前的 Observable 的创建操符作以及 doOnSubscribe 操作符 ，换句话说就是 doOnSubscribe 以及 Observable 的创建操作符总是被其之后最近的 subscribeOn 控制
observeOn()改变调用它之后代码的线程，多次调用observeOn()却可以切换到不同线程
observeOn()与subscribeOn()的详解
Observable.just(1, 2)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.map(new Function<Integer, String>() {
@Override
public String apply(@NonNull Integer integer) throws Exception {
Logger.i("apply testChangeThread:" + Thread.currentThread().getName());
return integer.intValue()+" - ";
}
})
.observeOn(Schedulers.io())
.map(new Function<String, Integer>() {
@Override
public Integer apply(@NonNull String s) throws Exception {
Logger.i("apply3 testChangeThread:" + Thread.currentThread().getName());
return 1;
}
})
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Consumer<Integer>() {
@Override
public void accept(@NonNull Integer integer) throws Exception {
Logger.i("subscribe testChangeThread:" + Thread.currentThread().getName());
}
});
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二、使用debounce做textSearch RxBinding
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。
RxJava also implements the switchMap operator. It behaves much like flatMap, except that whenever a new item is emitted by the source Observable, it will unsubscribe to and stop mirroring the Observable that was generated from the previously-emitted item, and begin only mirroring the current one.
switch()和flatMap()很像，除了一点:当源Observable发射一个新的数据项时，如果旧数据项订阅还未完成，就取消旧订阅数据和停止监视那个数据项产生的Observable,开始监视新的数据项.
RxTextView.textChanges(mEditSearch)
.debounce(500, TimeUnit.MILLISECONDS)
.subscribeOn(AndroidSchedulers.mainThread())
//过滤数据
.filter(new Predicate<CharSequence>() {
@Override
public boolean test(@NonNull CharSequence charSequence) throws Exception {
Logger.i("filter = " + charSequence);
return charSequence.toString().trim().length() > 0;
}
})
.switchMap(new Function<CharSequence, ObservableSource<List<String>>>() {
@Override
public ObservableSource<List<String>> apply(@NonNull CharSequence charSequence) throws Exception {
Logger.i("flatMap = " + charSequence);
//search from net
List<String> stringList = new ArrayList<String>();
stringList.add("abc");
stringList.add("ada");
return Observable.just(stringList);
}
})
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Consumer<List<String>>() {
@Override
public void accept(@NonNull List<String> strings) throws Exception {
Logger.i("subscribe = " + strings.toString());
}
}, new Consumer<Throwable>() {
@Override
public void accept(@NonNull Throwable throwable) throws Exception {
throwable.printStackTrace();
}
});
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三、防止按钮重复点击
ThrottleFirst:允许设置一个时间长度，之后它会发送固定时间长度内的第一个事件，而屏蔽其它事件，在间隔达到设置的时间后，可以再发送下一个事件。用debounce也可以
RxView.clicks(mBtnThrottleFirst)
.throttleFirst(1,TimeUnit.SECONDS)
.subscribe(new Consumer<Object>() {
@Override
public void accept(@NonNull Object o) throws Exception {
Logger.i("按钮点击："+System.currentTimeMillis());
}
});
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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。
Observable.timer(2, TimeUnit.SECONDS)
// Run on a background thread
.subscribeOn(Schedulers.io())
// Be notified on the main thread
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Observer<Long>() {
@Override
public void onSubscribe(Disposable disposable) {
Log.i(TAG, " onSubscribe : " + disposable.isDisposed());
}
@Override
public void onNext(Long aLong) {
Log.i(TAG, " onNext : value : " + aLong);
}
@Override
public void onError(Throwable throwable) {
Log.i(TAG, " onError : " + throwable.getMessage());
}
@Override
public void onComplete() {
Log.i(TAG, " onComplete");
}
});
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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”。
Observable.interval(0, 2, TimeUnit.SECONDS)
// Run on a background thread
.subscribeOn(Schedulers.io())
// Be notified on the main thread
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Observer<Long>() {
@Override
public void onSubscribe(Disposable disposable) {
Log.i(TAG, " onSubscribe : " + disposable.isDisposed());
}
@Override
public void onNext(Long aLong) {
Log.i(TAG, " onNext : value : " + aLong);
}
@Override
public void onError(Throwable throwable) {
Log.i(TAG, " onError : " + throwable.getMessage());
}
@Override
public void onComplete() {
Log.i(TAG, " onComplete");
}
});
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十、使用throttleFirst防止按钮重复点击
ps：debounce也能达到同样的效果
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十一、发送验证码倒计时案例
@OnClick(R.id.btn_code)
public void mBtnCode() {
//倒计时十秒
int time = 10;
Observable.interval(0, 1, TimeUnit.SECONDS)
.take(time + 1)
.map(new Function<Long, Long>() {
@Override
public Long apply(@NonNull Long aLong) throws Exception {
return 10 - aLong;
}
})
// Run on a background thread
.subscribeOn(Schedulers.io())
// Be notified on the main thread
.observeOn(AndroidSchedulers.mainThread())
.doOnSubscribe(new Consumer<Disposable>() {
@Override
public void accept(@NonNull Disposable disposable) throws Exception {
Log.i(TAG, " accept : " + disposable.isDisposed());
mBtnCode.setEnabled(false);
mBtnCode.setTextColor(Color.GRAY);
}
})
.subscribe(new Observer<Long>() {
@Override
public void onSubscribe(Disposable disposable) {
}
@Override
public void onNext(Long aLong) {
mBtnCode.setText("剩余" + aLong + "秒");
}
@Override
public void onError(Throwable throwable) {
throwable.printStackTrace();
}
@Override
public void onComplete() {
mBtnCode.setEnabled(true);
mBtnCode.setText("发送验证码");
mBtnCode.setTextColor(Color.BLACK);
}
});
}
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十二、购物车合并本地和网络数据的案例
public void testMerge(){
Observable.merge(getDataFromLocal(),getDataFromNetWork())
.subscribe(new Observer<List<String>>() {
@Override
public void onSubscribe(@NonNull Disposable d) {
}
@Override
public void onNext(@NonNull List<String> strings) {
for (int i = 0; i < strings.size(); i++) {
Log.i(TAG,"onNext string = "+strings.get(i));
}
}
@Override
public void onError(@NonNull Throwable e) {
e.printStackTrace();
}
@Override
public void onComplete() {
Log.i(TAG,"onComplete. ");
}
});
}
private Observable<List<String>> getDataFromLocal(){
List<String> list = new ArrayList<>();
list.add("Local");
list.add("Local2");
return Observable.just(list);
}
private Observable<List<String>> getDataFromNetWork(){
List<String> list = new ArrayList<>();
list.add("NetWork");
list.add("NetWork2");
return Observable.just(list).subscribeOn(Schedulers.io());
}
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十三、登录后获取用户信息
FlatMap是返回一个Observable，而Map是返回基础数据，这是他们的区别
Retrofit retrofit = new Retrofit.Builder()
.baseUrl("http://")
.addConverterFactory(GsonConverterFactory.create())
.build();
mDemoApi = retrofit.create(DemoApi.class);
Observable.just(getUserParam())
.flatMap(new Function<UserParam, ObservableSource<BaseResult>>() {
@Override
public ObservableSource<BaseResult> apply(@NonNull UserParam userParam) throws Exception {
BaseResult baseResult = mDemoApi.login(userParam).execute().body();
return Observable.just(baseResult);
//方法二
//return mDemoApi.login2(userParam);
}
})
.flatMap(new Function<BaseResult, ObservableSource<User>>() {
@Override
public ObservableSource<User> apply(@NonNull BaseResult baseResult) throws Exception {
User user = mDemoApi.getUserInfoWithPath(baseResult.getUser_id()).execute().body();
return Observable.just(user);
}
})
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Consumer<User>() {
@Override
public void accept(@NonNull User user) throws Exception {
}
});
public interface DemoApi {
@GET("user/{id}")
Call<User> getUserInfoWithPath(@Path("id") int user_id);
@POST("login/json")
Call<BaseResult> login(@Body UserParam userParam);
@POST("login/json")
Observable<BaseResult> login2(@Body UserParam userParam);
}
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十四、优先内存缓存、其次磁盘缓存，找不到在网络上查找
final Observable<String> memoryObservable = Observable.create(new ObservableOnSubscribe<String>() {
@Override
public void subscribe(@NonNull ObservableEmitter<String> e) throws Exception {
e.onNext("");
e.onComplete();
}
});
final Observable<String> diskObservable = Observable.create(new ObservableOnSubscribe<String>() {
@Override
public void subscribe(@NonNull ObservableEmitter<String> e) throws Exception {
e.onNext("disk");
e.onComplete();
}
});
final Observable<String> networkObservable = Observable.create(new ObservableOnSubscribe<String>() {
@Override
public void subscribe(@NonNull ObservableEmitter<String> e) throws Exception {
e.onNext("network");
e.onComplete();
}
});
RxView.clicks(mButton).subscribe(new Consumer<Object>() {
@Override
public void accept(@NonNull Object o) throws Exception {
Observable.concat(memoryObservable,diskObservable,networkObservable)
.filter(new Predicate<String>() {
@Override
public boolean test(@NonNull String s) throws Exception {
return s!=null || !TextUtils.isEmpty(s.toString());
}
})
.firstElement()
.subscribe(new Consumer<String>() {
@Override
public void accept(@NonNull String s) throws Exception {
Logger.i("accept = "+s);
}
});
}
});
