前言
上一篇文章命锄，我們已經(jīng)了解了RxJava的相關(guān)概念以及基礎(chǔ)使用方式衣洁。這篇文章將會結(jié)合RxJava知識點與開發(fā)中遇到的實際場景進(jìn)行講解，讓大家能夠通過這些例子更好的理解與掌握RxJava的用法與思想
數(shù)據(jù)請求
這是一個完整的數(shù)據(jù)請求例子，從緩存、網(wǎng)絡(luò)以及數(shù)據(jù)解析等垛吗。本例要實現(xiàn)的是若數(shù)據(jù)庫有對應(yīng)的數(shù)據(jù)則直接使用緩存的數(shù)據(jù)，否則再通過網(wǎng)絡(luò)請求獲取數(shù)據(jù)抱既，并且完成解析與緩存等操作
1.創(chuàng)建網(wǎng)絡(luò)請求Observable從網(wǎng)絡(luò)獲取數(shù)據(jù)
（1）Observable.create()調(diào)起網(wǎng)絡(luò)請求獲取數(shù)據(jù)
（2）map操作符將網(wǎng)絡(luò)響應(yīng)映射為數(shù)據(jù)實體
（3）doOnNext操作符將數(shù)據(jù)存儲到數(shù)據(jù)庫
2.創(chuàng)建數(shù)據(jù)庫緩存讀取Observable讀取緩存
3.Observable.concat合并上述兩個Observable
Observable net = Observable.create(new ObservableOnSubscribe<Response>() {
@Override
public void subscribe(ObservableEmitter<Response> e) throws Exception {
Request.Builder builder = new Request.Builder()
.url("http://gank.io/api/data/Android/10/1")
.get();
Request request = builder.build();
Call call = new OkHttpClient().newCall(request);
Response response = call.execute();
e.onNext(response);
}
}).map(new Function<Response, GankIOAndroidEntity>() {
@Override
public GankIOAndroidEntity apply(Response response) throws Exception {
ResponseBody body = response.body();
if(body!=null){
return JSON.parseObject(body.toString(),GankIOAndroidEntity.class);
}
return null;
}
}).doOnNext(new Consumer<GankIOAndroidEntity>() {
@Override
public void accept(GankIOAndroidEntity gankIOAndroidEntity) throws Exception {
saveDB();
}
});
Observable cache = Observable.create(new ObservableOnSubscribe<GankIOAndroidEntity>() {
@Override
public void subscribe(ObservableEmitter<GankIOAndroidEntity> e) throws Exception {
GankIOAndroidEntity entity = getFromDB();
if(entity!=null){
e.onNext(entity);
}else{
e.onComplete();
}
}
});
Observable.concat(cache,net)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Consumer<GankIOAndroidEntity>() {
@Override
public void accept(GankIOAndroidEntity gankIOAndroidEntity) throws Exception {
displayUI();
}
});
當(dāng)然還有一種情況职烧，就是進(jìn)入頁面時若有緩存先展示緩存，但不管是否有緩存都請求網(wǎng)絡(luò)數(shù)據(jù)并更新緩存防泵。咱們只需要修改一下cache對象即可，不管緩存查詢結(jié)果如何蝗敢，都執(zhí)行net操作
Observable cache = Observable.create(new ObservableOnSubscribe<GankIOAndroidEntity>() {
@Override
public void subscribe(ObservableEmitter<GankIOAndroidEntity> e) throws Exception {
GankIOAndroidEntity entity = getFromDB();
if(entity!=null){
e.onNext(entity);
}
e.onComplete(); // 不管緩存查詢結(jié)果如何捷泞，都執(zhí)行net操作
}
});
網(wǎng)絡(luò)請求嵌套
我想大家肯定都遇到過類似這樣的情況，在某個接口請求完成后再進(jìn)行下一個請求的調(diào)用寿谴。比如：先注冊成功后再調(diào)用登陸接口锁右、先上傳頭像再保存資料、先更改數(shù)據(jù)再查詢數(shù)據(jù)等等例子
我們可以通過flatMap操作符來方便的實現(xiàn)上述的請求嵌套讶泰，擺脫天花亂墜的回調(diào)嵌套咏瑟。復(fù)習(xí)一下flatMap的作用：FlatMap將一個發(fā)射數(shù)據(jù)的Observable變換為多個Observables，然后將它們發(fā)射的數(shù)據(jù)合并后放進(jìn)一個單獨的Observable
Observable.create(new ObservableOnSubscribe<CallBackEntity>() {
@Override
public void subscribe(ObservableEmitter<CallBackEntity> e) throws Exception {
RequestBody body = new FormBody.Builder()
.add("username","lee")
.add("password","lee")
.build();
Request.Builder builder = new Request.Builder()
.url("http://xxx/register")
.post(body);
Request request = builder.build();
Call call = new OkHttpClient().newCall(request);
Response response = call.execute();
CallBackEntity entity =
JSON.parseObject(response.body().toString(),CallBackEntity.class);
e.onNext(entity);
}
}).flatMap(new Function<CallBackEntity, ObservableSource<CallBackEntity>>() {
@Override
public ObservableSource<CallBackEntity> apply(CallBackEntity callBackEntity) throws Exception {
// register successful
if(callBackEntity.getCode() == 0){
return Observable.create(new ObservableOnSubscribe<CallBackEntity>() {
@Override
public void subscribe(ObservableEmitter<CallBackEntity> e) throws Exception {
RequestBody body = new FormBody.Builder()
.add("username","lee")
.add("password","lee")
.build();
Request.Builder builder = new Request.Builder()
.url("http://xxx/login")
.post(body);
Request request = builder.build();
Call call = new OkHttpClient().newCall(request);
Response response = call.execute();
CallBackEntity entity =
JSON.parseObject(response.body().toString(),CallBackEntity.class);
}
});
}
return null;
}
}).subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Consumer<CallBackEntity>() {
@Override
public void accept(CallBackEntity callBackEntity) throws Exception {
displayUI();
}
}, new Consumer<Throwable>() {
@Override
public void accept(Throwable throwable) throws Exception {
// error
}
});
數(shù)據(jù)合并
某個頁面的展示可能需要同時調(diào)用好多個接口來得到完整的數(shù)據(jù)痪署，可以用zip合并數(shù)據(jù)
Observable data1 = Observable.create(subscibe1);
Observable data2 = Observable.create(subscibe2);
Observable.zip(data1, data2, new BiFunction() {
@Override
public Object apply(Data1 o, Data2 o2) throws Exception {
Data data = new Data(o,o2);
return data;
}
}).subscribe(new Consumer() {
@Override
public void accept(Object o) throws Exception {
displayUI();
}
});
按鈕防點擊
登陸按鈕码泞、發(fā)送驗證碼按鈕等各種與接口請求或者邏輯操作關(guān)聯(lián)按鈕，防止多次點擊造成的非預(yù)期效果
RxView.clicks(btn)
.throttleFirst(1, TimeUnit.SECONDS)
.subscribe(new Consumer<Object>() {
@Override
public void accept(Object o) throws Exception {
}
});
復(fù)雜的數(shù)據(jù)變換
Observable.just(dbData)
.map(new Function<List<String>, Object>() {
@Override
public Object apply(List<String> strings) throws Exception {
return null;
}
})
.filter(new Predicate<Object>() {
@Override
public boolean test(Object o) throws Exception {
return false;
}
}).distinct(new Function<Object, Object>() {
@Override
public Object apply(Object o) throws Exception {
return null;
}
}).take(pageSize)
.subscribe(new Consumer<Object>() {
@Override
public void accept(Object o) throws Exception {
}
});
按鈕的增量監(jiān)聽
addTextChangedListener與setOnClickListener狼犯，相信大家都不陌生吧余寥，不知道大家知道它們倆對于事件的監(jiān)聽有什么區(qū)別嗎？不了解的同學(xué)我解釋下悯森，addTextChangedListener內(nèi)部維護(hù)了一個集合存儲設(shè)置的所有監(jiān)聽對象宋舷，當(dāng)事件產(chǎn)生時會向這所有監(jiān)聽發(fā)送回調(diào)。而setOnClickListener內(nèi)部存儲了OnClickListener對象瓢姻，用于保存設(shè)置的監(jiān)聽對象祝蝠，也就是說只有一個。結(jié)果很明顯幻碱，addTextChangedListener是增量監(jiān)聽绎狭，setOnClickListener是覆蓋
那么有沒有辦法實現(xiàn)OnClickListener的增量監(jiān)聽呢？有的~
當(dāng)然收班，類似的還有OnTouchListener坟岔、focusChanges、drags等等
Observable<Object> shareClick = RxView.clicks(textView).share();
Observable<MotionEvent> shareTouch = RxView.touches(textView).share();
shareClick.subscribe(new Consumer<Object>() {
@Override
public void accept(Object o) throws Exception {
// listener1
}
});
shareClick.subscribe(new Consumer<Object>() {
@Override
public void accept(Object o) throws Exception {
// listener2
}
});
獲取驗證碼倒計時
verifyCodeObservable = RxView.clicks(mBt)
.throttleFirst(SECOND, TimeUnit.SECONDS)
.subscribeOn(AndroidSchedulers.mainThread())
.doOnNext(new Action1<Void>() {
@Override
public void call(Void aVoid) {
RxView.enabled(mBt).call(false);
}
});
verifyCodeObservable.subscribe(new Action1<Void>() {
@Override
public void call(Void aVoid) {
Observable.interval(1, TimeUnit.SECONDS, AndroidSchedulers.mainThread())
.take(SECOND)
.subscribe(new Observer<Long>() {
@Override
public void onCompleted() {
RxTextView.text(mBt).call("獲取驗證碼");
RxView.enabled(mBt).call(true);
}
@Override
public void onError(Throwable e) {
Log.e(TAG, e.toString());
}
@Override
public void onNext(Long aLong) {
RxTextView.text(mBt).call("剩余" + (SECOND - aLong) + "秒");
}
});
}
});
必填項/表單驗證
Observable<CharSequence> ObservableName = RxTextView.textChanges(mEtPhone);
Observable<CharSequence> ObservablePassword = RxTextView.textChanges(mEtPassword);
Observable.combineLatest(ObservableName, ObservablePassword, new Func2<CharSequence, CharSequence, Boolean>() {
@Override
public Boolean call(CharSequence phone, CharSequence password) {
return isPhoneValid(phone.toString()) && isPasswordValid(password.toString());
}
}).subscribe(new Action1<Boolean>() {
@Override
public void call(Boolean aBoolean) {
RxView.enabled(mBtLogin).call(aBoolean);
}
});
RxView.clicks(mBtLogin)
.throttleFirst(1, TimeUnit.SECONDS)
.subscribeOn(AndroidSchedulers.mainThread())
.subscribe(new Action1<Void>() {
@Override
public void call(Void aVoid) {
Toast.makeText(LoginActivity.this, "登錄成功摔桦！" ,Toast.LENGTH_SHORT).show();
}
});
響應(yīng)式SP
SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this);
RxSharedPreference rxSharedPreference = RxSharedPreference.create(preferences);
Preferences<Boolean> choose = rxSharedPreference.getBoolean("choose",false);
RxCompoundButton.checkedChanges(checkBox)
.subscribe(rxSharedPreference.asAction());
RxJava各種擴(kuò)展庫
rx-preferences -使SharedPreferences支持RxJava
RxAndroid -RxJava的Android拓展
RxLifecycle -幫助使用了RxJava的安卓應(yīng)用控制生命周期
RxBinding -安卓UI控件的RxJava綁定API
storio -支持RxJava的數(shù)據(jù)庫
retrofit -支持RxJava的網(wǎng)絡(luò)請求庫
sqlbrite -支持RxJava的sqlite數(shù)據(jù)庫
RxPermissions -RxJava實現(xiàn)的Android運(yùn)行時權(quán)限控制
reark -RxJava architecture library for Android
frodo -Android Library for Logging RxJava Observables and Subscribers.
總結(jié)
沒有做不到社付，只有想不到承疲。加油~
