RxJava替換嵌套接口回調(diào)
有時項目中需要進(jìn)行兩次或者三次以上的接口訪問哮翘，這時如果使用同步方式走接口就需要實現(xiàn)嵌套的接口回調(diào)
傳統(tǒng)方式的代碼是如下實現(xiàn)的：
- 定義回調(diào)接口
public interface Callback {
void onSuccess(Object result);
void onFail(Exception e);
}
- 封裝兩個接口的訪問
//第一次接口訪問
public void firstApi(Callback callback) {
Request request = new Request.Builder().url("http://www.example1.com").build();
new OkHttpClient().newCall(request).enqueue(new okhttp3.Callback() {
@Override
public void onFailure(Call call, IOException e) {
callback.onFail(e);
}
@Override
public void onResponse(Call call, Response response) throws IOException {
if (response.isSuccessful()) {
byte[] bytes = response.body().bytes();
if (bytes != null) {
callback.onSuccess(bytes);
}
} else {
callback.onFail(new IllegalStateException("response code is not 200"));
}
}
});
}
//第二次接口訪問
public void secondApi(Callback callback) {
Request request = new Request.Builder().url("http://www.example2.com").build();
new OkHttpClient().newCall(request).enqueue(new okhttp3.Callback() {
@Override
public void onFailure(Call call, IOException e) {
callback.onFail(e);
}
@Override
public void onResponse(Call call, Response response) throws IOException {
if (response.isSuccessful()) {
String jsonString = response.body().string();
callback.onSuccess(jsonString);
} else {
callback.onFail(new IllegalStateException("response code is not 200"));
}
}
});
}
- 使用時會造成嵌套接口回調(diào)
public void test() {
firstApi(new Callback() {
@Override
public void onSuccess(Object result) {
secondApi(new Callback() {
@Override
public void onSuccess(Object result) {
//do something...
}
@Override
public void onFail(Exception e) {
}
});
}
@Override
public void onFail(Exception e) {
}
});
}
像這樣的回調(diào)兩個還行监嗜，三個以上根本沒法看
改用RxJava的方式
- 主要是利用flatMap切換Observable來替換被觀察主題
- 每次嵌套就調(diào)用一次flatMap
/**
* @author zjy
* @date 2018/6/25
*/
public class RxJavaTestActivity extends AppCompatActivity {
private TextView mTvInfo;
public static void start(Context context) {
Intent intent = new Intent(context, RxJavaTestActivity.class);
context.startActivity(intent);
}
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_rx_test);
mTvInfo = findViewById(R.id.tv_info);
}
@SuppressLint("CheckResult")
public void onTest(View view) {
firstFun()
.flatMap((Function<String, ObservableSource<String>>) this::secondFun)//核心方法：利用flatMap操作符更換數(shù)據(jù)提供者（也就是被觀察者Observable）
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(s -> mTvInfo.append("accept result: " + s));
}
//第一層接口回調(diào)
public Observable<String> firstFun() {
return Observable.create(emitter -> new Thread(() -> {
//模仿異步訪問接口
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
final String result = "first observable class\n";
runOnUiThread(() -> mTvInfo.append("first result: " + result));
emitter.onNext(result);
emitter.onComplete();
}).start());
}
//第二層接口回調(diào)
public Observable<String> secondFun(String param) {
return Observable.create((ObservableEmitter<String> emitter) -> new Thread(() -> {
//模仿異步訪問接口
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
final String result = "second observable class\n";
runOnUiThread(() -> {
mTvInfo.append("second: upstream param \"" + param + "\"");
mTvInfo.append("second result: " + result);
});
emitter.onNext(result);
emitter.onComplete();
}).start());
}
}
