RxJava替换嵌套接口回调
有时项目中需要进行两次或者三次以上的接口访问，这时如果使用同步方式走接口就需要实现嵌套的接口回调
传统方式的代码是如下实现的：
- 定义回调接口
public interface Callback {
void onSuccess(Object result);
void onFail(Exception e);
}
- 封装两个接口的访问
//第一次接口访问
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"));
}
}
});
}
//第二次接口访问
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"));
}
}
});
}
- 使用时会造成嵌套接口回调
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) {
}
});
}
像这样的回调两个还行，三个以上根本没法看
改用RxJava的方式
- 主要是利用flatMap切换Observable来替换被观察主题
- 每次嵌套就调用一次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操作符更换数据提供者（也就是被观察者Observable）
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(s -> mTvInfo.append("accept result: " + s));
}
//第一层接口回调
public Observable<String> firstFun() {
return Observable.create(emitter -> new Thread(() -> {
//模仿异步访问接口
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());
}
//第二层接口回调
public Observable<String> secondFun(String param) {
return Observable.create((ObservableEmitter<String> emitter) -> new Thread(() -> {
//模仿异步访问接口
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());
}
}
