1.需求场景
发送网络请求过程中，会出现某些错误，从而导致这次网络请求不成功，当发生错误是的网络请求不成功时，自动重新发送网络请求。
2.具体使用
利用retryWhen()操作符实现，通过断开网络连接模拟网络异常错误，限制重试次数 = 10次。
public class RequestRetryActivity extends AppCompatActivity {
@BindView(R.id.webview)
WebView webview;
//可重试次数
private int maxConnectCount = 10;
//当前已重试次数
private int currentRetryCount = 0;
//重试等待时间
private int waitRetryTime = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_request_retry);
ButterKnife.bind(this);
webview.loadUrl("https://www.jianshu.com/p/508c30aef0c1");
Retrofit retrofit = new Retrofit.Builder()
.baseUrl(UrlManager.BASE_URL_JS)
.addCallAdapterFactory(RxJava2CallAdapterFactory.create())
.addConverterFactory(GsonConverterFactory.create())
.build();
RequestApi request = retrofit.create(RequestApi.class);
Observable<TranslationBean> observable = request.getCall();
observable.retryWhen(new Function<Observable<Throwable>, ObservableSource<?>>() {
@Override
public ObservableSource<?> apply(Observable<Throwable> throwableObservable) throws Exception {
return throwableObservable.flatMap(new Function<Throwable, ObservableSource<?>>() {
@Override
public ObservableSource<?> apply(Throwable throwable) throws Exception {
Log.d(Constant.TAG, "发生异常 = " + throwable.toString());
if (throwable instanceof IOException) {
Log.d(Constant.TAG, "属于IO异常，需重试");
if (currentRetryCount < maxConnectCount) {
//记录重试次数
currentRetryCount++;
Log.d(Constant.TAG, "重试次数 = " + currentRetryCount);
/**
* 需求2：实现重试
* 通过返回的Observable发送的事件 = Next事件，从而使得retryWhen重新订阅，最终实现重试功能
*
* 需求3：延迟一段事件再重试
* 采用delay操作符 = 延迟一段时间发送，以实现重试间隔设置
*
* 需求4：遇到的异常越多，时间越长
* 在delay操作符的等待时间内设置 = 每重试一次，增多延迟重试时间1s
*/
//设置等待时间
waitRetryTime = 1000 + currentRetryCount * 1000;
Log.d(Constant.TAG, "等待时间 = " + waitRetryTime);
return Observable.just(1).delay(waitRetryTime, TimeUnit.MILLISECONDS);
} else {
//若重试次数 > 设置重试次数，则不重试
//通过发送error来停止重试（可在观察者的onError中获取信息）
return Observable.error(new Throwable("重试次数已超过设置次数 = " + currentRetryCount));
}
//若发生的异常不属于I/O异常，则不重试
//通过返回的Observable发送的事件 = error事件 实现（可再观察者的onError()中获取信息）
} else {
return Observable.error(new Throwable("发生了非网络异常（非I/O异常）"));
}
}
});
}
}).subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Observer<TranslationBean>() {
@Override
public void onSubscribe(Disposable d) {
}
@Override
public void onNext(TranslationBean translationBean) {
Log.d(Constant.TAG, "接收成功");
Log.d(Constant.TAG, translationBean.getContent().getOut());
}
@Override
public void onError(Throwable e) {
Log.d(Constant.TAG, e.toString());
}
@Override
public void onComplete() {
}
});
}
}
3.测试结果
07-03 16:12:07.529 9876-9930/com.gjj.frame D/RxJava: 发生异常 = java.net.UnknownHostException: Unable to resolve host "fy.iciba.com": No address associated with hostname
07-03 16:12:07.532 9876-9930/com.gjj.frame D/RxJava: 属于IO异常，需重试
07-03 16:12:07.532 9876-9930/com.gjj.frame D/RxJava: 重试次数 = 1
07-03 16:12:07.532 9876-9930/com.gjj.frame D/RxJava: 等待时间 = 2000
07-03 16:12:09.541 9876-9932/com.gjj.frame D/RxJava: 发生异常 = java.net.UnknownHostException: Unable to resolve host "fy.iciba.com": No address associated with hostname
07-03 16:12:07.532 9876-9930/com.gjj.frame D/RxJava: 属于IO异常，需重试
07-03 16:12:07.532 9876-9930/com.gjj.frame D/RxJava: 重试次数 = 2
07-03 16:12:07.532 9876-9930/com.gjj.frame D/RxJava: 等待时间 = 3000
07-03 16:12:12.547 9876-9937/com.gjj.frame D/RxJava: 发生异常 = java.net.UnknownHostException: Unable to resolve host "fy.iciba.com": No address associated with hostname
07-03 16:12:07.532 9876-9930/com.gjj.frame D/RxJava: 属于IO异常，需重试
07-03 16:12:07.532 9876-9930/com.gjj.frame D/RxJava: 重试次数 = 3
07-03 16:12:07.532 9876-9930/com.gjj.frame D/RxJava: 等待时间 = 4000
07-03 16:12:16.553 9876-9939/com.gjj.frame D/RxJava: 发生异常 = java.net.UnknownHostException: Unable to resolve host "fy.iciba.com": No address associated with hostname
07-03 16:12:07.532 9876-9930/com.gjj.frame D/RxJava: 属于IO异常，需重试
07-03 16:12:07.532 9876-9930/com.gjj.frame D/RxJava: 重试次数 = 4
07-03 16:12:07.532 9876-9930/com.gjj.frame D/RxJava: 等待时间 = 5000
07-03 16:12:21.559 9876-9941/com.gjj.frame D/RxJava: 发生异常 = java.net.UnknownHostException: Unable to resolve host "fy.iciba.com": No address associated with hostname
07-03 16:12:07.532 9876-9930/com.gjj.frame D/RxJava: 属于IO异常，需重试
07-03 16:12:07.532 9876-9930/com.gjj.frame D/RxJava: 重试次数 = 5
07-03 16:12:07.532 9876-9930/com.gjj.frame D/RxJava: 等待时间 = 6000
07-03 16:12:28.923 9876-9876/com.gjj.frame D/RxJava: 接收成功
07-03 16:12:07.532 9876-9930/com.gjj.frame D/RxJava: 嗨世界
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