問(wèn)題描述

最近在使用RxJava時(shí)，出現(xiàn)了一個(gè)錯(cuò)誤悼沈，錯(cuò)誤日志如下：

02-28 09:42:16.962 16647-17731/com.aspire.mpus E/AndroidRuntime: FATAL EXCEPTION: RxCachedThreadScheduler-1
                                                                Process: com.aspire.mpus, PID: 16647
                                                                java.lang.Throwable: 網(wǎng)絡(luò)連接超時(shí)
                                                                    at com.aspire.mpus.core.api.Api.onError(Api.java:84)
                                                                    at com.aspire.mpus.core.api.Api.access$100(Api.java:23)
                                                                    at com.aspire.mpus.core.api.Api$1.subscribe(Api.java:116)
                                                                    at io.reactivex.internal.operators.observable.ObservableCreate.subscribeActual(ObservableCreate.java:40)
                                                                    at io.reactivex.Observable.subscribe(Observable.java:10514)
                                                                    at io.reactivex.internal.operators.observable.ObservableSubscribeOn$1.run(ObservableSubscribeOn.java:39)
                                                                    at io.reactivex.Scheduler$1.run(Scheduler.java:134)
                                                                    at io.reactivex.internal.schedulers.ScheduledRunnable.run(ScheduledRunnable.java:59)
                                                                    at io.reactivex.internal.schedulers.ScheduledRunnable.call(ScheduledRunnable.java:51)
                                                                    at java.util.concurrent.FutureTask.run(FutureTask.java:237)
                                                                    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:269)
                                                                    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
                                                                    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
                                                                    at java.lang.Thread.run(Thread.java:818)

拋出異常的原因是我在onError方法中會(huì)指定一些錯(cuò)誤的原因嘲叔，例如網(wǎng)絡(luò)連接超時(shí)、連接服務(wù)器失敗等蜒犯。

 private void onError(Exception e, ObservableEmitter emitter, String message) {
        e.printStackTrace();
        LogUtils.error(e);

        if (e instanceof SocketTimeoutException) {
            emitter.onError(new Throwable("網(wǎng)絡(luò)連接超時(shí)"));
        } else if (e instanceof ConnectException) {
            emitter.onError(new Throwable("連接服務(wù)器失敗"));
        } else {
            emitter.onError(new Throwable(message));
        }
        emitter.onComplete();
    }

解決方法

判斷emitter是否被取消訂閱组橄。如果當(dāng)前的emitter未被取消訂閱荞膘，則正常拋出異常，否則不執(zhí)行玉工。

private void onError(Exception e, ObservableEmitter emitter, String message) {
        e.printStackTrace();
        LogUtils.error(e);

        if (!emitter.isDisposed()) {
            if (e instanceof SocketTimeoutException) {
                emitter.onError(new Throwable("網(wǎng)絡(luò)連接超時(shí)"));
            } else if (e instanceof ConnectException) {
                emitter.onError(new Throwable("連接服務(wù)器失敗"));
            } else {
                emitter.onError(new Throwable(message));

            }
            emitter.onComplete();
        }
    }

重現(xiàn)步驟

• 開(kāi)始一個(gè)網(wǎng)絡(luò)請(qǐng)求
• 在請(qǐng)求未結(jié)束時(shí)結(jié)束當(dāng)前頁(yè)面
• 請(qǐng)求結(jié)束后羽资，如果未能請(qǐng)求成功，則onError方法中會(huì)判斷異常信息遵班，并拋出異常屠升，但是Observable未能捕捉到異常，最終導(dǎo)致APP crash

Observable生命周期管理

在執(zhí)行網(wǎng)絡(luò)請(qǐng)求時(shí)狭郑，會(huì)生成一個(gè)Disposable對(duì)象腹暖，該對(duì)象保存了Observable的狀態(tài)（訂閱、取消訂閱）翰萨。
查看ObservableEmitter源碼脏答，

public interface ObservableEmitter<T> extends Emitter<T> {

    /**
     * Sets a Disposable on this emitter; any previous Disposable
     * or Cancellation will be unsubscribed/cancelled.
     * @param d the disposable, null is allowed
     */
    void setDisposable(@Nullable Disposable d);

    /**
     * Sets a Cancellable on this emitter; any previous Disposable
     * or Cancellation will be unsubscribed/cancelled.
     * @param c the cancellable resource, null is allowed
     */
    void setCancellable(@Nullable Cancellable c);

    /**
     * Returns true if the downstream disposed the sequence.
     * @return true if the downstream disposed the sequence
     */
    boolean isDisposed();

    /**
     * Ensures that calls to onNext, onError and onComplete are properly serialized.
     * @return the serialized ObservableEmitter
     */
    @NonNull
    ObservableEmitter<T> serialize();
}

發(fā)現(xiàn)ObservableEmitter也持有Disposable的屬性，所以增加對(duì)當(dāng)前訂閱事件的判斷亩鬼，然后選擇是否拋出異常殖告，即可解決問(wèn)題。