简单介绍一下业务逻辑：获取字符串，如果获取失败进行10次重试，超出10次未成功视为失败。
模拟获取字符串场景
代码块
class MsgTool {
int count;
String getMsg() throws Exception {
count++;
LogUtils.d("execute getMsg count : " + count);
if (count == 15) {
return "getMsg";
} else {
throw new Exception("exception getMsg");
}
}
}
Java代码实现逻辑（实现方式很多种，这里不是重点）
代码块
public void testMain() {
LogUtils.d("result : " + getSyncMsg());
}
private String getSyncMsg() {
MsgTool msgTool = new MsgTool();
String result = null;
boolean isSuccess = false;
int count = 0;
while ((count < 10) && !isSuccess) {
try {
result = msgTool.getMsg();
isSuccess = true;
} catch (Exception e) {
count++;
}
}
return result;
}
输出结果
23:33:14.908 32364-32377/? D/LogUtils: execute getMsg count : 1
23:33:14.908 32364-32377/? D/LogUtils: execute getMsg count : 2
23:33:14.908 32364-32377/? D/LogUtils: execute getMsg count : 3
23:33:14.909 32364-32377/? D/LogUtils: execute getMsg count : 4
23:33:14.909 32364-32377/? D/LogUtils: execute getMsg count : 5
23:33:14.909 32364-32377/? D/LogUtils: execute getMsg count : 6
23:33:14.909 32364-32377/? D/LogUtils: execute getMsg count : 7
23:33:14.909 32364-32377/? D/LogUtils: execute getMsg count : 8
23:33:14.909 32364-32377/? D/LogUtils: execute getMsg count : 9
23:33:14.909 32364-32377/? D/LogUtils: execute getMsg count : 10
23:33:14.909 32364-32377/? D/LogUtils: result : null
针对上述业务逻辑改为RxJava实现，使用操作符retry可实现
代码块
public void testMain() {
getSyncMsg().subscribe(getSubscriber());
}
private Observable<String> getSyncMsg() {
MsgTool msgTool = new MsgTool();
Observable<String> o = Observable.create(subscriber -> {
try {
subscriber.onNext(msgTool.getMsg());
subscriber.onCompleted();
} catch (Exception e) {
subscriber.onError(e);
}
});
return o.retry(10);
}
private Subscriber<Object> getSubscriber() {
return new Subscriber<Object>() {
@Override
public void onCompleted() {
LogUtils.d("onCompleted");
}
@Override
public void onError(Throwable e) {
LogUtils.d("onError : " + e.toString());
}
@Override
public void onNext(Object o) {
LogUtils.d("onNext : " + o);
}
};
}
输出结果
23:45:43.761 3285-3307/? D/LogUtils: execute getMsg count : 1
23:45:43.762 3285-3307/? D/LogUtils: execute getMsg count : 2
23:45:43.763 3285-3307/? D/LogUtils: execute getMsg count : 3
23:45:43.763 3285-3307/? D/LogUtils: execute getMsg count : 4
23:45:43.763 3285-3307/? D/LogUtils: execute getMsg count : 5
23:45:43.763 3285-3307/? D/LogUtils: execute getMsg count : 6
23:45:43.763 3285-3307/? D/LogUtils: execute getMsg count : 7
23:45:43.763 3285-3307/? D/LogUtils: execute getMsg count : 8
23:45:43.764 3285-3307/? D/LogUtils: execute getMsg count : 9
23:45:43.764 3285-3307/? D/LogUtils: execute getMsg count : 10
23:45:43.764 3285-3307/? D/LogUtils: execute getMsg count : 11
23:45:43.765 3285-3307/? D/LogUtils: onError : java.lang.Exception: exception getMsg
下面我们增加一个业务逻辑，每次重试延迟一秒种。此功能不做Java代码实现（使用定时器、Android系统下使用Handler等），而用RxJava代码实现，虽然看着很迷糊，但是慢慢品味就会发觉它的魅力所在。
public void testMain() {
getSyncMsg().subscribe(getSubscriber());
}
private Observable<String> getSyncMsg() {
MsgTool msg = new MsgTool();
Observable<String> o = Observable.create(subscriber -> {
try {
subscriber.onNext(msg.getMsg());
subscriber.onCompleted();
} catch (Exception e) {
subscriber.onError(e);
}
});
return o.retryWhen(this::delayRetry);
}
//此方法就是魅力的所在
private Observable<Object> delayRetry(Observable<? extends Throwable> o) {
return o.zipWith(Observable.range(1, 10), //控制10次以内
(throwable, integer) -> {
if (integer == 10) { //如果是最后一次，结合的结果是异常。
return throwable;
} else {
return integer;
}
})
.flatMap(object -> Observable.create(subscriber -> {
//转换retryWhey发射的数据
if (object instanceof Throwable) {
subscriber.onError((Throwable) object);
} else {
subscriber.onNext(o);
subscriber.onCompleted();
}
}).delay(1, TimeUnit.SECONDS)); //延迟一秒发射
}
private Subscriber<Object> getSubscriber() {
return new Subscriber<Object>() {
@Override
public void onCompleted() {
LogUtils.d("onCompleted");
}
@Override
public void onError(Throwable e) {
LogUtils.d("onError : " + e.toString());
}
@Override
public void onNext(Object o) {
LogUtils.d("onNext : " + o);
}
};
}
输出结果
00:36:57.271 19355-19372/? D/LogUtils: onStart
00:36:57.297 19355-19372/? D/LogUtils: execute getMsg count : 1
00:36:58.305 19355-19377/? D/LogUtils: execute getMsg count : 2
00:36:59.306 19355-19404/? D/LogUtils: execute getMsg count : 3
00:37:00.307 19355-19375/? D/LogUtils: execute getMsg count : 4
00:37:01.308 19355-19376/? D/LogUtils: execute getMsg count : 5
00:37:02.308 19355-19377/? D/LogUtils: execute getMsg count : 6
00:37:03.309 19355-19404/? D/LogUtils: execute getMsg count : 7
00:37:04.309 19355-19375/? D/LogUtils: execute getMsg count : 8
00:37:05.310 19355-19376/? D/LogUtils: execute getMsg count : 9
00:37:06.311 19355-19377/? D/LogUtils: execute getMsg count : 10
00:37:06.320 19355-19377/? D/LogUtils: onError : java.lang.Exception: exception getMsg