RxJava操作符：创建操作

Create

——使用一个函数从头开始创建一个Observable

Create操作符

代码：

Observable.create(new Observable.OnSubscribe() {
        @Override
        public void call(Subscriber subscriber) {
            if (!subscriber.isUnsubscribed()) {//判断观察者的状态，如果没有订阅则不发送数据
                subscriber.onNext("created 操作符1");
                subscriber.onNext("created 操作符2");
                subscriber.onNext("created 操作符3");
                subscriber.onNext("created 操作符4");
                subscriber.onCompleted();
            }

        }
    }).subscribe(new Subscriber() {
        @Override
        public void onCompleted() {
            Log.d(TAG, "onCompleted");
        }

        @Override
        public void onError(Throwable e) {
            Log.d(TAG, "onError:" + e.toString());
        }

        @Override
        public void onNext(String s) {
            Log.d(TAG, s);

        }
    });

输出结果：

03-17 23:46:43.137 12009-12009/com.io.github.hjianfei.demo D/onResponse: created 操作符1
03-17 23:46:43.137 12009-12009/com.io.github.hjianfei.demo D/onResponse: created 操作符2
03-17 23:46:43.137 12009-12009/com.io.github.hjianfei.demo D/onResponse: created 操作符3
03-17 23:46:43.137 12009-12009/com.io.github.hjianfei.demo D/onResponse: created 操作符4
03-17 23:46:43.137 12009-12009/com.io.github.hjianfei.demo D/onResponse: onCompleted

From

——将其它种类的对象和数据类型转换为Observable

From操作符

代码：

String from[] = {"From操作符1", "From操作符2", "From操作符3", "From操作符4"};
    Observable.from(from)
            .subscribe(new Subscriber() {
                @Override
                public void onCompleted() {
                    Log.d(TAG, "onCompleted");
                }

                @Override
                public void onError(Throwable e) {
                    Log.d(TAG, "onError:" + e.toString());

                }

                @Override
                public void onNext(String s) {
                    Log.d(TAG, s);

                }
            });

结果：

03-18 00:02:39.591 28131-28131/com.io.github.hjianfei.demo D/onResponse: From操作符1
03-18 00:02:39.591 28131-28131/com.io.github.hjianfei.demo D/onResponse: From操作符2
03-18 00:02:39.591 28131-28131/com.io.github.hjianfei.demo D/onResponse: From操作符3
03-18 00:02:39.591 28131-28131/com.io.github.hjianfei.demo D/onResponse: From操作符4
03-18 00:02:39.591 28131-28131/com.io.github.hjianfei.demo D/onResponse: onCompleted

Interval

——创建一个按固定时间间隔发射整数序列的Observable

Interval

Interval操作符返回一个Observable，它按固定的时间间隔发射一个无限递增的整数序列。它接受一个表示时间间隔的参数和一个表示时间单位的参数。

interval(long,TimeUnit))
interval(long,TimeUnit,Scheduler))

代码：

Observable.interval(5, TimeUnit.SECONDS)
                .subscribe(new Subscriber() {
                    @Override
                    public void onCompleted() {
                        Log.d(TAG, "onCompleted");
                    }

                    @Override
                    public void onError(Throwable e) {
                        Log.d(TAG, "onError:" + e.toString());
                    }

                    @Override
                    public void onNext(Long aLong) {
                        Log.d(TAG, aLong+"");

                    }
                });

结果：

03-18 00:08:58.024 6346-6651/com.io.github.hjianfei.demo D/onResponse: 0
03-18 00:09:03.023 6346-6651/com.io.github.hjianfei.demo D/onResponse: 1
03-18 00:09:08.024 6346-6651/com.io.github.hjianfei.demo D/onResponse: 2
03-18 00:09:13.024 6346-6651/com.io.github.hjianfei.demo D/onResponse: 3
03-18 00:09:18.024 6346-6651/com.io.github.hjianfei.demo D/onResponse: 4
03-18 00:09:23.025 6346-6651/com.io.github.hjianfei.demo D/onResponse: 5
......
......

Just

——创建一个发射指定值的Observable

Just将单个数据转换为发射那个数据的Observable。

Just类似于From，但是From会将数组或Iterable的数据取出然后逐个发射，而Just只是简单的原样发射，将数组或Iterable当做单个数据。

Just操作符

代码：

    Observable.just("Just操作符1", "Just操作符2", "Just操作符3", "Just操作符4")
            .subscribe(new Subscriber() {
                @Override
                public void onCompleted() {
                    Log.d(TAG, "onCompleted");
                }

                @Override
                public void onError(Throwable e) {
                    Log.d(TAG, "onError:" + e.toString());

                }

                @Override
                public void onNext(String just) {
                    Log.d(TAG, just);

                }
            });

结果：

03-18 00:16:30.458 16301-16301/com.io.github.hjianfei.demo D/onResponse: Just操作符1
03-18 00:16:30.458 16301-16301/com.io.github.hjianfei.demo D/onResponse: Just操作符2
03-18 00:16:30.458 16301-16301/com.io.github.hjianfei.demo D/onResponse: Just操作符3
03-18 00:16:30.458 16301-16301/com.io.github.hjianfei.demo D/onResponse: Just操作符4
03-18 00:16:30.458 16301-16301/com.io.github.hjianfei.demo D/onResponse: onCompleted

Range

——创建一个发射特定整数序列的Observable

Range操作符发射一个范围内的有序整数序列，你可以指定范围的起始和长度。

RxJava将这个操作符实现为range函数，它接受两个参数，一个是范围的起始值，一个是范围的数据的数目。如果你将第二个参数设为0，将导致Observable不发射任何数据（如果设置为负数，会抛异常）。

Range操作符

代码：

    Observable.range(1, 5)
            .subscribe(new Subscriber() {
                @Override
                public void onCompleted() {
                    Log.d(TAG, "onCompleted");
                }

                @Override
                public void onError(Throwable e) {
                    Log.d(TAG, "onError:" + e.toString());
                }

                @Override
                public void onNext(Integer integer) {
                    Log.d(TAG, integer + "");

                }
            });

结果：

03-18 00:19:55.669 22020-22020/com.io.github.hjianfei.demo D/onResponse: 1
03-18 00:19:55.669 22020-22020/com.io.github.hjianfei.demo D/onResponse: 2
03-18 00:19:55.669 22020-22020/com.io.github.hjianfei.demo D/onResponse: 3
03-18 00:19:55.669 22020-22020/com.io.github.hjianfei.demo D/onResponse: 4
03-18 00:19:55.669 22020-22020/com.io.github.hjianfei.demo D/onResponse: 5
03-18 00:19:55.669 22020-22020/com.io.github.hjianfei.demo D/onResponse: onCompleted

Repeat

——创建一个发射特定数据重复多次的Observable

Repeat重复地发射数据。某些实现允许你重复的发射某个数据序列，还有一些允许你限制重复的次数。

RxJava将这个操作符实现为repeat方法。它不是创建一个Observable，而是重复发射原始Observable的数据序列，这个序列或者是无限的，或者通过repeat(n)指定重复次数。

Repeat操作符

代码：

    Observable.just("Repeat操作符1", "Repeat操作符2", "Repeat操作符3")
            .repeat(2)
            .subscribe(new Subscriber() {
                @Override
                public void onCompleted() {
                    Log.d(TAG, "onCompleted");
                }

                @Override
                public void onError(Throwable e) {
                    Log.d(TAG, "onError:" + e.toString());

                }

                @Override
                public void onNext(String just) {
                    Log.d(TAG, just);

                }
            });

结果：

03-18 00:24:50.660 28474-28474/com.io.github.hjianfei.demo D/onResponse: Repeat操作符1
03-18 00:24:50.661 28474-28474/com.io.github.hjianfei.demo D/onResponse: Repeat操作符2
03-18 00:24:50.661 28474-28474/com.io.github.hjianfei.demo D/onResponse: Repeat操作符3
03-18 00:24:50.665 28474-28474/com.io.github.hjianfei.demo D/onResponse: Repeat操作符1
03-18 00:24:50.665 28474-28474/com.io.github.hjianfei.demo D/onResponse: Repeat操作符2
03-18 00:24:50.665 28474-28474/com.io.github.hjianfei.demo D/onResponse: Repeat操作符3
03-18 00:24:50.665 28474-28474/com.io.github.hjianfei.demo D/onResponse: onCompleted

Timer

——创建一个Observable，它在一个给定的延迟后发射一个特殊的值。

Timer操作符创建一个在给定的时间段之后返回一个特殊值的Observable。

RxJava将这个操作符实现为timer函数。

timer返回一个Observable，它在延迟一段给定的时间后发射一个简单的数字0。

Timer操作符

代码：

    Observable.timer(2, java.util.concurrent.TimeUnit.SECONDS)
            .subscribe(new Subscriber() {
                @Override
                public void onCompleted() {
                    Log.d(TAG, "onCompleted");
                }

                @Override
                public void onError(Throwable e) {
                    Log.d(TAG, "onError:" + e.toString());
                }

                @Override
                public void onNext(Long aLong) {
                    Log.d(TAG, aLong + "");

                }
            });

结果：

03-18 00:29:42.656 3065-3533/com.io.github.hjianfei.demo D/onResponse: 0
03-18 00:29:42.656 3065-3533/com.io.github.hjianfei.demo D/onResponse: onCompleted

还有更多的操作符请查看 RXJava官方文档