三、RxJava转换map，flatMap

原创已于 2022-02-09 11:14:16 修改 · 453 阅读

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于 2021-11-24 14:30:21 首次发布

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本文深入探讨了RxJava中map和flatMap操作符的使用，展示了如何将整型数据转换为字符串，进一步转换为位图，并通过flatMap实现多个值的拼接和延迟打印。示例代码详细解释了转换过程，帮助理解这两个关键操作符在实际开发中的应用。

1.项目地址

在：MainActivity4

2.讲解

1.map,

int类型转为String

Observable.just(1)
                .map(new Function<Integer, String>() {//int转String
                    @Override
                    public String apply(Integer integer) throws Throwable {
                        //1
                        Log.d(TAG, "apply: "+integer);
                        return "["+integer+"]";
                    }
                })
                .subscribe(new Observer<String>() {
                    @Override
                    public void onSubscribe(@NonNull Disposable d) {

                    }

                    @Override
                    public void onNext(@NonNull String s) {
                        Log.d(TAG, "onNext: "+s);
                    }

                    @Override
                    public void onError(@NonNull Throwable e) {

                    }

                    @Override
                    public void onComplete() {

                    }
                });

int转String再转Bitmap

Observable.just(1)
                .map(new Function<Integer, String>() {
                    @Override
                    public String apply(Integer integer) throws Throwable {
                        Log.d(TAG, "apply: "+integer);
                        return "["+integer+"]";
                    }
                })
                .map(new Function<String, Bitmap>() {
                    @Override
                    public Bitmap apply(String s) throws Throwable {
                        Log.d(TAG, "apply: "+s);
                        return Bitmap.createBitmap(1920,1280,Bitmap.Config.ARGB_8888);
                    }
                }).subscribe(new Observer<Bitmap>() {
            @Override
            public void onSubscribe(@NonNull Disposable d) {

            }

            @Override
            public void onNext(@NonNull Bitmap bitmap) {
                Log.d(TAG, "onNext: "+bitmap);
            }

            @Override
            public void onError(@NonNull Throwable e) {

            }

            @Override
            public void onComplete() {

            }
        });

2.flatMap

返回一个观察者（int 转String）：

Observable.just(1111)
                .flatMap(new Function<Integer, ObservableSource<String>>() {
                    @Override
                    public ObservableSource<String> apply(Integer integer) throws Throwable {
                        return Observable.create(new ObservableOnSubscribe<String>() {
                            @Override
                            public void subscribe(@NonNull ObservableEmitter<String> emitter) throws Throwable {
                                emitter.onNext(integer+"flatMap变换操作符");
                                emitter.onNext(integer+"flatMap变换操作符");
                                emitter.onComplete();
                            }
                        });
                    }
                })

                //订阅
        .subscribe(new Consumer<String>() {
            @Override
            public void accept(String s) throws Throwable {
                Log.d(TAG, "accept: "+s);
            }
        });

为每个值拼接，转为list，然后延迟打印：

Observable.create(new ObservableOnSubscribe<String>() {
            @Override
            public void subscribe(@NonNull ObservableEmitter<String> emitter) throws Throwable {
                emitter.onNext("步惊云");
                emitter.onNext("雄霸");
                emitter.onNext("无名");
            }
        })
                .flatMap(new Function<String, ObservableSource<?>>() {
                    @Override
                    public ObservableSource<?> apply(String s) throws Throwable {
                        List<String> list=new ArrayList<>();
                        for (int i = 0; i < 3; i++) {
                            list.add(s+"下标："+1+i);
                        }
                        return Observable.fromIterable(list).delay(1, TimeUnit.SECONDS);//创建型操作符，创建被观察者

                    }
                })
                //订阅
        .subscribe(new Consumer<Object>() {
            @Override
            public void accept(Object o) throws Throwable {
                Log.d(TAG, "accept: "+o);
            }
        });