RxBinding-让UI控件事件化身数据流

0. 目录

简介
好处
GitHub 地址
依赖
示例

1. 简介

RxBinding 是 Jake Wharton 写的框架,它的 Api 能够把 Android 平台和兼容包内的 UI 控件变为 Observable 对象,这样就可以把 UI 控件的事件当做 Rxjava 中的数据流来使用了.

2. 好处

能对 View 事件使用 Rxjava 的各种操作.
提供了与 Rxjava 一致的回调,代码简洁明了.
几乎支持所有的常用控件和事件.
每个库还有对应的 Kotlin 支持库.

3. GitHub 地址

https://github.com/JakeWharton/RxBinding/

4. 依赖

implementation 'com.jakewharton.rxbinding2:rxbinding:2.1.1'

5. 示例

用标准简洁的实现方式,作用于整个App的所有UI事件.

点击事件:

        Button button = findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // TODO
            }
        });
        RxView.clicks(button)
                .subscribe(new Consumer<Object>() {
                    @Override
                    public void accept(Object o) throws Exception {
                        // TODO
                    }
                });

文本输入

EditText editText = findViewById(R.id.editText);
        editText.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
                
            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                    // TODO
            }

            @Override
            public void afterTextChanged(Editable s) {

            }
        });
        RxTextView.textChanges(editText)
                .subscribe(new Consumer<CharSequence>() {
            @Override
            public void accept(CharSequence charSequence) throws Exception {
                // TODO
            }
        });

长点击事件:

 RxView.longClicks(button).subscribe(new Consumer<Object>() {
            @Override
            public void accept(Object o) throws Exception {
                
            }
            // TODO
        });

防止重复点击(弱网络环境下):

加入依赖:
implementation 'com.safframework:saf-rxlifecycle:1.0.0'

RxView.clicks(button)
                .compose(useRxViewTransformer(this))
                .subscribe(new Consumer<Object>() {
                    @Override
                    public void accept(Object o) throws Exception {
                        // TODO
                    }
                });
    /**
     * 绑定内存泄漏,解决Rxjava内存泄漏的问题
     * @param targetActivity
     * @return
     */
    public ObservableTransformer useRxViewTransformer(final AppCompatActivity targetActivity) {
        return new ObservableTransformer() {

            @Override
            public ObservableSource apply(Observable upstream) {
                return upstream.compose(preventDuplicateClicksTransformer())
                        .compose(RxLifecycle.bind(targetActivity).toLifecycleTransformer());
            }
        };
    }

    /**
     * 防止重复点击
     *
     * @return
     */
    public static ObservableTransformer preventDuplicateClicksTransformer() {
        return new ObservableTransformer() {
            @Override
            public ObservableSource apply(Observable upstream) {
                return upstream.throttleFirst(1000, TimeUnit.MICROSECONDS);
            }
        };
    }

说明:
① Android App 使用Rxjava 存在一个缺点: 不完整的订阅会导致内存泄漏.
② 当Observable 正在运行,Activity或Fragment 销毁后,其观察者仍然会持有对它的引用,系统无法对此Activity/Fragment 进行垃圾回收.
③ RxLifecycle 可以通过绑定声明周期的方式,来解决内存泄漏的问题.

验证码倒计时:

RxView.clicks(button)
                .throttleFirst(MAX_COUNT_TIME, TimeUnit.SECONDS)
                .flatMap(new Function<Object, ObservableSource<Long>>() {
                    @Override
                    public ObservableSource<Long> apply(Object o) throws Exception {
                        // 更新发送按钮的状态,并初始化显示倒计时文字
                        RxView.enabled(button).accept(false);
                        RxTextView.text(button).accept("剩余" + MAX_COUNT_TIME + " 秒");
                        // 返回 n 秒内的倒计时观察者对象
                        return Observable.interval(1, TimeUnit.SECONDS, Schedulers.io())
                              .take(MAX_COUNT_TIME);
                    }
                })
                // 将递增数字替换成递减的倒计时数字
                .map(new Function<Long, Long>() {
                    @Override
                    public Long apply(Long aLong) throws Exception {
                        return MAX_COUNT_TIME - (aLong + 1);
                    }
                })
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(new Consumer<Long>() {
                    @Override
                    public void accept(Long aLong) throws Exception {
                        if (aLong == 0){
                            RxView.enabled(button).accept(true);
                            RxTextView.text(button).accept("获取验证码");
                        }else{
                            RxTextView.text(button).accept("剩余"+aLong +" 秒");
                        }
                    }
                });

RecyclerView:

implementation 'com.jakewharton.rxbinding2:rxbinding-recyclerview-v7:2.1.1'

    // recycerview 当前没有滚动
    private static final int SCROLL_STATE_IDLE = 0;  
    // recyclerview 正在被拖动
    private static final int SCROLL_STATE_DRAGGING = 1;
     // 手已经离开屏幕,recyclerview正在做动画移动到最终位置
    private static final int SCROLL_STATE_SETTLING = 2;
    RxRecyclerView.scrollStateChanges(recyclerView)
                .subscribe(new Consumer<Integer>() {
                    @Override
                    public void accept(Integer scrollState) throws Exception {
                        Log.d("state",scrollState.toString());
                    }
                });

说明:

RecyclerView 提供几个状态的观察.
① scrollStateChanges 观察 RecyclerView 的滚动状态.
② scrollEvents 观察 RecyclerView 的滚动事件.
③ childAttachStateChangeEvents 观察 child view 的 detached 状态 ,当 LayoutManager 或者 RecyclerView 认为不再需要一个 child view 时,就会调用这个方法. 如果child view 占用资源,则应当释放资源.
④ 以上的例子是对滚动状态的监听.
以下是对RecyclerView 点击事件的监听:

@Override
    protected void convert(ViewHolder holder, final String s, int position) {
        holder.setText(R.id.text, s);
        RxView.clicks(holder.itemView)
                .subscribe(new Consumer<Object>() {

                    @Override
                    public void accept(Object o) throws Exception {
                        Toast.makeText(mContext, s, Toast.LENGTH_SHORT).show();
                    }
                });
    }

表单验证:

public class ValidationResult {
    public boolean flag;
    public String message;

    public ValidationResult() {
        flag = true;
        message = "";
    }
}

 final Button button = findViewById(R.id.button);
        final EditText edit02 = findViewById(R.id.editText2);
        final EditText edit03 = findViewById(R.id.editText3);
        Observable<CharSequence> observable_phone = RxTextView.textChanges(edit02);
        Observable<CharSequence> observable_password = RxTextView.textChanges(edit03);
        Observable.combineLatest(observable_phone, observable_password, 
new BiFunction<CharSequence, CharSequence, ValidationResult>() {
            @Override
            public ValidationResult apply(CharSequence phone, CharSequence passwrod) throws Exception {
                if (phone.length() > 0 && passwrod.length() > 0) {
                    button.setBackground(getResources().getDrawable(R.drawable.shape_login_pressed));
                } else {
                    button.setBackground(getResources().getDrawable(R.drawable.shape_login_normal));
                }

                ValidationResult validationResult = new ValidationResult();
                if (phone.length() == 0) {
                    validationResult.flag = false;
                    validationResult.message = "手机号码不能为空";
                } else if (phone.length() != 11) {
                    validationResult.flag = false;
                    validationResult.message = "手机号码需要11位";
                } else if (passwrod.length() == 0) {
                    validationResult.flag = false;
                    validationResult.message = "密码不能为空";
                }
                return validationResult;
            }
        }).subscribe(new Consumer<ValidationResult>() {
            @Override
            public void accept(ValidationResult validationResult) throws Exception {
                mReslut = validationResult;
            }
        });
        RxView.clicks(button)
                .compose(useRxViewTransformer(this))
                .subscribeOn(AndroidSchedulers.mainThread())
                .subscribe(new Consumer() {
                    @Override
                    public void accept(Object o) throws Exception {
                        if (mReslut == null) return;
                        if (mReslut.flag) {
                            Toast.makeText(MainActivity.this, "success", Toast.LENGTH_SHORT).show();
                        } else {
                            Toast.makeText(MainActivity.this, mReslut.message, Toast.LENGTH_SHORT).show();
                        }
                    }
                });

说明:
① combineLatest 的作用就是将过个Observable发射的数据组装起来然后再发射出来.
② 这里两个输入框只要内容发生变化,就会发送 Observable , 此时我们即可在 BiFunction 中利用验证方法去判断输入框中最新的内容,最终返回一个ValidationResult 对象.

6. 后续

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