最近微博不时看到有提到rx-java，联系到之前看到的reactjs，也就抽时间学习了一下，并一直在思考此种模式的优劣。目前得出的结论是：

** 优点**

• 天然支持并发
• 代码更易读

缺点

• 抽象程度太过了（纠结中，觉得也算优点）
• java语言上及android对其的支持上还不够（对比.NET）

今天就拿从ReactiveCocoa处看到的一个使用场景来练手，先上代码：

public class LoginActivity extends Activity {
    @InjectView(R.id.username)
    EditText usernameEditText;
    @InjectView(R.id.password)
    EditText passwordEditText;
    @InjectView(R.id.signin)
    Button signinButton;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);

        ButterKnife.inject(this);

        Observable<Boolean> observableUsername =  WidgetObservable.text(usernameEditText).map(new Func1<OnTextChangeEvent, Boolean>() {
            @Override
            public Boolean call(OnTextChangeEvent onTextChangeEvent) {
                Boolean validateState = onTextChangeEvent.view().getText().length() > 6;
                if(!validateState) {
                    onTextChangeEvent.view().setError("length must great 6");
                }
                return validateState;
            }
        });

        Observable<Boolean> observablePassword =  WidgetObservable.text(passwordEditText).map(new Func1<OnTextChangeEvent, Boolean>() {
            @Override
            public Boolean call(OnTextChangeEvent onTextChangeEvent) {
                Boolean validateState = onTextChangeEvent.view().getText().length() > 3;
                if(!validateState) {
                    onTextChangeEvent.view().setError("length must great 3");
                }
                return validateState;
            }
        });


        Observable.combineLatest(observableUsername, observablePassword, new Func2<Boolean, Boolean, Boolean>(){
            @Override
            public Boolean call(Boolean validateStateUsername, Boolean validateStatePassword) {
                return validateStateUsername && validateStatePassword;
            }
        }).startWith(false).subscribe(new Action1<Boolean>() {
            @Override
            public void call(Boolean state) {
                signinButton.setEnabled(state);
            }
        });
    }
}

要在有lambda表达式的情况下，代码可更精简易读。