Доклад включает в себя рассмотрение ключевых особенностей библиотеки. Также описывает обработку событий внутри библиотеки и в сформированных биндингах. Дополнительно рассматривается создание собственных компонентов, расширяющих возможности элементов интерфейса, и в конце будет уделено отдельное внимание реализации двустороннего биндинга.

1. Data Binding 2.0
Анохин Михаил / Android Developer / MWDN Ltd.

2. Data Binding
● представлен на Google I/O 2015
● официальная библиотека от Google
● генерирует биндинг во время компиляции
● позволяет реализовать двусторонний биндинг
● доступна стабильная версия 2.1
2

3. public class FindViewByIdFragment extends Fragment {
private TextView firstName;
private TextView lastName;
@Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(
R.layout.fragment_simple_as_is, container, false);
firstName = (TextView) view.findViewById(R.id.first_name);
lastName = (TextView) view.findViewById(R.id.last_name);
return view;
}
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
User user = User.getDefault();
firstName.setText(user.firstName);
lastName.setText(user.lastName);
}
}
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:id="@+id/first_name"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<TextView
android:id="@+id/last_name"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
findViewById
3

4. public class ButterKnifeFragment extends Fragment {
@Bind(R.id.first_name)
TextView firstName;
@Bind(R.id.last_name)
TextView lastName;
@Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(
R.layout.fragment_simple_as_is, container, false);
ButterKnife.bind(this, view);
return view;
}
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
User user = User.getDefault();
firstName.setText(user.firstName);
lastName.setText(user.lastName);
}
@Override
public void onDestroyView() {
super.onDestroyView();
ButterKnife.unbind(this);
}
}
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:id="@+id/first_name"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<TextView
android:id="@+id/last_name"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
ButterKnife
4

5. Binding (Model)
<layout
xmlns:android="http://schemas.android.com/apk/res/android">
<data>
< variable
name="user"
type="com.anokmik.databinding.model.User" />
</data>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
< TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@{user.firstName}"/>
< TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@{user.lastName}"/>
</LinearLayout>
</layout>
public class BindingModelFragment extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(
R.layout.fragment_binding_model, container, false);
FragmentBindingModelBinding binding
= FragmentBindingModelBinding.bind(view);
binding.setUser(User.getDefault());
return view;
}
}
5

6. Binding (Ids)
public class BindingIdsFragment extends Fragment {
private TextView firstName;
private TextView lastName;
@Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(
R.layout.fragment_binding_ids, container, false);
FragmentBindingIdsBinding binding
= FragmentBindingIdsBinding.bind(view);
firstName = binding.firstName;
lastName = binding.lastName;
return view;
}
@Override
public void onViewCreated(View view,
Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
User user = User.getDefault();
firstName.setText(user.firstName);
lastName.setText(user.lastName);
}
}
<layout
xmlns:android="http://schemas.android.com/apk/res/android">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
< TextView
android:id="@+id/first_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
< TextView
android:id="@+id/last_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
</LinearLayout>
</layout>
6

7. Data Model
public class User {
private final String firstName;
private final String lastName;
public User(String firstName, String lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
public String getFirstName() {
return firstName;
}
public String getLastName() {
return lastName;
}
}
public class User {
public final String firstName;
public final String lastName;
public User(String firstName, String lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
}
7

8. Configuration
android {
...
buildToolsVersion "23.0.2"
...
dataBinding {
enabled = true
}
...
}
buildscript {
repositories {
jcenter()
}
dependencies {
classpath 'com.android.tools.build:gradle:2.1.0'
}
}
8

9. Compile-time Generation
View view = inflater.inflate(R.layout.fragment_main, container, false);
FragmentMainBinding binding = FragmentMainBinding.bind(view);
<data class="FragmentMainBinding">
...
</data>
<data class=".FragmentMainBinding">
...
</data>
<data class="com.example.FragmentMainBinding">
...
</data>
9
Generated classes location: /build/intermediates/classes/{$buildType}/{$applicationId}/databinding

10. Variables and Imports
public abstract User getUser();
public abstract void setUser(User user);
public abstract Drawable getImage();
public abstract void setImage(Drawable image);
public abstract String getText();
public abstract void setText(String text);
<data>
<import type="android.graphics.drawable.Drawable" />
<import type="com.anokmik.databinding.model.User" />
<variable name="user" type="User" />
<variable name="image" type="Drawable" />
<variable name="text" type="String" />
</data>
10

11. Variables and Imports
<data>
<import type="android.util.SparseArray"/>
<import type="java.util.Map"/>
<import type="java.util.List"/>
<variable name="array" type="String[]" />
<variable name="list" type="List&lt;String>"/>
<variable name="sparse" type="SparseArray&lt;String>"/>
<variable name="map" type="Map&lt;String, String>"/>
<variable name="index" type="int"/>
<variable name="key" type="String"/>
</data>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@{titles[0]}" />
<data>
<import type="android.app.Fragment"/>
<import type="android.support.v4.app.Fragment" alias="SupportFragment"/>
</data>
11

12. Data Objects
public class NotifyGreeting extends BaseObservable {
private String name;
@Bindable
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
notifyPropertyChanged(BR.name);
}
}
public class ObservableGreeting {
public ObservableString name
= new ObservableString();
}
12

13. Data Objects (Example)
13

14. Include and Merge
<layout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:bind="http://schemas.android.com/apk/res-auto">
<data>
<variable name="user" type="com.example.User" />
</data>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<include
layout="@layout/name"
bind:user="@{user}" />
</LinearLayout>
</layout>
<layout
xmlns:bind="http://schemas.android.com/apk/res-auto">
<data>
<variable name="user" type="com.example.User"/>
</data>
<merge>
<include layout="@layout/name"
bind:user="@{user}"/>
</merge>
</layout>
14

15. Expressions
● mathematical +, -, /, *, %
● string concatenation +
● logical &&, ||
● binary &, |, ^
● unary +, -, !, ~
● shift >>, >>>, <<
● comparison ==, >, <, >=, <=
● instanceof
● grouping ()
● literals - character, String, numeric, null
● cast
● method calls
● field access
● array access []
● ternary operator ?:
android:enabled="@{communicator.isLoginValid &amp; communicator.isPasswordValid}"
15

16. Expressions (Example)
16

17. Null
android:text="@{user.firstName ?? user.lastName}"
android:text="@{user.firstName != null ? user.firstName : user.lastName}"
android:visibility="@{communicator.greeting.name.length > 0 ? View.VISIBLE : View.GONE}"
17

18. Setters and Binding Adapters
bind:layoutManager="@{communicator.layoutManager}"
18
android:text="@{user.firstName}"
@BindingAdapter("android:text")
public static void setText(TextView view, CharSequence text) {
...
}
android:onTextChanged="@{communicator.onLoginTextChanged}"
@BindingAdapter(value = {"android:beforeTextChanged", "android:onTextChanged",
"android:afterTextChanged", "android:textAttrChanged"}, requireAll = false)
public static void setTextWatcher(TextView view, final BeforeTextChanged before, final OnTextChanged on,
final AfterTextChanged after, final InverseBindingListener textAttrChanged) {
...
}
bind:adapter="@{communicator.adapter}"

19. Data Binding Component
19
public class MainDataBindingComponent {
@BindingAdapter(value = {"defaultColor", "pressedColor"})
public void setButtonStateListBackground(Button button, int defaultColor, int pressedColor) {
button.setBackground(getButtonStateListDrawable(defaultColor, pressedColor));
}
...
} public class DataBindingComponentProvider implements DataBindingComponent {
@Override
public MainDataBindingComponent getMainDataBindingComponent() {
return new MainDataBindingComponent();
}
...
}
DataBindingUtil.setDefaultComponent(new DataBindingComponentProvider());
DataBindingUtil.setContentView(this, R.layout.activity_main, new DataBindingComponentProvider());
DataBindingUtil.inflate(inflater, R.layout.fragment_main, container, false, new DataBindingComponentProvider());

20. Binding Methods
20
@BindingMethods({
@BindingMethod(type = View.class, attribute = "android:onDrag", method = "setOnDragListener"),
@BindingMethod(type = View.class, attribute = "android:onClick", method = "setOnClickListener"),
@BindingMethod(type = View.class, attribute = "android:onTouch", method = "setOnTouchListener"),
})
public class ViewBindingAdapter {
...
}
@BindingMethods({
@BindingMethod(type = TextView.class, attribute = "android:autoLink", method = "setAutoLinkMask"),
@BindingMethod(type = TextView.class, attribute = "android:inputType", method = "setRawInputType")
})
public class TextViewBindingAdapter {
...
}

21. Binding Converters
public class Converters {
@BindingConversion
public static String convertObservableToString(ObservableString observableString) {
return observableString.get();
}
}
21

22. Two Way Binding
22
android:text="@={communicator.editTextValue}"
AdapterView android:selectedItemPosition
CalendarView android:date
CompoundButton android:checked
DatePicker android:year / android:month / android:day
NumberPicker android:value
RadioGroup android:checkedButton
RatingBar android:rating
SeekBar android:progress
TabHost android:currentTab
TextView android:text
TimePicker android:hour / android:minute
app:color="@={communicator.color}"

23. Two Way Binding
23
@InverseBindingMethods({
@InverseBindingMethod(type = MaterialDesignPrimaryPaletteView.class, attribute = "color")
})
public class MaterialDesignPrimaryPaletteView extends GridLayout implements View.OnClickListener {
private OnColorChangeListener listener;
private int color;
...
public int getColor() {
return color;
}
public void setColor(int color) {
this.color = color;
}
public void setOnColorChangeListener(OnColorChangeListener listener) {
this.listener = listener;
}
public interface OnColorChangeListener {
void onColorChange(MaterialDesignPrimaryPaletteView view, int color);
}
}

24. Two Way Binding
24
public class TwoWayDataBindingComponent {
@BindingAdapter(value = {"onColorChange", "colorAttrChanged"}, requireAll = false)
public void setColorListener(MaterialDesignPrimaryPaletteView view,
final OnColorChangeListener listener, final InverseBindingListener colorChange) {
if (colorChange == null) {
view.setOnColorChangeListener(listener);
} else {
view.setOnColorChangeListener(new OnColorChangeListener() {
@Override
public void onColorChange(MaterialDesignPrimaryPaletteView view, int color) {
if (listener != null) {
listener.onColorChange(view, color);
}
colorChange.onChange();
}
});
}
}
@BindingAdapter("color")
public void setColor(MaterialDesignPrimaryPaletteView view, int color) {
if (color != view.getColor()) {
view.setColor(color);
}
}
}

25. Lambda Expressions
25
android:onClick="@{() -> communicator.showToast()}"
android:onClick="@{() -> communicator.switchState()}"
android:onClick="@{(v) -> communicator.replaceFragment(v.id)}"

26. Binding Executor
26
private static final boolean USE_CHOREOGRAPHER = SDK_INT >= 16;
...
protected ViewDataBinding(DataBindingComponent bindingComponent,
View root, int localFieldCount) {
...
if (USE_CHOREOGRAPHER) {
mChoreographer = Choreographer.getInstance();
mFrameCallback = new Choreographer.FrameCallback() {
@Override
public void doFrame(long frameTimeNanos) {
mRebindRunnable.run();
}
};
} else {
mFrameCallback = null;
mUIThreadHandler = new Handler(Looper.myLooper());
}
}

27. Binding Execution
27
protected void requestRebind() {
...
if (USE_CHOREOGRAPHER) {
mChoreographer.postFrameCallback(mFrameCallback);
} else {
mUIThreadHandler.post(mRebindRunnable);
}
}
private final Runnable mRebindRunnable = new Runnable() {
@Override
public void run() {
...
executePendingBindings();
}
};
public void executePendingBindings() {
...
if (!mRebindHalted) {
executeBindings();
...
}
...
}

28. Generated Binding
28
public class FragmentBindingModelBinding
extends android.databinding.ViewDataBinding {
...
@Override
protected void executeBindings() {
long dirtyFlags = 0;
synchronized(this) {
dirtyFlags = mDirtyFlags;
mDirtyFlags = 0;
}
java.lang.String firstNameUser = null;
java.lang.String lastNameUser = null;
com.anokmik.databinding.model.User user = mUser;
if ((dirtyFlags & 0x3L) != 0) {
user = user;
if (user != null) {
firstNameUser = user.firstName;
lastNameUser = user.lastName;
}
}
if ((dirtyFlags & 0x3L) != 0) {
this.mboundView1.setText(firstNameUser);
this.mboundView2.setText(lastNameUser);
}
}
...
}

29. References
● http://developer.android.com/tools/data-binding/guide.html
● https://realm.io/news/data-binding-android-boyar-mount/
● https://speakerdeck.com/rciovati/binding-data-with-android-databinding
● https://medium.com/@fabioCollini/android-data-binding-f9f9d3afc761
● https://halfthought.wordpress.com/2016/03/23/2-way-data-binding-on-android/
● https://www.youtube.com/watch?v=ssayKH0tudk
● https://www.youtube.com/watch?v=WdUbXWztKNY
● https://www.youtube.com/watch?v=DAmMN7m3wLU
29

30. Thanks for your attention!
source: https://github.com/anokmik/data-binding
mail: anokmik@gmail.com
skype: anokmik

31. AMA
(Ask Me Anything)