DataBinding解决了Android UI编程中的一个痛点，官方原生支持MVVM模型可以让我们在不改变既有代码框架的前提下，非常容易地使用这些新特性。Google 2015 IO大会中对于Android开发曾了Data Binding。DataBinding文章地址 Demo下载地址
创建一个空的Project，并修改Project的build.gradle，为build script添加一条依赖，Gradle版本最低为1.5.0。
classpath 'com.android.tools.build:gradle:1.5.0'为用到Data Binding的模块添加插件，修改对应的build.gradle。
dataBinding {
enabled = true
}创建用户的实体User :
public class User {
public final String name;
public final String age;
public User(String name, String age) {
this.age = age;
this.name = name;
}
}Activity的布局文件如下:
<?xml version="1.0" encoding="utf-8"?>
<layout
xmlns:android="http://schemas.android.com/apk/res/android">
<data>
<variable
name="user"
type="com.ihongqiqu.databinding.data.User" />
</data>
<LinearLayout
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center_horizontal"
android:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.ihongqiqu.databinding.DataBindingSampleActivity1">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="20dp"
android:text="@{user.name}"
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_marginTop="27dp"
android:text="@{user.age}"
android:textAppearance="?android:attr/textAppearanceMedium" />
</LinearLayout>
</layout>Actvity的onCreate()方法实现数据绑定。
第一种方式：
User user = new User("jingle1267", "20");
// 第一种初始化方式
ActivityDataBindingSample1Binding binding = DataBindingUtil.setContentView(this,
R.layout.activity_data_binding_sample1);
binding.setUser(user);ActivityDataBindingSample1Binding, 而不是我们的Activity： DataBindingSample1BindingActivity
第二种方式：
User user = new User("jingle1267", "20");
// 第二种初始化方式
ViewDataBinding binding1 = DataBindingUtil.setContentView(this,
R.layout.activity_data_binding_sample1);
binding1.setVariable(BR.user, user);实现上述步骤之后，编译运行，就可以看到用户名和年龄显示到对应的控件。
编写事件处理类，代码如下：
public class MyHandlers {
public final void onClickName(View view) {
Toast.makeText(view.getContext(), "onClickName()", Toast.LENGTH_SHORT).show();
}
public final void onClickAge(View view) {
Toast.makeText(view.getContext(), "onClickAge()", Toast.LENGTH_SHORT).show();
}
}<?xml version="1.0" encoding="utf-8"?>
<layout
xmlns:android="http://schemas.android.com/apk/res/android">
<data>
<variable name="myHandlers" type="com.ihongqiqu.databinding.event.MyHandlers"/>
<variable name="user" type="com.ihongqiqu.databinding.data.User" />
</data>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center_horizontal"
android:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin" >
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="20dp"
android:text="@{user.name}"
android:onClick="@{myHandlers.onClickName}"
android:clickable="true"
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/textView2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="27dp"
android:text="@{user.age}"
android:onClick="@{myHandlers.onClickAge}"
android:clickable="true"
android:textAppearance="?android:attr/textAppearanceMedium" />
</LinearLayout>
</layout>Activityd的onCreate()方法添加绑定代码：
这一步很重要，不实现这一步会导致事件无法出发。
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setTitle("事件绑定");
User user = new User("jingle1267", "20");
MyHandlers myHandlers = new MyHandlers();
ActivityDataBindingSample2Binding binding = DataBindingUtil.setContentView(this,
R.layout.activity_data_binding_sample2);
binding.setUser(user);
binding.setMyHandlers(myHandlers);
}👌OK，通过上述三个步骤就实现了事件的绑定！
实现数据实时更新，需要在在之前的基础上，额外实现一部分操作。
POJO需要做一下修改，修改后如下，重点是@Bindable和notifyPropertyChanged(BR.XXX);，其中BR.XXX为对应需要更新的ID。具体代码如下：
/**
* 猪，有标签和重量两个属性
* <p/>
* Created by zhenguo on 3/13/16.
*/
public class Pig extends BaseObservable {
private String label;
private String weight;
@Bindable
public String getLabel() {
return label;
}
public void setLabel(String label) {
this.label = label;
notifyPropertyChanged(BR.label);
}
@Bindable
public String getWeight() {
return weight;
}
public void setWeight(String weight) {
this.weight = weight;
notifyPropertyChanged(BR.weight);
}
}事件处理类需要调整如下(仅供参考)，代码中直接修改了实体的属性就实现了对UI的更新：
/**
* 事件处理
* <p/>
* Created by zhenguo on 3/13/16.
*/
public class PigHandler {
DataBindingSampleActivity3 sampleActivity3;
public PigHandler(DataBindingSampleActivity3 sampleActivity3) {
this.sampleActivity3 = sampleActivity3;
}
public void onClick(View view) {
if (sampleActivity3 != null && sampleActivity3.pig != null) {
sampleActivity3.pig.setLabel("长白山");
sampleActivity3.pig.setWeight("280Kg");
}
}
}The MIT License (MIT)
Copyright (c) 2016 Jin
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