一、DataBinding介绍
2015年谷歌I/O大会上介绍了一个框架DataBinding,DataBinding是一个数据绑定框架,以前我们在Activity里写很多的findViewById,很多人不想写这个于是用了一些注解框架,可是注解框架无论性能多好,效率总是要低于findViewById的,现在如果我们使用DataBinding,就可以抛弃findViewById。DataBinding主要解决了两个问题:
反射,注解(butterKnife)、DataBinding
就让我们具体来看看怎么使用它吧。
二、DataBinding的基本使用
(1)DataBinding的导入
在应用的build.gradle文件中添加如下代码:
android {
...
//导入dataBinding支持
dataBinding{
enabled true
}
...
}
注:如果出现找不到databinding的library的话是因为跟gradle的版本不兼容,改成2.0.0
classpath 'com.android.tools.build:gradle:2.0.0'
(2)DataBinding基本使用包括以下内容:
● 单纯的摆脱findviewbyid
● 绑定基本数据类型及String
● 绑定Model数据
● 绑定事件
● 通过静态方法转换数据类型
● 通过运算符操作数据
● 自定义Binding的类名
● 绑定相同Model的操作
● model变量改变自动更新数据
● 绑定List/Map等集合数据
● Observable自动更新
● Databinding与include标签的结合
● DataBinding与RecyclerView的结合
● DataBinding和Fragment的使用
● DataBinding在Activity或Fragment中加载其他布局
● DataBinding实现自定义DataBindingAdapter
(3)功能使用
3.1单纯的摆脱findviewbyid
布局文件
<layout>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="www.zhang.com.databinding.MainActivity">
<Button
android:id="@+id/main_tv1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="单纯的摆脱findviewbyid" />
LinearLayout>
layout>
布局通过DataBindingUtils.setContentView()加载到代码中,而且会生成对应一个Binding对象,对象名是布局文件文称加上Binding后缀
MainActivity中代码
public class MainActivity extends AppCompatActivity {
private ActivityMainBinding binding;//这个类是自动生成的
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//通过DataBInding加载布局都会对应的生成Binding对象,如ActivityMainBinding,对象名在布局文件名称后加上了一个后缀Binding
binding = DataBindingUtil.setContentView(MainActivity.this, R.layout.activity_main);
//通过binfding.id名称---就相当于获取了改控件对象了
binding.mainTv1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
binding.mainTv1.setText("没有findviewbyid了");
}
});
}
}
通过Binding对象.id名称,就相当于拿到了指定的布局中的id的控件了,使用起来和findviewbyid获取的控件是一样的
3.2绑定基本数据和String
布局文件
<layout>
<data>
<variable
name="content"
type="String" />
<variable
name="enabled"
type="boolean" />
data>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<Button
android:id="@+id/main_tv2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:clickable="@{enabled}"
android:text="@{content}" />
LinearLayout>
layout>
在布局中是通过@{}来绑定数据的,{}中是布局中该控件属性对应的数据类型数据,同时还可以支持运算符运算和静态方法调用和转换,这个后面会介绍
MainActivity文件中
public class MainActivity extends AppCompatActivity {
private ActivityMainBinding binding;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//通过DataBInding加载布局都会对应的生成一个对象,如ActivityMainBinding,对象名在布局文件名称后加上了一个后缀Binding
binding = DataBindingUtil.setContentView(MainActivity.this, R.layout.activity_main);
//2.绑定基本数据类型及String
binding.setContent("对String类型数据的绑定");//setContent就是给布局文件text属性绑定的content设置值
binding.setEnabled(false);//设置enabled值为false
//给控件设置点击事件,发现其实点击无效,因为在布局文件中给cilckable属性绑定了enabled,在代码中设置enabled值为false,所以点击事件无效
binding.mainTv2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(MainActivity.this, "我被点击了", Toast.LENGTH_SHORT).show();
}
});
}
}
3.3绑定model数据
Model数据类型
public class User {
private String text;
public User(String text) {
this.text = text;
}
public String getText() {
return text;
}
public void setText(String text) {
this.text = text;
}
}
后面会对model数据做更详细的讲解,这里先让大家知道一下用法
布局文件
<layout>
<data>
<variable
name="user"
type="www.zhang.com.databinding.User" />
data>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<Button
android:id="@+id/main_btn3"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@{user.text}" />
LinearLayout>
layout>
MainActivity中代码:
public class MainActivity extends AppCompatActivity {
private ActivityMainBinding binding;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//通过DataBInding加载布局都会对应的生成一个对象,如ActivityMainBinding,对象名在布局文件名称后加上了一个后缀Binding
binding = DataBindingUtil.setContentView(MainActivity.this, R.layout.activity_main);
//3.绑定model对象数据
User user = new User("绑定Model数据类型");
binding.setUser(user);//或者 binding.setVariable(BR.user,user);
}
}
●
binding设置数据有2中方式:
1.binding.setUser(user)
2.binding.setVariable(BR.user,user)–采用BR指定
3.4事件的绑定
布局文件
<layout>
<data>
<variable
name="event"
type="www.zhang.com.databinding.model.EventListener" />
<variable
name="title1"
type="String" />
<variable
name="title2"
type="String" />
<variable
name="title3"
type="String" />
<variable
name="title4"
type="String" />
data>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:onClick="@{event.click1}"
android:text="@{title1}" />
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:onClick="@{event::click2}"
android:text="@{title2}" />
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:onClick="@{()->event.cilck3(title4)}"
android:text="@{title3}" />
LinearLayout>
layout>
事件有多种写法
1.android:onClick="@{event.click1}"
2.android:onClick="@{event::click2}"
3.android:onClick="@{()->event.cilck3(title4)}"
[注]:()->event.cilck3(title4)是lambda表达式写法,
也可以写成:(view)->event.cilck3(title4),前面(view)表示onClick方法的传递的参数,
如果event.click3()方法中不需要用到view参数,可以将view省略。
当然event.click1也可以写成(view)->event.click1(view),将onClick(View view)的view参数传递给event.click1(view)方法。
大概就这意思,以下是伪代码
onclick(View view){
event.click1(view)
}
EventListener接口
public interface EventListener{
public void click1(View v);
public void click2(View v);
public void cilck3(String s);
}
MainActivity
public class MainActivity extends AppCompatActivity{
private ActivityMainBinding binding;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//通过DataBInding加载布局都会对应的生成一个对象,如ActivityMainBinding,对象名在布局文件名称后加上了一个后缀Binding
binding = DataBindingUtil.setContentView(MainActivity.this, R.layout.activity_main);
binding.setTitle1("事件绑定1");
binding.setTitle2("事件绑定2");
binding.setTitle3("事件绑定3");
binding.setTitle4("change ok");
binding.setEvent(new EventListener() {
@Override
public void click1(View v) {
binding.setTitle1("事件1方法调用");
}
@Override
public void click2(View v) {
binding.setTitle2("事件2方法调用");
}
@Override
public void cilck3(String s) {
binding.setTitle3(s);
}
});
}
}
3.5通过静态方法转化数据类型
布局文件
<layout>
<data>
<variable
name="user"
type="www.zhang.com.databinding.User" />
<import type="www.zhang.com.databinding.Utils" />
data>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="www.zhang.com.databinding.MainActivity">
<Button
android:id="@+id/main_btn5"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@{Utils.getName(user)}" />
LinearLayout>
layout>
静态方法的类(当然也可以使用Java自带API)
public class Utils {
public static String getName(Object o) {
return o.getClass().getName();
}
}
3.6通过运算符操作数据
布局文件
<layout>
<data>
<variable
name="user2"
type="www.zhang.com.databinding.model.User" />
data>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="www.zhang.com.databinding.MainActivity">
<Button
android:id="@+id/main_btn5"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingLeft="@{user2.state ? @dimen/largepadding : (int)@dimen/smallpadding}"
android:text="@{user2.content ?? @string/app_name}" />
<Button
android:id="@+id/main_btn6"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@{`Hello World`+ @string/app_name}" />
LinearLayout>
layout>
public class User {
private String content;
private boolean state;
public User(String content, boolean state) {
this.content = content;
this.state = state;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
public boolean isState() {
return state;
}
public void setState(boolean state) {
this.state = state;
}
}
MainActivity中
package www.zhang.com.databinding;
import android.databinding.DataBindingUtil;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;
import www.zhang.com.databinding.databinding.ActivityMainBinding;
public class MainActivity extends AppCompatActivity {
private ActivityMainBinding binding;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//通过DataBInding加载布局都会对应的生成一个对象,如ActivityMainBinding,对象名在布局文件名称后加上了一个后缀Binding
binding = DataBindingUtil.setContentView(MainActivity.this, R.layout.activity_main);
//运算符操作
www.zhang.com.databinding.model.User user2 = new www.zhang.com.databinding.model.User("通过运算符操作数据", true);
// user2 = new www.zhang.com.databinding.model.User(null, false); 改变数据作为测试DataBinding是否有效
binding.setUser2(user2);
}
}
DataBinding支持的表达式有:
数学表达式: + - / * %
字符串拼接 +
逻辑表达式 && ||
位操作符 & | ^
一元操作符 + - ! ~
位移操作符 >> >>> <<
比较操作符 == > < >= <=
instanceof
分组操作符 ()
字面量 - character, String, numeric, null
强转、方法调用
字段访问
数组访问 []
三元操作符 ?:
聚合判断(Null Coalescing Operator)语法 ‘??’
3.7自定义Binding的类名
data标签有个class属性,它可以用来对Binding对象重新命名(一般是以布局文件名加上Binding后缀作为该Binding类名)
文件目录如下
自定义类名有3中方式
1. 通过指定全类名的方式
"www.zhang.com.databinding.activity.Item">
...
import www.zhang.com.databinding.activity.Item;
Item binding = DataBindingUtil.setContentView(FiveActivity.this, R.layout.activity_five);
".Item">
...
import www.zhang.com.databinding.Item;
Item binding = DataBindingUtil.setContentView(FiveActivity.this, R.layout.activity_five);
"Item">
...
import www.zhang.com.databinding.databinding.Item;
Item binding =DataBindingUtil.setContentView(FiveActivity.this, R.layout.activity_five);
3.8绑定相同model的操作
绑定相同model我的理解有2种,一种是同类的2个对象,另一种是不同类的2个类,但类名相同,具体看代码:
● 第一种,同一个类的2个对象,只需对象名不同就可以
布局文件
<layout>
<data>
<import type="www.zhang.com.databinding.User" />
<variable
name="user3"
type="User" />
<variable
name="user4"
type="User" />
data>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="www.zhang.com.databinding.MainActivity">
<Button
android:id="@+id/main_btn7"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@{user3.text}" />
<Button
android:id="@+id/main_btn8"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@{user4.text}" />
LinearLayout>
layout>
User类
public class User {
private String text;
public User(String text) {
this.text = text;
}
public String getText() {
return text;
}
public void setText(String text) {
this.text = text;
}
}
MainActivity中
public class MainActivity extends AppCompatActivity {
private ActivityMainBinding binding;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//通过DataBInding加载布局都会对应的生成一个对象,如ActivityMainBinding,对象名在布局文件名称后加上了一个后缀Binding
binding = DataBindingUtil.setContentView(MainActivity.this, R.layout.activity_main);
User user3 = new User("相同类,不同对象1");
binding.setUser3(user3);
User user4 = new User("相同类,不同对象2");
binding.setUser4(user4);
}
}
● 第二种不同的2个类,对象名相同
布局文件
<layout>
<data>
<import type="www.zhang.com.databinding.User" />
<variable
name="user4"
type="User" />
<import type="www.zhang.com.databinding.model.User" alias="Model"/>
<variable
name="user5"
type="Model" />
data>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="www.zhang.com.databinding.MainActivity">
<Button
android:id="@+id/main_btn8"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@{user4.text}" />
<Button
android:id="@+id/main_btn9"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@{user5.content}" />
LinearLayout>
layout>
因为2个地方都有type=”User”都为User类,会导致不知道导入哪个包,所以可以通过alias属性重命名type的类型,但实际上是alias被指定的那个类型(如:www.zhang.com.databinding.model.User)
2个不同的User类
package www.zhang.com.databinding;
public class User {
private String text;
public User(String text) {
this.text = text;
}
public String getText() {
return text;
}
public void setText(String text) {
this.text = text;
}
}
package www.zhang.com.databinding.model;
public class User {
private String content;
private boolean state;
public User(String content, boolean state) {
this.content = content;
this.state = state;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
public boolean isState() {
return state;
}
public void setState(boolean state) {
this.state = state;
}
}
MainActivity
public class MainActivity extends AppCompatActivity {
private ActivityMainBinding binding;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//通过DataBInding加载布局都会对应的生成一个对象,如ActivityMainBinding,对象名在布局文件名称后加上了一个后缀Binding
binding = DataBindingUtil.setContentView(MainActivity.this, R.layout.activity_main);
User user4 = new User("相同类,不同对象2");
binding.setUser4(user4);
www.zhang.com.databinding.model.User user5 = new www.zhang.com.databinding.model.User("类名相同,但不是相同的2个类",false);
binding.setUser5(user5);
}
}
3.9model变量改变自动更新数据
前面讲了DataBinding对基本数据类型及Model的使用以及运算符等操作,但这些基本是静态的去设置数据,现在我们来看看 如何在数据改变时,不手动设置,让其自动改变。
布局文件
<layout>
<data>
<import type="www.zhang.com.databinding.model.Person" />
<variable
name="person"
type="Person" />
data>
<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:layout_width="match_parent"
android:layout_height="56dp"
android:text="@{`firstName:`+person.firstName}" />
<TextView
android:layout_width="match_parent"
android:layout_height="56dp"
android:text="@{`lastName:`+person.lastName}" />
<TextView
android:layout_width="match_parent"
android:layout_height="56dp"
android:text="@{`age:`+person.age}" />
<Button
android:id="@+id/second_btn1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="改变数据" />
LinearLayout>
layout>
Person类
package www.zhang.com.databinding.model;
import android.databinding.BaseObservable;
import android.databinding.Bindable;
import www.zhang.com.databinding.BR;
public class Person extends BaseObservable {
private String firstName;
private String lastName;
private int age;
public Person(String firstName, String lastName, int age) {
this.firstName = firstName;
this.lastName = lastName;
this.age = age;
}
@Bindable
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
notifyPropertyChanged(BR.firstName);
}
@Bindable
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
notifyPropertyChanged(BR.lastName);
}
@Bindable
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
notifyPropertyChanged(BR.age);
}
}
Model类继承BaseObservable,BaseObservable实现Android.databinding.Observable接口,Observable接口可以允许附加一个监听器到model对象以便监听对象上的所有属性的变化。
Observable接口有一个机制来添加和删除监听器,但通知与否由开发人员管理。为了使开发更容易,BaseObservable实现了监听器注册机制。DataBinding实现类依然负责通知当属性改变时。这是通过指定一个Bindable注解给getter以及setter内通知来完成的。
notifyPropertyChanged(BR.参数名)通知更新这一个参数,需要与@Bindable注解配合使用。notifyChange()通知更新所有参数,可以不用和@Bindable注解配合使用
SecondActivity
public class SecondActivity extends AppCompatActivity {
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ActivitySecondBinding binding = DataBindingUtil.setContentView(SecondActivity.this, R.layout.activity_second);
final Person person = new Person("zhang","san",38);
binding.setPerson(person);
binding.secondBtn1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
person.setFirstName("li");
person.setLastName("si");
person.setAge(40);
}
});
}
}
3.10绑定List/Map等集合数据
布局文件
<layout>
<data>
<import type="java.util.ArrayList" />
<import type="java.lang.String" />
<variable
name="list"
type="ArrayList<String>" />
<import type="java.util.Map" />
<variable
name="map"
type="Map<String,String>" />
<variable
name="arrays"
type="String[]" />
data>
<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:layout_width="match_parent"
android:layout_height="56dp"
android:text="@{list[0]}" />
<TextView
android:layout_width="match_parent"
android:layout_height="56dp"
android:text="@{list.get(1)}" />
<TextView
android:layout_width="match_parent"
android:layout_height="56dp"
android:text="@{map[`name`]}" />
<TextView
android:layout_width="match_parent"
android:layout_height="56dp"
android:text="@{map.get(`age`)}" />
<TextView
android:layout_width="match_parent"
android:layout_height="56dp"
android:text="@{arrays[0]}" />
<TextView
android:layout_width="match_parent"
android:layout_height="56dp"
android:text="@{arrays[1]}" />
LinearLayout>
layout>
泛型的支持会在编译时期报红线,是可以直接运行的,但是需要通过转义字符才行,如:\<数据类型> 或者\<数据类型>
ThirdActivity
public class ThirdActivity extends AppCompatActivity {
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ActivityThirdBinding binding = DataBindingUtil.setContentView(ThirdActivity.this, R.layout.activity_third);
ArrayList list = new ArrayList<>();
list.add("first");
list.add("second");
binding.setList(list);
Map map = new HashMap<>();
map.put("name", "zhangsan");
map.put("age", "40");
binding.setMap(map);
String[] arrays = {"lisi", "laowang"};
binding.setArrays(arrays);
}
}
3.11 Observable数据改变自动更新
Observable是一个接口,它的子类有BaseObservable,ObservableField,ObservableBoolean, ObservableByte, ObservableChar, ObservableShort, ObservableInt, ObservableLong, ObservableFloat, ObservableDouble, and ObservableParcelable,ObservableArrayList,ObservableArrayMap
<layout>
<data>
<import type="www.zhang.com.databinding.model.Animal"/>
<variable
name="animal"
type="Animal"/>
<variable
name="list"
type="android.databinding.ObservableArrayList<String>"/>
<variable
name="map"
type="android.databinding.ObservableArrayMap<String,String>"/>
data>
<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:layout_width="match_parent"
android:layout_height="56dp"
android:text="@{animal.field}" />
<TextView
android:layout_width="match_parent"
android:layout_height="56dp"
android:text="@{String.valueOf(animal.age)}" />
<TextView
android:layout_width="match_parent"
android:layout_height="56dp"
android:text="@{list[0]}" />
<TextView
android:layout_width="match_parent"
android:layout_height="56dp"
android:text="@{list[1]}" />
<TextView
android:layout_width="match_parent"
android:layout_height="56dp"
android:text="@{map[`name`]}" />
<TextView
android:layout_width="match_parent"
android:layout_height="56dp"
android:text="@{map[`age`]}" />
<Button
android:id="@+id/four_btn"
android:layout_width="match_parent"
android:text="改变数据"
android:layout_height="wrap_content" />
LinearLayout>
layout>
Animal类
public class Animal {
public final ObservableField field = new ObservableField<>();
public final ObservableInt age = new ObservableInt();
}
FourActivity
package www.zhang.com.databinding;
public class FourActivity extends AppCompatActivity {
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ActivityFourBinding binding = DataBindingUtil.setContentView(FourActivity.this, R.layout.activity_four);
final Animal animal = new Animal();
animal.field.set("cat");
animal.age.set(2);
binding.setAnimal(animal);
final ObservableArrayList list = new ObservableArrayList<>();
list.add("dog");
list.add("mouse");
binding.setList(list);
final ObservableArrayMap map = new ObservableArrayMap<>();
map.put("name","Tom");
map.put("age","4");
binding.setMap(map);
binding.fourBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
animal.field.set("dog");
animal.age.set(4);
list.set(0,"cat");
list.set(1,"dog");
map.put("name","Sam");
map.put("age","5");
}
});
}
当Animal属性数据改变,list/map集合数据改变,会自动更新数据,我们不需要自己手动设置,省去了一个操作,让我们更专注于业务逻辑。
3.12 Databinding与include标签的结合
布局文件
activity_five.xml
<layout>
<data >
<import type="www.zhang.com.databinding.model.Content"/>
<variable
name="con"
type="Content"/>
data>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:bind="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<include
android:id="@+id/toolbar"
layout="@layout/toolbar"
android:layout_height="56dp"
android:layout_width="match_parent"
bind:content="@{con}" />
<TextView
android:text="@string/app_name"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
LinearLayout>
layout>
toolbar.xml
<layout >
<data>
<import type="www.zhang.com.databinding.model.Content"/>
<variable
name="content"
type="Content"/>
data>
<android.support.v7.widget.Toolbar
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/toolbar"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_height="56dp"
android:layout_width="match_parent"
app:title="@{content.title}"
app:subtitle="@{content.subTitle}"
android:background="@color/colorPrimary"
app:titleTextColor="@android:color/white"
app:subtitleTextColor="@android:color/white" />
layout>
在activity_five.xml中的include属性中定义了一个id,同时又在toolbar.xml中的Toolbar标签中又定义了一个id,其作用是通过binding.toolbar.toolbar等同于Toolbar控件,可以方便做一些操作等
FiveActivity中
public class FiveActivity extends AppCompatActivity {
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
supportRequestWindowFeature(Window.FEATURE_NO_TITLE);
ActivityFiveBinding binding =DataBindingUtil.setContentView(FiveActivity.this, R.layout.activity_five);
Content con = new Content("Title","SubTitle");
binding.setCon(con);
// binding.toolbar.setContent(con); //这个测试没有效果,不会显示toolbar的title/subTitle
// binding.toolbar.toolbar.setTitle("");
// binding.toolbar.toolbar.setSubtitle("");
//下面的代码也可以通过DataBinding绑定数据
binding.toolbar.toolbar.setNavigationIcon(R.mipmap.ic_launcher);
setSupportActionBar(binding.toolbar.toolbar);
binding.toolbar.toolbar.setNavigationOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
finish();
}
});
}
}
Content
public class Content extends BaseObservable {
private String title;
private String subTitle;
public Content(String title, String subTitle) {
this.title = title;
this.subTitle = subTitle;
}
@Bindable public String getSubTitle() {
return subTitle;
}
public void setSubTitle(String subTitle) {
this.subTitle = subTitle;
notifyPropertyChanged(BR.subTitle);
}
@Bindable public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
notifyPropertyChanged(BR.title);
}
}
3.13 DataBinding与RecyclerView的结合
布局文件
activity_five.xml
<layout>
<data >
<import type="www.zhang.com.databinding.model.Content"/>
<variable
name="con"
type="Content"/>
data>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:bind="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<include
android:id="@+id/toolbar"
layout="@layout/toolbar"
android:layout_height="56dp"
android:layout_width="match_parent"
bind:content="@{con}" />
<android.support.v7.widget.RecyclerView
android:id="@+id/recycler"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
LinearLayout>
layout>
recycler_item.xml
<layout>
<data>
<variable
name="str"
type="String"/>
data>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:orientation="vertical">
<TextView
android:text="@{str}"
android:gravity="center_vertical"
android:textColor="@android:color/black"
android:textSize="16sp"
android:layout_width="match_parent"
android:layout_height="48dp" />
LinearLayout>
layout>
FiveActivity
public class FiveActivity extends AppCompatActivity {
private ActivityFiveBinding binding;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
supportRequestWindowFeature(Window.FEATURE_NO_TITLE);
binding = DataBindingUtil.setContentView(FiveActivity.this, R.layout.activity_five);
initToolbar();
initRecyclerView();
}
private void initRecyclerView() {
LinearLayoutManager manager = new LinearLayoutManager(FiveActivity.this);
binding.recycler.setLayoutManager(manager);
binding.recycler.setHasFixedSize(true);
MyAdapter adapter = new MyAdapter(getApplicationContext());
binding.recycler.setAdapter(adapter);
}
private void initToolbar() {
Content con = new Content("Title","SubTitle");
binding.setCon(con);
// binding.toolbar.setContent(con); //这个测试没有效果,不会显示toolbar的title/subTitle
// binding.toolbar.toolbar.setTitle("");
// binding.toolbar.toolbar.setSubtitle("");
//下面的代码也可以通过DataBinding绑定数据
binding.toolbar.toolbar.setNavigationIcon(R.mipmap.ic_launcher);
setSupportActionBar(binding.toolbar.toolbar);
binding.toolbar.toolbar.setNavigationOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
finish();
}
});
}
}
MyAdapter
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> {
private Context mContext;
String[] datas;
public MyAdapter(Context context) {
mContext = context;
datas = context.getResources().getStringArray(R.array.item_list);
}
@Override
public MyAdapter.MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
RecyclerItemBinding binding = DataBindingUtil.inflate(LayoutInflater.from(mContext), R.layout.recycler_item, parent, false);
return new MyViewHolder(binding);
}
@Override
public void onBindViewHolder(MyAdapter.MyViewHolder holder, int position) {
String name = datas[position];
holder.getBinding().setVariable(www.zhang.com.databinding.BR.str,name);
//holder.getBinding().setStr(name); //两者都可以
//executePendingBindings()方法说明
// When a variable or observable changes, the binding will be scheduled to change before the next frame.
// There are times, however, when binding must be executed immediately.
// To force execution, use the executePendingBindings() method.
holder.getBinding().executePendingBindings();//此方法必须执行在UI线程,当绑定的数据修改时更新视图(不知道翻译的准不准)
}
@Override
public int getItemCount() {
return datas.length;
}
public class MyViewHolder extends RecyclerView.ViewHolder {
private RecyclerItemBinding binding;
public MyViewHolder(ViewDataBinding binding) {
super(binding.getRoot());
this.binding = (RecyclerItemBinding) binding;
}
public RecyclerItemBinding getBinding() {
return binding;
}
public void setBinding(RecyclerItemBinding binding) {
this.binding = binding;
}
}
}
3.14 DataBinding在Fragment中使用
DataBinding在Fragment中使用和Activity中使用大体相同不同的是获取对象要在
DataBindingUtil.inflate(inflater, R.layout.homepage_fragment, container, false);
3.15 DataBinding在Activity或Fragment中加载其他布局
此处以PopupWindow 为例,其他如Dialog等类同;
ItemMapInfoBinding infoBinding = ItemMapInfoBinding.inflate(getLayoutInflater());
View popupView = infoBinding.getRoot();
PopupWindow mPopupWindow = new PopupWindow(mContext);
mPopupWindow.setContentView(popupView);
3.16 重新BindingAdapter来实现动画等非点击事件
安卓上新的binding framework可以轻松实现视图根据model的改变而改变。你只需要让model能被观测,然后framework会做好其余的事情。比如,你可以通过下面的代码来实现一个加载提示的显示和隐藏:
@BindingAdapter("fadeVisible")
public static void setFadeVisible(final View view, boolean visible) {
view.animate().cancel();
if (visible) {
view.setVisibility(View.VISIBLE);
view.setAlpha(0);
view.animate().alpha(1).setListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
view.setAlpha(1);
}
});
} else {
view.animate().alpha(0).setListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
view.setAlpha(1);
view.setVisibility(View.GONE);
}
});
}
}
<ProgressBar
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
app:fadeVisible="@{model.loading}"/>
但是,这种方式有个问题,每次值发生改变的时候都会产生动画效果,即使是在第一次绑定的时候。比如,你会在旋转屏幕的时候也看到淡入淡出。我们需要一种能判断是否是第一次绑定的办法。
可以利用view的tag不被保持的特点,如果没有tag,则这是第一次绑定,我们设置tag而不运行动画:
@BindingAdapter("fadeVisible")
public static void setFadeVisible(final View view, boolean visible) {
if (view.getTag() == null) {
view.setTag(true);
view.setVisibility(visible ? View.VISIBLE : View.GONE);
} else {
view.animate().cancel();
if (visible) {
view.setVisibility(View.VISIBLE); view.setAlpha(0);
view.animate().alpha(1).setListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
view.setAlpha(1);
}
});
} else {
view.animate().alpha(0).setListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
view.setAlpha(1);
view.setVisibility(View.GONE);
}
});
}
}
}
嗯,就是这样,加载提示便会很好的根据model的变化正确的显示淡入淡出了。