DataBinding使用介绍

1. DataBinding使用

build.gradle中添加dataBinding {    enabled true}

2. 创建JavaBean对象

public class User extends BaseObservable{    private String name;    private String phone;    public int isHandSome;    public User(String name,String phone){        this.name = name;        this.phone = phone;    }    @Bindable    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;        notifyPropertyChanged(BR.name);    }    @Bindable    public String getPhone() {        return phone;    }    public void setPhone(String phone) {        this.phone = phone;        notifyPropertyChanged(BR.phone);    }}

3.创建布局文件

<?xml version="1.0" encoding="utf-8"?><layout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:bind="http://schemas.android.com/apk/res-auto">    <data>        <import type="android.view.View"/>        <import type="java.util.ArrayList"/>        <import type="java.util.Map"/>        <variable            name="user"            type="com.zlc.mvvm.User"/>        <variable            name="age"            type="String"/>        <variable            name="list"            type="ArrayList&lt;String>"/>        <variable            name="map"            type="Map&lt;String,String>"/>        <variable            name="handler"            type="com.zlc.mvvm.EventHandler"/>    </data>    <LinearLayout        android:orientation="vertical"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:padding="10dp">        <TextView            android:id="@+id/id_tv1"            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:text="@{user.name}"            android:paddingBottom="10dp"/>        <TextView            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:text="@{age}"            android:layout_marginTop="10dp"/>        <TextView            android:id="@+id/id_tv3"            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:text="@{user.isHandSome == 0 ? @string/hand1 : @string/hand2}"            android:layout_marginTop="10dp"            android:layout_marginBottom="10dp"/>        <include layout="@layout/phone_layout"            bind:user="@{user}"            />        <TextView            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:text="@{list[1]}"            android:layout_marginTop="10dp"            android:layout_marginBottom="10dp"/>        <TextView            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:text='@{map["name"]}'            android:layout_marginBottom="10dp"            android:onClick="@{handler.handOnClick}"            />        <Button            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="点我点我"            android:onClick="@{handler.handOnClick}"/>    </LinearLayout></layout>

4.简单赋值使用

新建变量值 user 导入User类型<variable    name="user"    type="com.zlc.mvvm.User"/><TextView    android:id="@+id/id_tv1"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:text="@{user.name}"    android:paddingBottom="10dp"/>代码中使用ActivityMainBinding dataBinding = DataBindingUtil.setContentView(this, R.layout.activity_main);User user = new User("zlc","18684732678");user.isHandSome = 0;dataBinding.setUser(user);

5.变量赋值

 <variable     name="age"     type="String"/><TextView     android:layout_width="match_parent"     android:layout_height="wrap_content"     android:text="@{String.valueOf(age)}"     android:layout_marginTop="10dp"/>dataBinding.setAge(25);

6. inclue加载布局

两个布局里面都需要有<variable    name="user"    type="com.zlc.mvvm.User"/>新布局<?xml version="1.0" encoding="utf-8"?><layout>    <data>        <variable            name="user"            type="com.zlc.mvvm.User"/>    </data>    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"        android:orientation="vertical"        android:layout_width="match_parent"        android:layout_height="wrap_content">        <TextView            android:id="@+id/id_tv2"            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:text="@{user.phone}"/>    </LinearLayout></layout><include layout="@layout/phone_layout"         bind:user="@{user}"/>

7. 引用资源文件的值

<resources>    <string name="app_name">MVVMProject</string>    <string name="hand1">帅</string>    <string name="hand2">帅而且有钱</string></resources><TextView     android:id="@+id/id_tv3"     android:layout_width="match_parent"     android:layout_height="wrap_content"     android:text="@{user.isHandSome == 0 ? @string/hand1 : @string/hand2}"     android:layout_marginTop="10dp"     android:layout_marginBottom="10dp"/>

8. import导入

<import type="android.view.View"/><TextView     android:id="@+id/id_tv3"     android:layout_width="match_parent"     android:layout_height="wrap_content"     android:text="@string/hand2}"android:visibility="@{user.isHandSome == 0 ? View.VISIBLE : View.GONE}""     android:layout_marginTop="10dp"     android:layout_marginBottom="10dp"/>

9. List集合使用

<import type="java.util.ArrayList"/>不能出现< 用&lt;替代<variable    name="list"    type="ArrayList&lt;String>"/><TextView    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:text="@{list[1]}"    android:layout_marginTop="10dp"    android:layout_marginBottom="10dp"/>    ArrayList list = new ArrayList();    list.add("哈哈哈");    list.add("嘻嘻嘻");    list.add("呵呵呵");    dataBinding.setList(list);

10. Map集合使用

<import type="java.util.Map"/><variable    name="map"    type="Map&lt;String,String>"/>//根据key取value<TextView    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:text='@{map["name"]}'    android:layout_marginBottom="10dp"    android:onClick="@{handler.handOnClick}"    />Map map = new HashMap();map.put("name","hhhzlc");dataBinding.setMap(map);

11. 事件绑定

public void onClick(View view){    user.setName("郑乐成");    user.setPhone("18888888888");     Toast.makeText(this,"zqwxhni",Toast.LENGTH_LONG).show();}<variable    name="click"    type="com.zlc.mvvm.MainActivity"/><Button    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="点我点我"    android:onClick="@{click.onClick}"/> dataBinding.setClick(this);

12. 通过Observable的方式去通知UI数据已经改变

官方为我们提供了更加简便的方式BaseObservable，我们的实体类只需要继承该类，稍做几个操作，就能轻松实现数据变化的通知。如何使用呢？ 首先我们的实体类要继承BaseObservale类，第二步在Getter上使用注解@Bindable，第三步，在Setter里调用方法notifyPropertyChanged，第四步，完成    package com.zlc.mvvm;    import android.databinding.BaseObservable;    import android.databinding.Bindable;    /**     * Created by Administrator on 2017/10/21.     */    public class User extends BaseObservable{        private String name;        private String phone;        public int isHandSome;        public User(String name,String phone){            this.name = name;            this.phone = phone;        }        @Bindable        public String getName() {            return name;        }        public void setName(String name) {            this.name = name;            notifyPropertyChanged(BR.name);        }        @Bindable        public String getPhone() {            return phone;        }        public void setPhone(String phone) {            this.phone = phone;            notifyPropertyChanged(BR.phone);        }    }     public void onClick(View view){        user.setName("郑乐成");        user.setPhone("18888888888");      Toast.makeText(this,"zqwxhni",Toast.LENGTH_LONG).show();    }    dataBinding.setClick(this);

13. Inflate

ViewDataBinding binding = DataBindingUtil.inflate(inflate,layoutId,viewGroup,attachToParent)；     View view = inflate.getRoot();  //获取view对象

14. DataBinding VS RecyclerView VS ListView

item布局<layout xmlns:android="http://schemas.android.com/apk/res/android">    <data>        <variable            name="user"            type="com.zlc.mvvm.User" />    </data>    <LinearLayout        android:layout_width="match_parent"        android:layout_height="40dp"        android:gravity="center_vertical">        <TextView            android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1"            android:text="@{user.name}"            android:layout_alignParentLeft="true"            android:gravity="center"            />        <TextView            android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1"            android:text="@{user.phone}"            android:layout_alignParentRight="true"            android:gravity="center"/>    </LinearLayout></layout>适配器public class MyAdapter extends  RecyclerView.Adapter<MyAdapter.MyHolder>{        private ArrayList<User> mData;        private Context mContext;        public MyAdapter(Context context, ArrayList<User> data) {            this.mContext = context;            this.mData = data;        }        @Override        public MyHolder onCreateViewHolder(ViewGroup parent, int viewType) {            ViewDataBinding binding = DataBindingUtil.inflate(LayoutInflater.from(mContext), R.layout.list_item, parent, false);            MyHolder holder = new MyHolder(binding.getRoot());                holder.setBinding(binding);                return holder;        }        @Override        public void onBindViewHolder(MyHolder holder, int position) {                    holder.getBinding().setVariable(BR.user,mData.get(position));                holder.getBinding().executePendingBindings();        }        @Override        public int getItemCount() {            return mData.size();        }        public class MyHolder extends RecyclerView.ViewHolder{              private ViewDataBinding binding;              public MyHolder(View itemView) {                super(itemView);        }        public void setBinding(ViewDataBinding binding) {             this.binding = binding;        }       public ViewDataBinding getBinding() {             return binding;       }    }}

15.自定义setter(BindingAdapter)

<layout xmlns:android="http://schemas.android.com/apk/res/android"      xmlns:app="http://schemas.android.com/apk/res-auto">          <data class=".Custom">              <variable                  name="imageUrl"                  type="String" />          </data>          <ImageView              android:layout_width="match_parent"              android:layout_height="wrap_content"              app:imageUrl="@{imageUrl}"/>  </layout> binding.setImageUrl("http://images.csdn.net/20150810/Blog-Image%E5%89%AF%E6%9C%AC.jpg");  @BindingAdapter({"bind:imageUrl"})  public static void imageLoader(ImageView imageView, String url) {          ImageLoaderUtils.getInstance().displayImage(url, imageView);  }

16. Converters

Converter是什么呢？举个例子吧：假如你的控件需要一个格式化好的时间，但是你只有一个Date类型额变量咋办？肯定有人会说这个简单，转化完成后在设置，恩，这也是一种办法，但是DataBinding还给我们提供了另外一种方式，虽然原理一样，但是这种方式使用的场景更多，那就是——Converter    <layout xmlns:android="http://schemas.android.com/apk/res/android">          <data class=".Custom">              <variable                  name="time"                  type="java.util.Date" />          </data>          <TextView              android:layout_width="match_parent"              android:layout_height="wrap_content"              android:text="@{time}"/>      </layout>    binding.setTime(new Date());      @BindingConversion       public static String convertDate(Date date) {           SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");           return sdf.format(date);    }