android studio DataBinding

在app的gradle的android添加

dataBinding{
        enabled=true
    }

xml使用

然后再要使用的布局里，选中最外面的布局，Alt+enter —》选择类似DataBinding的字样
然后会在最外面生成：layout、data

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">

    <data>

        <variable
            name="accountBean"
            type="com.zfg.mvcmvpmvvm.bean.AccountBean" />
        <variable
            name="activity"
            type="com.zfg.mvcmvpmvvm.mvvm.databinding.DemoActivity" />

    </data>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center"
        android:orientation="vertical"
        tools:context=".mvvm.databinding.DemoActivity">

        <TextView
            android:id="@+id/tv_info"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="50dp"
            android:gravity="center"
            android:text="@{accountBean.name+'|'+accountBean.level}"
            tools:text="账号|等级" />

        <Button
            android:id="@+id/bt_addLevel"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="50dp"
            android:gravity="center"
            tools:text="账号等级+1"
            android:onClick="@{activity.onClick}"/>

    </LinearLayout>
</layout>

在Data添加名字与类型

<data>

        <variable
            name="accountBean"
            type="com.zfg.mvcmvpmvvm.bean.AccountBean" />
        <variable
            name="activity"
            type="com.zfg.mvcmvpmvvm.mvvm.databinding.DemoActivity" />

    </data>

在控件中添加

android:text="@{accountBean.name+'|'+accountBean.level}"
            tools:text="账号|等级" />     //注意：这里前缀是tools，自己敲出来
            android:onClick="@{activity.onClick}"/>

bean

package com.zfg.mvcmvpmvvm.bean;

import androidx.databinding.BaseObservable;
import androidx.databinding.Bindable;

import com.zfg.mvcmvpmvvm.BR;

public class AccountBean extends BaseObservable {
    private String name;//账号名称
    private int level;//账号等级

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
    //希望getLevel自动发生改变，我们就在这上面添加一个注解
    @Bindable
    public int getLevel() {
        return level;
    }

    public void setLevel(int level) {
        this.level = level;
        notifyPropertyChanged(BR.level);
    }
}

继承和执行上面的bean会自动生成，其中level是自己敲的时候加上去的

package com.zfg.mvcmvpmvvm;

public class BR {
  public static final int _all = 0;

  public static final int activity = 1;

  public static final int level = 2;

  public static final int accountBean = 3;//AccountBean的这里：notifyPropertyChanged(BR.level);
}

activity

package com.zfg.mvcmvpmvvm.mvvm.databinding;

import androidx.appcompat.app.AppCompatActivity;
import androidx.databinding.DataBindingUtil;

import android.os.Bundle;
import android.view.View;
import android.widget.Toast;

import com.zfg.mvcmvpmvvm.R;
import com.zfg.mvcmvpmvvm.bean.AccountBean;
import com.zfg.mvcmvpmvvm.databinding.ActivityDemoBinding;

public class DemoActivity extends AppCompatActivity {

    private ActivityDemoBinding binding;
    private AccountBean accountBean;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        binding = DataBindingUtil.setContentView(this,R.layout.activity_demo);
        accountBean=new AccountBean();
        accountBean.setName("TEST");
        accountBean.setLevel(100);
        binding.setAccountBean(accountBean);
        binding.setActivity(this);

    }
    public void onClick(View view){
//        Toast.makeText(this,"点击了",Toast.LENGTH_SHORT).show();
        int level=accountBean.getLevel();
        accountBean.setLevel(level+1);
//        binding.setAccountBean(accountBean);//每次都用到，我们可以优化
    }
}