Android dataBinding 的綁定數(shù)據(jù)、列表、點擊事件等使用

dataBinding是google推出來的一個mvvm的框架，出來有一段時間了，由于之前的項目都是用mvc或者mvp的模式開發(fā)，沒有使用mvvm模式進行開發(fā)，這次公司項目用的是jetpack框架，涉及到ViewModel、dataBinding等，所以就利用些空閑時間了解和學(xué)習(xí)下dataBinding的一些使用。

準(zhǔn)備工作：

要使用dataBinding的話，首先要在app model 下build.gradle文件的android節(jié)點下添加

dataBinding{
        enabled=true
    }

如：

image

數(shù)據(jù)綁定

在xml布局中使用dataBinding時，要將xml布局文件的節(jié)點進行修改，如：

<?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">
    <data>

    </data>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

    </LinearLayout>
</layout>

將layout節(jié)點放最外面，接著是data節(jié)點，在data節(jié)點中可以新增variable節(jié)點，在data節(jié)點下面可以寫之前的布局節(jié)點；

<?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">
    <data>
        <variable
            name="employee"
            type="com.lsm.databindingtest.Employee" />
    </data>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">
        <TextView
            android:id="@+id/first_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center_horizontal"
            android:layout_marginTop="10dp"
            android:text="@{employee.firstName}" />
        <TextView
            android:id="@+id/last_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center_horizontal"
            android:layout_marginTop="10dp"
            android:text="@{employee.lastName}" />
    </LinearLayout>
</layout>

variable節(jié)點中name是type的一個名稱，type是對應(yīng)model類的包名路徑，通過@{}的方式對TextView進行賦值；在activity文件中通過DataBindingUtil進行引用；

public class SimpleActivity extends AppCompatActivity {
    private ActivitySimpleBinding binding;
    private Employee employee = new Employee("Zhai", "Mark");
    private Worker worker = new Worker("1111", "2222");

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        binding = DataBindingUtil.setContentView(this, R.layout.activity_simple);
        //通過直接賦值
//        binding.firstName.setText(employee.getFirstName());
//        binding.lastName.setText(employee.getLastName());
//        binding.setEmployee(employee);
        binding.setVariable(BR.employee, employee);
    }
}

ActivitySimpleBinding命名：布局文件名稱(第一字母大寫，遇到，去掉并將首字母大寫)+Binding;
這里賦值有三種方式：

1、通過ActivitySimpleBinding.控件id，直接賦值;
如：binding.firstName.setText(employee.getFirstName());

2、ActivitySimpleBinding調(diào)用set方法;
如：binding.setEmployee(employee);

3、ActivitySimpleBinding調(diào)用setVariable方法;
binding.setVariable(BR.employee, employee);
image

事件綁定

事件可以通過方法或者監(jiān)聽器的形式來實現(xiàn)；
在對應(yīng)的activity中聲明一個事件的內(nèi)部類，在內(nèi)部類中定義對應(yīng)的事件方法，在xml布局中通過新增variable節(jié)點，對它的name和type屬性進行設(shè)置，也是用過@{}的方式綁定事件；

<?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">
    <data>
        <variable
            name="eventlistener"
            type="com.lsm.databindingtest.SimpleActivity.EventListener" />
    </data>
    <LinearLayout
        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:layout_marginTop="10dp"
            android:onClick="@{eventlistener.clickFirst}"
            android:text="點擊(方法)" />
        <Button
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="10dp"
            android:onClick="@{(view)->eventlistener.btnClick(view)}"
            android:text="點擊(監(jiān)聽器)" />
        <Button
            android:id="@+id/longc"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="10dp"
            android:onLongClick="@{eventlistener::onLongClick}"
            android:text="長按" />
    </LinearLayout>
</layout>


public class SimpleActivity extends AppCompatActivity {
    private ActivitySimpleBinding binding;
    private Employee employee = new Employee("Zhai", "Mark");
    private Worker worker = new Worker("1111", "2222");

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        binding = DataBindingUtil.setContentView(this, R.layout.activity_simple);
        binding.setEventlistener(new EventListener());
    }
    public class EventListener {
        public void clickFirst(View view) {
            worker.setFirstName("55555");
            worker.setLastName("7777777");
            Toast.makeText(SimpleActivity.this, "點擊了并刷新worker對象的值", Toast.LENGTH_LONG).show();
        }
        public void btnClick(View view){
            Toast.makeText(SimpleActivity.this, "監(jiān)聽器方式", Toast.LENGTH_LONG).show();
        }
        public boolean onLongClick(View view) {
            Toast.makeText(SimpleActivity.this, "長按了", Toast.LENGTH_LONG).show();
            return false;
        }
    }
}

activity中通過setEventlistener方法傳入EventListener對象，setEventlistener方法是自動生成的就可以了；在定義事件方法名稱時需要注意：方法的名稱可以和之前寫法不一樣，但是方法名稱的參數(shù)要和之前的寫法一樣，不然會報錯，比如：clickFirst(View view)必須要有view參數(shù)，如果沒有會報錯

image

BaseObservable

BaseObservable在數(shù)據(jù)發(fā)生改變時通知xml布局試圖進行刷新

public class Worker extends BaseObservable {
    private String mLastName;
    private String mFirstName;
    private boolean mIsFired=false;

    public Worker(String mLastName, String mFirstName) {
        this.mLastName = mLastName;
        this.mFirstName = mFirstName;
    }
    @Bindable
    public String getLastName() {
        return mLastName;
    }

    public void setLastName(String mLastName) {
        this.mLastName = mLastName;
        notifyPropertyChanged(BR.lastName);
    }
    @Bindable
    public String getFirstName() {
        return mFirstName;
    }

    public void setFirstName(String mFirstName) {
        this.mFirstName = mFirstName;
        notifyPropertyChanged(BR.firstName);
    }
    @Bindable
    public boolean getFired() {
        return mIsFired;
    }

    public void setFired(boolean mIsFired) {
        this.mIsFired = mIsFired;
        //刷新所有有關(guān)的ui
//        notifyChange();
    }
}

定義一個model類繼承自BaseObservable，在get方法上添加@Bindable注解，在set方法中notifyPropertyChanged(BR.lastName)方法更新指定的視圖，通過notifyChange();方法更新所有的視圖，即使數(shù)據(jù)沒有更新也會重新刷新視圖；

<?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">
    <data>
        <variable
            name="eventlistener"
            type="com.lsm.databindingtest.SimpleActivity.EventListener" />
        <variable
            name="worker"
            type="com.lsm.databindingtest.Worker"/>
    </data>
    <LinearLayout
        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:layout_marginTop="10dp"
            android:onClick="@{eventlistener.clickFirst}"
            android:text="點擊(方法)" />
        <include
            bind:worker="@{worker}"
            layout="@layout/name" />
    </LinearLayout>
</layout>

name.xml

<?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">
    <data>
        <variable
            name="worker"
            type="com.lsm.databindingtest.Worker"/>
    </data>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="10dp"
            android:layout_gravity="center_horizontal"
            android:text="@{worker.firstName}"/>
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="10dp"
            android:layout_gravity="center_horizontal"
            android:text="@{worker.lastName}"/>
    </LinearLayout>
</layout>

點擊調(diào)用clickFirst方法時改變inclue 中name.xml中的視圖；

public class SimpleActivity extends AppCompatActivity {
    private ActivitySimpleBinding binding;
    private Worker worker = new Worker("1111", "2222");

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        binding = DataBindingUtil.setContentView(this, R.layout.activity_simple);
        binding.setEventlistener(new EventListener());
        binding.setWorker(worker);
    }
    public class EventListener {
        public void clickFirst(View view) {
            worker.setFirstName("55555");
            worker.setLastName("7777777");
            Toast.makeText(SimpleActivity.this, "點擊了并刷新worker對象的值", Toast.LENGTH_LONG).show();
        }
    }
}

在觸發(fā)點擊事件，重新對model進行賦值后，并沒有做其他動作，視圖就更新了；

image

include

在BaseObservable視圖更新中其實就提到了include的使用了；

<?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">
    <data>
        <variable
            name="worker"
            type="com.lsm.databindingtest.Worker"/>
    </data>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">
        <include
            bind:worker="@{worker}"
            layout="@layout/name" />
    </LinearLayout>
</layout>

name.xml

<?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">
    <data>
        <variable
            name="worker"
            type="com.lsm.databindingtest.Worker"/>
    </data>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="10dp"
            android:layout_gravity="center_horizontal"
            android:text="@{worker.firstName}"/>
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="10dp"
            android:layout_gravity="center_horizontal"
            android:text="@{worker.lastName}"/>
    </LinearLayout>
</layout>

activity中的邏輯和上面都差不多，這里就不說了；

ViewStub

有時候在項目開發(fā)中會使用ViewStub進行加載視圖，看看在dataBinding中如何使用ViewStub；

<?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">

    <data>

    </data>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">
        <ViewStub
            android:id="@+id/view_stub"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout="@layout/viewstub"/>
    </LinearLayout>
</layout>

viewstub.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@mipmap/ic_launcher_round"/>
</LinearLayout>
image

和之前的使用一樣沒有區(qū)別；

RecyclerView

在開發(fā)過程中列表(RecyclerView,ListView,GridView等)的使用是比較頻繁的，所有就來看看RecyclerView在dataBinding中是如何綁定數(shù)據(jù)的；

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:tools="http://schemas.android.com/tools"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <data>
        <variable
            name="controllrecyclerview"
            type="com.lsm.databindingtest.RecyclerViewActivity.ControllRecyclerView"/>
    </data>
    <android.support.constraint.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <Button
            android:id="@+id/btn_add"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="增加"
            tools:ignore="MissingConstraints"
            android:onClick="@{controllrecyclerview.addItem}"/>
        <Button
            android:id="@+id/btn_remove"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="刪除"
            tools:ignore="MissingConstraints"
            app:layout_constraintTop_toBottomOf="@+id/btn_add"
            android:onClick="@{controllrecyclerview::removeItem}"/>
        <android.support.v7.widget.RecyclerView
            android:id="@+id/recycler_view"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            tools:ignore="MissingConstraints"
            app:layout_constraintTop_toBottomOf="@+id/btn_remove">
        </android.support.v7.widget.RecyclerView>
    </android.support.constraint.ConstraintLayout>
</layout>

布局中和之前的寫法一樣，看看它adapter的寫法有什么不同；

public class BindingViewHolder<T extends ViewDataBinding> extends RecyclerView.ViewHolder {
    private T mBinding;
    public BindingViewHolder(@NonNull T binding) {
        super(binding.getRoot());
        mBinding = binding;
    }
    public T getBinding() {
        return mBinding;
    }
}

這了ViewHolder弄一個單獨的類，沒有將其弄成adapter的內(nèi)部類了，實例化的時和以前不同的時傳入dataBinding對象而不是View對象，然后通過getRoot方法去獲取View對象；

public class EmployeeAdapter extends RecyclerView.Adapter<BindingViewHolder> {
    private LayoutInflater mLayoutInflater;
    private OnItemClickListener mListener;
    private List<Worker> mWorkList;

    public interface OnItemClickListener {
        void onItemClickListener(Worker worker);
    }

    public EmployeeAdapter(Context context) {
        this.mLayoutInflater = LayoutInflater.from(context);
        this.mWorkList = new ArrayList<>();
    }

    @NonNull
    @Override
    public BindingViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
        ViewDataBinding binding = DataBindingUtil.inflate(mLayoutInflater, R.layout.item_work_on, viewGroup, false);
        return new BindingViewHolder(binding);
    }

    @Override
    public void onBindViewHolder(@NonNull BindingViewHolder bindingViewHolder, int i) {
        final Worker item = mWorkList.get(i);
        ViewDataBinding binding = bindingViewHolder.getBinding();
        binding.setVariable(BR.item, item);
        binding.executePendingBindings();
        bindingViewHolder.itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (mListener != null) {
                    mListener.onItemClickListener(item);
                }
            }
        });
    }
    @Override
    public int getItemCount() {
        return mWorkList.size();
    }

    public void setOnItemClickListener(OnItemClickListener listener) {
        this.mListener = listener;
    }

    public void addAll(List<Worker> workers) {
        mWorkList.addAll(workers);
    }

    Random mRandom = new Random(System.currentTimeMillis());

    public void add(Worker worker) {
        int position = mRandom.nextInt(mWorkList.size() +1);
        mWorkList.add(position,worker);
        notifyItemInserted(mWorkList.size());
    }

    public void remove() {
        if (mWorkList.size() == 0) {
            return;
        }
        int position = mRandom.nextInt(mWorkList.size());
        mWorkList.remove(position);
        notifyItemRemoved(position);
    }
}

在onCreateViewHolder方法中通過DataBindingUtil.inflate加載視圖布局，并創(chuàng)建ViewDataBinding實例對象；onBindViewHolder方法中就不用像之前那樣通過獲取控件，然后對控件進行賦值，直接通過ViewHolder獲取到對應(yīng)的ViewDataBinding，然后調(diào)用setVariable對視圖進行賦值，點擊事件這些也可以按照之前的方式實現(xiàn)；
item_work_on.xml

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:tools="http://schemas.android.com/tools"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <data>
        <variable
            name="item"
            type="com.lsm.databindingtest.Worker"/>
    </data>
    <android.support.constraint.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="50dp">
        <TextView
            android:id="@+id/id_first_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            tools:ignore="MissingConstraints"
            android:text="@{item.firstName}"
            app:layout_constraintBottom_toTopOf="parent"
            app:layout_constraintTop_toBottomOf="parent"
            app:layout_constraintLeft_toLeftOf="parent"
            android:layout_marginLeft="10dp"/>
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            tools:ignore="MissingConstraints"
            android:text="@{item.lastName}"
            app:layout_constraintBottom_toTopOf="parent"
            app:layout_constraintTop_toBottomOf="parent"
            app:layout_constraintLeft_toRightOf="@+id/id_first_name"
            android:layout_marginLeft="30dp"/>
    </android.support.constraint.ConstraintLayout>
</layout>


public class RecyclerViewActivity extends AppCompatActivity {
    private ActivityRecyclerviewBinding binding;
    private EmployeeAdapter adapter;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        binding = DataBindingUtil.setContentView(this, R.layout.activity_recyclerview);
        binding.recyclerView.setLayoutManager(new LinearLayoutManager(this));

        adapter = new EmployeeAdapter(this);
        binding.recyclerView.setAdapter(adapter);
        adapter.setOnItemClickListener(new EmployeeAdapter.OnItemClickListener() {
            @Override
            public void onItemClickListener(Worker worker) {
                Toast.makeText(RecyclerViewActivity.this, worker.getFirstName() + "--" + worker.getLastName(), Toast.LENGTH_LONG).show();
            }
        });
        binding.setControllrecyclerview(new ControllRecyclerView());
        List<Worker> demoList = new ArrayList<>();
        for (int i = 0; i < 5; i++) {
            Worker worker = new Worker("Zhai", "Mark");
            demoList.add(worker);
        }
        adapter.addAll(demoList);
    }

    public class ControllRecyclerView {
        public void addItem(View view) {
            Worker worker = new Worker("1111", "11111");
            adapter.add(worker);
        }

        public void removeItem(View view) {
            adapter.remove();
        }
    }
}

activity中直接通過dataBinding獲取RecyclerView實例，然后設(shè)置LayoutMananger和adapter；這樣就實現(xiàn)了列表數(shù)據(jù)的綁定，對于ListView和GridView列表數(shù)據(jù)的綁定差不多；

image

@BindingAdapter自定義屬性

要將后臺返回的url圖片鏈接通過ImageView顯示在界面上，需要通過第三方圖片加載庫將其加載顯示出來，在dataBinding中xml布局中ImageView并不能通過@{}的方式加載url鏈接，那怎么來實現(xiàn)圖片加載呢？通過@BindingAdapter自定義屬性的方式可以實現(xiàn)；

public class DemoBindingAdapter {
    @BindingAdapter({"app:imageUrl","app:placeholder"})
    public static void loadImageFromUrl(ImageView view, String url, Drawable drawable){
        Glide.with(view.getContext())
                .load(url)
                .placeholder(drawable)
                .into(view);
    }
}

定義一個loadImageFromUrl的靜態(tài)方法，并給方法添加@BindingAdapter注解，在注解中聲明一個imageUrl和placeholder，在xml中給imageUrl和placeholder進行賦值；

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">
    <data>
        <variable
            name="employee"
            type="com.lsm.databindingtest.Employee" />
    </data>
    <android.support.constraint.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <ImageView
            android:id="@+id/iv_a"
            android:layout_width="150dp"
            android:layout_height="150dp"
            app:imageUrl="@{employee.avatar}"
            app:placeholder="@{@drawable/default_avatar}"
            tools:ignore="MissingConstraints" />

        <ImageView
            android:id="@+id/iv_b"
            android:layout_width="150dp"
            android:layout_height="150dp"
            app:imageUrl="@{employee.avatar}"
            app:layout_constraintTop_toBottomOf="@+id/iv_a"
            app:placeholder="@{@drawable/default_avatar}"
            tools:ignore="MissingConstraints" />
    </android.support.constraint.ConstraintLayout>
</layout>

通過app:imageUrl和app:placeholder進行引用；

public class ExpressionActivity extends AppCompatActivity {
    private ActivityExpressionBinding binding;
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        binding= DataBindingUtil.setContentView(this,R.layout.activity_expression);
        Employee employee=new Employee("111","3333");
        employee.setAvatar("http://img.tupianzj.com/uploads/allimg/160728/9-160HP91408.jpg");
        binding.setEmployee(employee);
    }
}
image

雙向綁定

雙向綁定的意思就是將數(shù)據(jù)model的值顯示到視圖上面，model改變時自動更新視圖，視圖改變時自動更新model；在dataBinding中通過BaseObservable和@={}來實現(xiàn)，注意不是@{}(賦值)，是@={}

public class FormModel extends BaseObservable {
    private String userName;
    private String passWord;

    public FormModel() {
    }

    public FormModel(String userName, String passWord) {
        this.userName = userName;
        this.passWord = passWord;
    }
    @Bindable
    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
        notifyPropertyChanged(BR.userName);
    }
    @Bindable
    public String getPassWord() {
        return passWord;
    }

    public void setPassWord(String passWord) {
        this.passWord = passWord;
        notifyPropertyChanged(BR.passWord);
    }
}

數(shù)據(jù)model的寫法還是和BaseObservable視圖自動更新寫法一樣的；

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:tools="http://schemas.android.com/tools"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <data>
        <variable
            name="formmodel"
            type="com.lsm.databindingtest.FormModel"/>
        <variable
            name="commitFrom"
            type="com.lsm.databindingtest.TwoWayActivity.CommitFrom"/>
    </data>
    <android.support.constraint.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <EditText
            android:id="@+id/et_name"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="請輸入用戶名"
            tools:ignore="MissingConstraints"
            android:inputType="textNoSuggestions"
            android:text="@={formmodel.userName}"/>
        <EditText
            android:id="@+id/et_pwd"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="請輸入密碼"
            tools:ignore="MissingConstraints"
            android:inputType="textNoSuggestions"
            android:text="@={formmodel.passWord}"
            app:layout_constraintTop_toBottomOf="@+id/et_name"/>
        <Button
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="提交"
            tools:ignore="MissingConstraints"
            app:layout_constraintTop_toBottomOf="@+id/et_pwd"
            android:onClick="@{commitFrom.commitFrom}"/>

    </android.support.constraint.ConstraintLayout>
</layout>


public class TwoWayActivity extends AppCompatActivity {
    private ActivityTwoWayBinding binding;
    private FormModel formmodel;
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        binding= DataBindingUtil.setContentView(this,R.layout.activity_two_way);

        formmodel=new FormModel("111","222");
        binding.setFormmodel(formmodel);
        binding.setCommitFrom(new CommitFrom());
        formmodel.addOnPropertyChangedCallback(new Observable.OnPropertyChangedCallback() {
            @Override
            public void onPropertyChanged(Observable sender, int propertyId) {
                //監(jiān)聽發(fā)送改變
            }
        });
    }
    public class CommitFrom{
        public void commitFrom(View view){
            Toast.makeText(TwoWayActivity.this,formmodel.getUserName()+"----"+formmodel.getPassWord(),Toast.LENGTH_LONG).show();
        }
    }
}

在activity中還可以通過addOnPropertyChangedCallback來監(jiān)聽視圖的改變；

image

這樣就實現(xiàn)了數(shù)據(jù)和視圖的雙向綁定，在點擊提交的時候并沒有做其他操作，就只是做了一個Toast提示；

動畫

接下來看下動畫的簡單實現(xiàn)；

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <data>
        <import type="android.view.View" />
        <variable
            name="persenter"
            type="com.lsm.databindingtest.AnimationActivity.Persenter" />
        <variable
            name="showImage"
            type="boolean" />
    </data>
    <android.support.constraint.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <ImageView
            android:id="@+id/iv"
            android:layout_width="100dp"
            android:layout_height="100dp"
            android:src="@drawable/default_avatar"
            android:visibility="@{showImage?View.VISIBLE:View.GONE}"
            tools:ignore="MissingConstraints" />
        <CheckBox
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:onCheckedChanged="@{persenter.onCheckedChanged}"
            android:text="圖片顯示或者隱藏"
            tools:ignore="MissingConstraints"
            app:layout_constraintTop_toBottomOf="@+id/iv"/>
    </android.support.constraint.ConstraintLayout>
</layout>

需要注意：不管是不是動畫的實現(xiàn)，如果在布局中通過三元運算符等操作運算符來控制視圖的顯示或者隱藏，需要在data節(jié)點標(biāo)簽中做引用；

<import type="android.view.View" />


public class AnimationActivity extends AppCompatActivity {
    private ActivityAnimationBinding binding;
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        binding= DataBindingUtil.setContentView(this,R.layout.activity_animation);

        binding.addOnRebindCallback(new OnRebindCallback() {
            @Override
            public boolean onPreBind(ViewDataBinding binding) {
                ViewGroup viewGroup= (ViewGroup) binding.getRoot();
                TransitionManager.beginDelayedTransition(viewGroup);
                return true;
            }
        });
        binding.setPersenter(new Persenter());
    }
    public class Persenter{
        public void onCheckedChanged(View buttonView, boolean isChanged){
            binding.setShowImage(isChanged);
        }
    }
}
image

上面這些只是dataBinding的部分用法，更多的用法可以查閱更多的資料進行學(xué)習(xí)。
源碼

來源：Android dataBinding 的綁定數(shù)據(jù)、列表、點擊事件等使用

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