Android官方DataBinding（三）：RecyclerView 使用ViewDataBinding更新数据

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Android官方DataBinding（三）：RecyclerView 使用ViewDataBinding更新数据

本例基于Android官方DataBinding，在RecyclerView上实现一个简单需求：点击一个button按钮，增加一个数据元素，并更新的view上。

（1）首先写一个布局，这个布局上面放一个按钮button，下面一个标准Android RecyclerView。Button按钮的实现一个简单的功能：没点击一次就增加一个数据元素，然后更新到RecyclerView。recycler_view_layout.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">    <Button        android:id="@+id/button"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="添加元素" />    <android.support.v7.widget.RecyclerView        android:id="@+id/recycler_view"        android:layout_width="match_parent"        android:layout_height="match_parent" /></LinearLayout>

（2）和附录文章1,2，写数据模型User，对比这个User和附录1,2的User建模时候的异同，User.java：

package zhangphil.test;import android.databinding.BaseObservable;//import android.databinding.Bindable;/** * Created by Phil on 2017/8/17. */public class User extends BaseObservable {    private String id;    private String name;    private String blog;    public void setId(String id) {        this.id = id;        //notifyPropertyChanged(BR.id);    }    //@Bindable    public String getId() {        return this.id;    }    public void setName(String name) {        this.name = name;        //notifyPropertyChanged(BR.name);    }    //@Bindable    public String getName() {        return this.name;    }    public void setBlog(String blog) {        this.blog = blog;        //notifyPropertyChanged(BR.blog);    }    //@Bindable    public String getBlog() {        return this.blog;    }}

（3）因为是一个RecyclerView，RecyclerView需要Adapter，在Adapter中需要一个布局layout，为User的数据找到View，Adapter需要的子view布局这里将写View和Model的绑定代码，item.xml：

<?xml version="1.0" encoding="utf-8"?><layout xmlns:android="http://schemas.android.com/apk/res/android">    <data>        <variable            name="user"            type="zhangphil.test.User" />    </data>    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="vertical">        <TextView            android:id="@+id/id"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="@{user.id}"            android:textColor="@android:color/holo_red_light" />        <TextView            android:id="@+id/name"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="@{user.name}"            android:textColor="@android:color/holo_red_light" />        <TextView            android:id="@+id/blog"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="@{user.blog}"            android:textColor="@android:color/holo_red_light" />        <View            android:layout_width="match_parent"            android:layout_height="1px"            android:background="@android:color/holo_blue_bright" />    </LinearLayout></layout>

（4）上层Java代码，注意观察ViewHolder的写法。比较关键的是在创建ViewHolder时候传入的ViewDataBinding。在Adapter的onBindViewHolder里面，仅需两行代码就实现数据模型和View的绑定，MainActivity.java：

package zhangphil.test;import android.databinding.DataBindingUtil;import android.databinding.ViewDataBinding;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.support.v7.widget.LinearLayoutManager;import android.support.v7.widget.RecyclerView;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import java.util.ArrayList;import static zhangphil.test.BR.user;public class MainActivity extends AppCompatActivity {    private int index = 0;    private ItemAdapter mItemAdapter;    private ArrayList<User> mItems;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.recycler_view_layout);        mItems = new ArrayList();        for (int i = 0; i < 1; i++) {            User u = new User();            u.setId(index + "");            u.setName("zhangphil @" + index);            u.setBlog("blog.csdn.net/zhangphil @" + index);            mItems.add(u);            index++;        }        RecyclerView mRecyclerView = (RecyclerView) findViewById(R.id.recycler_view);        mRecyclerView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false));        mItemAdapter = new ItemAdapter();        mRecyclerView.setAdapter(mItemAdapter);        findViewById(R.id.button).setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                User u = new User();                u.setId(index + "");                u.setName("zhangphil @" + index);                u.setBlog("blog.csdn.net/zhangphil @" + index);                mItems.add(u);                mItemAdapter.notifyDataSetChanged();                index++;            }        });    }    private class ItemAdapter extends RecyclerView.Adapter<ItemViewHolder> {        @Override        public ItemViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {            ViewDataBinding binding = DataBindingUtil.inflate(LayoutInflater.from(viewGroup.getContext()), R.layout.item, viewGroup, false);            ItemViewHolder holder = new ItemViewHolder(binding);            return holder;        }        @Override        public void onBindViewHolder(ItemViewHolder viewHolder, int i) {            viewHolder.getBinding().setVariable(user, mItems.get(i));            viewHolder.getBinding().executePendingBindings();        }        @Override        public int getItemCount() {            return mItems.size();        }    }    private class ItemViewHolder extends RecyclerView.ViewHolder {        private ViewDataBinding binding;        public ItemViewHolder(ViewDataBinding binding) {            super(binding.getRoot());            this.binding = binding;        }        public void setBinding(ViewDataBinding binding) {            this.binding = binding;        }        public ViewDataBinding getBinding() {            return this.binding;        }    }}

代码运行结果，每点击一次button，数据增加一个，更新：

附录：
1，《Android官方DataBinding简例（一）》链接：http://blog.csdn.net/zhangphil/article/details/77322530
2，《Android官方DataBinding（二）：动态数据更新notifyPropertyChanged》链接：http://blog.csdn.net/zhangphil/article/details/77328688

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