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

约定不等于承诺〃 2024-02-18 14:25 6阅读 0赞

**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：

![Center][]

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

[Center]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/cc897470622148d6a2529554cb5b7d05.png