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

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