今天来说说DataBinding在列表RecyclerView中的使用
列表绑定
App中经常用到列表展示，Data Binding在列表中一样可以扮演重要的作用，直接绑定数据和事件到每一个列表的item。
RecyclerView
过去我们往往会使用ListView、GridView、或者GitHub上一些自定义的View来做瀑布流。自从RecyclerView出现后，我们有了新选择，只需要使用LayoutManager就可以。
RecyclerView内置的垃圾回收，ViewHolder、ItemDecoration装饰器机制都让我们可以毫不犹豫地替换掉原来的ListView和GridView。
主布局：
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">
<data>
</data>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<Button
android:id="@+id/btn_demo8_add"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="添加" />
<Button
android:id="@+id/btn_demo8_refresh"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:layout_weight="1"
android:text="刷新" />
<Button
android:id="@+id/btn_demo8_delete"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:layout_weight="1"
android:text="删除" />
</LinearLayout>
<android.support.v7.widget.RecyclerView
android:id="@+id/demo8_recyclerview"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="5dp"></android.support.v7.widget.RecyclerView>
</LinearLayout>
</layout>
item布局：
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"> <data> <import type="com.zhangqie.databinding.demo8.UserObservableBean"/> <variable
name="userObserBean"
type="UserObservableBean"/>
</data> <LinearLayout
android:layout_width="match_parent"
android:layout_height="100dp"
android:descendantFocusability="blocksDescendants"
android:orientation="horizontal"> <LinearLayout
android:layout_width="wrap_content"
android:layout_weight="1"
android:layout_height="match_parent"
android:orientation="vertical"
android:gravity="center"
> <TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@{`编号：` + userObserBean.userId }" /> <TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@{`姓名：` +userObserBean.userName}"
android:layout_marginTop="5dp"
/>
</LinearLayout> <LinearLayout
android:layout_width="wrap_content"
android:layout_weight="1"
android:layout_height="match_parent"
android:orientation="vertical"
android:gravity="center"
> <TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@{`年龄：` +userObserBean.userAge}"
/> <!--一定要使用1f而不能是使用1 ，类型必须相对应-->
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="5dp"
android:text="@{`性别：` + (userObserBean.userSex == 1f ? `男` : `女`)}" /> </LinearLayout> <LinearLayout
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:orientation="vertical"
android:layout_marginRight="10dp"
android:paddingBottom="10dp"
> <Button
android:id="@+id/btn_update"
android:layout_width="wrap_content"
android:layout_height="40dp"
android:text="修改数据" /> <Button
android:id="@+id/btn_delete"
android:layout_width="wrap_content"
android:layout_height="40dp"
android:layout_marginTop="5dp"
android:text="删除数据" />
</LinearLayout>
</LinearLayout>
</layout>
ViewHolder
public class RecyclerViewHolder extends RecyclerView.ViewHolder {
public Item8MvvmBinding getItem8MvvmBinding() {
return item8MvvmBinding;
}
public void setItem8MvvmBinding(Item8MvvmBinding item8MvvmBinding) {
this.item8MvvmBinding = item8MvvmBinding;
}
//这里只要给RecyclerView.ViewHolder返回一个view就可以，所以我们将构造方法中传入databinding
Item8MvvmBinding item8MvvmBinding;
public RecyclerViewHolder(Item8MvvmBinding item8MvvmBinding) {
super(item8MvvmBinding.getRoot());
this.item8MvvmBinding = item8MvvmBinding;
}
}
adapter：
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewHolder> implements View.OnClickListener{
private List<UserObservableBean> list;
private Random random = new Random(System.currentTimeMillis());
public RecyclerViewAdapter(List<UserObservableBean> list) {
this.list = list;
}
public OnItemOnClickListener getOnItemOnClickListener() {
return onItemOnClickListener;
}
public void setOnItemOnClickListener(OnItemOnClickListener onItemOnClickListener) {
this.onItemOnClickListener = onItemOnClickListener;
}
private OnItemOnClickListener onItemOnClickListener;
public interface OnItemOnClickListener{
void onItemClick(View view, int position);
}
@Override
public RecyclerViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
Item8MvvmBinding item8MvvmBinding = DataBindingUtil.inflate(LayoutInflater.from(parent.getContext()), R.layout.item8_mvvm,parent,false);
item8MvvmBinding.getRoot().setOnClickListener(this);
return new RecyclerViewHolder(item8MvvmBinding);
}
@Override
public void onBindViewHolder(RecyclerViewHolder holder, int position) {
Item8MvvmBinding item8MvvmBinding = holder.getItem8MvvmBinding();
UserObservableBean userObservableBean = list.get(position);
item8MvvmBinding.setVariable(com.zhangqie.databinding.BR.userObserBean,userObservableBean);
//将position保存在itemView的Tag中，以便点击时进行获取
item8MvvmBinding.getRoot().setTag(position);
item8MvvmBinding.btnUpdate.setOnClickListener(new OnBtnClickListener(1, userObservableBean));
item8MvvmBinding.btnDelete.setOnClickListener(new OnBtnClickListener(2, position));
// 立刻执行绑定
item8MvvmBinding.executePendingBindings();
}
@Override
public int getItemCount() {
return list.size();
}
public void addData(UserObservableBean userObservableBean){
int position = random.nextInt(list.size()+1);
list.add(position,userObservableBean);
notifyItemInserted(position);//添加操作的动画
}
public void deleteData(int positionn){
if (list.size() == 0){
return;
}
int position = random.nextInt(list.size());
list.remove(position);
notifyItemRemoved(position);//删除操作的动画
}
@Override
public void onClick(View view) {
if (onItemOnClickListener != null)
onItemOnClickListener.onItemClick(view, (int) view.getTag());
}
private class OnBtnClickListener implements View.OnClickListener{
private int stats;//1,修改；2，删除
private UserObservableBean userBean;
private int position;
OnBtnClickListener(int stats, UserObservableBean userBean) {
this.stats = stats;
this.userBean = userBean;
}
OnBtnClickListener(int stats, int position) {
this.stats = stats;
this.position = position;
}
@Override
public void onClick(View v) {
switch (stats) {
case 1:
userBean.userName.set("修改后的名字");
break;
case 2:
list.remove(position);
notifyDataSetChanged();
break;
}
}
}
}
主Activity：
public class Demo8 extends AppCompatActivity {
Demo8Binding demo8Binding;
RecyclerViewAdapter recyclerViewAdapter;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
demo8Binding = DataBindingUtil.setContentView(this, R.layout.demo8);
initView();
}
private void initView(){
RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(this);
demo8Binding.demo8Recyclerview.setLayoutManager(layoutManager);
recyclerViewAdapter = new RecyclerViewAdapter(initObservableData());
demo8Binding.demo8Recyclerview.setAdapter(recyclerViewAdapter);
//item的点击事件
recyclerViewAdapter.setOnItemOnClickListener(new RecyclerViewAdapter.OnItemOnClickListener() {
@Override
public void onItemClick(View view, int position) {
Toast.makeText(Demo8.this, "行数：" + position, Toast.LENGTH_LONG).show();
}
});
demo8Binding.btnDemo8Add.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
UserObservableBean userBean = new UserObservableBean();
userBean.userId.set(8);
userBean.userName.set("切切心语"+8);
userBean.userAge.set(25);
userBean.userSex.set(8 % 2 == 0 ? 1 : 0);
recyclerViewAdapter.addData(userBean);
}
});
demo8Binding.btnDemo8Refresh.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
recyclerViewAdapter.notifyDataSetChanged();
}
});
demo8Binding.btnDemo8Delete.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
recyclerViewAdapter.deleteData(1);
}
});
}
//初始化测试数据
private List<UserObservableBean> initObservableData() {
List<UserObservableBean> list = new ArrayList<>();
for (int i = 1; i < 6; i++) {
UserObservableBean userBean = new UserObservableBean();
userBean.userId.set(i);
userBean.userName.set("切切心语"+i);
userBean.userAge.set(18 + i);
userBean.userSex.set(i % 2 == 0 ? 1 : 0);
list.add(userBean);
}
return list;
}
}
自己练习的一个RecyclerView + Databinding使用
效果如图：