当RecycleView遇上DataBinding

想让RecycleView的代码更简洁吗？ 那就使用DataBinding吧~~

DataBinding可以直接将数据和View绑定 具体可以看一下layout文件

recycleView的layout

<layout xmlns:android="http://schemas.android.com/apk/res/android">
<data>
</data>
<android.support.v7.widget.RecyclerView
    android:id="@+id/stu_recycle_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />
</layout>

item的layout

<layout xmlns:android="http://schemas.android.com/apk/res/android">
<data>
    <variable
        name="stu"
        type="com.example.guoss.databindingdemo.entity.StuBean" />
</data>

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginLeft="20dp"
    android:layout_marginRight="20dp"
    android:orientation="vertical">

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@{stu.name}"
    android:padding="12dp"
    android:textColor="@{@color/text_color_3}"
    android:textSize="16sp" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@{stu.addr}"
    android:padding="12dp"
    android:textColor="@{@color/text_color_6}"
    android:textSize="14sp" />
</LinearLayout>
</layout>

那DataBinding怎么和RecycleView.Adapter 中使用呢？ 看一下adapter和ViewHolder中的代码

重点是在 onCreateViewHolder函数中 初始化ViewDataBinding相当于初始化view，将初始化后的ViewDataBinding放置在ViewHolder中方便在 onBindViewHolder 函数中使用 setStu 或 setVariable 绑定数据

@Override
public StuViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    StuItemLayoutBinding itemLayoutBinding = DataBindingUtil.inflate(LayoutInflater.from(parent.getContext()),R.layout.stu_item_layout,parent,false);
    StuViewHolder viewHolder = new StuViewHolder(itemLayoutBinding.getRoot());
    viewHolder.setBinding(itemLayoutBinding);
    return viewHolder;
}


@Override
public void onBindViewHolder(StuViewHolder holder, int position) {
    StuBean stuBean = mStuList.get(position);
    holder.getBinding().setStu(stuBean);
    //holder.getBinding().setVariable(BR.stu,stuBean);
    holder.getBinding().executePendingBindings();
}

@Override
public int getItemCount() {
    return mStuList == null ?0:mStuList.size();
}

使用了DataBinding后ViewHolder 就不用使用findViewById ，但是需要提供ViewDataBinding对象方便后面绑定数据

class StuViewHolder extends RecyclerView.ViewHolder{

private StuItemLayoutBinding binding;

public StuViewHolder(View itemView) {
    super(itemView);
}

public void setBinding(StuItemLayoutBinding stuItemLayoutBinding){
    this.binding = stuItemLayoutBinding;
}

public StuItemLayoutBinding getBinding() {
    return binding;
}
}

接着可以给RecycleView setAdapter了

   dataBinding.stuRecycleView.setLayoutManager(new LinearLayoutManager(this));
   dataBinding.stuRecycleView.setAdapter(new StuAdapter(stuList));

再想一下，在这个基础上是不是可以将变量抽取出来 用泛型打造一个通用的Adapter

public class BaseRecycleAdapter<E,T extends ViewDataBinding> extends RecyclerView.Adapter<BaseRecycleAdapter.BaseViewHolder>{
private List<E> mList;
private int itemLayoutId;
private int variableId;

public BaseRecycleAdapter(List<E> mList, int itemLayoutId, int variableId) {
    this.mList = mList;
    this.itemLayoutId = itemLayoutId;
    this.variableId = variableId;
}

@Override
public BaseViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    T itemDataBinding = DataBindingUtil.inflate(LayoutInflater.from(parent.getContext()),itemLayoutId,parent,false);
    BaseViewHolder viewHolder = new BaseViewHolder(itemDataBinding.getRoot());
    viewHolder.setDataBinding(itemDataBinding);
    return viewHolder;
}

@Override
public void onBindViewHolder(BaseViewHolder holder, int position) {
    E data = mList.get(position);
    holder.getDataBinding().setVariable(variableId,data);
    holder.getDataBinding().executePendingBindings();
}

@Override
public int getItemCount() {
    return mList == null ? 0 : mList.size();
}

public class BaseViewHolder <T extends ViewDataBinding> extends RecyclerView.ViewHolder{

    private T dataBinding;

    public BaseViewHolder(View itemView) {
        super(itemView);
    }

    public void setDataBinding(T dataBindding){
        this.dataBinding = dataBindding;
    }

    public T getDataBinding(){
        return dataBinding;
    }
}

}

这样在使用时就更方便了

 dataBinding.stuRecycleView.setLayoutManager(new LinearLayoutManager(this));
 dataBinding.stuRecycleView.setAdapter(new BaseRecycleAdapter(stuList,R.layout.stu_item_layout,BR.stu));

总结：以上只是DataBinding和RecycleView的简单使用，但对我们的代码结构还是有很大帮助的。