Android 开源框架 ( 十三 ) RecyclerView
RecyclerView是Android 5.0推出的。
RecyclerView是support:recyclerview-v7中提供的控件,最低兼容到android 3.0版本。可以通过导入support-v7对其进行使用。
RecyclerView已经标准化ViewHolder,我们自定义的ViewHoler需要继承 RecyclerView.ViewHolder,然后在构造方法中初始化控件,后面会有具体介绍。通过设置不同的LayoutManager,以及结合ItemDecoration , ItemAnimator,ItemTouchHelper,可以实现非常炫酷的效果。
一.布局
<android.support.v7.widget.RecyclerView android:id="@+id/recyclerView" android:layout_width="match_parent" android:layout_height="match_parent"/>
二.基本使用
//设置RecyclerView的适配器 adapter = new MyRecyclerViewAdapter(RecyclerViewActivity.this,datas); recyclerview.setAdapter(adapter); //设置添加或删除item时的动画,这里使用默认动画 mRecyclerView.setItemAnimator(new DefaultItemAnimator()); //添加RecyclerView的分割线 recyclerview.addItemDecoration(new DividerListItemDecoration(RecyclerViewActivity.this,DividerListItemDecoration.VERTICAL_LIST)); //LayoutManager recyclerview.setLayoutManager(new LinearLayoutManager(RecyclerViewActivity.this, LinearLayoutManager.VERTICAL, false));
public class MyRecyclerViewAdapter extends RecyclerView.Adapter<MyRecyclerViewAdapter.ViewHolder> { private final Context context; private ArrayList<String> datas; public MyRecyclerViewAdapter(Context context, ArrayList<String> datas) { this.context = context; this.datas = datas; } /** * 相当于getView方法中创建View和ViewHolder * @param parent * @param viewType * @return */ @Override public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { View itemView = View.inflate(context, R.layout.item_recyclerview,null); return new ViewHolder(itemView); } /**相当于于getView绑定数据部分的代码 * 数据和View绑定 * @param holder * @param position */ @Override public void onBindViewHolder(ViewHolder holder, int position) { //根据位置得到对应的数据 String data = datas.get(position); holder.tv_title.setText(data); } /** * 得到总条数 * @return */ @Override public int getItemCount() { return datas.size(); } class ViewHolder extends RecyclerView.ViewHolder { private ImageView iv_icon; private TextView tv_title; public ViewHolder(View itemView) { super(itemView); iv_icon = (ImageView) itemView.findViewById(R.id.iv_icon); tv_title = (TextView) itemView.findViewById(R.id.tv_title); } } }
三.三种显示方式
//设置List类型效果 recyclerview.setLayoutManager(new LinearLayoutManager(RecyclerViewActivity.this,LinearLayoutManager.VERTICAL,false)); //设置Grid类型效果 recyclerview.setLayoutManager(new GridLayoutManager(RecyclerViewActivity.this, 2, GridLayoutManager.VERTICAL, false)); //设置瀑布流类型效果 recyclerview.setLayoutManager(new StaggeredGridLayoutManager(3,StaggeredGridLayoutManager.VERTICAL));
四.分割线
//添加RecyclerView的分割线 recyclerview.addItemDecoration(new DividerListItemDecoration(RecyclerViewActivity.this,DividerListItemDecoration.VERTICAL_LIST));
import android.content.Context; import android.content.res.TypedArray; import android.graphics.Canvas; import android.graphics.Rect; import android.graphics.drawable.Drawable; import android.support.v7.widget.LinearLayoutManager; import android.support.v7.widget.RecyclerView; import android.view.View; public class DividerListItemDecoration extends RecyclerView.ItemDecoration { private static final int[] ATTRS = new int[]{ android.R.attr.listDivider }; public static final int HORIZONTAL_LIST = LinearLayoutManager.HORIZONTAL; public static final int VERTICAL_LIST = LinearLayoutManager.VERTICAL; private Drawable mDivider; private int mOrientation; public DividerListItemDecoration(Context context, int orientation) { final TypedArray a = context.obtainStyledAttributes(ATTRS); mDivider = a.getDrawable(0); a.recycle(); setOrientation(orientation); } public void setOrientation(int orientation) { if (orientation != HORIZONTAL_LIST && orientation != VERTICAL_LIST) { throw new IllegalArgumentException("invalid orientation"); } mOrientation = orientation; } @Override public void onDraw(Canvas c, RecyclerView parent) { // Log.e("recyclerview - itemdecoration", "onDraw()"); if (mOrientation == VERTICAL_LIST) { drawVertical(c, parent); } else { drawHorizontal(c, parent); } } public void drawVertical(Canvas c, RecyclerView parent) { final int left = parent.getPaddingLeft(); final int right = parent.getWidth() - parent.getPaddingRight(); final int childCount = parent.getChildCount(); for (int i = 0; i < childCount; i++) { final View child = parent.getChildAt(i); android.support.v7.widget.RecyclerView v = new android.support.v7.widget.RecyclerView(parent.getContext()); final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child .getLayoutParams(); final int top = child.getBottom() + params.bottomMargin; final int bottom = top + mDivider.getIntrinsicHeight(); mDivider.setBounds(left, top, right, bottom); mDivider.draw(c); } } public void drawHorizontal(Canvas c, RecyclerView parent) { final int top = parent.getPaddingTop(); final int bottom = parent.getHeight() - parent.getPaddingBottom(); final int childCount = parent.getChildCount(); for (int i = 0; i < childCount; i++) { final View child = parent.getChildAt(i); final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child .getLayoutParams(); final int left = child.getRight() + params.rightMargin; final int right = left + mDivider.getIntrinsicHeight(); mDivider.setBounds(left, top, right, bottom); mDivider.draw(c); } } @Override public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) { if (mOrientation == VERTICAL_LIST) { outRect.set(0, 0, 0, mDivider.getIntrinsicHeight()); } else { outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0); } } }
RecyclerView 和 ListView 都可以加头和尾。 在后面列表的上拉加载,下拉刷新控件中再讲。