Android 5.0 RecyclerView 使用

RecyclerView 是5.0开始出来的新的ListView，主要是提高了性能，显示方式也多样化。

老版本中我们优化view都是通过定义一个Holder来实行的，现在的RecyclerView就封装了一个Holder

支持水平滚动和垂直滚动2种列表

还支持Grid格子布局和乱序的布局

ICON + TEXT

public class Item {    public int imgId;    public String desc;    public Item(String desc, int imgId) {        this.desc = desc;        this.imgId = imgId;    }}

简单的Holder

public class MyViewHolder extends RecyclerView.ViewHolder {    public MyViewHolder(View itemView) {        super(itemView);    }}

public class MyRecyclerAdapter extends RecyclerView.Adapter<MyViewHolder> {    private Activity activity;    private List<Item> list;    public MyRecyclerAdapter (Activity act, List<Item> list) {        this.activity = act;        this.list = list;    }    @Override  //绑定一个UI作为Holder 提高性能    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {        View v = LayoutInflater.from(activity).inflate(R.layout.recy_item,null);        MyViewHolder holder = new MyViewHolder(v);        return holder;    }    //设置数据    @Override    public void onBindViewHolder(MyViewHolder holder, int position) {        Item item = list.get(position);        TextView text1 = (TextView) holder.itemView.findViewById(R.id.text) ;        text1.setText(item.desc);        ImageView img = (ImageView) holder.itemView.findViewById(R.id.img);        img.setImageResource(item.imgId);    }    @Override    public int getItemCount() {        return list.size();    }}

recy_item.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="horizontal"    >    <ImageView        android:layout_width="70dp"        android:layout_height="70dp"        android:id = "@+id/img"        android:scaleType="fitCenter"        android:layout_marginLeft="2dp"        android:layout_gravity="center_vertical"        />     <TextView         android:id="@+id/text"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_marginLeft="3dp"         android:layout_marginTop="5dp"         android:textColor="#336699"         android:textSize="18sp"         /></LinearLayout>

public class MainActivity extends ActionBarActivity {    private List<Item> itemList;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        initView();    }    private void initView() {        String title = "To travel hopefully is a better thing than to arrive";  //    String title = "";        itemList = new ArrayList<Item>(5);        itemList.add(new Item(title,R.drawable.cat0));        itemList.add(new Item(title,R.drawable.cat0));        itemList.add(new Item(title,R.drawable.cat2));        itemList.add(new Item(title,R.drawable.cat3));        itemList.add(new Item(title,R.drawable.cat4));        itemList.add(new Item(title,R.drawable.cat4));        itemList.add(new Item(title,R.drawable.cat3));        itemList.add(new Item(title,R.drawable.cat2));        itemList.add(new Item(title,R.drawable.cat3));        itemList.add(new Item(title,R.drawable.cat2));        itemList.add(new Item(title,R.drawable.cat4));        itemList.add(new Item(title,R.drawable.cat4));        itemList.add(new Item(title,R.drawable.cat4));        itemList.add(new Item(title,R.drawable.cat0));        itemList.add(new Item(title,R.drawable.cat3));        RecyclerView list = (RecyclerView) findViewById(R.id.listview);    //    LinearLayoutManager mg = new LinearLayoutManager(this);        //水平或垂直摆放，可以不用 HorizontalScrollView   //     mg.setOrientation(LinearLayoutManager.HORIZONTAL);       GridLayoutManager mg = new GridLayoutManager(this,3);//格子摆放     //交错性的摆放，有点win8那种格子风格，最好使用CardView作为item，有边框和圆角    //    StaggeredGridLayoutManager mg = new StaggeredGridLayoutManager(2,StaggeredGridLayoutManager.VERTICAL);       list.setLayoutManager(mg);        MyRecyclerAdapter adapter = new MyRecyclerAdapter(this, itemList);        list.setAdapter(adapter);    } }

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    tools:context=".MainActivity">    <android.support.v7.widget.RecyclerView        android:id = "@+id/listview"        android:layout_width="fill_parent"        android:layout_height = "fill_parent"        /></RelativeLayout>

几种运行情况：

正常的List View

水平滚动

格子情况

GridLayoutManager mg = new GridLayoutManager(this,3); //3列

混合交错的。我们的图片需要动态大小，才能看到效果。把文字注释掉，只显示图片。

StaggeredGridLayoutManager mg = new StaggeredGridLayoutManager(2,StaggeredGridLayoutManager.VERTICAL);

    public void onBindViewHolder(MyViewHolder holder, int position) {        Item item = list.get(position);        TextView text1 = (TextView) holder.itemView.findViewById(R.id.text) ;        text1.setText(item.desc);        ImageView img = (ImageView) holder.itemView.findViewById(R.id.img);        int ww = 60 + (int)(position * new Random().nextInt(100));        if (ww > 300) {            ww = 200;//每个图片太宽不好看，计算一个恰当值        }        img.getLayoutParams().width = ww;        img.getLayoutParams().height = 50 + (int)(position * new Random().nextInt(50));//随机高宽        img.setImageResource(item.imgId);    }

交错的这种 内容大小是不固定的，所以建议用CardView 可以有边框效果

这个演示较为简单，基本用法就这些。