RecyclerView的简单使用

• 前言
• 1.控件使用
• 2.Adapter和LayoutManager
  
  • ①LayoutManager布局管理器
  • ②Adapter适配器
  • ③Decoration修饰器
• 3.添加和删除
• 4.点击事件

前言

RecyclerView不仅可以完全取缔ListView和GridView,还可以有很多其他的效果,可以非常炫酷,今天先来记录下最简单的使用.

RecyclerView是自Android 5.0之后才发布的,要使用它要先根据自己sdk的版本进行导包:

compile 'com.android.support:recyclerview-v7:25.3.1'

导包完成后就可以开始使用了.

1.控件使用

RecyclerView是一个控件,它的使用方法跟ListView的用法差不多,直接在布局中使用.

<LinearLayout    xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:id="@+id/activity_main2"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical"    android:background="#5555"    tools:context="com.simon.demo.my.Main2Activity">    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="horizontal">        <Button            android:id="@+id/add_btn"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="添加item"/>        <Button            android:id="@+id/delete_btn"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="删除item"/>    </LinearLayout>    <android.support.v7.widget.RecyclerView        android:id="@+id/recycler_view"        android:paddingLeft="3dp"        android:layout_width="match_parent"        android:layout_height="match_parent"/></LinearLayout>

2.Adapter和LayoutManager

在使用RecyclerView时候，必须指定一个适配器Adapter和一个布局管理器LayoutManager。适配器继承RecyclerView.Adapter类，具体实现类似ListView的适配器，取决于数据信息以及展示的UI。布局管理器用于确定RecyclerView中Item的展示方式以及决定何时复用已经不可见的Item，避免重复创建以及执行高成本的findViewById()方法。

①LayoutManager布局管理器

RecyclerView提供了三种布局管理器：

• LinerLayoutManager 以垂直或者水平列表方式展示Item
• GridLayoutManager 以网格方式展示Item
• StaggeredGridLayoutManager 以瀑布流方式展示Item

//这里使用了线性垂直列表mLinearLayoutManager = new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false);mRecyclerView.setLayoutManager(mLinearLayoutManager);

②Adapter适配器

创建一个类继承RecyclerView.Adapter

public class RecycleAdapter extends RecyclerView.Adapter<RecycleAdapter.ViewHolder>{    private final Context context;    private final ArrayList<String> mData;    public RecycleAdapter(Context c, ArrayList<String> data){        this.context = c;        this.mData = data;    }    //获取item布局,并创建ViewHolder与之绑定    @Override    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {        //这里填充的布局root写parent的话,会只显示一个item,改为null后才正常显示        //解决http://blog.csdn.net/fantasiasango/article/details/52188064        //如果用View.inflate填充的布局没有调用到设置的属性//        View view = View.inflate(parent.getContext(), R.layout.view_rv_item, null);        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.view_rv_item, parent, false);        ViewHolder viewHolder = new ViewHolder(view);        return viewHolder;    }    //    @Override    public void onBindViewHolder(ViewHolder holder, int position) {        holder.mTx.setText(mData.get(position));    }    @Override    public int getItemCount() {        return mData.size();    }    public static class ViewHolder extends RecyclerView.ViewHolder{ //有写情况下需要手动设置属性,不然布局会显示不正常        RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);        itemView.setLayoutParams(layoutParams);        private final TextView mTx;        public ViewHolder(View itemView) {            super(itemView);            mTx = (TextView) itemView.findViewById(R.id.item_tv);        }    }}

Activity中使用代码

 mRecycleAdapter = new RecycleAdapter(this,getData()); mRecyclerView.setAdapter(mRecycleAdapter); //模拟数据    private ArrayList<String> getData() {        ArrayList<String> strings = new ArrayList<>();        for(int i = 0; i < 50; i++) {            strings.add("我是超人"+i);        }        return strings;    }

③Decoration修饰器

这是用来自定义RecycleView的样式,decoration的样式可以同时使用多个,不同的decoration效果会重叠起来,从而达到不同的效果.

主要使用的三个方法:

public void onDraw(Canvas c, RecyclerView parent, State state)public void onDrawOver(Canvas c, RecyclerView parent, State state)public void getItemOffsets(Rect outRect, View view, RecyclerView parent, State state)

举例使用:

public class MyItemDecoration extends RecyclerView.ItemDecoration {    private final Paint mPaint;    private final int mDividerHeight;    public MyItemDecoration(Context context) {        mPaint = new Paint();        mPaint.setColor(Color.BLUE);        mDividerHeight = 10;    }    //    这两个方法都是用于绘制间隔样式    @Override    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {        super.onDraw(c, parent, state);    }    @Override    public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {        super.onDrawOver(c, parent, state);        int childCount = parent.getChildCount();        int left = parent.getPaddingLeft();        int right = parent.getWidth() - parent.getPaddingRight();        for (int i = 0; i < childCount - 1; i++) {            View view = parent.getChildAt(i);            int top = view.getBottom();            int bottom = view.getBottom() + 5;            Log.v("cherish233", "left:" + left + "---" + "top:" + top + "---" + "right:" + right + "---" + "bottom:" + bottom + "---");            c.drawRect(left, top, right, bottom, mPaint);        }        //        View view = parent.getChildAt(0);        //        int top = view.getBottom();        //        int bottom = view.getBottom() + mDividerHeight;        //        Log.v("cherish233", "left:" + left + "---" + "top:" + top + "---" + "right:" + right + "---" + "bottom:" + bottom + "---");        //        c.drawRect(left, top, right, bottom, mPaint);    }    //设置item的偏移量，偏移的部分用于填充间隔样式    @Override    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {        super.getItemOffsets(outRect, view, parent, state);        outRect.bottom = mDividerHeight;    }}

在Activity中的使用代码

mMyItemDecoration = new MyItemDecoration(this);mRecyclerView.addItemDecoration(mMyItemDecoration);

完整的Activity代码:

public class Main2Activity extends AppCompatActivity implements View.OnClickListener {    private Button mAddBtn;    private Button mDeleteBtn;    private RecyclerView mRecyclerView;    private LinearLayout mActivityMain2;    private LinearLayoutManager mLinearLayoutManager;    private RecycleAdapter mRecycleAdapter;    private MyItemDecoration mMyItemDecoration;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main2);        initView();        initData();    }    private void initData() {        mLinearLayoutManager = new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false);        mRecycleAdapter = new RecycleAdapter(this,getData());        mMyItemDecoration = new MyItemDecoration(this);        mRecyclerView.setLayoutManager(mLinearLayoutManager);        mRecyclerView.setAdapter(mRecycleAdapter);        mRecyclerView.addItemDecoration(mMyItemDecoration);    }    //模拟数据    private ArrayList<String> getData() {        ArrayList<String> strings = new ArrayList<>();        for(int i = 0; i < 50; i++) {            strings.add("我是超人"+i);        }        return strings;    }    private void initView() {        mAddBtn = (Button) findViewById(R.id.add_btn);        mAddBtn.setOnClickListener(this);        mDeleteBtn = (Button) findViewById(R.id.delete_btn);        mDeleteBtn.setOnClickListener(this);        mRecyclerView = (RecyclerView) findViewById(R.id.recycler_view);    }    @Override    public void onClick(View v) {        switch (v.getId()) {            case R.id.add_btn:                break;            case R.id.delete_btn:                break;        }    }}

最终效果:

3.添加和删除

要想添加和删除数据,只需要在Adapter中添加两个方法

//添加数据    public void addNewItem(){        if(mData == null) {            mData = new ArrayList<>();        }        mData.add(0, "new Item");        //用notifyItemInserted(0)来刷新需要更新的Item,如果用notifyDataSetChanged()没有动画效果        notifyItemInserted(0);    }    //删除数据    public void deleteItem(int position) {        if (mData == null || mData.isEmpty()) {            return;        }        mData.remove(position);        notifyItemRemoved(position);        //删除数据后要进行刷新,否则下次删除的时候position会对应错误       notifyDataSetChanged();    }

然后在你需要的地方进行调用,我是在MainActivity中添加了两个按钮进行简单的添加和删除操作

 @Override    public void onClick(View v) {        switch (v.getId()) {            case R.id.add_btn:                mRecycleAdapter.addNewItem();                //回到第一个Item                mLinearLayoutManager.scrollToPosition(0);                break;            case R.id.delete_btn:                mRecycleAdapter.deleteItem();                mLinearLayoutManager.scrollToPosition(0);                break;        }    }

效果如下:

RecyclerView可以设置列表中Item删除和添加的动画,V7包中提供了一个默认动画,只需设置一下就可以了.

// 设置Item添加和移除的动画mRecyclerView.setItemAnimator(new DefaultItemAnimator());

效果:

4.点击事件

RecyclerView并没有像ListView一样提供点击事件,需要自己自定义点击事件和长按事件.
通过在绑定ViewHolder的时候设置监听，然后通过Apater回调出去

在Adapter里创建一个监听器,并提供一个方法:

    interface OnItemClickListener {        void onClick();        void onLongClick();    }    //设置为全局变量    private OnItemClickListener mOnItemClickListener;    public void setItemClickListener(OnItemClickListener listener) {        mOnItemClickListener = listener;    }

然后对ViewHolder设置监听

 @Override    public void onBindViewHolder(ViewHolder holder, final int position) {        Log.v("cherish233","onBindViewHolder:"+position);        holder.mTx.setText(mData.get(position));        holder.itemView.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                mOnItemClickListener.onClick(position);            }        });        holder.itemView.setOnLongClickListener(new View.OnLongClickListener() {            @Override            public boolean onLongClick(View v) {                mOnItemClickListener.onLongClick(position);                return true;            }        });    }

设置完监听后,就回到Activity,对Adapter设置监听,并实现方法

//设置点击事件    private void setClickEvent() {        mRecycleAdapter.setItemClickListener(new RecycleAdapter.OnItemClickListener() {            @Override            public void onClick() {                Toast.makeText(getApplicationContext(),"我点击了一下",Toast.LENGTH_SHORT).show();            }            @Override            public void onLongClick() {                Toast.makeText(getApplicationContext(),"我长按了item",Toast.LENGTH_SHORT).show();            }        });    }

现在只是简单睇地介绍了一下,不仅不够完善,而且还有很多效果没有做出来,等有时间再好好研究下.