这两天在公司没有什么任务分配，就研究了下咱们Google在Android5.0 推出的一个用来取代ListView的列表控件----RecyclerView。

发现功能上确实比ListView强大了不少，可扩展性也增强了不少。

可是使用过RecyclerView的Programmers应该都知道，RecyclerView无法直接代码加入头布局和脚布局。

那么他喵的怎么样实现最经常使用的底部载入很多其它数据呢？带着这种疑惑我在StackOverFlow上搜索到了一个有參考价值的答案并写了一个Demo实现了它。

參考链接附上：http://stackoverflow.com/questions/30681905/adding-items-to-endless-scroll-recyclerview-with-progressbar-at-bottom?answertab=active#tab-top

废话不多说。開始进入正题，直接上代码。

第一步：创建两个接口

public interface LoadMoreDataListener {

    public abstract void loadMoreData();

}
public interface RecyclerOnItemClickListener {

    public abstract void onClick(View view);

}




第二步：依据XML中的布局来创建一个Activity


public class MainActivity extends AppCompatActivity {

    private RecyclerView mRecyclerView;

    private TextView tv_empty;

    private List<String> list = new ArrayList<>();

    private List<String> moreData = new ArrayList<>();

    private List<String> refreshData = new ArrayList<>();

    private MyAdapter myAdapter;

    private Handler handler = new Handler();

    private SwipeRefreshLayout sfl;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);

        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);

        fab.setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View view) {

                //// TODO: 点击FAB后的操作

            }

        });

        init();

    }

    private void init() {

        initData();

        initRefreshData();

        initMoreData();

        initView();

        initListener();

    }

    private void initView() {

        mRecyclerView = (RecyclerView) findViewById(R.id.mRecyclerView);

        tv_empty = (TextView) findViewById(R.id.tv_empty);

        sfl = (SwipeRefreshLayout) findViewById(R.id.sfl);

        sfl.setColorSchemeColors(Color.parseColor("#FF4081"));

        //创建一个LinearLayoutManager对象

        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false);

        mRecyclerView.setLayoutManager(linearLayoutManager);

        //创建adapter对象

        myAdapter = new MyAdapter(this, mRecyclerView);

        mRecyclerView.setAdapter(myAdapter);

        myAdapter.setData(list);//设置数据

        if (list.isEmpty()) {

            mRecyclerView.setVisibility(View.GONE);

            tv_empty.setVisibility(View.VISIBLE);

        } else {

            mRecyclerView.setVisibility(View.VISIBLE);

            tv_empty.setVisibility(View.GONE);

        }

    }

    //初始化数据

    private void initData() {

        for (int i = 0; i < 20; i++) {

            list.add("handsome is wrong?" + i);

        }

    }

    //初始化载入很多其它数据

    private void initMoreData() {

        for (int i = 0; i < 10; i++) {

            moreData.add("life is good" + i);

        }

    }

    private void initRefreshData() {

        for (int i = 0; i < 2; i++) {

            refreshData.add("refreshData" + i);

        }

    }

    //初始化监听

    private void initListener() {

        sfl.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {

            @Override

            public void onRefresh() {

                //模拟下拉刷新数据操作

                handler.postDelayed(new Runnable() {

                    @Override

                    public void run() {

                        list.addAll(0, refreshData);

                        myAdapter.notifyDataSetChanged();

                        sfl.setRefreshing(false);

                    }

                }, 1000);

            }

        });

        //载入很多其它回调监听

        myAdapter.setOnMoreDataLoadListener(new LoadMoreDataListener() {

            @Override

            public void loadMoreData() {

                //增加null值此时adapter会推断item的type

                list.add(null);

                myAdapter.notifyDataSetChanged();

                handler.postDelayed(new Runnable() {

                    @Override

                    public void run() {

                        //移除刷新的progressBar

                        list.remove(list.size() - 1);

                        myAdapter.notifyDataSetChanged();

                        list.addAll(moreData);

                        myAdapter.notifyDataSetChanged();

                        myAdapter.setLoaded();

                    }

                }, 2000);

            }

        });

        myAdapter.setOnItemClickListener(new RecyclerOnItemClickListener() {

            @Override

            public void onClick(View view) {

                //Toast.makeText(MainActivity.this, "能不能不要这么帅", Toast.LENGTH_SHORT).show();

                Snackbar.make(view, "Iam BadGuy_Leo", Snackbar.LENGTH_SHORT).show();

            }

        });

    }

}


activity_main


<?xml version="1.0" encoding="utf-8"?

>

<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:app="http://schemas.android.com/apk/res-auto"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:fitsSystemWindows="true"

    tools:context="com.byzk.loadmorerecyclerview.MainActivity">

    <android.support.design.widget.AppBarLayout

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar

            android:id="@+id/toolbar"

            android:layout_width="match_parent"

            android:layout_height="?attr/actionBarSize"

            android:background="?attr/colorPrimary"

            app:popupTheme="@style/AppTheme.PopupOverlay" />

    </android.support.design.widget.AppBarLayout>

    <include layout="@layout/content_main" />

    <android.support.design.widget.FloatingActionButton

        android:id="@+id/fab"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_gravity="bottom|end"

        android:layout_margin="@dimen/fab_margin"

        android:src="@android:drawable/ic_dialog_email" />

</android.support.design.widget.CoordinatorLayout>


content_main


<?xml version="1.0" encoding="utf-8"?

>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:app="http://schemas.android.com/apk/res-auto"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    app:layout_behavior="@string/appbar_scrolling_view_behavior"

    tools:context="com.byzk.loadmorerecyclerview.MainActivity"

    tools:showIn="@layout/activity_main">

    <android.support.v4.widget.SwipeRefreshLayout

        android:id="@+id/sfl"

        android:layout_width="match_parent"

        android:layout_height="match_parent">

        <android.support.v7.widget.RecyclerView

            android:id="@+id/mRecyclerView"

            android:layout_width="match_parent"

            android:layout_height="wrap_content"

            android:layout_margin="5dp"

            android:padding="5dp"

            android:scrollbars="vertical">

        </android.support.v7.widget.RecyclerView>

    </android.support.v4.widget.SwipeRefreshLayout>

    <TextView

        android:id="@+id/tv_empty"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_centerInParent="true"

        android:text="暂无数据"

        android:textColor="@color/colorAccent"

        android:visibility="gone" />

</RelativeLayout>



创建RecyclerView的条目布局 item_view


<?xml version="1.0" encoding="utf-8"?>

<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:card_view="http://schemas.android.com/apk/res-auto"

    android:layout_width="match_parent"

    android:layout_height="wrap_content"

    android:clickable="true"

    android:orientation="horizontal"

    card_view:cardUseCompatPadding="true">

    <RelativeLayout

        android:layout_width="match_parent"

        android:layout_height="80dp"

        android:background="?

android:selectableItemBackground"

        android:gravity="center">

        <TextView

            android:id="@+id/tv_name"

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:layout_centerInParent="true"

            android:layout_margin="5dp"

            android:text="Name"

            android:textColor="@android:color/black"

            android:textSize="18sp" />

    </RelativeLayout>

</android.support.v7.widget.CardView>


创建脚布局item_footer


<?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="wrap_content"

    android:gravity="center"

    android:orientation="vertical"

    android:padding="10dp">

    <ProgressBar

        android:id="@+id/pb"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content" />

</LinearLayout>


第三步：创建一个RecyclerView的Adapter 这一步是很关键的一步。使用过RecyclerView的programmer应该都知道它无法设置条目点击事件——！


所以必须自己写一个接口回调，来自己定制点击事件。代码例如以下


/**

 * Author: lihongxiang

 * Time: 上午 11:14

 * Email:lihongxiangleo@163.com

 */

public class MyAdapter extends RecyclerView.Adapter {

    private static final int VIEW_ITEM = 0;

    private static final int VIEW_PROG = 1;

    private final Context mContext;

    private final RecyclerView mRecyclerView;

    private List<String> mData;

    private final LayoutInflater inflater;

    private boolean isLoading;

    private int totalItemCount;

    private int lastVisibleItemPosition;

    //当前滚动的position以下最小的items的临界值

    private int visibleThreshold = 5;

    public MyAdapter(Context context, RecyclerView recyclerView) {

        mContext = context;

        inflater = LayoutInflater.from(context);

        mRecyclerView = recyclerView;

        if (mRecyclerView.getLayoutManager() instanceof LinearLayoutManager) {

            final LinearLayoutManager linearLayoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();

            //mRecyclerView加入滑动事件监听

            mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {

                @Override

                public void onScrolled(RecyclerView recyclerView, int dx, int dy) {

                    super.onScrolled(recyclerView, dx, dy);

                    totalItemCount = linearLayoutManager.getItemCount();

                    lastVisibleItemPosition = linearLayoutManager.findLastVisibleItemPosition();

                    Log.d("test", "totalItemCount =" + totalItemCount + "-----" + "lastVisibleItemPosition =" + lastVisibleItemPosition);

                    if (!isLoading && totalItemCount <= (lastVisibleItemPosition + visibleThreshold)) {

                        //此时是刷新状态

                        if (mMoreDataListener != null)

                            mMoreDataListener.loadMoreData();

                        isLoading = true;

                    }

                }

            });

        }

    }

    public void setLoaded() {

        isLoading = false;

    }

   @Override

    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        RecyclerView.ViewHolder holder;

        if (viewType == VIEW_ITEM) {

            holder = new MyViewHolder(inflater.inflate(R.layout.item_view, parent, false));

        } else {

            holder = new MyProgressViewHolder(inflater.inflate(R.layout.item_footer, parent, false));

        }

        return holder;

    }


 @Override

    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {

        if (holder instanceof MyViewHolder) {

            if (((MyViewHolder) holder).tv_name != null)

                ((MyViewHolder) holder).tv_name.setText(mData.get(position));

        } else if (holder instanceof MyProgressViewHolder) {

            if (((MyProgressViewHolder) holder).pb != null)

                ((MyProgressViewHolder) holder).pb.setIndeterminate(true);

        }

    }

    @Override

    public int getItemCount() {

        return mData == null ? 0 : mData.size();

    }

    //依据不同的数据返回不同的viewType

    @Override

    public int getItemViewType(int position) {

        return mData.get(position) != null ? VIEW_ITEM : VIEW_PROG;

    }

    public class MyViewHolder extends RecyclerView.ViewHolder {

        private final TextView tv_name;

        public MyViewHolder(View itemView) {

            super(itemView);

            tv_name = (TextView) itemView.findViewById(R.id.tv_name);

            itemView.setOnClickListener(new View.OnClickListener() {

                @Override

                public void onClick(View v) {

                    if (mOnitemClickListener != null)

                        mOnitemClickListener.onClick(v);

                }

            });

        }

    }

    public class MyProgressViewHolder extends RecyclerView.ViewHolder {

        private final ProgressBar pb;

        public MyProgressViewHolder(View itemView) {

            super(itemView);

            pb = (ProgressBar) itemView.findViewById(R.id.pb);

        }

    }

    //设置数据的方法

    public void setData(List<String> data) {

        mData = data;

    }

    private LoadMoreDataListener mMoreDataListener;

    //载入很多其它监听方法

    public void setOnMoreDataLoadListener(LoadMoreDataListener onMoreDataLoadListener) {

        mMoreDataListener = onMoreDataLoadListener;

    }

    private RecyclerOnItemClickListener mOnitemClickListener;

    //点击事件监听方法

    public void setOnItemClickListener(RecyclerOnItemClickListener onItemClickListener) {

        mOnitemClickListener = onItemClickListener;

    }

}







通过以上几部操作，就能够实现RecyclerView的底部载入很多其它的功能了，同一时候我用SwipeRefreshLayout实现了下拉刷新。


今天第一次写技术博客，应该有非常多地方写的不够妥当，望各位大神们指点。实现效果例如以下！




												


																

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