SwipeRefreshLayout+RecyclerView实现下拉刷新上拉加载功能

Android Studio 的gradle中添加如下依赖，SwipeRefreshLayout在 support V4 包下,RecyclerView在V7包下，由于V7包内包涵了V4，所以就不需要添加V4的依赖了。

  compile 'com.android.support:appcompat-v7:23.0.0'  compile 'com.android.support:recyclerview-v7:23.0.0'

实现继承自RecyclerView.Adapter<>的适配器，实现上拉加载功能，在RecyclerView的底部添加一个footer，（根据ViewType的类型判断是添加Item还是Footer），需要重写的三个方法:

①onCreateViewHolder()
这个方法主要为每个Item inflater出一个View，但是该方法返回的是一个ViewHolder。该方法把View直接封装在ViewHolder中，然后我们面向的是ViewHolder这个实例，当然这个ViewHolder需要我们自己去编写。直接省去了当初的convertView.setTag(holder)和convertView.getTag()这些繁琐的步骤。

②onBindViewHolder()
这个方法主要用于适配渲染数据到View中。方法提供给你了一个viewHolder，而不是原来的convertView。

③getItemCount()
这个方法就类似于BaseAdapter的getCount方法了，即总共有多少个条目。

public class MyAdapter  extends RecyclerView.Adapter {    public enum LoadStatus{        CLICK_LOAD_MORE,//上拉加载更多        LOADING_MORE//正在加载更多    }    private LoadStatus mLoadStatus = LoadStatus.CLICK_LOAD_MORE;//上拉加载的状态    private static final int VIEW_TYPE_FOOTER = 0;    private static final int VIEW_TYPE_ITEM = 1;    private List mList;    private Context mContext;    public MyAdapter(Context context, List list) {        mContext = context;        mList = list;    }    @Override    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {        if (viewType == VIEW_TYPE_FOOTER) {            return onCreateFooterViewHolder(parent, viewType);        } else if (viewType == VIEW_TYPE_ITEM) {            return onCreateItemViewHolder(parent, viewType);        }        return null;    }    @Override    public void onBindViewHolder(ViewHolder holder, int position) {        switch (getItemViewType(position)) {            case VIEW_TYPE_ITEM:                onBindItemViewHolder(holder, position);                break;            case VIEW_TYPE_FOOTER:                onBindFooterViewHolder(holder, position, mLoadStatus);                break;            default:                break;        }    }    public RecyclerView.ViewHolder onCreateFooterViewHolder(ViewGroup parent, int viewType) {        View view = LayoutInflater.from(mContext).inflate(R.layout.footer_layout,parent,false);        return new FooterViewHolder(view);    }    public RecyclerView.ViewHolder onCreateItemViewHolder(ViewGroup parent, int viewType) {        View view =LayoutInflater.from(mContext).inflate(R.layout.item_layout,parent,false);        return new ItemViewHolder(view);    }    public void onBindFooterViewHolder(RecyclerView.ViewHolder holder, int poition, LoadStatus loadStatus) {        FooterViewHolder viewHolder = (FooterViewHolder) holder;        switch (loadStatus) {            case CLICK_LOAD_MORE:                viewHolder.mLoadingLayout.setVisibility(View.GONE);viewHolder.mClickLoad.setVisibility(View.VISIBLE); break;            case LOADING_MORE:                viewHolder.mLoadingLayout.setVisibility(View.VISIBLE);viewHolder.mClickLoad.setVisibility(View.GONE); break;        }    }    public void onBindItemViewHolder(RecyclerView.ViewHolder holder, int position) {        ItemViewHolder viewHolder = (ItemViewHolder) holder;        viewHolder.mTextView.setText(getItem(position));    }    @Override    public int getItemCount() {        return mList.size() + 1;    }   public  void refresh(){       notifyDataSetChanged();   }    public String getItem(int position) {        return mList.get(position);    }    public void addAll(List list) {        this.mList.addAll(list);        notifyDataSetChanged();    }    @Override    public int getItemViewType(int position) {        if (position + 1 == getItemCount()) {//最后一条为FooterView            return VIEW_TYPE_FOOTER;        }        return VIEW_TYPE_ITEM;    }    public void reSetData(List list) {        this.mList = list;        notifyDataSetChanged();    }    public void setLoadStatus(LoadStatus loadStatus) {        this.mLoadStatus = loadStatus;    }}  class FooterViewHolder extends  RecyclerView.ViewHolder{        public LinearLayout mLoadingLayout;        public TextView mClickLoad;        public FooterViewHolder(View itemView) {            super(itemView);            mLoadingLayout=(LinearLayout) itemView.findViewById(R.id.loading);            mClickLoad=(TextView) itemView.findViewById(R.id.click_load_txt);/* mClickLoad.setOnClickListener(new View.OnClickListener() {//添加点击加载更多监听                @Override                public void onClick(View view) {                    loadMore();                }            });*/        }    }  class ItemViewHolder extends  RecyclerView.ViewHolder{          public TextView mTextView;          public ItemViewHolder(View itemView) {              super(itemView);              mTextView = (TextView) itemView.findViewById(R.id.textView);          }      }

footer的layout

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="40dp"    android:gravity="center_horizontal"    android:orientation="horizontal">    <LinearLayout        android:id="@+id/loading"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:gravity="center"        android:orientation="horizontal">        <ProgressBar            android:layout_width="wrap_content"            android:layout_height="match_parent"/>        <TextView            android:layout_width="wrap_content"            android:layout_height="match_parent"            android:gravity="center_vertical"            android:text="正在加载..."/>    LinearLayout>    <TextView        android:id="@+id/click_load_txt"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:gravity="center"        android:paddingTop="5dp"        android:paddingBottom="5dp"        android:text="点击加载更多"        android:visibility="gone"/>RelativeLayout>

Item的layout

<?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"><TextView    android:gravity="center"    android:id="@+id/textView"    android:layout_width="match_parent"    android:layout_height="wrap_content"    />LinearLayout>

activity_main

<?xml version="1.0" encoding="utf-8"?>"http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context="com.example.yzppp.recycle.MainActivity">    .support.v4.widget.SwipeRefreshLayout        android:id="@+id/swipeRefreshLayout"        android:layout_width="match_parent"        android:layout_height="match_parent">        .support.v7.widget.RecyclerView            android:id="@+id/recyclerView"            android:layout_width="match_parent"            android:layout_height="match_parent">        .support.v7.widget.RecyclerView>    .support.v4.widget.SwipeRefreshLayout>

MainActivity的实现，下拉刷新通过SwipeRefreshLayout.OnRefreshListener()
接口来实现。

public class MainActivity extends Activity {private RecyclerView mRecyclerView;private  SwipeRefreshLayout mSwipeRefreshLayout;private MyAdapter mAdapter;    private int mLastVisibleItemPosition=0;    private LinearLayoutManager mLayoutManager;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        mRecyclerView= (RecyclerView) findViewById(R.id.recyclerView);        mSwipeRefreshLayout= (SwipeRefreshLayout) findViewById(R.id.swipeRefreshLayout);        mLayoutManager=new LinearLayoutManager(this);        mRecyclerView.setLayoutManager(mLayoutManager);        mRecyclerView.setItemAnimator(new DefaultItemAnimator());        mAdapter=new MyAdapter(this,getData("init"));        mRecyclerView.setAdapter(mAdapter);        mSwipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener(){                         @Override                         public void onRefresh() {                        new Thread(){                          @Override                          public void run() {                              try{                                Thread.sleep(3000);                                final List list=getData("refresh");                                runOnUiThread(new Runnable() {                                    @Override                                    public void run() {                                        mAdapter.reSetData(list);                                        mSwipeRefreshLayout.setRefreshing(false);                                    }                                });                              }                              catch (InterruptedException e){                                  e.printStackTrace();                              }                          }                      }.start();                      }             });        mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener(){            @Override//滚动状态变化时回调            public void onScrollStateChanged(RecyclerView recyclerView, int newState)    {                super.onScrollStateChanged(recyclerView, newState);               // mLastVisibleItemPosition=mLayoutManager.findLastVisibleItemPosition();                //滑动停止并且底部不可滚动（即滑动到底部） 加载更多                if(newState==RecyclerView.SCROLL_STATE_IDLE&&!(ViewCompat.canScrollVertically(recyclerView,1))                       ){                         loadMore();                }            }            @Override//滚动时回调            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {                super.onScrolled(recyclerView, dx, dy);            }        });   }    public void loadMore(){        mAdapter.setLoadStatus(MyAdapter.LoadStatus.LOADING_MORE);        mAdapter.refresh();        new Thread(){            @Override            public void run() {                try{                    Thread.sleep(3000);                    final List list=getData("load more");                    runOnUiThread(new Runnable() {                        @Override                        public void run() {                            mAdapter.addAll(list);                            mAdapter.setLoadStatus(MyAdapter.LoadStatus.CLICK_LOAD_MORE);                        }                    });                }catch (InterruptedException e){                  e.printStackTrace();                };            }        }.start();    }    public  List getData(String flag){        int idx=1;        if(mAdapter!=null){            idx=mAdapter.getItemCount();        }        List list=new ArrayList<>(10);        for (int i=0;i<10;i++){            list.add(flag+":"+(idx+i));        }        return list;    }}

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