Android5.0新特性：RecyclerView实现上拉加载更多
2024-05-24 05:14:43
RecyclerView是Android5.0以后推出的新控件，相比于ListView可定制性更大，大有取代ListView之势。下面这篇博客主要来实现RecyclerView的上拉加载更多功能。
基本思路是让RecyclerView的Adapter加载两种布局，第一个布局来显示主界面，第二个布局来显示上拉加载时的提示信息，让RecyclerView监听是否滑动到最后一个item，如果是，则调用上拉刷新的逻辑，拉取远程数据，并显示第二个布局。等加载完毕时，刷新
Adapter，并隐藏第二个布局。下面分析代码。
要加载两种不同的布局，Adapter要重写getItemViewType方法。
@Overridepublic int getItemViewType(int position) {if (position == dataList.size())return 1;elsereturn 0;}
onCreateViewHolder根据viewtype加载ViewHolder.
@Overridepublic RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {View view;if (viewType == 0) {view = LayoutInflater.from(context).inflate(R.layout.grid_redu_item, parent, false);return new NormalHolder(view);} else {view = LayoutInflater.from(context).inflate(R.layout.sample_common_list_footer, parent, false);mFooterHolder = new FooterHolder(view);return mFooterHolder;}}
注意getItemCount长度要加1。
@Overridepublic int getItemCount() {return dataList.size() + 1;}
NormalHolder
1 class NormalHolder extends RecyclerView.ViewHolder {
2 ImageView img;
3 TextView name;
4
5 public NormalHolder(View itemView) {
6 super(itemView);
7 img = (ImageView) itemView.findViewById(R.id.homepage_grid_picpic);
8 name = (TextView) itemView.findViewById(R.id.homepage_grid_name);
9 }
10
11 public void setData(int position) {
12 imageLoader.displayImage(context, imgUrls[position % imgUrls.length], img);
13 name.setText(dataList.get(position));
14 }
15 }
FooterHolder
1 public class FooterHolder extends RecyclerView.ViewHolder {
2 View mLoadingViewstubstub;
3 View mEndViewstub;
4 View mNetworkErrorViewstub;
5
6 public FooterHolder(View itemView) {
7 super(itemView);
8 mLoadingViewstubstub = itemView.findViewById(R.id.loading_viewstub);
9 mEndViewstub = itemView.findViewById(R.id.end_viewstub);
10 mNetworkErrorViewstub = itemView.findViewById(R.id.network_error_viewstub);
11 }
12
13 //根据传过来的status控制哪个状态可见
14 public void setData(LoadingFooter.FooterState status) {
15 Log.d("TAG", "reduAdapter" + status + "");
16 switch (status) {
17 case Normal:
18 setAllGone();
19 break;
20 case Loading:
21 setAllGone();
22 mLoadingViewstubstub.setVisibility(View.VISIBLE);
23 break;
24 case TheEnd:
25 setAllGone();
26 mEndViewstub.setVisibility(View.VISIBLE);
27 break;
28 case NetWorkError:
29 setAllGone();
30 mNetworkErrorViewstub.setVisibility(View.VISIBLE);
31 break;
32 default:
33 break;
34 }
35
36 }
37
38 //全部不可见
39 void setAllGone() {
40 if (mLoadingViewstubstub != null) {
41 mLoadingViewstubstub.setVisibility(View.GONE);
42 }
43 if (mEndViewstub != null) {
44 mEndViewstub.setVisibility(View.GONE);
45 }
46 if (mNetworkErrorViewstub != null) {
47 mNetworkErrorViewstub.setVisibility(View.GONE);
48 }
49 }
50
51 }
FooterHolder布局：
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:tools="http://schemas.android.com/tools"android:id="@+id/loading_view"android:layout_width="match_parent"android:layout_height="40dp"android:gravity="center"android:orientation="vertical"tools:layout_height="wrap_content"><includeandroid:id="@+id/loading_viewstub"layout="@layout/sample_common_list_footer_loading"android:layout_width="match_parent"android:layout_height="40dp" /><includeandroid:id="@+id/end_viewstub"layout="@layout/sample_common_list_footer_end"android:layout_width="match_parent"android:layout_height="40dp" /><includeandroid:id="@+id/network_error_viewstub"layout="@layout/sample_common_list_footer_network_error"android:layout_width="match_parent"android:layout_height="40dp" /> </LinearLayout>
显示效果：
主要逻辑放在Fragment里。 首先我们要绑定为RecyclerView绑定一个监听器，监听RecyclerView是否滑到了底部。 Listener代码：
package com.yctime.truelove.LoadMore;import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;
import android.view.View;import com.yctime.truelove.ImageLoader.UILPauseOnScrollListener;/*** Created by xjx* <p/>* 继承自RecyclerView.OnScrollListener，一：可以监听到是否滑动到页面最低部。二：滑动时停止加载图片*/
public class EndlessRecyclerOnScrollListener extends UILPauseOnScrollListener {/*** 当前RecyclerView类型*/protected LayoutManagerType layoutManagerType;/*** 最后一个的位置*/private int[] lastPositions;/*** 最后一个可见的item的位置*/private int lastVisibleItemPosition;/*** 当前滑动的状态*/private int currentScrollState = 0;@Overridepublic void onScrolled(RecyclerView recyclerView, int dx, int dy) {super.onScrolled(recyclerView, dx, dy);RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();if (layoutManagerType == null) {if (layoutManager instanceof LinearLayoutManager) {layoutManagerType = LayoutManagerType.LinearLayout;} else if (layoutManager instanceof GridLayoutManager) {layoutManagerType = LayoutManagerType.GridLayout;} else if (layoutManager instanceof StaggeredGridLayoutManager) {layoutManagerType = LayoutManagerType.StaggeredGridLayout;} else {throw new RuntimeException("Unsupported LayoutManager used. Valid ones are LinearLayoutManager, GridLayoutManager and StaggeredGridLayoutManager");}}switch (layoutManagerType) {case LinearLayout:lastVisibleItemPosition = ((LinearLayoutManager) layoutManager).findLastVisibleItemPosition();break;case GridLayout:lastVisibleItemPosition = ((GridLayoutManager) layoutManager).findLastVisibleItemPosition();break;case StaggeredGridLayout:StaggeredGridLayoutManager staggeredGridLayoutManager = (StaggeredGridLayoutManager) layoutManager;if (lastPositions == null) {lastPositions = new int[staggeredGridLayoutManager.getSpanCount()];}staggeredGridLayoutManager.findLastVisibleItemPositions(lastPositions);lastVisibleItemPosition = findMax(lastPositions);break;}}@Overridepublic void onScrollStateChanged(RecyclerView recyclerView, int newState) {super.onScrollStateChanged(recyclerView, newState);currentScrollState = newState;RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();int visibleItemCount = layoutManager.getChildCount();int totalItemCount = layoutManager.getItemCount();if ((visibleItemCount > 0 && currentScrollState == RecyclerView.SCROLL_STATE_IDLE && (lastVisibleItemPosition) >= totalItemCount - 1)) {onLoadNextPage(recyclerView);}}/*** 取数组中最大值** @param lastPositions* @return*/private int findMax(int[] lastPositions) {int max = lastPositions[0];for (int value : lastPositions) {if (value > max) {max = value;}}return max;}public void onLoadNextPage(final View view) {}public static enum LayoutManagerType {LinearLayout,StaggeredGridLayout,GridLayout}
}
下面是Fragment完整代码：
1 package com.yctime.truelove.fragment;
2
3
4 import android.support.v4.app.Fragment;
5 import android.support.v7.widget.DefaultItemAnimator;
6 import android.support.v7.widget.GridLayoutManager;
7 import android.support.v7.widget.LinearLayoutManager;
8 import android.support.v7.widget.RecyclerView;
9 import android.util.Log;
10 import android.view.LayoutInflater;
11 import android.view.View;
12
13 import com.yctime.truelove.LoadMore.EndlessRecyclerOnScrollListener;
14 import com.yctime.truelove.LoadMore.LoadingFooter;
15 import com.yctime.truelove.MainActivity;
16 import com.yctime.truelove.Utils.NetworkUtils;
17 import com.yctime.truelove.login.R;
18
19 import java.util.ArrayList;
20
21
22 /**
23 * A simple {@link Fragment} subclass.
24 */
25 public class HomeReDuFragment extends BaseFragment {
26
27 private RecyclerView mRecyclerView;
28 private GridAdapter_Redu gridReDuAdapter;
29 // 服务器端一共多少条数据
30 private static final int TOTAL_COUNTER = 50;
31 // 每一页展示多少条数据
32 private static final int REQUEST_COUNT = 12;
33 // 已经获取到多少条数据了
34 private int mCurrentCounter = 0;
35 //模拟的数据源
36 private ArrayList<String> dataList;
37
38
39 protected LoadingFooter.FooterState mState = LoadingFooter.FooterState.Normal;
40
41 protected void setState(LoadingFooter.FooterState mState) {
42 this.mState = mState;
43 ((MainActivity) mContext).runOnUiThread(new Runnable() {
44 @Override
45 public void run() {
46 changeAdaperState();
47 }
48 });
49 }
50
51 //改变底部bottom的样式
52 protected void changeAdaperState() {
53 if (gridReDuAdapter != null && gridReDuAdapter.mFooterHolder != null) {
54 gridReDuAdapter.mFooterHolder.setData(mState);
55 }
56 }
57
58 public HomeReDuFragment() {
59 }
60
61
62 @Override
63 protected View initView() {
64 View mView = LayoutInflater.from(mContext).inflate(R.layout.homepage_viewpager_item_redu, null);
65 mRecyclerView = (RecyclerView) mView.findViewById(R.id.home_page_recyclerview);
66 return mView;
67 }
68
69 @Override
70 protected void initData() {
71 initGridView();
72 }
73
74
75 private View initGridView() {
76 mRecyclerView.setHasFixedSize(true);
77 //滑动暂停加载网络图片,而且可以监听recycler是否滑动到底部
78 mRecyclerView.addOnScrollListener(mOnScrollListener);
79 mRecyclerView.setItemAnimator(new DefaultItemAnimator());
80 gridReDuAdapter = new GridAdapter_Redu(mContext);
81 gridReDuAdapter.addAll(getRemoteData());
82 mRecyclerView.setAdapter(gridReDuAdapter);
83 GridLayoutManager layoutManager = new GridLayoutManager(mContext, 3);
84 layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
85 layoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
86 @Override
87 public int getSpanSize(int position) {
88 //如果是最后一个item，则设置占据3列，否则占据1列
89 boolean isFooter = position == gridReDuAdapter.getItemCount() - 1;
90 return isFooter ? 3 : 1;
91 }
92 });
93 mRecyclerView.setLayoutManager(layoutManager);
94 return mRecyclerView;
95 }
96
97 private EndlessRecyclerOnScrollListener mOnScrollListener = new EndlessRecyclerOnScrollListener() {
98 @Override
99 public void onLoadNextPage(View view) {
100 super.onLoadNextPage(view);
101
102 if (mState == LoadingFooter.FooterState.Loading) {
103 Log.d("@TAG", "the state is Loading, just wait..");
104 return;
105 }
106
107 if (mCurrentCounter < TOTAL_COUNTER) {
108 // loading more
109 requestData();
110 Log.d("TAG", "请求数据");
111 } else {
112 //the end
113 setState(LoadingFooter.FooterState.TheEnd);
114 }
115 }
116 };
117
118
119 /**
120 * 模拟请求网络
121 */
122 private void requestData() {
123 setState(LoadingFooter.FooterState.Loading);
124 new Thread() {
125 @Override
126 public void run() {
127 super.run();
128 try {
129 Thread.sleep(1000);
130 } catch (InterruptedException e) {
131 e.printStackTrace();
132 }
133 if (NetworkUtils.isNetAvailable(mContext)) {
134 //模拟请求远程数据
135 gridReDuAdapter.addAll(getRemoteData());
136 //加载完毕时
137 setState(LoadingFooter.FooterState.Normal);
138 Log.d("TAG", mCurrentCounter + "");
139 } else {
140 //模拟一下网络请求失败的情况
141 setState(LoadingFooter.FooterState.NetWorkError);
142 }
143 }
144 }.start();
145 }
146
147 //模拟请求数据
148 private ArrayList<String> getRemoteData() {
149 if (dataList == null)
150 dataList = new ArrayList<>();
151 //每次都清空一下
152 dataList.clear();
153 //要减去adapter最后一页
154 for (int i = 0; i < REQUEST_COUNT; i++) {
155 if (dataList.size() + mCurrentCounter >= TOTAL_COUNTER) {
156 break;
157 }
158 dataList.add("账号" + (mCurrentCounter + i));
159 }
160 mCurrentCounter += dataList.size();
161 return dataList;
162 }
163
164
165 }
需要注意的是这个方法：
//改变底部bottom的样式protected void changeAdaperState() {if (gridReDuAdapter != null && gridReDuAdapter.mFooterHolder != null) {gridReDuAdapter.mFooterHolder.setData(mState);}}
Adapter的应用调用Adapter里面的方法，来切换Adaper的样式。 Adapter完整代码：
1 package com.yctime.truelove.fragment;
2
3 import android.content.Context;
4 import android.content.Intent;
5 import android.support.v7.widget.RecyclerView;
6 import android.util.Log;
7 import android.view.LayoutInflater;
8 import android.view.View;
9 import android.view.ViewGroup;
10 import android.widget.ImageView;
11 import android.widget.TextView;
12
13 import com.yctime.truelove.ImageLoader.MyImageLoader;
14 import com.yctime.truelove.ImageLoader.UILImageLoader;
15 import com.yctime.truelove.LoadMore.LoadingFooter;
16 import com.yctime.truelove.drawer.MyZoneActivity;
17 import com.yctime.truelove.login.R;
18
19 import java.util.ArrayList;
20
21
22 public class GridAdapter_Redu extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
23
24
25 public String[] imgUrls = {
26 "http://img5.duitang.com/uploads/item/201402/22/20140222113830_X3ddd.jpeg",
27 "http://v1.qzone.cc/avatar/201403/01/10/36/531147afa4197738.jpg!200x200.jpg",
28 "http://g.hiphotos.baidu.com/zhidao/wh%3D450%2C600/sign=e4d7ed147af40ad115b1cfe7621c3de9/b7fd5266d016092445b47837d50735fae6cd340d.jpg",
29 "http://img5q.duitang.com/uploads/item/201502/19/20150219182507_vGVaK.jpeg",
30 "http://p1.qqyou.com/touxiang/uploadpic/2013-3/12/2013031212190118646.jpg",
31 "http://img5.duitang.com/uploads/item/201412/08/20141208221323_YVJFk.png",
32 "http://cdn.duitang.com/uploads/item/201408/02/20140802222651_GWuU2.png",
33 "http://ent.dzwww.com/yulezhuanti/mtcbg/201510/W020151027467479100669.jpg",
34 "http://p1.qqyou.com/touxiang/uploadpic/2013-3/10/2013031009323656495.jpg",
35 "http://p1.qqyou.com/touxiang/uploadpic/2013-3/12/2013031212295986807.jpg",
36 "http://f.hiphotos.baidu.com/zhidao/wh%3D600%2C800/sign=10742594d739b6004d9b07b1d9601912/9f2f070828381f30ec9eabdeab014c086f06f0c5.jpg",
37 "http://a.hiphotos.baidu.com/zhidao/wh%3D600%2C800/sign=5bda8a18a71ea8d38a777c02a73a1c76/5882b2b7d0a20cf4598dc37c77094b36acaf9977.jpg",
38 "http://a1.att.hudong.com/36/98/300001051406133039983418031.jpg"
39 };
40 public Context context;
41 MyImageLoader imageLoader = new UILImageLoader();
42 private ArrayList<String> dataList = new ArrayList<>();
43
44
45 private final int NORMALLAYOUT = 0;
46 private final int FOOTERLAYOUT = 1;
47 public FooterHolder mFooterHolder;
48
49 public GridAdapter_Redu(Context context) {
50 this.context = context;
51 }
52
53 public void addAll(ArrayList<String> list) {
54 int lastIndex = this.dataList.size();
55 if (this.dataList.addAll(list)) {
56 notifyItemRangeInserted(lastIndex, list.size());
57 }
58 }
59
60 @Override
61 public int getItemViewType(int position) {
62 if (position == dataList.size())
63 return FOOTERLAYOUT;
64 else
65 return NORMALLAYOUT;
66 }
67
68
69 @Override
70 public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
71 View view;
72 if (viewType == NORMALLAYOUT) {
73 view = LayoutInflater.from(context).inflate(R.layout.grid_redu_item, parent, false);
74 return new NormalHolder(view);
75 } else {
76 view = LayoutInflater.from(context).inflate(R.layout.sample_common_list_footer, parent, false);
77 mFooterHolder = new FooterHolder(view);
78 return mFooterHolder;
79 }
80 }
81
82 @Override
83 public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
84 if (holder instanceof NormalHolder) {
85 //点击事件
86 holder.itemView.setOnClickListener(new View.OnClickListener() {
87 @Override
88 public void onClick(View v) {
89 Intent intent = new Intent(context, MyZoneActivity.class);
90 context.startActivity(intent);
91 }
92 });
93 ((NormalHolder) holder).setData(position);
94 }
95 }
96
97 @Override
98 public int getItemCount() {
99 return dataList.size() + 1;
100 }
101
102
103 class NormalHolder extends RecyclerView.ViewHolder {
104 ImageView img;
105 TextView name;
106
107 public NormalHolder(View itemView) {
108 super(itemView);
109 img = (ImageView) itemView.findViewById(R.id.homepage_grid_picpic);
110 name = (TextView) itemView.findViewById(R.id.homepage_grid_name);
111 }
112
113 public void setData(int position) {
114 imageLoader.displayImage(context, imgUrls[position % imgUrls.length], img);
115 name.setText(dataList.get(position));
116 }
117 }
118
119 public class FooterHolder extends RecyclerView.ViewHolder {
120 View mLoadingViewstubstub;
121 View mEndViewstub;
122 View mNetworkErrorViewstub;
123
124 public FooterHolder(View itemView) {
125 super(itemView);
126 mLoadingViewstubstub = itemView.findViewById(R.id.loading_viewstub);
127 mEndViewstub = itemView.findViewById(R.id.end_viewstub);
128 mNetworkErrorViewstub = itemView.findViewById(R.id.network_error_viewstub);
129 }
130
131 //根据传过来的status控制哪个状态可见
132 public void setData(LoadingFooter.FooterState status) {
133 Log.d("TAG", "reduAdapter" + status + "");
134 switch (status) {
135 case Normal:
136 setAllGone();
137 break;
138 case Loading:
139 setAllGone();
140 mLoadingViewstubstub.setVisibility(View.VISIBLE);
141 break;
142 case TheEnd:
143 setAllGone();
144 mEndViewstub.setVisibility(View.VISIBLE);
145 break;
146 case NetWorkError:
147 setAllGone();
148 mNetworkErrorViewstub.setVisibility(View.VISIBLE);
149 break;
150 default:
151 break;
152 }
153
154 }
155
156 //全部不可见
157 void setAllGone() {
158 if (mLoadingViewstubstub != null) {
159 mLoadingViewstubstub.setVisibility(View.GONE);
160 }
161 if (mEndViewstub != null) {
162 mEndViewstub.setVisibility(View.GONE);
163 }
164 if (mNetworkErrorViewstub != null) {
165 mNetworkErrorViewstub.setVisibility(View.GONE);
166 }
167 }
168
169 }
170
171 }
运行效果：
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