基于Android官方Paging Library的RecyclerView分页加载框架

基于Android官方Paging Library的RecyclerView分页加载框架

我之前写了一篇RecyclerView分页加载机制的文章，是基于Android官方的AsyncListUtil实现的，详情见附录文章1。现在再介绍一种RecyclerView分页加载框架：Android Paging Library。
Android Paging Library是Android官方support-v7支持包中专门做的分页框架，详细文档见谷歌官方文档附录2页面。我写这篇文章时候Paging Library的版本是1.0.0-alpha3。
使用Android Paging Library首先需要在gradle添加引用：

[plain] view plain copy

print?

implementation 'android.arch.paging:runtime:1.0.0-alpha3'

下面我写示例代码做一个简单的演示：

[java] view plain copy

print?

1. package
3. import
4. import
5. import
6. import
7. import
8. import
9. import
10. import
11. import
12. import
13. import
14. import
15. import
16. import
17. import
18. import
19. import
21. import
22. import
23. import
25. publicclassextends
26. private
27. private
29. private
30. private
32. private
34. @Override
35. protectedvoid
36. super
39. new
44. newthis
48. new
53. new
54. privateint
56. @Override
57. publicvoidint
58. super
67. privatevoid
68. new
69. 3//分页数据的数量。在后面的DataSource之loadRange中，count即为每次加载的这个设定值。
70. 5//初始化时候，预取数据数量。
71. false
74. new
77. new//初始化阶段启用
78. new//初始化阶段启动
82. privateclassimplements
83. public
84. this.execute(new
85. @Override
86. publicvoid
87. ”BackgroundThreadTask”“run”
92. @Override
93. publicvoid@NonNull
98. privateclassimplements
99. public
100. this.execute(new
101. @Override
102. publicvoid
103. ”MainThreadTask”“run”
108. @Override
109. publicvoid@NonNull
114. privateclassextends
116. @Override
117. publicint
118. return
121. /**
128. @Override
129. publicintint
130. ”MyDataSource”“loadRange:”“,”
132. return
136. /**
143. privateintint
144. new
146. forint0
147. new
149. ”zhangphil@”
153. return
156. privateclassextends
157. public
158. public
160. public
161. super
171. privateclassextends
172. public
173. super
176. @Override
177. publicint
178. null
179. new
180. return
183. @Override
184. publicvoidint
191. privatenew
193. @Override
194. publicboolean@NonNull@NonNull
195. ”DiffCallback”“areItemsTheSame”
196. return
199. @Override
200. publicboolean@NonNull@NonNull
201. ”DiffCallback”“areContentsTheSame”
202. return
206. privateclass
207. publicint
208. public

package zhangphil.demo;  import android.arch.paging.PagedList; import android.arch.paging.PagedListAdapter; import android.arch.paging.TiledDataSource; import android.graphics.Color; import android.support.annotation.NonNull; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.support.v7.recyclerview.extensions.DiffCallback; import android.support.v7.widget.LinearLayoutManager; import android.support.v7.widget.RecyclerView; import android.text.TextUtils; import android.util.Log; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.LinearLayout; import android.widget.TextView;  import java.util.ArrayList; import java.util.List; import java.util.concurrent.Executor;  public class MainActivity extends AppCompatActivity {     private PagedList<DataBean> mPagedList;     private MyDataSource mDataSource;      private RecyclerView mRecyclerView;     private PagedListAdapter mAdapter;      private LinearLayoutManager mLayoutManager;      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);          mDataSource = new MyDataSource();         makePageList();          mRecyclerView = findViewById(R.id.recycler_view);          mLayoutManager = new LinearLayoutManager(this);         mLayoutManager.setOrientation(LinearLayout.VERTICAL);         mRecyclerView.setLayoutManager(mLayoutManager);          mAdapter = new MyAdapter();         mRecyclerView.setAdapter(mAdapter);          mAdapter.setList(mPagedList);          mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {             private int lastPos;              @Override             public void onScrollStateChanged(RecyclerView recyclerView, int newState) {                 super.onScrollStateChanged(recyclerView, newState);                  lastPos = mLayoutManager.findLastVisibleItemPosition();                  mPagedList.loadAround(lastPos);//触发Android Paging的加载事务逻辑。             }         });     }      private void makePageList() {         PagedList.Config mPagedListConfig = new PagedList.Config.Builder()                 .setPageSize(3) //分页数据的数量。在后面的DataSource之loadRange中，count即为每次加载的这个设定值。                 .setPrefetchDistance(5) //初始化时候，预取数据数量。                 .setEnablePlaceholders(false)                 .build();          mPagedList = new PagedList.Builder()                 .setConfig(mPagedListConfig)                 .setDataSource(mDataSource)                 .setMainThreadExecutor(new BackgroundThreadTask()) //初始化阶段启用                 .setBackgroundThreadExecutor(new MainThreadTask()) //初始化阶段启动                 .build();     }      private class BackgroundThreadTask implements Executor {         public BackgroundThreadTask() {             this.execute(new Runnable() {                 @Override                 public void run() {                     Log.d("BackgroundThreadTask", "run");                 }             });         }          @Override         public void execute(@NonNull Runnable runnable) {             runnable.run();         }     }      private class MainThreadTask implements Executor {         public MainThreadTask() {             this.execute(new Runnable() {                 @Override                 public void run() {                     Log.d("MainThreadTask", "run");                 }             });         }          @Override         public void execute(@NonNull Runnable runnable) {             runnable.run();         }     }      private class MyDataSource extends TiledDataSource<DataBean> {          @Override         public int countItems() {             return TiledDataSource.COUNT_UNDEFINED;         }          /**          * 注意，这里需要后台线程化。          *          * @param startPosition          * @param count          * @return          */         @Override         public List<DataBean> loadRange(int startPosition, int count) {             Log.d("MyDataSource", "loadRange:" + startPosition + "," + count);             List<DataBean> list = loadData(startPosition, count);             return list;         }     }      /**      * 假设这里需要做一些后台线程的数据加载任务。      *      * @param startPosition      * @param count      * @return      */     private List<DataBean> loadData(int startPosition, int count) {         List<DataBean> list = new ArrayList();          for (int i = 0; i < count; i++) {             DataBean data = new DataBean();             data.id = startPosition + i;             data.content = "zhangphil@" + data.id;             list.add(data);         }          return list;     }      private class MyViewHolder extends RecyclerView.ViewHolder {         public TextView text1;         public TextView text2;          public MyViewHolder(View itemView) {             super(itemView);              text1 = itemView.findViewById(android.R.id.text1);             text1.setTextColor(Color.RED);              text2 = itemView.findViewById(android.R.id.text2);             text2.setTextColor(Color.BLUE);         }     }      private class MyAdapter extends PagedListAdapter<DataBean, MyViewHolder> {         public MyAdapter() {             super(mDiffCallback);         }          @Override         public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {             View view = LayoutInflater.from(getApplicationContext()).inflate(android.R.layout.simple_list_item_2, null);             MyViewHolder holder = new MyViewHolder(view);             return holder;         }          @Override         public void onBindViewHolder(MyViewHolder holder, int position) {             DataBean data = mPagedList.get(position);             holder.text1.setText(String.valueOf(position));             holder.text2.setText(String.valueOf(data.content));         }     }      private DiffCallback<DataBean> mDiffCallback = new DiffCallback<DataBean>() {          @Override         public boolean areItemsTheSame(@NonNull DataBean oldItem, @NonNull DataBean newItem) {             Log.d("DiffCallback", "areItemsTheSame");             return oldItem.id == newItem.id;         }          @Override         public boolean areContentsTheSame(@NonNull DataBean oldItem, @NonNull DataBean newItem) {             Log.d("DiffCallback", "areContentsTheSame");             return TextUtils.equals(oldItem.content, newItem.content);         }     };      private class DataBean {         public int id;         public String content;     } }

代码实现的功能很简单，当RecyclerView不断下滑时，就触发分页加载，把RecyclerView后续使用的数据分页加载显示出来。暂时我将现阶段对Android Paging Library技术的心得记录下来，作为我学习Android Paging Library技术的阶段性备忘录。这部分代码还有待进一步完善，Android Paging Library技术细节后续会继续跟进研究。


附录：

2，谷歌Android官方Android Paging Library技术文档主页：https://developer.android.google.cn/topic/libraries/architecture/paging.html#classes

转自:https://blog.csdn.net/zhangphil/article/details/78627332

基于Android官方Paging Library的RecyclerView分页加载框架

我之前写了一篇RecyclerView分页加载机制的文章，是基于Android官方的AsyncListUtil实现的，详情见附录文章1。现在再介绍一种RecyclerView分页加载框架：Android Paging Library。
Android Paging Library是Android官方support-v7支持包中专门做的分页框架，详细文档见谷歌官方文档附录2页面。我写这篇文章时候Paging Library的版本是1.0.0-alpha3。
使用Android Paging Library首先需要在gradle添加引用：

[plain] view plain copy

print?

implementation 'android.arch.paging:runtime:1.0.0-alpha3'

下面我写示例代码做一个简单的演示：

[java] view plain copy

print?

1. package
3. import
4. import
5. import
6. import
7. import
8. import
9. import
10. import
11. import
12. import
13. import
14. import
15. import
16. import
17. import
18. import
19. import
21. import
22. import
23. import
25. publicclassextends
26. private
27. private
29. private
30. private
32. private
34. @Override
35. protectedvoid
36. super
39. new
44. newthis
48. new
53. new
54. privateint
56. @Override
57. publicvoidint
58. super
67. privatevoid
68. new
69. 3//分页数据的数量。在后面的DataSource之loadRange中，count即为每次加载的这个设定值。
70. 5//初始化时候，预取数据数量。
71. false
74. new
77. new//初始化阶段启用
78. new//初始化阶段启动
82. privateclassimplements
83. public
84. this.execute(new
85. @Override
86. publicvoid
87. ”BackgroundThreadTask”“run”
92. @Override
93. publicvoid@NonNull
98. privateclassimplements
99. public
100. this.execute(new
101. @Override
102. publicvoid
103. ”MainThreadTask”“run”
108. @Override
109. publicvoid@NonNull
114. privateclassextends
116. @Override
117. publicint
118. return
121. /**
128. @Override
129. publicintint
130. ”MyDataSource”“loadRange:”“,”
132. return
136. /**
143. privateintint
144. new
146. forint0
147. new
149. ”zhangphil@”
153. return
156. privateclassextends
157. public
158. public
160. public
161. super
171. privateclassextends
172. public
173. super
176. @Override
177. publicint
178. null
179. new
180. return
183. @Override
184. publicvoidint
191. privatenew
193. @Override
194. publicboolean@NonNull@NonNull
195. ”DiffCallback”“areItemsTheSame”
196. return
199. @Override
200. publicboolean@NonNull@NonNull
201. ”DiffCallback”“areContentsTheSame”
202. return
206. privateclass
207. publicint
208. public

package zhangphil.demo;  import android.arch.paging.PagedList; import android.arch.paging.PagedListAdapter; import android.arch.paging.TiledDataSource; import android.graphics.Color; import android.support.annotation.NonNull; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.support.v7.recyclerview.extensions.DiffCallback; import android.support.v7.widget.LinearLayoutManager; import android.support.v7.widget.RecyclerView; import android.text.TextUtils; import android.util.Log; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.LinearLayout; import android.widget.TextView;  import java.util.ArrayList; import java.util.List; import java.util.concurrent.Executor;  public class MainActivity extends AppCompatActivity {     private PagedList<DataBean> mPagedList;     private MyDataSource mDataSource;      private RecyclerView mRecyclerView;     private PagedListAdapter mAdapter;      private LinearLayoutManager mLayoutManager;      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);          mDataSource = new MyDataSource();         makePageList();          mRecyclerView = findViewById(R.id.recycler_view);          mLayoutManager = new LinearLayoutManager(this);         mLayoutManager.setOrientation(LinearLayout.VERTICAL);         mRecyclerView.setLayoutManager(mLayoutManager);          mAdapter = new MyAdapter();         mRecyclerView.setAdapter(mAdapter);          mAdapter.setList(mPagedList);          mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {             private int lastPos;              @Override             public void onScrollStateChanged(RecyclerView recyclerView, int newState) {                 super.onScrollStateChanged(recyclerView, newState);                  lastPos = mLayoutManager.findLastVisibleItemPosition();                  mPagedList.loadAround(lastPos);//触发Android Paging的加载事务逻辑。             }         });     }      private void makePageList() {         PagedList.Config mPagedListConfig = new PagedList.Config.Builder()                 .setPageSize(3) //分页数据的数量。在后面的DataSource之loadRange中，count即为每次加载的这个设定值。                 .setPrefetchDistance(5) //初始化时候，预取数据数量。                 .setEnablePlaceholders(false)                 .build();          mPagedList = new PagedList.Builder()                 .setConfig(mPagedListConfig)                 .setDataSource(mDataSource)                 .setMainThreadExecutor(new BackgroundThreadTask()) //初始化阶段启用                 .setBackgroundThreadExecutor(new MainThreadTask()) //初始化阶段启动                 .build();     }      private class BackgroundThreadTask implements Executor {         public BackgroundThreadTask() {             this.execute(new Runnable() {                 @Override                 public void run() {                     Log.d("BackgroundThreadTask", "run");                 }             });         }          @Override         public void execute(@NonNull Runnable runnable) {             runnable.run();         }     }      private class MainThreadTask implements Executor {         public MainThreadTask() {             this.execute(new Runnable() {                 @Override                 public void run() {                     Log.d("MainThreadTask", "run");                 }             });         }          @Override         public void execute(@NonNull Runnable runnable) {             runnable.run();         }     }      private class MyDataSource extends TiledDataSource<DataBean> {          @Override         public int countItems() {             return TiledDataSource.COUNT_UNDEFINED;         }          /**          * 注意，这里需要后台线程化。          *          * @param startPosition          * @param count          * @return          */         @Override         public List<DataBean> loadRange(int startPosition, int count) {             Log.d("MyDataSource", "loadRange:" + startPosition + "," + count);             List<DataBean> list = loadData(startPosition, count);             return list;         }     }      /**      * 假设这里需要做一些后台线程的数据加载任务。      *      * @param startPosition      * @param count      * @return      */     private List<DataBean> loadData(int startPosition, int count) {         List<DataBean> list = new ArrayList();          for (int i = 0; i < count; i++) {             DataBean data = new DataBean();             data.id = startPosition + i;             data.content = "zhangphil@" + data.id;             list.add(data);         }          return list;     }      private class MyViewHolder extends RecyclerView.ViewHolder {         public TextView text1;         public TextView text2;          public MyViewHolder(View itemView) {             super(itemView);              text1 = itemView.findViewById(android.R.id.text1);             text1.setTextColor(Color.RED);              text2 = itemView.findViewById(android.R.id.text2);             text2.setTextColor(Color.BLUE);         }     }      private class MyAdapter extends PagedListAdapter<DataBean, MyViewHolder> {         public MyAdapter() {             super(mDiffCallback);         }          @Override         public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {             View view = LayoutInflater.from(getApplicationContext()).inflate(android.R.layout.simple_list_item_2, null);             MyViewHolder holder = new MyViewHolder(view);             return holder;         }          @Override         public void onBindViewHolder(MyViewHolder holder, int position) {             DataBean data = mPagedList.get(position);             holder.text1.setText(String.valueOf(position));             holder.text2.setText(String.valueOf(data.content));         }     }      private DiffCallback<DataBean> mDiffCallback = new DiffCallback<DataBean>() {          @Override         public boolean areItemsTheSame(@NonNull DataBean oldItem, @NonNull DataBean newItem) {             Log.d("DiffCallback", "areItemsTheSame");             return oldItem.id == newItem.id;         }          @Override         public boolean areContentsTheSame(@NonNull DataBean oldItem, @NonNull DataBean newItem) {             Log.d("DiffCallback", "areContentsTheSame");             return TextUtils.equals(oldItem.content, newItem.content);         }     };      private class DataBean {         public int id;         public String content;     } }

代码实现的功能很简单，当RecyclerView不断下滑时，就触发分页加载，把RecyclerView后续使用的数据分页加载显示出来。暂时我将现阶段对Android Paging Library技术的心得记录下来，作为我学习Android Paging Library技术的阶段性备忘录。这部分代码还有待进一步完善，Android Paging Library技术细节后续会继续跟进研究。


附录：

2，谷歌Android官方Android Paging Library技术文档主页：https://developer.android.google.cn/topic/libraries/architecture/paging.html#classes

文章来源: 基于Android官方Paging Library的RecyclerView分页加载框架