Android提高之SQLite分页读取实现方法

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_height="wrap_content" android:paddingBottom="4dip" android:layout_width="fill_parent"> <TextView android:layout_width="wrap_content" android:layout_below="@+id/ItemImage" android:layout_height="wrap_content" android:text="TextView01" android:layout_centerHorizontal="true" android:id="@+id/ItemText"> </TextView></RelativeLayout> 

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent"> <Button android:layout_height="wrap_content" android:layout_width="fill_parent" android:id="@+id/btnCreateDB" android:text="创建数据库"></Button> <Button android:layout_height="wrap_content" android:layout_width="fill_parent" android:text="插入一串实验数据" android:id="@+id/btnInsertRec"></Button> <Button android:layout_height="wrap_content" android:id="@+id/btnClose" android:text="关闭数据库" android:layout_width="fill_parent"></Button> <EditText android:text="@+id/EditText01" android:id="@+id/EditText01" android:layout_width="fill_parent" android:layout_height="256dip"></EditText> <GridView android:id="@+id/gridview" android:layout_width="fill_parent" android:layout_height="32dip" android:numColumns="auto_fit" android:columnWidth="40dip"></GridView></LinearLayout>

package com.testSQLite; import java.util.ArrayList; import java.util.HashMap; import android.app.Activity; import android.database.Cursor; import android.database.SQLException; import android.database.sqlite.SQLiteDatabase; import android.os.Bundle; import android.util.Log; import android.view.View; import android.widget.AdapterView; import android.widget.AdapterView.OnItemClickListener; import android.widget.Button; import android.widget.EditText; import android.widget.GridView; import android.widget.SimpleAdapter; public class testSQLite extends Activity {   /** Called when the activity is first created. */   Button btnCreateDB, btnInsert, btnClose;   EditText edtSQL;//显示分页数据   SQLiteDatabase db;   int id;//添加记录时的id累加标记，必须全局   static final int PageSize=10;//分页时，每页的数据总数   private static final String TABLE_NAME = "stu";   private static final String ID = "id";   private static final String NAME = "name";   SimpleAdapter saPageID;// 分页栏适配器   ArrayList<HashMap<String, String>> lstPageID;// 分页栏的数据源，与PageSize和数据总数相关   @Override   public void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.main);     btnCreateDB = (Button) this.findViewById(R.id.btnCreateDB);     btnCreateDB.setOnClickListener(new ClickEvent());     btnInsert = (Button) this.findViewById(R.id.btnInsertRec);     btnInsert.setOnClickListener(new ClickEvent());     btnClose = (Button) this.findViewById(R.id.btnClose);     btnClose.setOnClickListener(new ClickEvent());     edtSQL=(EditText)this.findViewById(R.id.EditText01);     GridView gridview = (GridView) findViewById(R.id.gridview);//分页栏控件     // 生成动态数组，并且转入数据     lstPageID = new ArrayList<HashMap<String, String>>();     // 生成适配器的ImageItem <====> 动态数组的元素，两者一一对应     saPageID = new SimpleAdapter(testSQLite.this, // 没什么解释         lstPageID,// 数据来源         R.layout.pagebuttons,//XML实现         new String[] { "ItemText" },         new int[] { R.id.ItemText });      // 添加并且显示     gridview.setAdapter(saPageID);     // 添加消息处理     gridview.setOnItemClickListener(new OnItemClickListener(){       @Override       public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,           long arg3) {         LoadPage(arg2);//根据所选分页读取对应的数据       }     });   }   class ClickEvent implements View.OnClickListener {     @Override     public void onClick(View v) {       if (v == btnCreateDB) {         CreateDB();       } else if (v == btnInsert) {         InsertRecord(16);//插入16条记录         RefreshPage();       }else if (v == btnClose) {         db.close();       }     }   }   /*    * 读取指定ID的分页数据    * SQL:Select * From TABLE_NAME Limit 9 Offset 10;    * 表示从TABLE_NAME表获取数据，跳过10行，取9行    */   void LoadPage(int pageID)   {     String sql= "select * from " + TABLE_NAME +      " Limit "+String.valueOf(PageSize)+ " Offset " +String.valueOf(pageID*PageSize);     Cursor rec = db.rawQuery(sql, null);     setTitle("当前分页的数据总数:"+String.valueOf(rec.getCount()));     // 取得字段名称     String title = "";     int colCount = rec.getColumnCount();     for (int i = 0; i < colCount; i++)       title = title + rec.getColumnName(i) + "   ";     // 列举出所有数据     String content="";     int recCount=rec.getCount();     for (int i = 0; i < recCount; i++) {//定位到一条数据       rec.moveToPosition(i);       for(int ii=0;ii<colCount;ii++)//定位到一条数据中的每个字段       {         content=content+rec.getString(ii)+"   ";       }       content=content+"/r/n";     }          edtSQL.setText(title+"/r/n"+content);//显示出来     rec.close();   }   /*    * 在内存创建数据库和数据表    */   void CreateDB() {     // 在内存创建数据库     db = SQLiteDatabase.create(null);     Log.e("DB Path", db.getPath());     String amount = String.valueOf(databaseList().length);     Log.e("DB amount", amount);     // 创建数据表     String sql = "CREATE TABLE " + TABLE_NAME + " (" + ID         + " text not null, " + NAME + " text not null " + ");";     try {       db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);       db.execSQL(sql);     } catch (SQLException e) {}   }   /*    * 插入N条数据    */   void InsertRecord(int n) {     int total = id + n;     for (; id < total; id++) {       String sql = "insert into " + TABLE_NAME + " (" + ID + ", " + NAME           + ") values('" + String.valueOf(id) + "', 'test');";       try {         db.execSQL(sql);       } catch (SQLException e) {       }     }   }   /*    * 插入之后刷新分页    */   void RefreshPage()   {     String sql = "select count(*) from " + TABLE_NAME;     Cursor rec = db.rawQuery(sql, null);     rec.moveToLast();     long recSize=rec.getLong(0);//取得总数     rec.close();     int pageNum=(int)(recSize/PageSize) + 1;//取得分页数          lstPageID.clear();     for (int i = 0; i < pageNum; i++) {       HashMap<String, String> map = new HashMap<String, String>();       map.put("ItemText", "No." + String.valueOf(i));      lstPageID.add(map);     }     saPageID.notifyDataSetChanged();   } }