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(); 
  } 
}