公共代码参考（SQLiteOpenHelper）

package com.fredric.util;



import android.content.ContentValues;

import android.content.Context;

import android.database.Cursor;

import android.database.sqlite.SQLiteDatabase;

import android.database.sqlite.SQLiteDatabase.CursorFactory;

import android.database.sqlite.SQLiteOpenHelper;



/*-

 * sqlite数据库操作封装

 */



public class DBHelper extends SQLiteOpenHelper{

    private final static String DB_NAME  = "demo.db";

    private final static String TBL_NAME = "users";

    private static final int DB_VERSION  = 1;

    private final static String CREATE_TBL 

        = "CREATE TABLE IF NOT EXISTS users (_id INTEGER PRIMARY KEY AUTOINCREMENT, username VARCHAR, password VARCHAR)"; 

    private SQLiteDatabase db;



    public DBHelper(Context context, String name, CursorFactory factory,

            int version) {

        super(context, name, factory, version);

    }

    

    public DBHelper(Context context){  

        this(context, DB_NAME, null, DB_VERSION);  

    }



    //当数据库第一次被建立的时候被执行，例如创建表,初始化数据等

    @Override

    public void onCreate(SQLiteDatabase db) {

        this.db = db;

        db.execSQL(CREATE_TBL);

    }



    //当数据库需要被更新的时候执行，例如删除表，创建表

    @Override

    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

        

    }

    

    public void insert(ContentValues values){  

        SQLiteDatabase db = getWritableDatabase();  

        db.insert(TBL_NAME, null, values);  

        db.close();  

    }  

          

    //查询方法  

    public Cursor rawQuery(String sql, String[] args){  

        SQLiteDatabase db = getReadableDatabase();  

        Cursor cursor = db.rawQuery(sql, args);  

        return cursor;           

    }  

          

    //删除数据  

    public void delete(int id){  

        SQLiteDatabase db = getWritableDatabase();  

        db.delete(TBL_NAME, "_id=?", new String[]{String.valueOf(id)});  

    }  

                

    //更新数据库的内容  

    public void update(ContentValues values, String whereClause, String[] whereArgs){  

        SQLiteDatabase db = getWritableDatabase();  

        db.update(TBL_NAME, values, whereClause, whereArgs);  

    }  

          

    //关闭数据库  

    public void close(){  

        if(db != null){  

            db.close();  

        }  

    }     

}