Android 数据存储与读取：SQLite

    

        Android 数据存储与读取：SQLite             

分类：             Android 基础              2012-09-15 20:36     2309人阅读     评论(0)     收藏     举报    

sqlite android 存储 user 数据库 integer

在Android平台上，集成了一个嵌入式关系型数据库—SQLite。如果你想要开发 Android 应用程序，一定需要在 Android 上存储数据，使用SQLite 数据库是一种非常好的选择。

下面介绍的基本使用：

是一个抽象类不能直接实例化，所以新建一个类DBOpenHelper继承自SQLiteOpenHelper ：

public class DBOpenHelper extends SQLiteOpenHelper {
    public DBOpenHelper(Context context) {
        super(context, "yhn.db", null, 1);
    }

    //数据库第一次创建时候调用，
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table user(uid integer primary key autoincrement, uname varchar(20), uaddress varchar(20))");
    }

    //数据库文件版本号发生变化时调用
    public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {

    }

public class DBOpenHelper extends SQLiteOpenHelper {
	public DBOpenHelper(Context context) {
		super(context, "yhn.db", null, 1);
	}

	//数据库第一次创建时候调用，
	public void onCreate(SQLiteDatabase db) {
		db.execSQL("create table user(uid integer primary key autoincrement, uname varchar(20), uaddress varchar(20))");
	}

	//数据库文件版本号发生变化时调用
	public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {

	}

如果执行上边的代码，则会创建一个数据库文件xx.db

数据库操作类：

public class DBDao {
    DBOpenHelper dbOpenHelper;

    public DBDao(Context context){
        this.dbOpenHelper=new DBOpenHelper(context);
    }
    /**
     * 添加一条数据
     * @param user
     */
    public void save(User user){
        SQLiteDatabase db=dbOpenHelper.getWritableDatabase();
        db.execSQL("insert into user(uname,uaddress) values(?,?)", new Object[]{user.getUname(),user.getUaddress()});
        db.close();
    }
    /**
     * 删除一条数据
     * @param uid
     */
    public void delete(Integer uid){
        SQLiteDatabase db=dbOpenHelper.getWritableDatabase();
        db.execSQL("delete from user where uid=?", new Object[]{uid});
        db.close();
    }
    /**
     * 更新一条数据
     * @param user
     */
    public void update(User user){
        SQLiteDatabase db=dbOpenHelper.getWritableDatabase();
        db.execSQL("update user set uname=?,uaddress=? where uid=?", new Object[]{user.getUname(),user.getUaddress(),user.getUid()});
        db.close();
    }
    /**
     * 查找一条数据
     * @param uid
     */
    public User find(Integer uid){
        SQLiteDatabase db=dbOpenHelper.getReadableDatabase();
        Cursor cursor =db.rawQuery("select * from user where uid=?", new String[]{uid.toString()});
        if(cursor.moveToFirst()){
            int uid2=cursor.getInt(cursor.getColumnIndex("uid"));
            String uname=cursor.getString(cursor.getColumnIndex("uname"));
            String uaddress=cursor.getString(cursor.getColumnIndex("uaddress"));
            User user=new User();
            user.setUid(uid2);
            user.setUname(uname);
            user.setUaddress(uaddress);
            return user;
        }
        cursor.close();
        return null;
    }
    /**
     * 分页查找数据
     * @param offset 跳过多少条数据
     * @param maxResult 每页多少条数据
     * @return
     */
    public List<User> getScrollData(int offset, int maxResult){
        List<User>users=new ArrayList<User>();
        SQLiteDatabase db=dbOpenHelper.getReadableDatabase();
        Cursor cursor =db.rawQuery("select * from user order by uid asc limit ?,?", new String[]{String.valueOf(offset), String.valueOf(maxResult)});
        while(cursor.moveToNext()){
            int uid2=cursor.getInt(cursor.getColumnIndex("uid"));
            String uname=cursor.getString(cursor.getColumnIndex("uname"));
            String uaddress=cursor.getString(cursor.getColumnIndex("uaddress"));
            User user=new User();
            user.setUid(uid2);
            user.setUname(uname);
            user.setUaddress(uaddress);
            users.add(user);
        }
        return users;
    }
    /**
     * 获取数据总数
     * @return
     */
    public long getCount(){
        SQLiteDatabase db=dbOpenHelper.getReadableDatabase();
        Cursor cursor =db.rawQuery("select count(*) from user", null);
        cursor.moveToFirst();
        long reslut=cursor.getLong(0);
        return reslut;
    }
}

public class DBDao {
	DBOpenHelper dbOpenHelper;
	
	public DBDao(Context context){
		this.dbOpenHelper=new DBOpenHelper(context);
	}
	/**
	 * 添加一条数据
	 * @param user
	 */
	public void save(User user){
		SQLiteDatabase db=dbOpenHelper.getWritableDatabase();
		db.execSQL("insert into user(uname,uaddress) values(?,?)", new Object[]{user.getUname(),user.getUaddress()});
		db.close();
	}
	/**
	 * 删除一条数据
	 * @param uid
	 */
	public void delete(Integer uid){
		SQLiteDatabase db=dbOpenHelper.getWritableDatabase();
		db.execSQL("delete from user where uid=?", new Object[]{uid});
		db.close();
	}
	/**
	 * 更新一条数据
	 * @param user
	 */
	public void update(User user){
		SQLiteDatabase db=dbOpenHelper.getWritableDatabase();
		db.execSQL("update user set uname=?,uaddress=? where uid=?", new Object[]{user.getUname(),user.getUaddress(),user.getUid()});
		db.close();
	}
	/**
	 * 查找一条数据
	 * @param uid
	 */
	public User find(Integer uid){
		SQLiteDatabase db=dbOpenHelper.getReadableDatabase();
		Cursor cursor =db.rawQuery("select * from user where uid=?", new String[]{uid.toString()});
		if(cursor.moveToFirst()){
			int uid2=cursor.getInt(cursor.getColumnIndex("uid"));
			String uname=cursor.getString(cursor.getColumnIndex("uname"));
			String uaddress=cursor.getString(cursor.getColumnIndex("uaddress"));
			User user=new User();
			user.setUid(uid2);
			user.setUname(uname);
			user.setUaddress(uaddress);
			return user;
		}
		cursor.close();
		return null;
	}
	/**
	 * 分页查找数据
	 * @param offset 跳过多少条数据
	 * @param maxResult 每页多少条数据
	 * @return 
	 */
	public List<User> getScrollData(int offset, int maxResult){
		List<User>users=new ArrayList<User>();
		SQLiteDatabase db=dbOpenHelper.getReadableDatabase();
		Cursor cursor =db.rawQuery("select * from user order by uid asc limit ?,?", new String[]{String.valueOf(offset), String.valueOf(maxResult)});
		while(cursor.moveToNext()){
			int uid2=cursor.getInt(cursor.getColumnIndex("uid"));
			String uname=cursor.getString(cursor.getColumnIndex("uname"));
			String uaddress=cursor.getString(cursor.getColumnIndex("uaddress"));
			User user=new User();
			user.setUid(uid2);
			user.setUname(uname);
			user.setUaddress(uaddress);
			users.add(user);
		}
		return users;
	}
	/**
	 * 获取数据总数
	 * @return
	 */
	public long getCount(){
		SQLiteDatabase db=dbOpenHelper.getReadableDatabase();
		Cursor cursor =db.rawQuery("select count(*) from user", null);
		cursor.moveToFirst();
		long reslut=cursor.getLong(0);
		return reslut;
	}
}

示例：向数据库中添加一条数据

DBDao dbDao=new DBDao(this);
        User user=new User();
        user.setUname("qixiaohu");
        user.setUaddress("chengdu");
        dbDao.save(user);

DBDao dbDao=new DBDao(this);
        User user=new User();
        user.setUname("qixiaohu");
        user.setUaddress("chengdu");
        dbDao.save(user);

PC上管理SQLite数据库的方法：

上边添加数据后可以看到数据添加成功：