Android(安卓)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 ：

[java] view plain copy print ?

publicclassDBOpenHelperextendsSQLiteOpenHelper{
publicDBOpenHelper(Contextcontext){
super(context,"yhn.db",null,1);
}
//数据库第一次创建时候调用，
publicvoidonCreate(SQLiteDatabasedb){
db.execSQL("createtableuser(uidintegerprimarykeyautoincrement,unamevarchar(20),uaddressvarchar(20))");
}
//数据库文件版本号发生变化时调用
publicvoidonUpgrade(SQLiteDatabasearg0,intarg1,intarg2){
}

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：

[java] view plain copy print ?

publicclassDBDao{
DBOpenHelperdbOpenHelper;
publicDBDao(Contextcontext){
this.dbOpenHelper=newDBOpenHelper(context);
}
/**
*添加一条数据
*@paramuser
*/
publicvoidsave(Useruser){
SQLiteDatabasedb=dbOpenHelper.getWritableDatabase();
db.execSQL("insertintouser(uname,uaddress)values(?,?)",newObject[]{user.getUname(),user.getUaddress()});
db.close();
}
/**
*删除一条数据
*@paramuid
*/
publicvoiddelete(Integeruid){
SQLiteDatabasedb=dbOpenHelper.getWritableDatabase();
db.execSQL("deletefromuserwhereuid=?",newObject[]{uid});
db.close();
}
/**
*更新一条数据
*@paramuser
*/
publicvoidupdate(Useruser){
SQLiteDatabasedb=dbOpenHelper.getWritableDatabase();
db.execSQL("updateusersetuname=?,uaddress=?whereuid=?",newObject[]{user.getUname(),user.getUaddress(),user.getUid()});
db.close();
}
/**
*查找一条数据
*@paramuid
*/
publicUserfind(Integeruid){
SQLiteDatabasedb=dbOpenHelper.getReadableDatabase();
Cursorcursor=db.rawQuery("select*fromuserwhereuid=?",newString[]{uid.toString()});
if(cursor.moveToFirst()){
intuid2=cursor.getInt(cursor.getColumnIndex("uid"));
Stringuname=cursor.getString(cursor.getColumnIndex("uname"));
Stringuaddress=cursor.getString(cursor.getColumnIndex("uaddress"));
Useruser=newUser();
user.setUid(uid2);
user.setUname(uname);
user.setUaddress(uaddress);
returnuser;
}
cursor.close();
returnnull;
}
/**
*分页查找数据
*@paramoffset跳过多少条数据
*@parammaxResult每页多少条数据
*@return
*/
publicList<User>getScrollData(intoffset,intmaxResult){
List<User>users=newArrayList<User>();
SQLiteDatabasedb=dbOpenHelper.getReadableDatabase();
Cursorcursor=db.rawQuery("select*fromuserorderbyuidasclimit?,?",newString[]{String.valueOf(offset),String.valueOf(maxResult)});
while(cursor.moveToNext()){
intuid2=cursor.getInt(cursor.getColumnIndex("uid"));
Stringuname=cursor.getString(cursor.getColumnIndex("uname"));
Stringuaddress=cursor.getString(cursor.getColumnIndex("uaddress"));
Useruser=newUser();
user.setUid(uid2);
user.setUname(uname);
user.setUaddress(uaddress);
users.add(user);
}
returnusers;
}
/**
*获取数据总数
*@return
*/
publiclonggetCount(){
SQLiteDatabasedb=dbOpenHelper.getReadableDatabase();
Cursorcursor=db.rawQuery("selectcount(*)fromuser",null);
cursor.moveToFirst();
longreslut=cursor.getLong(0);
returnreslut;
}
}

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

[java] view plain copy print ?

DBDaodbDao=newDBDao(this);
Useruser=newUser();
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：

Android 数据存储与读取：SQLite

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