android之数据存取

android 中数据存取有5种，SharedPreference、File、SQLite、网络和Content Provider。

1、SharedPreference接口

SharedPreference.Editor.putString("name","小明");

SharedPreference.getString("name","");

2、File

openFileOutput("msg.txt",MODE_PRIVATE).write("小明有话说".getBytes());

byte[] b=new byte[1024];

int len=openFileInput("msg.txt").read(b);

String str=new String(b,0,len);

InputStream is=getResources().openRawResource(R.raw.data);

byte[] b=new byte[is.avaliable()];

is.read(b);

String str=new String(b);

3、SQLite

SQLiteDatabase sql=SQLiteDatabase.openOrCreateDatabase("/data/data/com.example.app/databases/user.db",null);

String str="create table student(_id integer primary key autoincrement,name nvarchar(10))";

sql.execSQL(str);

str="insert into student(name) values('小明')";

sql.execSQL(str);

ContentValues valuse=new ContentValues();

valuse.put("name","小华");

sql.insert("student",null,valuse);

Cursor cur=sql.query("student",new String[]{"name"},"_id=?",new String[]{"1"},null,,null,null,null,null);
while(cur.moveToNext()){

System.out.println(cur.getString(cur.getColumnIndex("name")));

}

ContentValues valuse=new ContentValues();

valuse.put("name","小黄");

sql.update("student",valuse,"_id=?",new String[]{"2"});
sql.delete("student", "_id=?", new String[]{"1"});

class UserDao extends SQLiteOpenHelper{

public StuDao(Context context, String name, int version) {

        super(context, name, null, version);

    }

public void getAll(){

        Cursor cur=getWritableDatabase().query("student", null, null, null, null, null, null);

        while(cur.moveToNext()){

            String name=cur.getString(cur.getColumnIndex("name"));

            System.out.println("name"+name);

        }

    }

}