android sqlite

DBOpenHelper.java

package cn.itcast.service;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class DBOpenHelper extends SQLiteOpenHelper {

	public DBOpenHelper(Context context) {
		super(context, "itcast.db", null, 2);
	}

	@Override
	public void onCreate(SQLiteDatabase db) {
		db.execSQL("CREATE TABLE person (personid integer primary key autoincrement, name varchar(20))");
	}

	@Override
	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
		db.execSQL("ALTER TABLE person ADD phone VARCHAR(12) NULL");
		db.execSQL("ALTER TABLE person ADD amount integer");
	}

}

PersonService.java

package cn.itcast.service;

import java.util.ArrayList;
import java.util.List;

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;

import cn.itcast.domain.Person;

public class PersonService {
	private DBOpenHelper dbOpenHelper;
	
	public PersonService(Context context){
		dbOpenHelper = new DBOpenHelper(context);
	}
	
	public void payment(){
		SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
		db.beginTransaction();//开启事务
		try{
			db.execSQL("update person set amount=amount-10 where personid=?", new Object[]{1});
			db.execSQL("update person set amount=amount+10 where personid=?", new Object[]{2});
			db.setTransactionSuccessful();//设置事务标志为成功，在结束事务时才会提供事务，否则回滚事务
		}finally{
			db.endTransaction();//结束事务
		}
	}
	
	public void save(Person person){
		SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
		db.execSQL("insert into person(name, phone, amount) values(?,?,?)", 
				new Object[]{person.getName(), person.getPhone(), person.getAmount()});
		//db.close();
	}
	
	public void update(Person person){
		SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
		db.execSQL("update person set name=?,phone=?, amount=? where personid=?", 
				new Object[]{person.getName(), person.getPhone(), person.getAmount(), person.getId()});
	}
	
	public void delete(Integer id){
		SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
		db.execSQL("delete from person where personid=?", new Object[]{id});
	}
	
	public Person find(Integer id){
		SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
		Cursor cursor = db.rawQuery("select * from person where personid=?", new String[]{id.toString()});
		if(cursor.moveToFirst()){
			int personid = cursor.getInt(cursor.getColumnIndex("personid"));
			String name = cursor.getString(cursor.getColumnIndex("name"));
			String phone = cursor.getString(cursor.getColumnIndex("phone"));
			int amount = cursor.getInt(cursor.getColumnIndex("amount"));
			cursor.close();
			return new Person(personid, name, phone, amount);
		}
		return null;
	}
	
	public List<Person> getScrollData(int offset, int maxResult){
		List<Person> persons = new ArrayList<Person>();
		SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
		Cursor cursor = db.rawQuery("select * from person limit ?,?", 
				new String[]{String.valueOf(offset), String.valueOf(maxResult)});
		while(cursor.moveToNext()){
			int personid = cursor.getInt(cursor.getColumnIndex("personid"));
			String name = cursor.getString(cursor.getColumnIndex("name"));
			String phone = cursor.getString(cursor.getColumnIndex("phone"));
			int amount = cursor.getInt(cursor.getColumnIndex("amount"));
			persons.add(new Person(personid, name, phone, amount));
		}
		return persons;
	}
	
	public Cursor getCursorScrollData(int offset, int maxResult){
		SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
		return db.rawQuery("select personid as _id,name,phone,amount from person limit ?,?", 
				new String[]{String.valueOf(offset), String.valueOf(maxResult)});
	}
	
	public long getCount(){
		SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
		Cursor cursor = db.rawQuery("select count(*) from person", null);
		cursor.moveToFirst();
		return cursor.getLong(0);
	}
}