Android之SQLLite

package com.duantl.service;import java.util.ArrayList;import java.util.List;import android.content.Context;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import com.duantl.domain.Person;public class PersonService {private DBOpenHelper dbOpenHelper;private Context context;public PersonService(Context context) {this.dbOpenHelper = new DBOpenHelper(context);}public void save(Person person) {// 如果要对数据进行更改，就调用此方法得到用于操作数据库的实例,该方法一读和写方式打开数据库SQLiteDatabase db = dbOpenHelper.getWritableDatabase();// 如果只对数据库进行读取，建议使用此方法,但此方法并不是以只读方式打开数据库的。因为该方法内部调用了getWritableDatabase方法// SQLiteDatabase db2 = dbOpenHelper.getReadableDatabase();// 用占位符可防止用户输入出现问题db.execSQL("insert into person (name) values (?)",new Object[] { person.getName() });// 如果该数据库只被本应用访问，android不建议关闭数据库，为了性能// db.close();}public void update(Person person) {SQLiteDatabase db = dbOpenHelper.getWritableDatabase();db.execSQL("update person set name=? where personid=?", new Object[] {person.getName(), person.getId() });}public void delete(Integer id) {SQLiteDatabase db = dbOpenHelper.getWritableDatabase();db.execSQL("delete from person where personid=?", new Object[] { id.toString() });}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"));return new Person(personid,name);}return null;}public List<Person> getScrollData(Integer offset, Integer maxResult) {List<Person> persons = new ArrayList<Person>();SQLiteDatabase db = dbOpenHelper.getReadableDatabase();Cursor cursor = db.rawQuery("select * from person limit ?,?", new String[]{offset.toString(),maxResult.toString()});while(cursor.moveToNext()) {int personid = cursor.getInt(cursor.getColumnIndex("personid"));String name = cursor.getString(cursor.getColumnIndex("name"));Person person = new Person(personid, name);persons.add(person);}cursor.close();return persons;}public long getCount() {SQLiteDatabase db = dbOpenHelper.getReadableDatabase();Cursor cursor = db.rawQuery("select count(*) from person", null);cursor.moveToFirst();return cursor.getLong(0);}}

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