Android SQLite增删改查

skyleemon

2011-12-05

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//目录结构

Android SQLite增删改查

//编写DbOpenHelper.java类，继承SQLiteOpenHelper

package sn.len.sqlite.service;
import Android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DbOpenHelper extends SQLiteOpenHelper
{
private static final String DATABASENAME="database.db";
private static final int DATABASVERSION=1;
public DbOpenHelper(Context context)
{
//实例化父类，创建数据库
super(context, DATABASENAME, null, DATABASVERSION);
}
@Override
public void onCreate(SQLiteDatabase db)
{
db.execSQL("create table sqlitetable(id integer primary key autoincrement,name varchar(20))");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
}
/*
*1.如果数据库文件不存在，SQLiteOpenHelper在自动创建数据库后会调用oncreate()方法，
*在该方法中一般需要创建表、视图等组件。在创建前数据库一般是空的，因此不需要先删除数据库中相关的组件。
*2.如果数据库文件存在，并且当前版本号高于上次创建或升级的版本号，SQLiteOpenHelper会调用onUpdate()方法
*调用该方法后会更新数据库的版本号。在onupdate()方法中除了创建表、视图等组件外，还需要先删除这些相关的组件，
*因此，在调用onupdate()方法前，数据库是存在的，里面还原许多数据库组建。
*详细了解:请看:http://hi.baidu.com/%C8%F4%CB%AA/blog/item/3d839c132e80353bdc54017b.html
* */
}

编写bean Person.java

package sn.len.sqllite.domain;
public class Person
{
private Integer id;
private String name;
public Integer getId()
{
return id;
}
public void setId(Integer id)
{
this.id = id;
}
public String getName()
{
return name;
}
public void setName(String name)
{
this.name = name;
}
public Person(Integer id, String name)
{
this.id = id;
this.name = name;
}
public Person()
{
}
@Override
public String toString()
{
return "Person [id=" + id + + name + }

//编写具体实现功能的service层PersonServic.java

package sn.len.sqlite.service;
import java.util.ArrayList;
import java.util.List;
import sn.len.sqllite.domain.Person;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
public class PersonService
{
//拿到SQLiteDatabase对象
private DbOpenHelper dbhelp;
public PersonService(Context context)
{
this.dbhelp=new DbOpenHelper(context);
}
//保存
public void save(Person person)
{
SQLiteDatabase dbopen=dbhelp.getWritableDatabase();
dbopen.execSQL("insert into sqlitetable(name) values(?)", new Object[]{person.getName()});
}
//删除
public void del(Integer id)
{
SQLiteDatabase dbopen=dbhelp.getWritableDatabase();
dbopen.execSQL("delete from sqlitetable where id=?", new Object[]{id});
}
//更新
public void update(Person person)
{
SQLiteDatabase dbopen=dbhelp.getWritableDatabase();
dbopen.execSQL("update sqlitetable set name=? where id=?", new Object[]{person.getName(),person.getId()});
}
//查找
public Person select(Integer id)
{
SQLiteDatabase dbopen=dbhelp.getReadableDatabase();
Cursor cursor=dbopen.rawQuery("select * from sqlitetable where id=?",new String[]{id.toString()});
int db_id=cursor.getInt(cursor.getColumnIndex("id"));
String name=cursor.getString(cursor.getColumnIndex("name"));
return new Person(db_id,name);
}
//分页
public List<Person> getScrollData(Integer offset,Integer maxResult)
{
List<Person> p=new ArrayList<Person>();
SQLiteDatabase dbopen=dbhelp.getReadableDatabase();
Cursor cursor=dbopen.rawQuery("select * from sqlitetable limit ?,?", new String[]{offset.toString(),maxResult.toString()});
while(cursor.moveToNext())
{
int id=cursor.getInt(cursor.getColumnIndex("id"));
String name=cursor.getString(cursor.getColumnIndex("name"));
Person persons=new Person(id,name);
p.add(persons);
}
cursor.close();
return p;
}
//得到总行数
public long getCount()
{
SQLiteDatabase dbopen=dbhelp.getReadableDatabase();
Cursor cusor=dbopen.rawQuery("select count(*) from sqlitetable", null);
cusor.moveToFirst();//不用判断，不管有没能结果都会返回一条记录
long count=cusor.getLong(0);
return count;
}
//操作数据，基本都用execSQL();
//查询数据，基本都用rawQuery();
}