WP7使用Linq进行数据库的操作

    最近在做wp7手机手机程序的开发，那么数据库的操作，我们不可以避免。其实wp7对sqlite数据库的支持不太好（我折腾将近一周，还是不行【个人意见，仅供参考】），后来没有办法，在网上看资料，说wp7对数据库的操作，还是使用linq比较的好，本人对linq没有太多了解，没办法，只有baidu，google。经过自己的摸索，终于将添加，修改，删除，查询弄好了（刚开始，只能进行添加，查询操作）。
    我因为要进行系统配置的存储，因此设计的数据表名称为SysConfig,表中有三个字段，分别为ID,Key, Value。很是简单吧。按照三层架构的模型，我设计了SysConfig，SysConfigDao，SysConfigService。三个类，代码如下：

using System;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

using System.Data.Linq;
using System.Data.Linq.Mapping;
using System.ComponentModel;
using System.Collections;
using System.Collections.Generic;
namespace SheenClient.classes.dbmanager
{
    ///
    /// 系统配置数据上下文类
    ///
    public class SysConfigDataContext : DataContext
    {
        public const string ConnectionStr = "Data Source=isostore:/sysconfig.sdf";
        public Table<SysConfig> rows;
        ///
        /// 默认构造函数
        ///
        public SysConfigDataContext() : base(ConnectionStr)
        {

        }

    }

    ///
    /// 系统配置类
    ///
    [Table]
    public class SysConfig : INotifyPropertyChanged, INotifyPropertyChanging
    {
        #region 私有成员

        private int _id;
        private string _key;
        private string _value;

        #endregion

        [Column(IsPrimaryKey = true, CanBeNull = false, IsDbGenerated = true, DbType="INT NOT NULL Identity", AutoSync = AutoSync.OnInsert)]
        public int ID
        {
            get { return _id; }
            set
            {
                if (_id != value)
                {
                    NotifyPropertyChanging("ID");
                    _id = value;
                    NotifyPropertyChanged("ID");
                }
            }
        }

        [Column]
        public string Key
        {
            get { return _key; }
            set
            {
                NotifyPropertyChanging("Key");
                _key = value;
                NotifyPropertyChanged("Key");
            }
        }

        [Column]
        public string Value
        {
            get { return _value; }
            set
            {
                NotifyPropertyChanging("Value");
                _value = value;
                NotifyPropertyChanged("Value");
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;
        private void NotifyPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }

        public event PropertyChangingEventHandler PropertyChanging;
        private void NotifyPropertyChanging(string propertyName)
        {
            if (PropertyChanging != null)
            {
                PropertyChanging(this, new PropertyChangingEventArgs(propertyName));
            }
        }
    }

    ///
    /// 系统配置数据访问层类
    ///
    public class SysConfigDao
    {
        #region 私有成员

        private SysConfigDataContext _db;

        #endregion

        ///
        /// 默认构造函数
        ///
        public SysConfigDao()
        {
            _db = new SysConfigDataContext();
            if(!_db.DatabaseExists())
                _db.CreateDatabase();
        }

        ///
        /// 添加系统配置
        ///
        /// 配置的对象
        /// 添加成功：true;添加失败：false
        public bool addSysConfig(SysConfig config)
        {
            try
            {
                if (_db.DatabaseExists())
                {
                    _db.rows.InsertOnSubmit(config);
                    _db.SubmitChanges();
                }
            }
            catch
            {
                return false;
            }
            return true;
        }

        ///
        /// 获取系统配置
        ///
        /// 键
        /// 存在返回：SysConfig对象；不存在返回null
        public SysConfig getSysConfig(string key)
        {
            SysConfig result = null;
            if (_db.DatabaseExists())
            {
                IEnumerator<SysConfig> enumerator = _db.rows.GetEnumerator();
                while (enumerator.MoveNext())
                {
                    if (enumerator.Current.Key == key)
                    {
                        result = new SysConfig();
                        result.ID = enumerator.Current.ID;
                        result.Key = enumerator.Current.Key;
                        result.Value = enumerator.Current.Value;
                        break;
                    }
                }
            }
            return result;
        }

        ///
        /// 是否含有系统配置项
        ///
        /// 键
        /// 存在：true;不存在：false
        public bool isSysConfig(string key)
        {
            SysConfig config = getSysConfig(key);
            if (config == null)
                return false;
            else
                return true;
        }

        ///
        /// 删除系统配置
        ///
        /// 要删除的键
        /// 删除成功：true;删除失败:false
        public bool deleteSysConfig(string key)
        {
            bool result = false;
            if (_db.DatabaseExists())
            {
                IEnumerator<SysConfig> enumerator = _db.rows.GetEnumerator();
                while (enumerator.MoveNext())
                {
                    if (enumerator.Current.Key == key)
                    {
                        _db.rows.DeleteOnSubmit(enumerator.Current);
                        _db.SubmitChanges();
                        result = true;
                        break;
                    }
                }
            }
            return result;
        }

        ///
        /// 更新系统配置信息
        ///
        /// 系统配置对象
        ///
        public bool updateSysConfig(SysConfig config)
        {
            bool result = false;
            if (_db.DatabaseExists())
            {
                IEnumerator<SysConfig> enumerator = _db.rows.GetEnumerator();
                while (enumerator.MoveNext())
                {
                    if (enumerator.Current.Key == config.Key)
                    {
                        enumerator.Current.Value = config.Value;
                        _db.SubmitChanges();
                        result = true;
                        break;
                    }
                }
            }
            return result;
        }
    }

}

上面的代码，是最基本的操作，下面的代码，为SysConfigService服务类，实现对SysConfigDao类的调用，代码如下：

using System;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

using SheenClient.classes.dbmanager;
namespace SheenClient.classes.dbmanager.service
{
    ///
    /// 系统配置服务类
    ///
    ///
    /// 使用SysConfigStorageSetting替换SysConfigDao，
    /// 因对sqlite在wp7的操作还不理解，因此采用SysConfigStorageSetting
    ///
    public class SysConfigService
    {
        #region 私有成员

        SysConfigDao _dao = null;
        //SysConfigStorageSetting _setting = null;
        #endregion

        ///
        /// 默认构造函数
        ///
        public SysConfigService()
        {
            _dao = new SysConfigDao();
            //_setting = new SysConfigStorageSetting();

        }

        ///
        /// 保存配置信息
        ///
        /// 配置的键
        /// 键对应的值
        public void save(string key, string value)
        {
            SysConfig config = new SysConfig();
            config.Key = key;
            config.Value = value;
            if (_dao.isSysConfig(key))
                _dao.updateSysConfig(config);
            else
                _dao.addSysConfig(config);

            //if (_setting.hasSysConfig(key))
            //    _setting.updateSysConfig(key, value);
            //else
            //    _setting.addSysConfig(key, value);

        }

        ///
        /// 获取系统配置值
        ///
        /// 要查找的键
        /// 键对应的值
        public string getSysConfig(string key)
        {
            string result = "";
            if (_dao.isSysConfig(key))
                result = _dao.getSysConfig(key).Value;
            //if (_setting.hasSysConfig(key))
            //    result = _setting.getSysConfig(key);

            return result;
        }
    }
}