fileaccess.cs

微软的行业应用解决方案实例！非常优秀的Windows Mobile开发案例

using System;
using System.IO;
using System.Xml;
using HardwareDistributor.Business;
using System.Runtime.InteropServices;
using Microsoft.WindowsMobile.Status;


namespace HardwareDistributor.Data
{
    /// <summary>
    /// Data layer class that interacts with the file system
    /// </summary>
    public class FileAccess
    {
        /// <summary>
        /// Takes a thrown exception and writes it to a log file
        /// </summary>
        /// <param name="ex"></param>
        public static void LogError(Exception ex)
        {
            StreamWriter _sw = null;

            try
            {
                //Instantiate an appendable streamwriter that writes to a file called ErrorLog.txt
                _sw = new StreamWriter(GlobalCache.Instance.AppPath + "ErrorLog.txt", true, System.Text.Encoding.ASCII);
                //Write a row of data containing the time, the error message, and the stack trace
                _sw.WriteLine("* " + System.DateTime.Now.ToString() + " | " + ex.Message + " | " + ex.StackTrace);
            }
            finally
            {
                //Ensure the streamwriter gets closed
                if (_sw != null)
                {
                    _sw.Close();
                    _sw = null;
                }
            }
        }


        /// <summary>
        /// Captures device metrics and writes them to a log file
        /// </summary>
        public static void LogAppState()
        {
            StreamWriter _sw = null;

            try
            {
                //Get physical and available device memory
                uint _storePages = 0;
                uint _ramPages = 0;
                uint _pageSize = 0;
                int _res = GetSystemMemoryDivision(ref _storePages, ref _ramPages, ref _pageSize);
                MEMORYSTATUS _memStatus = new MEMORYSTATUS();
                GlobalMemoryStatus(_memStatus);
                uint _total = _memStatus.dwTotalPhys / 1024;
                uint _available = _memStatus.dwAvailPhys / 1024;

                //Instantiate an appendable streamwriter that writes to a file called AppStateLog.txt
                _sw = new StreamWriter(GlobalCache.Instance.AppPath + "AppStateLog.txt", true, System.Text.Encoding.ASCII);
                //Write a row of data containing the time plus the follow device metrics
                _sw.WriteLine("* " + System.DateTime.Now.ToString() + " | " + 
                              GlobalCache.Instance.DeviceId + " | " + 
                              GlobalCache.Instance.DeviceName + " | " +
                              GlobalCache.Instance.IpAddress + " | " +
                              GlobalCache.Instance.OperatingSystem + " | " +
                              GlobalCache.Instance.OperatingSystemVersion + " | " +
                              GlobalCache.Instance.NetCFVersion + " | " +
                              GlobalCache.Instance.AppVersion + " | " +
                              SystemState.PowerBatteryStrength.ToString() + " | " +
                              _available.ToString() + " | " +
                              _total.ToString());
            }
            finally
            {
                //Ensure the streamwrite gets closed
                if (_sw != null)
                {
                    _sw.Close();
                    _sw = null;
                }
            }
        }


        /// <summary>
        /// Retrieves setting from the xml config file
        /// </summary>
        /// <param name="settingName"></param>
        /// <returns></returns>
        public static string GetAppSetting(string appSettingName)
        {
            //Create an XmlDocument object
            XmlDocument _settings = new XmlDocument();
            //Open the xml config file
            StreamReader _sr = new StreamReader(GlobalCache.Instance.ConfigFile);
            //Load the config file into the XmlDocument object
            _settings.Load(_sr);
            //Close the StreamReader
            _sr.Close();
            //Iterate through the xml nodes
            foreach (XmlNode node in _settings["configuration"]["appSettings"])
            {
                //Look for a match to the passed in settingName string
                if (string.Compare(appSettingName, node.Attributes["key"].Value) == 0)
                {
                    return node.Attributes["value"].Value;
                }
            }
            return "";
        }


        /// <summary>
        /// Writes settings to the xml config file
        /// </summary>
        /// <param name="settingName"></param>
        /// <param name="settingValue"></param>
        public static void SetAppSetting(string appSettingName, string appSettingValue)
        {
            //Create an XmlDocument object
            XmlDocument _settings = new XmlDocument();
            //Open the xml config file
            StreamReader _sr = new StreamReader(GlobalCache.Instance.ConfigFile);
            //Load the config file into the XmlDocument object
            _settings.Load(_sr);
            //Close the StreamReader
            _sr.Close();
            //Iterate through the xml nodes
            foreach (XmlNode node in _settings["configuration"]["appSettings"])
            {
                //Look for a match to the passed in settingName string
                if (string.Compare(appSettingName, node.Attributes["key"].Value) == 0)
                {
                    node.Attributes["value"].Value = appSettingValue;
                }
            }
            //Save the xml config file
            _settings.Save(GlobalCache.Instance.ConfigFile);
        }


        #region P/Invokes


        public class MEMORYSTATUS
        {
            public uint dwLength;
            public uint dwMemoryLoad;
            public uint dwTotalPhys;
            public uint dwAvailPhys;
            public uint dwTotalPageFile;
            public uint dwAvailPageFile;
            public uint dwTotalVirtual;
            public uint dwAvailVirtual;
        }

        [DllImport("CoreDll.dll")]
        public static extern void GlobalMemoryStatus
        (
          MEMORYSTATUS lpBuffer
        );

        [DllImport("CoreDll.dll")]
        public static extern int GetSystemMemoryDivision
        (
          ref uint lpdwStorePages,
          ref uint lpdwRamPages,
          ref uint lpdwPageSize
        );

        #endregion


    }
}