scoresservice.cs

中文名：Windows Forms 程序设计 英文名：Windows Forms Programming in c# 作者： Chris Sells 翻译： 荣耀 蒋贤哲 出版社：人民

using System;
using System.IO;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Formatters;
using System.Runtime.Serialization.Formatters.Soap;
using System.Web;
using System.Web.Caching;
using System.Web.Services;
using System.Web.Services.Protocols;

/// <summary>
/// Track Wahoo scores
/// </summary>
[WebService(Namespace = "http://www.sellsbrothers.com/WahooScoresService/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
public class ScoresService : System.Web.Services.WebService {

  // Only keep the big ones
  const byte _maxScores = 10;

  static ScoresService() {
    // Load cached high scores
    LoadScores();
  }

  /// <summary>
  /// Store a new high score
  /// </summary>
  [WebMethod]
  public void RegisterScore(string name, int score) {
    HttpContext context = HttpContext.Current;
    Cache cache = context.Cache;

    try {
      // Synchronize access to the scores
      context.Application.Lock();

      WahooScore[] scores = GetScores();

      // Check to see if score makes the cut
      if( scores[_maxScores - 1].Score >= score ) {
        //throw new ApplicationException("Sorry, but your score is too low to make the top " + _maxScores);
        throw new DiscreteSoapException("Sorry, " + name + ", but your score of " + score + " is too low to make the top " + _maxScores);
      }

      // Add score by bumping off the bottom guy
      scores[_maxScores - 1] = new WahooScore(name, score);

      // Sort list
      Array.Sort(scores, new WahooScoreComparer());

      // Save high scores now in case bad stuff happens later
      SaveScores(scores);

      // Cache the scores
      cache["scores"] = scores;
    }
    finally {
      context.Application.UnLock();
    }
  }

  /// <summary>
  /// Return scores sorted highest to lowest
  /// </summary>
  [WebMethod]
  public WahooScore[] GetScores() {
    Cache cache = HttpContext.Current.Cache;
    WahooScore[] scores;

    try {
      HttpContext.Current.Application.Lock();

      scores = (WahooScore[])cache["scores"];
      if( scores == null ) {
        cache["scores"] = scores = LoadScores();
      }
    }
    finally {
      HttpContext.Current.Application.UnLock();
    }

    return scores;
  }

  #region Wahoo score storage

  // Score storage
  // NOTE: This implementation requires a user with permissions to read/write files, e.g.
  // machine.config:
  // <system.web><processModel userName="SYSTEM" ... />...</system.web>

  static private string ScoresFileName {
    get {
      return HttpContext.Current.Request.PhysicalApplicationPath + @"App_Data\WahooScores.txt";
    }
  }

  static private WahooScore[] LoadScores() {
    WahooScore[] scores = new WahooScore[_maxScores];

    try {
      using( FileStream file = new FileStream(ScoresFileName, FileMode.Open) ) {
        IFormatter formatter = new SoapFormatter();
        scores = (WahooScore[])formatter.Deserialize(file);
      }
    }
    catch {
      for( int i = 0; i != _maxScores; ++i ) {
        scores[i] = new WahooScore("nobody", 0);
      }
    }

    return scores;
  }

  private void SaveScores(WahooScore[] scores) {
    using( FileStream file = new FileStream(ScoresFileName, FileMode.Create) ) {
      IFormatter formatter = new SoapFormatter();
      formatter.Serialize(file, scores);
    }
  }
  
  #endregion
}