C# 词典数据结构设计【附demo】

分析#

要建立词典，最基本的应该有词典的描述信息、词典索引文件以及词典数据文件。

/// <summary>
/// 索引文件
/// </summary>
string idxFile = "dic.idx";

/// <summary>
/// 数据文件
/// </summary>
string dictfile = "dic.dict";

/// <summary>
/// 词典信息文件
/// </summary>
string ifoFile = "dic.ifo";

我们建立对应的三个类



详细的代码如下：

/// <summary>
    ///  词语解释
    /// </summary>
    class DictWord
    {
        /// <summary>
        /// 解析
        /// </summary>
        public string Description
        {
            get;
            set;
        }
    }
 
    /// <summary>
    /// 词典索引
    /// </summary>
    class DictIndex
    {
        /// <summary>
        /// 词语
        /// </summary>
        public string Word
        {
            get;
            set;
        }
 
        /// <summary>
        /// 偏移
        /// </summary>
        public int Offset
        {
            get;
            set;
        }
 
        /// <summary>
        /// 数据大小
        /// </summary>
        public int DataSize
        {
            get;
            set;
        }
    }
 
    /// <summary>
    /// 词典信息
    /// </summary>
    class DictInfo
    {
        /// <summary>
        /// 词典名称
        /// </summary>
        public string BookName
        {
            get;
            set;
        }
 
        /// <summary>
        /// 收录词数
        /// </summary>
        public int WordCount
        {
            get;
            set;
        }
 
        /// <summary>
        /// 当前偏移
        /// </summary>
        public int CurrentOffset
        {
            get;
            set;
        }
    }

数据结构说明：

描述信息包含词典名字，词典词语数量
索引文件存储的是排好顺序词语的索引，每个索引包含词语名称、存在数据文件中的偏移量、以及数据块大小，排序的目的在于查找时直接用二分查找节省查找时间。
数据块就简单了，就纯粹的数据

建立词典#

建立词典比较简单，首先，定义几个变量来存储词典相关信息：

        DictInfo info;
        SortedList<string, DictIndex> indexs;
        List<DictWord> words;

ps： SortedList能直接排序，不用我们再手动排序了

然后我们来看添加词语：

?
///
        /// 添加词语
        ///
        ///
        ///
        public void Add(string word, string description)
        {

            words.Add(new DictWord() { Description = description });
            indexs.Add(word, new DictIndex { DataSize = Encoding.UTF8.GetBytes(description).Length, Offset = info.CurrentOffset, Word = word });
            // 数量++
            info.WordCount++;
            // 偏移++
            info.CurrentOffset += Encoding.UTF8.GetBytes(description).Length;
        }

非常简单，就是添加索引，同时把词典的数量加1

最后来看怎么存储到文件：

?
/// <summary>
/// 保存
/// </summary>
public void Save()
{

    StringBuilder dicBuilder = new StringBuilder();
    dicBuilder.AppendLine(string.Format("BookName={0}", info.BookName));
    dicBuilder.AppendLine(string.Format("WordCount={0}", info.WordCount));
    dicBuilder.AppendLine(string.Format("CurrentOffset={0}", info.CurrentOffset));
    File.WriteAllText(ifoFile, dicBuilder.ToString(), Encoding.UTF8);

    dicBuilder = new StringBuilder();

    using (BinaryWriter idxWriter = new BinaryWriter(File.Open(dictfile, FileMode.Create)))
    {
        foreach (var word in words)
        {
            idxWriter.Write(Encoding.UTF8.GetBytes(word.Description));
        }
    }

    using (BinaryWriter idxWriter = new BinaryWriter(File.Open(idxFile, FileMode.Create)))
    {
        foreach (var index in indexs)
        {
            // 分块大小 128+4+4 = 136

            // word 最长128
            byte[] word = new byte[128];
            var wordData = Encoding.UTF8.GetBytes(index.Key);
            var length = Math.Min(128, wordData.Length);
            for (var i = 0; i < length; i++)
            {
                word[i] = wordData[i];
            }
            idxWriter.Write(word);
            byte[] re = new byte[4];

            idxWriter.Write(index.Value.Offset);
            idxWriter.Write(index.Value.DataSize);
        }
    }

}

这里注意下word最多能存128个字节，每个index区地大小为128+4+4 = 136字节

查询词典#

前面做这么多准备，不都是为了查询吗？木有查询，神马都是浮云！

前面说到了，索引文件存储的是排序好的词语列表，所以查询就比较简单了

先给出两个辅助方法：

            idxStream = new FileStream(idxFile, FileMode.Open);
            idxReader = new BinaryReader(idxStream);
            dictStream = new FileStream(dictfile, FileMode.Open);
            dictReader = new BinaryReader(dictStream);

（1）获取指定位置的索引

?
///
/// 获取指定位置的索引
///
///
///
public DictIndex GetWordIndex(int wordIndex)
{
    idxStream.Seek(0, SeekOrigin.Begin);
    idxStream.Seek(wordIndex * 136, SeekOrigin.Begin);
    byte[] word = idxReader.ReadBytes(128);
    var dicIndex = new DictIndex();
    dicIndex.Word = Encoding.UTF8.GetString(word).Replace("\0", "");
    dicIndex.Offset = idxReader.ReadInt32();
    dicIndex.DataSize = idxReader.ReadInt32();
    return dicIndex;
}

（2）获取指定索引对应的词语解释

?
///
/// 获取指定词语的解释
///
///
///
public string GetWordDescription(DictIndex dictIndex)
{
    dictStream.Seek(0, SeekOrigin.Begin);
    if (dictIndex.Offset != 0)
        dictStream.Seek(dictIndex.Offset, SeekOrigin.Begin);
    byte[] word = dictReader.ReadBytes(dictIndex.DataSize);
    return Encoding.UTF8.GetString(word).Replace("\0", "");
} 现在开始二分查找：///
/// 获取词语解释
///
///
///
public string GetDescription(string word)
{
    var i = 0;
    var mid = info.WordCount / 2;
    var max = info.WordCount;
    DictIndex w = new DictIndex();
    while (i <= max)
    {
        mid = (i + max) / 2;
        w = GetWordIndex(mid);
        if (string.Compare(w.Word, word) > 0)
        {
            max = mid - 1;
        }
        else if (string.Compare(w.Word, word) < 0)
        {
            i = mid + 1;
        }
        else
        {
            break;
        }
    }

    return "[" + w.Word + "]\n" + GetWordDescription(w);
}

此部分完整代码：

/// 
    /// 词典
    /// 
    class Dict
    {
        DictInfo info;
        SortedList indexs;
        List words;
 
        /// 
        /// 索引文件
        /// 
        string idxFile = "dic.idx";
 
        /// 
        /// 数据文件
        /// 
        string dictfile = "dic.dict";
 
        /// 
        /// 词典信息文件
        /// 
        string ifoFile = "dic.ifo";
 
        BinaryReader idxReader;
        FileStream idxStream;
        BinaryReader dictReader;
        FileStream dictStream;
 
 
        /// 
        /// 查询使用
        /// 
        public Dict()
        {
            LoadDictInfo();
            idxStream = new FileStream(idxFile, FileMode.Open);
            idxReader = new BinaryReader(idxStream);
            dictStream = new FileStream(dictfile, FileMode.Open);
            dictReader = new BinaryReader(dictStream);
        }
 
        /// 
        /// 创建时使用
        /// 
        ///  
        public Dict(string name)
        {
            info = new DictInfo { BookName = name, WordCount = 0, CurrentOffset = 0 };
            indexs = new SortedList();
            words = new List();
 
        }
 
        /// 
        /// 获取词语解释
        /// 
        ///  
        /// 
        public string GetDescription(string word)
        {
            var i = 0;
            var mid = info.WordCount / 2;
            var max = info.WordCount;
            DictIndex w = new DictIndex();
            while (i <= max)
            {
                mid = (i + max) / 2;
                w = GetWordIndex(mid);
                if (string.Compare(w.Word, word) > 0)
                {
                    max = mid - 1;
                }
                else if (string.Compare(w.Word, word) < 0)
                {
                    i = mid + 1;
                }
                else
                {
                    break;
                }
            }
 
            return "[" + w.Word + "]\n" + GetWordDescription(w);
        }
 
 
 
        /// 
        ///  获取指定位置的索引
        /// 
        ///  
        /// 
        public DictIndex GetWordIndex(int wordIndex)
        {
            idxStream.Seek(0, SeekOrigin.Begin);
            idxStream.Seek(wordIndex * 136, SeekOrigin.Begin);
            byte[] word = idxReader.ReadBytes(128);
            var dicIndex = new DictIndex();
            dicIndex.Word = Encoding.UTF8.GetString(word).Replace("\0", "");
            dicIndex.Offset = idxReader.ReadInt32();
            dicIndex.DataSize = idxReader.ReadInt32();
            return dicIndex;
        }
 
        /// 
        ///  获取指定词语的解释
        /// 
        ///  
        /// 
        public string GetWordDescription(DictIndex dictIndex)
        {
            dictStream.Seek(0, SeekOrigin.Begin);
            if (dictIndex.Offset != 0)
                dictStream.Seek(dictIndex.Offset, SeekOrigin.Begin);
            byte[] word = dictReader.ReadBytes(dictIndex.DataSize);
            return Encoding.UTF8.GetString(word).Replace("\0", "");
        }
 
        /// 
        /// 添加词语
        /// 
        ///  
        ///  
        public void Add(string word, string description)
        {
 
            words.Add(new DictWord() { Description = description });
            indexs.Add(word, new DictIndex { DataSize = Encoding.UTF8.GetBytes(description).Length, Offset = info.CurrentOffset, Word = word });
            // 数量++
            info.WordCount++;
            // 偏移++
            info.CurrentOffset += Encoding.UTF8.GetBytes(description).Length;
        }
 
        /// 
        /// 加载词典信息
        /// 
        void LoadDictInfo()
        {
            var infos = File.ReadAllLines(ifoFile);
            info = new DictInfo
            {
                BookName = infos[0].Replace("BookName=", "").Trim(),
                WordCount = int.Parse(infos[1].Replace("WordCount=", "").Trim()),
                CurrentOffset = int.Parse(infos[2].Replace("CurrentOffset=", "").Trim()),
            };
        }
 
        /// 
        /// 保存
        /// 
        public void Save()
        {
 
            StringBuilder dicBuilder = new StringBuilder();
            dicBuilder.AppendLine(string.Format("BookName={0}", info.BookName));
            dicBuilder.AppendLine(string.Format("WordCount={0}", info.WordCount));
            dicBuilder.AppendLine(string.Format("CurrentOffset={0}", info.CurrentOffset));
            File.WriteAllText(ifoFile, dicBuilder.ToString(), Encoding.UTF8);
 
            dicBuilder = new StringBuilder();
 
            using (BinaryWriter idxWriter = new BinaryWriter(File.Open(dictfile, FileMode.Create)))
            {
                foreach (var word in words)
                {
                    idxWriter.Write(Encoding.UTF8.GetBytes(word.Description));
                }
            }
 
            using (BinaryWriter idxWriter = new BinaryWriter(File.Open(idxFile, FileMode.Create)))
            {
                foreach (var index in indexs)
                {
                    // 分块大小  128+4+4  = 136
 
                    // word 最长128
                    byte[] word = new byte[128];
                    var wordData = Encoding.UTF8.GetBytes(index.Key);
                    var length = Math.Min(128, wordData.Length);
                    for (var i = 0; i < length; i++)
                    {
                        word[i] = wordData[i];
                    }
                    idxWriter.Write(word);
                    byte[] re = new byte[4];
 
                    idxWriter.Write(index.Value.Offset);
                    idxWriter.Write(index.Value.DataSize);
                }
            }
 
        }
    }

演示#

如图所示

文件夹中放置了许多文本文件，内容为词语的解释

首先、建立词典：

Dict dic = new Dict("病症词典");
   
            var files = new DirectoryInfo(@"G:\Users\Administrator\Desktop\新建文件夹 (3)\新建文件夹 (3)").GetFiles();
            foreach (var file in files)
            {
                Console.WriteLine(file.FullName);
                dic.Add(file.Name.Replace("的症状.txt", ""), File.ReadAllText(file.FullName));
            }
            dic.Save();

然后、把玩一番：

var dict = new Dict();
            while (true)
            {
                Console.Write("请输入词语:");
                var w = Console.ReadLine();
                Stopwatch sw = new Stopwatch();
                sw.Start();
                Console.WriteLine("找到词语:");
                Console.WriteLine(dict.GetDescription(w));
                sw.Stop();
                Console.WriteLine("耗时:" + sw.ElapsedMilliseconds + "ms");
 
            }