数据字典生成工具之旅：多线程使用及介绍

这一篇将在之前的代码生成器上讲解多线程的应用，多线程的概念和好处这里就不多说了，另外从本篇开始后面的实例代码都将放到淘宝的SVN管理工具上维护，大家可以直接使用SVN工具进行下载。好了下面进入本篇内容。

阅读目录

线程的应用
winform程序中的多线程
本章总结
工具源代码下载
学习使用

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线程的应用

这里先讲一下线程在Web程序中的一个应用，之前的那一版代码生成器没有考虑表数量多的情形，这里先模拟一下在数据库中创建300张表的情形，下面给出创建表的语句。

--模拟创建300张表，@IsDropTable=0 表示创建表 IsDropTable=1 表示删除创建的模拟表DECLARE @IsDropTable AS BITDECLARE @total AS INT DECLARE @i AS INTSELECT @i=1,@total=300,@IsDropTable=0WHILE @i<=@totalBEGINDECLARE @strSQL AS VARCHAR(1000)  --创建表  SELECT @strSQL='    CREATE TABLE myTest'+CONVERT(VARCHAR,@i)+'    (      [UserGUID] [uniqueidentifier] NOT NULL    )    EXEC sp_addextendedproperty N''MS_Description'', N''用户表'', ''SCHEMA'', N''dbo'', ''TABLE'', N''myTest'+CONVERT(VARCHAR,@i)+''', NULL, NULL    EXEC sp_addextendedproperty N''MS_Description'', N''用户GUID'', ''SCHEMA'', N''dbo'', ''TABLE'', N''myTest'+CONVERT(VARCHAR,@i)+''', ''COLUMN'', N''UserGUID''  '    IF @IsDropTable=1  BEGIN    --删除表    SELECT @strSQL='DROP TABLE myTest'+CONVERT(VARCHAR,@i)  END    EXEC(@strSQL)  SELECT @i=@i+1END

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我们来看下执行时间，差不多用了22秒，时间还是挺长的。可以将代码改造一下，使用多线程来生成代码。

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Web;using System.Configuration;using System.Collections;using System.IO;using System.Data;using System.Threading;namespace Mysoft.Code.Services{  /// <summary>  /// 代码生成类  /// </summary>  public class CodeGenerator  {    //模版文件路径    private static string tmpPath = HttpContext.Current.Server.MapPath("/实体模版/Entity.vm");    //模版输出路径    private static string outPutPath = HttpContext.Current.Server.MapPath(ConfigurationManager.AppSettings["outputPath"]);    private static readonly int Number10 = 400;    private static readonly int MaxThreadCount = 4;    /// <summary>    /// 批量生成代码    /// </summary>    /// <param name="args">模版文件参数</param>    public static void BatchGenerator(List<Hashtable> args)    {      if (!Directory.Exists(outPutPath))      {        Directory.CreateDirectory(outPutPath);      }      //生成文件数量<Number10，则不开启线程生成      if (args.Count < Number10)      {        DoWork(args);      }      else      {        //计算需要的线程数        int threadCount = args.Count % Number10 == 0 ? args.Count / Number10 : args.Count / Number10 + 1;        if (threadCount > MaxThreadCount)        {          threadCount = MaxThreadCount;        }        //每个线程需要生成的实体数量        int threadPqgeSize = (args.Count / threadCount) + 1;        int total = 0;        //为每个线程准备参数        List<List<Hashtable>> threadParams = new List<List<Hashtable>>();        for (int i = 0; i < threadCount; i++)        {          threadParams.Add(args.Skip(total).Take(threadPqgeSize).ToList());          total += threadParams[i].Count;        }        //创建线程        List<Thread> threads = new List<Thread>();        for (int i = 1; i < threadCount; i++)        {          Thread thread = new Thread(DoWork);          thread.IsBackground = true;          thread.Name = "CodeGenerator #" + i.ToString();          threads.Add(thread);          thread.Start(threadParams[i]);        }        // 为当前线程指派生成任务。        DoWork(threadParams[0]);        // 等待所有的编译线程执行线束。        foreach (Thread thread in threads)        {          thread.Join();        }      }    }    private static void DoWork(Object listArgs)    {      List<Hashtable> list = (List<Hashtable>)listArgs;      foreach (Hashtable ht in list)      {        FileGen.GetFile(tmpPath, ht, string.Format("{0}\\{1}.cs", outPutPath, ((DataTable)ht["T"]).Rows[0]["table_name"].ToString()));      }    }  }}

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代码思路，判断要生成的实体数量和Number10的关系，然后计算所需的线程数。

关键的一点是 thread.Join()，这段是主线程等待每个线程执行完成。现在再来看下执行时间，差不多用了13秒，节省了将近10S的时间。

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winform程序中的多线程

下面来考虑这样的一个场景，在生成了文件的时候马上在列表中提示实体生成完成，即进度提示的功能。我们来看下winform中的两种实现方式。

1.利用委托实现

先看一下普通线程实现方式，执行的时候会抛出如下异常。

  foreach (var key in query)      {        dv.RowFilter = "tableid=" + key.tableid;        DataTable dtTable = dv.ToTable();        Hashtable ht = new Hashtable();        ht["T"] = dtTable;        string tableName = dtTable.Rows[0]["table_name"].ToString();        FileGen.GetFile(tmpPath, ht, string.Format("{0}\\{1}.cs", outPutPath, tableName));        Thread thread = new Thread(BindMessage);        thread.IsBackground = true;        thread.Name = "BindMessage:" + key.tableid;        thread.Start(tableName);      }

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先看一下msdn的介绍：

访问 Windows 窗体控件本质上不是线程安全的。如果有两个或多个线程操作某一控件的状态，则可能会迫使该控件进入一种不一致的状态。还可能出现其他与线程相关的 bug，包括争用情况和死锁。确保以线程安全方式访问控件非常重要。

　　C#中禁止跨线程直接访问控件，InvokeRequired是为了解决这个问题而产生的，当一个控件的InvokeRequired属性值为真时，说明有一个创建它以外的线程想访问它。

于是改变了思路，新建线程用以执行耗时的生成代码操作，在每生成一个实体时，通知UI线程更新dataGridView，达到实时更新的效果,这样主线程也不会阻塞了。

using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Windows.Forms;using Mysoft.Map.Extensions.DAL;using System.Collections;using Mysoft.Code.Services;using System.IO;using System.Threading;namespace ThreadWin{  public partial class MainForm : Form  {    //模版文件路径    private static string tmpPath = AppDomain.CurrentDomain.BaseDirectory + @"实体模版\Entity.vm";    //模版输出路径    private static string outPutPath = AppDomain.CurrentDomain.BaseDirectory + @"模版输出路径";    private DataTable dtInfo = new DataTable();    /// <summary>    /// 消息发送请求委托    /// </summary>    /// <param name="Msg">消息</param>    delegate void SetMessageCallBack(object Msg);    public MainForm()    {      InitializeComponent();      dtInfo.Columns.Add("TableName");      dtInfo.Columns.Add("Info");      dtInfo.Columns.Add("Time");      Control.CheckForIllegalCrossThreadCalls = false;    }    private void btn_OK_Click(object sender, EventArgs e)    {      dtInfo.Clear();            if (!Directory.Exists(outPutPath))      {        Directory.CreateDirectory(outPutPath);      }      //1.耗时的操作放在新建线程里面执行      Thread thread = new Thread(GeneratorFile);      thread.IsBackground = true;      thread.Start();      //2.使用系统的线程池进行线程操作      //ThreadPool.QueueUserWorkItem(GeneratorFile);    }    /// <summary>    /// 这里进行耗时的生成代码操作    /// </summary>    private void GeneratorFile()    {      //循环生成实体，并且在列表上显示进度      DataTable dt = GetAllTableInfo();      DataView dv = dt.DefaultView;      var query = (from p in dt.AsEnumerable()             group p by new { TableId = p.Field<int>("tableid"), TableName = p.Field<string>("table_name") } into q             select new { TableId = q.Key.TableId, TableName = q.Key.TableName }            );      foreach (var key in query)      {        dv.RowFilter = "tableid=" + key.TableId;        DataTable dtTable = dv.ToTable();        Hashtable ht = new Hashtable();        ht["T"] = dtTable;        string tableName = dtTable.Rows[0]["table_name"].ToString();        FileGen.GetFile(tmpPath, ht, string.Format("{0}\\{1}.cs", outPutPath, key.TableName));        //消息提示        DataRow dr = dtInfo.NewRow();        dr["TableName"] = tableName;        dr["Info"] = "生成成功";        dr["Time"] = DateTime.Now.ToString();        dtInfo.Rows.Add(dr);        DataView dvOrder = dtInfo.DefaultView;        dvOrder.Sort = "Time DESC";        DataTable dtinfo = dvOrder.ToTable();        if (this.dataGridView.InvokeRequired)        {          SetMessageCallBack stms = new SetMessageCallBack(BindMessage);          if (this != null)          {            this.Invoke(stms, new object[] { dtinfo });          }        }        else        {          dataGridView.DataSource = dvOrder.ToTable();        }      }          }    /// <summary>    /// 列表显示最新消息    /// </summary>    /// <param name="dt"></param>    private void BindMessage(object dt)    {      dataGridView.DataSource = dt;    }    /// <summary>    /// 获取所有表信息    /// </summary>    /// <returns></returns>    public DataTable GetAllTableInfo()    {      string strSQL = @"  SELECT T.name AS table_name ,      T.object_id AS tableid,      ISNULL(CONVERT(VARCHAR(MAX), E.value), '') AS table_name_c ,      C.name AS field_name ,      ISNULL(CONVERT(VARCHAR(MAX), D.value), '') AS field_name_c ,      ROW_NUMBER() OVER(PARTITION BY T.name ORDER BY C.colid) AS field_sequence ,      TYPE_NAME(C.xtype) AS date_type ,      (CASE WHEN EXISTS ( SELECT  1      FROM   sysobjects      WHERE  xtype = 'PK'      AND name IN (      SELECT name      FROM  sysindexes      WHERE  id = C.id      AND indid IN (      SELECT indid      FROM  sysindexkeys      WHERE  id = C.id      AND colid = C.colid ) ) )      THEN 1      ELSE 0      END) AS pk ,      ISNULL(C.isnullable, 1) AS isnullable ,      ISNULL(COLUMNPROPERTY(c.id, c.name, 'IsIdentity'), 0) AS isidentity      FROM  sys.tables AS T      LEFT JOIN syscolumns AS C ON c.id = T.object_id      LEFT JOIN sys.extended_properties AS D ON D.major_id = T.object_id      AND D.minor_id = C.colid      AND D.major_id = C.id      LEFT JOIN sys.extended_properties AS E ON E.major_id = T.object_id      AND E.minor_id = 0    WHERE T.object_id IN (SELECT object_id FROM sys.Tables)";      return CPQuery.From(strSQL).FillDataTable();    }  }}

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2.BackgroundWorker

除了自己使用Thread或者ThreadPool来实现跨线程更新UI还可以使用BackgroundWorker组件来实现该效果。

using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Windows.Forms;using Mysoft.Map.Extensions.DAL;using System.Collections;using Mysoft.Code.Services;using System.IO;using System.Threading;namespace ThreadWin{  public partial class BackgroundWorkerForm : Form  {    //模版文件路径    private static string tmpPath = AppDomain.CurrentDomain.BaseDirectory + @"实体模版\Entity.vm";    //模版输出路径    private static string outPutPath = AppDomain.CurrentDomain.BaseDirectory + @"模版输出路径";    private DataTable dtInfo = new DataTable();    /// <summary>    /// 消息发送请求委托    /// </summary>    /// <param name="Msg">消息</param>    delegate void SetMessageCallBack(object Msg);    public BackgroundWorkerForm()    {      InitializeComponent();      dtInfo.Columns.Add("TableName");      dtInfo.Columns.Add("Info");      dtInfo.Columns.Add("Time");      Control.CheckForIllegalCrossThreadCalls = false;    }    private void btn_OK_Click(object sender, EventArgs e)    {      dtInfo.Clear();            if (!Directory.Exists(outPutPath))      {        Directory.CreateDirectory(outPutPath);      }      //判断线程是否Busy      if (mBackgroundWorker.IsBusy)      {        MessageBox.Show("当前进程正在生成代码，请等待本次操作完成！");        return;      }      mBackgroundWorker.RunWorkerAsync();    }    private void mBackgroundWorker_DoWork(object sender, DoWorkEventArgs e)    {      BackgroundWorker bw = (BackgroundWorker)sender;      //循环生成实体，并且在列表上显示进度      DataTable dt = GetAllTableInfo();      DataView dv = dt.DefaultView;      var query = (from p in dt.AsEnumerable()             group p by new { TableId = p.Field<int>("tableid"), TableName = p.Field<string>("table_name") } into q             select new { TableId = q.Key.TableId, TableName = q.Key.TableName }            );      foreach (var key in query)      {        dv.RowFilter = "tableid=" + key.TableId;        DataTable dtTable = dv.ToTable();        Hashtable ht = new Hashtable();        ht["T"] = dtTable;        string tableName = dtTable.Rows[0]["table_name"].ToString();        FileGen.GetFile(tmpPath, ht, string.Format("{0}\\{1}.cs", outPutPath, key.TableName));        //消息提示        DataRow dr = dtInfo.NewRow();        dr["TableName"] = tableName;        dr["Info"] = "生成成功";        dr["Time"] = DateTime.Now.ToString();        dtInfo.Rows.Add(dr);        DataView dvOrder = dtInfo.DefaultView;        dvOrder.Sort = "Time DESC";        DataTable dtinfo = dvOrder.ToTable();        //通知进度改变        bw.ReportProgress(0, dtinfo);      }     }    /// <summary>    /// 进度改变执行    /// </summary>    /// <param name="sender"></param>    /// <param name="e"></param>    private void mBackgroundWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)    {      dataGridView.DataSource = e.UserState;    }    /// <summary>    /// 获取所有表信息    /// </summary>    /// <returns></returns>    public DataTable GetAllTableInfo()    {      string strSQL = @"  SELECT T.name AS table_name ,      T.object_id AS tableid,      ISNULL(CONVERT(VARCHAR(MAX), E.value), '') AS table_name_c ,      C.name AS field_name ,      ISNULL(CONVERT(VARCHAR(MAX), D.value), '') AS field_name_c ,      ROW_NUMBER() OVER(PARTITION BY T.name ORDER BY C.colid) AS field_sequence ,      TYPE_NAME(C.xtype) AS date_type ,      (CASE WHEN EXISTS ( SELECT  1      FROM   sysobjects      WHERE  xtype = 'PK'      AND name IN (      SELECT name      FROM  sysindexes      WHERE  id = C.id      AND indid IN (      SELECT indid      FROM  sysindexkeys      WHERE  id = C.id      AND colid = C.colid ) ) )      THEN 1      ELSE 0      END) AS pk ,      ISNULL(C.isnullable, 1) AS isnullable ,      ISNULL(COLUMNPROPERTY(c.id, c.name, 'IsIdentity'), 0) AS isidentity      FROM  sys.tables AS T      LEFT JOIN syscolumns AS C ON c.id = T.object_id      LEFT JOIN sys.extended_properties AS D ON D.major_id = T.object_id      AND D.minor_id = C.colid      AND D.major_id = C.id      LEFT JOIN sys.extended_properties AS E ON E.major_id = T.object_id      AND E.minor_id = 0    WHERE T.object_id IN (SELECT object_id FROM sys.Tables)";      return CPQuery.From(strSQL).FillDataTable();    }  }}

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1.操作步骤很简单，从组件里面拖一个BackgroundWorker组件设置WorkerReportsProgress（是否允许通知进度改变）为true

2.添加DoWork(进行耗时操作) 和 ProgressChanged(进度改变执行) 方法

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