数据字典生成工具之旅(9)：多线程使用及介绍

2018-01-05 15:21:51 浏览数 (1)

      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 。

代码语言：javascript复制
--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 BIT
DECLARE @total AS INT 
DECLARE @i AS INT
SELECT @i=1,@total=300,@IsDropTable=0
WHILE @i<=@total
BEGIN
DECLARE @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 1
END

    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。

代码语言：javascript复制
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()));
            }
        }

    }
}

    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。

代码语言：javascript复制
   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);
            }

     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。

代码语言：javascript复制
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();
        }
    }
}

    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。

代码语言：javascript复制
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();
        }
    }
}

    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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本章总结

     在写数据字典生成工具之前自己对线程的使用还是很模糊的，翻了很多资料和博客才学习到这些知识。如果您感觉本文不错，对您有所帮助，请您不吝点击下右边的推荐按钮，谢谢！

     本章代码示例代码下载地址：http://code.taobao.org/svn/DataDic_QuickCode ，请使用SVN进行下载！

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工具源代码下载

      目前总共有经过了七个版本的升级，现在提供最新版本的下载地址

数据字典生成工具V2.0安装程序

最新安装程序

数据字典生成工具源代码

最新源代码

http://code.taobao.org/svn/DataDicPub

SVN最新源码共享地址

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编程算法 svn http

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