博客园_Never give up - LEO

CN.Text开发笔记—利用反射将数据读入实体类

2010-06-11T03:46:00Z

在实际开发中，我们经常需要从数据库中读取数据并赋值给实体类的相应属性。在.Text的DataDTOProvider中存在大量这样的代码, 比如:

public Role[] GetRoles(int BlogID)
        {
            System.Collections.ArrayList al=new System.Collections.ArrayList();
            IDataReader reader=DbProvider.Instance().GetRoles(BlogID);
            try
            {
                while(reader.Read())
                {
                    Role role=new Role();
                    if(reader["RoleID"]!=DBNull.Value)
                    {
                        role.RoleID=(int)reader["RoleID"];
                    }
                    if(reader["Name"]!=DBNull.Value)
                    {
                        role.Name=(string)reader["Name"];
                    }
                    if(reader["Description"]!=DBNull.Value)
                    {
                        role.Description=(string)reader["Description"];
                    }
                    //ReaderToObject(reader,role);
                    al.Add(role);
                }
            }
            finally
            {
                reader.Close();
            }
            return (Role[])al.ToArray(typeof(Role));

        }

对于上面的代码，我觉得有几点不优雅之处：
1、每次对Role的属性进行赋值时，都要检查reader的值是否为DBNull，出现了很多重复代码
2、每次对Role的属性进行赋值时，都要进行类型转换, 而Role属性的类型是已知的，是不是可以自动完成这样的转换？
3、每次对Role的属性进行赋值时，都要进行Role属性与数据库字段的对应。如果我们在设计数据库与实体类时，保证数据库字段与实体类属性采用同样的名称，那利用反射，我们可以通过代码自动进行属性与字段的对应。即使数据库字段与属性不同名，我们也可以通过更改查询语句，来做到这一点。
是不是可以对上面的代码进行改进，使代码变得更优雅?那优雅的代码应该是什么样的呢?如果我们用上面代码中注释的代码行ReaderToObject(reader,role);取代它之前的对Role属性进行赋值的语句，是不是会使代码变得更优雅?ReaderToObject的作用就是自动完成将reader中的值写入到role中对应的属性中(前提是reader中的字段与role中对应的属性具有相同的名称)。现在我们的任务就是实现ReaderToObject, 有了强大的武器—Reflection，我们的任务就变得很轻松, 也不多说了，下面的代码是我的实现方法:

private void ReaderToObject(IDataReader reader,object targetObj)
        {
            for(int i=0;i<reader.FieldCount;i++)
            {
                System.Reflection.PropertyInfo propertyInfo=targetObj.GetType().GetProperty(reader.GetName(i));
                if(propertyInfo!=null)
                {
                    if(reader.GetValue(i)!=DBNull.Value)
                    {
                        propertyInfo.SetValue(targetObj,reader.GetValue(i),null);
                    }
                }
            }
        }

ReaderToObject可以将reader中的数据读入到任何实体类中。数据库字段与实体类属性的映射原则是名称相同。当然，我们也可以通过配置文件来进行两者映射。

个人想法：在开发中，面对那么多设计思想和设计模式，常常令人感到迷惑，当你把更多的精力放在选用哪个设计思想或设计模式时，我觉得不要忽略很重要的一点，尽可能地减少重复代码，只要我们能有效地减少重复代码，我们采用的方法就是好方法，而不要太在乎采用了哪种模式。就像独孤九剑，正因为摆脱了传统招式的束缚，才能战无不胜!

http://www.cnblogs.com/dudu/archive/2004/09/12/42389.html

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Cannot connect PHP 5.2.9 to SQL Server 2008

2010-06-11T03:45:00Z

I have a strange problem while connecting to MSSQL 2008 with php.
First I wrote the code myself and I got error message:

Warning: mssql_connect() [function.mssql-connect]: Unable to connect to server: 172.16.2.12:1433 in C:\xampp\htdocs\test.php on line 19After googleing for a few hours I found out that with the 2005 version there is some problems with ntwdblib.dll but I cannot find any bugs/problems for this with php 5.2.9 and SQL 2008.

Then I used the code from the Microsoft site:

<?php

// Server in the this format: <computer>\<instance name> or

// <server>,<port> when using a non default port number

$server = '172.16.2.12,1433';

$link = mssql_connect($server, 'Username', 'Password');

if(!$link)

{

die('Something went wrong while connecting to MSSQL');

}

?>But still I get the error:
Warning: mssql_connect() [function.mssql-connect]: Unable to connect to server: 172.16.2.12:1433 in C:\xampp\htdocs\test.php on line 19
Yes: The port is 1433;
Yes: The port is open;
Yes: I can connect with telnet;
Yes: The username is correct;
Yes: Also is the password.

Apache server is running local on my workstation.
SQL 2008 is running on remote server (172.17.2.12).

I have no idea what the problem is, and I am sure that the code is correct.

Someone any ideas what this might be?

Thanks in advance;

Lucas Mateijsen

Moved byStoyko Kostov - MSFT Friday, August 07, 2009 4:40 PM (From:SQL Server Data Access)

Answers

Wednesday, August 12, 2009 3:56 AMNai-dong Jin - MSFTMSFT, Moderator

0
Sign In to Vote
Hi,

I think the ntwdblib.dll you used does not support your current SQLServer version.

I suggest that you may try the following link and get the latest ntwdblib.dll and overwrite your original one.

http://www.theregister.co.uk/2008/04/24/database_connection_php/

Thanks.
Microsoft Online Community Support Please remember to mark the replies as answers if they help and unmark them if they provide no help.
- Marked As Answer byNai-dong Jin - MSFTMSFT, ModeratorFriday, August 14, 2009 3:08 AM
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- Quote
Wednesday, August 12, 2009 5:09 AMjtoddhanard

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The ntwdblib.dll has never worked for me with any version of sql server other than 7.0. There's so many different versions of the library floating around, its hard to know which one works with which server version. I think most people who use mssql functions in PHP use the FreeTDS libraries for either Unix or Windows. You can get binaries already made... website is www.freetds.org I've had success with both 2005 and 2008 sql server. But, since MS wrote a PHP driver, i've had better luck with it. Both ntwdblib.dll and the freetds libraries use mssql functions but you can only have one running at a time.

Now on a side note, the Microsoft PHP Driver doesn't use the mssql function set, it uses the sqlsrv function set. So, in order to use the MS PHP driver, you need to use sqlsrv_connect, sqlsrv_query, etc. You can run a phpinfo() command in order to determine if you have either of those installed.

This forum is specifically for the microsoft PHP driver, so if you have problems with the ntwdblib, you might want to check some other websites or forums for assistance.

Best of luck
- Marked As Answer byNai-dong Jin - MSFTMSFT, ModeratorFriday, August 14, 2009 3:08 AM
- Reply
- Quote

All Replies

Friday, August 07, 2009 4:41 PMStoyko Kostov - MSFT

0
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Please don't make duplicate posts.
- Unmarked As Answer byLucas Mateijsen Friday, August 07, 2009 7:05 PM
- Marked As Answer byLucas Mateijsen Friday, August 07, 2009 7:05 PM
- Reply
- Quote
Wednesday, August 12, 2009 3:56 AMNai-dong Jin - MSFTMSFT, Moderator

0
Sign In to Vote
Hi,

I think the ntwdblib.dll you used does not support your current SQLServer version.

I suggest that you may try the following link and get the latest ntwdblib.dll and overwrite your original one.

http://www.theregister.co.uk/2008/04/24/database_connection_php/

Thanks.
Microsoft Online Community Support Please remember to mark the replies as answers if they help and unmark them if they provide no help.
- Marked As Answer byNai-dong Jin - MSFTMSFT, ModeratorFriday, August 14, 2009 3:08 AM
- Reply
- Quote
Wednesday, August 12, 2009 5:09 AMjtoddhanard

0
Sign In to Vote
The ntwdblib.dll has never worked for me with any version of sql server other than 7.0. There's so many different versions of the library floating around, its hard to know which one works with which server version. I think most people who use mssql functions in PHP use the FreeTDS libraries for either Unix or Windows. You can get binaries already made... website is www.freetds.org I've had success with both 2005 and 2008 sql server. But, since MS wrote a PHP driver, i've had better luck with it. Both ntwdblib.dll and the freetds libraries use mssql functions but you can only have one running at a time.

Now on a side note, the Microsoft PHP Driver doesn't use the mssql function set, it uses the sqlsrv function set. So, in order to use the MS PHP driver, you need to use sqlsrv_connect, sqlsrv_query, etc. You can run a phpinfo() command in order to determine if you have either of those installed.

This forum is specifically for the microsoft PHP driver, so if you have problems with the ntwdblib, you might want to check some other websites or forums for assistance.

Best of luck
- Marked As Answer byNai-dong Jin - MSFTMSFT, ModeratorFriday, August 14, 2009 3:08 AM

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提供给 lock 的对象只是用来唯一地标识由多个线程共享的资源

2010-06-11T03:42:00Z

提供给 lock 的对象只是用来唯一地标识由多个线程共享的资源

通常，最好避免锁定 public 类型或锁定不受应用程序控制的对象实例。例如，如果该实例可以被公开访问，则 lock(this) 可能会有问题，因为不受控制的代码也可能会锁定该对象。这可能导致死锁，即两个或更多个线程等待释放同一对象。出于同样的原因，锁定公共数据类型（相比于对象）也可能导致问题。锁定字符串尤其危险，因为字符串被公共语言运行库 (CLR)“暂留”。这意味着整个程序中任何给定字符串都只有一个实例，就是这同一个对象表示了所有运行的应用程序域的所有线程中的该文本。因此，只要在应用程序进程中的任何位置处具有相同内容的字符串上放置了锁，就将锁定应用程序中该字符串的所有实例。因此，最好锁定不会被暂留的私有或受保护成员。某些类提供专门用于锁定的成员。例如，Array 类型提供 SyncRoot。许多集合类型也提供 SyncRoot。

本文链接

ASP.NET一个页面多个Button按钮事件避免数据验证控件RequiredFieldValidator冲突方法

2010-06-11T03:40:00Z

问题描述：在一个页面里创建多个按钮，其中默认情况下按钮事件与数据验证控件冲突：当其中的一个按钮被点击后想要特定的validator被激发而不是页面中的所有validator。而其他按钮则不需要validator。此时会都会启用数据验证控件。

说明：在ASP.NET 1.1中除了hack code没有更好的办法。ASP.NET 2.0中给所有的validator控件和按钮(button、linkbutton等等)增加了ValidatorGroup属性，就可以轻松地解决这个问题。如果在页面中有一个TextBox并且紧挨着他有一个RequiredFieldValidator 和Button控件，可以将RequiredFieldValidator和Button的ValidationGroup属性设置成一样的值从而使得点击button时只触发这个RequiredFieldValidator的validor，任何没有定义在ValidationGroup内的其他的 validator都会被忽略。

例子：
文本框和数据验证控件：
<asp:TextBox ID="TxtOldPs" runat="server" Width="150px"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ControlToValidate="TxtOldPs"
Display="None" ErrorMessage="<b>友情提醒</b><br />请输入原始密码！！" ValidationGroup="ValidataGroup1"></asp:RequiredFieldValidator>

按钮事件：
<asp:Button ID="ButtonOK" runat="server" Text="修改" OnClick="Edit_Click" ValidationGroup="ValidataGroup1" />

另一个按钮则不需要设置ValidationGroup
<asp:Button ID="ButtonOK" runat="server" Text="退出" OnClick="Exit_Click" />

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2009年5月软件设计师真题下载及参考答案

2009-05-23T11:30:00Z

2009年5月软件设计师真题下载及参考答案

Leo's 2007

2007-12-29T04:39:00Z

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2007-12-25T06:53:00Z

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javascript正则表达式使用详解

2007-12-12T01:27:00Z

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SQL Server 2008中四种DATETIME数据类型

2007-12-10T08:34:00Z

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博客园_Never give up - LEO

CN.Text开发笔记—利用反射将数据读入实体类

Cannot connect PHP 5.2.9 to SQL Server 2008

提供给 lock 的对象只是用来唯一地标识由多个线程共享的资源

ASP.NET一个页面多个Button按钮事件避免数据验证控件RequiredFieldValidator冲突方法

2009年5月软件设计师真题下载及参考答案

推荐一个不错的ASP无组件上传类

Leo's 2007

网页设计基本配色参考色谱

javascript正则表达式使用详解

SQL Server 2008中四种DATETIME数据类型