标签:blog http io os 使用 ar for 文件 数据
以前上学的时候,听到“一个学生在毕业后刚刚开始编程的头几年中,写出的代码多半是垃圾”这样的说法,均不屑一顾。现在工作一年多了,越发感觉自己代码中疏漏处甚多,故近来常做亡羊补牢的重构之举。拿自己4个月前写的数据访问层来说,这个层位于整个系统的最底端,根据传入的sql语句进行查询和更新操作。就拿查询来说吧,我当时觉得很简单,写出来的方法是这样的:
而此方法都是这样被我调用的:
1
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
//代码段2
2
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
string cmd = "select * from MaterialClass where MaterialClassCode = {0}";
3
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
cmd = string.Format(cmd, scope);
4
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
DataTable table = new BitAECSqlExe().ExecuteQuery(cmd);
有心的朋友很容易就能看出,如此的代码是非常脆弱的,根本无法应付查询字符串中出现特殊字符的情况(单引号,百分号等)。程序容错性差不说,还容易遭到sql注入的攻击。另外,对于sql操作可能抛出的异常,这里捕获之后就跳转到出错页的方式也是很糟糕的;因为这段底层代码,除了会被页面调用以外,还会被其他一些不是由客户端请求引发的功能所调用(如部署到服务器上的windows服务,处理复杂任务的专用工作线程等),在这些调用环境里HttpContext.Current是没有意义的。实际上,在这种底层的代码里,只能对异常作必要的处理,至于究竟是跳转到一个友好的错误提示界面,还是写入错误日志,应当交给更高层的代码去决定。
对这部分的重构其实很简单,那就是在进行查询的时候,对于所有参数都以SqlParameter进行封装。重构中新增了方法PrepareCommand,用来得到我们需要的SqlCommand对象。对ExecuteQuery的重构如下:
上面重构的是ExecuteQuery方法的定义部分,这其实只是重构的开始,因为现有代码中充满了类似代码段2那样的方法调用,都需要改成如下的形式:
1
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
//代码段4
2
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
string cmd = "select * from MaterialClass where MaterialClassCode = @MaterialClassCode and CompanyName = @CompanyName";
3
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
SqlParameter[] SqlParams =
4
{
5
new SqlParameter("@MaterialClassCode",MaterialClassCode ),
6
new SqlParameter("@CompanyName",CompanyName )
7
}
8
DataTable table = new BitAECSqlExe().ExecuteQuery(cmd);
比照一下上面贴出的代码段2和代码段4,它们之间的差异就是我很希望自己能通过正则表达式跨越的鸿沟(一个一个手工去改的话实在太累了,一百多处啊,呵呵)。需要注意的是,查询语句中可能出现的参数个数是不定的,每个文件中可能包含的方法调用的数量也是不定的。本想写一个C#的console小程序来完成这个批量操作,但又总觉得杀鸡用牛刀,后来写了一个简单的perl脚本,利用perl强大的文本处理能力,很容易就实现了这个功能。脚本代码如下:
1
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
use FileHandle;
2
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
use File::Find;
3
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
use strict;
4
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
5
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
#全局变量
6
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
my $directory = "E:/GEA52_SVN/GEA52/Web";
7
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
#my $directory = "E:/Temp/Perl";
8
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
9
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
find(\&editFile, $directory);
10
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
11
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
#使用这个方法来修改每一个代码文件
12
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
#xingyk 20070702
13
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
sub editFile()
14
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
{
15
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
if ( -f and /.cs?/ )
16
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
{
17
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
my $file = $_;
18
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
open FILE, $file;
19
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
my @lines = <FILE>;
20
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
close FILE;
21
22
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
my @maArr;
23
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
for my $line ( @lines )
24
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
{
25
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
@maArr = $line =~ /\s+(\w+)\s*={\d}/g;
26
27
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
#先替换原有查询字符串
28
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
$line =~ s/\s+(\w+)\s*={\d}/ $1=\@$1 /g;
29
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
#接下来添加SqlParameter数组的默认构造器
30
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
my $sqlParam = "\n\tSqlParameter[] sqlParams = { ";
31
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
if(@maArr>0)
32
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
{
33
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
for(@maArr)
34
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
{
35
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
$sqlParam = $sqlParam."\t\tnew SqlParameter(\"@".$_."\", ".$_."),\n";
36
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
}
37
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
$line = $line.$sqlParam."\t\t\t};\n";
38
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
}
39
40
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
}
41
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
42
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
open FILE, ">$file";
43
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
print FILE @lines;
44
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
close FILE;
45
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
}
46
![bubuko.com,布布扣](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
}
对数据访问层的重构(及重构中Perl的应用)
标签:blog http io os 使用 ar for 文件 数据
原文地址:http://www.cnblogs.com/yihaha/p/3977547.html