学习笔记 --- BLL层事物、asp.net异常处理
1. BLL层事务:
简单的BLL层的事物, 使用TransactionScope就可以, 在TransactionScope的代码块中, 无错误就调用TransactionScope对象上的Complete()方法提交数据, 若有错就自动回滚.
值得注意的是, 对于使用DataSet、DataTable等无连接存取数据时, 如果要实现BLL层事物, 则需要给出一个状态为Open的Connection. 详见文章中的System.Transactions and ADO.NET 2.0 (英文的).
//示例代码:
//DAL/Utility.cs
View Code
using
System;
using
System.Collections.Generic;
using
System.Linq;
using
System.Text;
using
System.Data.SqlClient;
using
System.Data;
namespace
DAL
{
public
class
Utility
{
public
static
void
ExeNoQuery(
string
sqlStr,
string
constr, CommandType type,
params
SqlParameter[] param)
{
SqlConnection con
=
new
SqlConnection(constr);
SqlCommand com
=
new
SqlCommand();
com.Connection
=
con;
com.CommandType
=
type;
com.CommandText
=
sqlStr;
if
(type
==
CommandType.StoredProcedure)
{
for
(
int
i
=
0
; i
<
param.Length; i
++
)
{
if
(param[i].Value
as
string
==
string
.Empty)
{
param[i].Value
=
DBNull.Value;
}
com.Parameters.Add(param[i]);
}
}
try
{
con.Open();
com.ExecuteNonQuery();
}
catch
(Exception ex)
{
throw
;
}
finally
{
if
(con.State
==
ConnectionState.Open)
con.Close();
}
}
public
static
DataSet ExeDataSet(
string
sqlStr,
string
constr, CommandType type,
params
SqlParameter[] param)
{
SqlConnection con
=
new
SqlConnection(constr);
SqlCommand com
=
new
SqlCommand();
com.Connection
=
con;
com.CommandType
=
type;
com.CommandText
=
sqlStr;
if
(type
==
CommandType.StoredProcedure)
{
for
(
int
i
=
0
; i
<
param.Length; i
++
)
com.Parameters.Add(param[i]);
}
DataSet ds
=
new
DataSet();
SqlDataAdapter da
=
new
SqlDataAdapter();
da.SelectCommand
=
com;
try
{
da.Fill(ds);
}
catch
(Exception ex)
{
}
return
ds;
}
public
static
SqlDataReader ExeQuery(
string
sqlStr,
string
constr, CommandType type,
params
SqlParameter[] param)
{
SqlDataReader dr
=
null
;
SqlConnection con
=
new
SqlConnection(constr);
SqlCommand com
=
new
SqlCommand();
com.Connection
=
con;
com.CommandType
=
type;
com.CommandText
=
sqlStr;
if
(type
==
CommandType.StoredProcedure)
{
for
(
int
i
=
0
; i
<
param.Length; i
++
)
com.Parameters.Add(param[i]);
}
try
{
con.Open();
dr
=
com.ExecuteReader(CommandBehavior.CloseConnection);
}
catch
(Exception ex)
{
}
return
dr;
}
}
}
//DAL/EmployeeDAL.cs
View Code
using
System;
using
System.Collections.Generic;
using
System.Linq;
using
System.Text;
namespace
DAL
{
public
class
EmployeeDAL
{
private
static
readonly
string
constr
=
System.Configuration.ConfigurationManager.ConnectionStrings[
"
MsSql
"
].ConnectionString;
public
void
InsertEmployee(
string
employeename,
int
departmentid)
{
System.Data.SqlClient.SqlParameter p_name
=
new
System.Data.SqlClient.SqlParameter(
"
@ename
"
, System.Data.SqlDbType.NVarChar,
30
);
p_name.Value
=
employeename;
System.Data.SqlClient.SqlParameter p_depid
=
new
System.Data.SqlClient.SqlParameter(
"
@depid
"
, System.Data.SqlDbType.Int);
p_depid.Value
=
departmentid;
Utility.ExeNoQuery(
"
SP_AddEmployee
"
, constr, System.Data.CommandType.StoredProcedure, p_name, p_depid);
}
}
}
//DAL/DepartmentDAL.cs
View Code
using
System;
using
System.Collections.Generic;
using
System.Linq;
using
System.Text;
namespace
DAL
{
public
class
DepartmentDAL
{
private
static
readonly
string
constr
=
System.Configuration.ConfigurationManager.ConnectionStrings[
"
MsSql
"
].ConnectionString;
public
int
InsertDepartment(
string
departmentname)
{
int
depid
=
-
1
;
System.Data.SqlClient.SqlParameter p_name
=
new
System.Data.SqlClient.SqlParameter(
"
@depname
"
, System.Data.SqlDbType.NVarChar,
30
);
p_name.Value
=
departmentname;
System.Data.SqlClient.SqlParameter p_id
=
new
System.Data.SqlClient.SqlParameter(
"
@return_value
"
, System.Data.SqlDbType.Int);
p_id.Direction
=
System.Data.ParameterDirection.ReturnValue;
Utility.ExeNoQuery(
"
SP_AddDepartment
"
, constr, System.Data.CommandType.StoredProcedure, p_name, p_id);
depid
=
(
int
)p_id.Value;
return
depid;
}
}
}
//BLL/DepartmentBLL.cs
View Code
using
System;
using
System.Collections.Generic;
using
System.Linq;
using
System.Text;
namespace
BLL
{
public
class
DepartmentBLL
{
#region
全局变量
DAL.DepartmentDAL dd
=
new
DAL.DepartmentDAL();
DAL.EmployeeDAL ed
=
new
DAL.EmployeeDAL();
#endregion
public
void
AddDepartmentWithSomeEmployees(
string
departmentname,
params
string
[] employeenames)
{
//
添加System.Transactions.dll.
//
开启分布式事务支持:把 C:\WINDOWS\system32\dtclog 这个目录重命名（如果有），然后重新建立该目录。然后在命令行下： msdtc -resetlog
//
在“开始”->“设置”->“控制面板”->“管理工具”->“组件服务”中，“控制台根目录”->“组件服务”->“计算机”->“我的电脑”->“COM+应用程序”中，有一个“IIS Out-Of-Process Pooled”鼠标右键“属性”--“标识”--把“此用户”调整为“交互式用户--目前已登录的用户”。然后“确定”，再鼠标右键“属性”--“启动.
using
(System.Transactions.TransactionScope ts
=
new
System.Transactions.TransactionScope())
{
int
departmentid
=
dd.InsertDepartment(departmentname);
for
(
int
i
=
0
; i
<
employeenames.Length; i
++
)
{
ed.InsertEmployee(employeenames[i], departmentid);
}
ts.Complete();
}
}
}
}
//UI/Default.aspx
View Code
<%
@ Page Language
=
"
C#
"
AutoEventWireup
=
"
true
"
CodeFile
=
"
Default.aspx.cs
"
Inherits
=
"
_Default
"
%>
<!
DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"
>
<
html
xmlns
="http://www.w3.org/1999/xhtml"
>
<
head
runat
="server"
>
<
title
></
title
>
</
head
>
<
body
>
<
form
id
="form1"
runat
="server"
>
<
div
>
<
span
>
部门:
</
span
><
asp:TextBox
ID
="txt_dep"
runat
="server"
></
asp:TextBox
>
<
hr
/>
<
span
>
员工1:
</
span
><
asp:TextBox
ID
="txt_emp1"
runat
="server"
></
asp:TextBox
>
<
span
>
员工2:
</
span
><
asp:TextBox
ID
="txt_emp2"
runat
="server"
></
asp:TextBox
>
<
span
>
员工3:
</
span
><
asp:TextBox
ID
="txt_emp3"
runat
="server"
></
asp:TextBox
>
<
asp:LinkButton
ID
="lbtn_submit"
runat
="server"
onclick
="lbtn_submit_Click"
>
添加
</
asp:LinkButton
>
</
div
>
</
form
>
</
body
>
</
html
>
//UI/default.aspx.cs
View Code
using
System;
using
System.Collections.Generic;
using
System.Linq;
using
System.Web;
using
System.Web.UI;
using
System.Web.UI.WebControls;
public
partial
class
_Default : System.Web.UI.Page
{
#region
全局变量
BLL.DepartmentBLL db
=
new
BLL.DepartmentBLL();
#endregion
protected
void
Page_Load(
object
sender, EventArgs e)
{
}
protected
void
lbtn_submit_Click(
object
sender, EventArgs e)
{
db.AddDepartmentWithSomeEmployees(
this
.txt_dep.Text,
this
.txt_emp1.Text,
this
.txt_emp2.Text,
this
.txt_emp3.Text);
}
}
//创建表的Sql命令
View Code
create
database
BLLTransactionDemo
go
use
BLLTransactionDemo
go
if
exists
(
select
[
name
]
from
sysobjects
where
[
name
]
=
'
T_Employee
'
and
[
type
]
=
'
U
'
)
drop
table
T_Employee
go
create
table
T_Employee
(
eid
int
identity
primary
key
not
null
,
ename
nvarchar
(
30
)
not
null
,
depid
int
)
go
if
exists
(
select
[
name
]
from
sysobjects
where
[
name
]
=
'
T_Department
'
and
[
type
]
=
'
U
'
)
drop
table
T_Department
go
create
table
T_Department
(
depid
int
identity
primary
key
not
null
,
depname
nvarchar
(
30
)
not
null
)
go
if
exists
(
select
[
name
]
from
sysobjects
where
[
name
]
=
'
SP_AddDepartment
'
and
[
type
]
=
'
P
'
)
drop
procedure
SP_AddDepartment
go
create
procedure
SP_AddDepartment
(
@depname
nvarchar
(
30
)
)
as
begin
insert
into
T_Department(depname)
values
(
@depname
);
return
@@identity
;
end
go
exec
SP_AddDepartment
'
32
'
if
exists
(
select
[
name
]
from
sysobjects
where
[
name
]
=
'
SP_AddEmployee
'
and
[
type
]
=
'
P
'
)
drop
procedure
SP_AddEmployee
go
create
procedure
SP_AddEmployee
(
@ename
nvarchar
(
30
),
@depid
int
)
as
begin
insert
into
T_Employee(ename,depid)
values
(
@ename
,
@depid
)
end
go
exec
SP_AddEmployee
'
王
'
,
10
select
*
from
T_employee
select
*
from
T_department
2. asp.net的错误处理机制(简述):
asp.net的错误处理机制共分3个层次, 代码级的错误处理, 页面级的错误处理, 网站级的错误处理.
首先, 代码级的错误处理: 很简单,就是try...catch的使用
其次, 页面级的错误处理: 在页面事件处理方法中抛出的异常可以被IHttpHandler中约定的ProcessRequest方法所捕获, 可以通过页面处理对象的Error事件来处理异常.但是Error事件的委托类型是EventHandler, 换句话说就是它无法获得异常信息. 这时, 可以通过HttpContext获得Server对象, 该对象提供了public Exception GetLastError()和pulic void ClearError()两个方法来处理异常. 若,页面级处理了异常, 异常将不再会被抛出到应用程序中.
最后, 网站级的错误处理: 可以在HttpApplication对象的Error事件中处理, 可以再IHttpModule中处理, 但为简单起见, 更常见的是在Global.asax中处理. 值得注意的是, 此时的异常已被包装, 需要通过Server.GetLastException().InnerException来获取异常.
网站级别的异常处理的配置: 当网站出现未处理的异常时, 可以通过web.config文件中的customErrors元素进行配置(mode有3种可选值,off关闭错误处理, 直接显示异常给客户;On想所有用户返回自定义错误信息页面;RemoteOnly向远程用户返回自定义错误信息页面, 向本级客户返回错误详细内容.), 且defaultRedirect属性用来指出自定义的错误信息页面的URL地址(地址可以是相对的, 也可以使绝对的, 相对地址是针对网站根目录的).