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:&nbsp;</span><asp:TextBox ID="txt_dep" runat="server"></asp:TextBox>
        <hr />
        <span>员工1:&nbsp;</span><asp:TextBox ID="txt_emp1" runat="server"></asp:TextBox>
        <span>员工2:&nbsp;</span><asp:TextBox ID="txt_emp2" runat="server"></asp:TextBox>
        <span>员工3:&nbsp;</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).

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原文地址：https://www.cnblogs.com/cs_net/p/2005003.html