初涉三层架构，UI层和DAL层的调用，ADO.NET对数据库的数据增删改

UI层：可以说是界面层吧

<Window x:Class="三层架构.CustomerListUI"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="CustomerListUI" Height="600" Width="800" Loaded="Window_Loaded_1">
<Grid>
<DockPanel>
<ToolBar DockPanel.Dock="Top" Height="70">
<Button x:Name="btnInsert" Click="btnInsert_Click">
<Button.Content>
<StackPanel>
<Image Height="40" Source="Image/insert.ico"></Image>
<TextBlock HorizontalAlignment="Center" Text="添加"></TextBlock>
</StackPanel>
</Button.Content>
</Button>
<Button x:Name="btnEdit" Click="btnEdit_Click">
<Button.Content>
<StackPanel>
<Image Height="40" Source="Image/edit.ico"></Image>
<TextBlock HorizontalAlignment="Center" Text="编辑"></TextBlock>
</StackPanel>
</Button.Content>
</Button>
<Button x:Name="btnDelete" Click="btnDelete_Click">
<Button.Content>
<StackPanel>
<Image Height="40" Source="Image/delete.ico"></Image>
<TextBlock HorizontalAlignment="Center" Text="删除"></TextBlock>
</StackPanel>
</Button.Content>
</Button>
<Button x:Name="btnleading" Click="btnleading_Click">
<Button.Content>
<StackPanel>
<Image Height="40" Source="Image/leading.ico"></Image>
<TextBlock HorizontalAlignment="Center" Text="导入"></TextBlock>
</StackPanel>
</Button.Content>
</Button>
</ToolBar>
<DataGrid AutoGenerateColumns="False" Name="gridCustomers" IsReadOnly="True" DockPanel.Dock="Top">
<DataGrid.Columns>
<DataGridTextColumn Width="80" Header="姓名" Binding="{Binding Name}"></DataGridTextColumn>
<DataGridTextColumn Width="150" Header="生日" Binding="{Binding BirthDay}"></DataGridTextColumn>
<DataGridTextColumn Width="100" Header="电话" Binding="{Binding TelNum}"></DataGridTextColumn>
<DataGridTextColumn Width="80" Header="级别" Binding="{Binding CustLevel}"></DataGridTextColumn>
<DataGridTextColumn Width="250" Header="地址" Binding="{Binding Address}"></DataGridTextColumn>
</DataGrid.Columns>
</DataGrid>
</DockPanel>
</Grid>
</Window>

.cs代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;
using 三层架构.DAL;
using 三层架构.Model;

namespace 三层架构
{
/// <summary>
/// CustomerEditUI.xaml 的交互逻辑
/// </summary>
public partial class CustomerEditUI : Window
{
//是新增数据还是修改数据
public bool IsInsert { get; set; }

//是编辑的话被编辑行的ID
public long EditingId { get; set; }

public CustomerEditUI()
{
InitializeComponent();
}

private void btnSave_Click(object sender, RoutedEventArgs e)
{
if (IsInsert)
{
Customer customer = new Customer();
customer.Name = txtName.Text;
customer.TelNum = txtTelNum.Text;
customer.CustLevel = Convert.ToInt32(txtCustLevel.Text);
customer.Address = txtAddress.Text;
customer.BirthDay = dpBirthDay.SelectedDate;

new CustomerDAL().Insert(customer);//插入数据库
}
else
{
//先从数据库中查询旧的值，然后把界面中的值设置到旧对象上
//uodate更新
CustomerDAL dal = new CustomerDAL();
Customer customer = dal.GetById(EditingId);
customer.Address = txtAddress.Text;
customer.BirthDay = dpBirthDay.SelectedDate;
customer.Name = txtName.Text;
customer.CustLevel = Convert.ToInt32(txtCustLevel.Text);
customer.TelNum = txtTelNum.Text;
dal.Update(customer);
}
DialogResult = true;
}

private void btnCancel_Click(object sender, RoutedEventArgs e)
{
DialogResult = false;
}

private void Window_Loaded_1(object sender, RoutedEventArgs e)
{
if (IsInsert)
{
txtCustLevel.Text = "1";//默认是一级用户
}
else//修改
{
//把要编辑的数据从数据库中提取出来
//可以把Customer直接在ListUI传进来，这样还省得查一次数据库
Customer customer = new CustomerDAL().GetById(EditingId);
//但是一个原则：窗口传值、容器中存储值尽量放简单数据类型
//填充到界面上，显示编辑前的值
txtName.Text = customer.Name;
txtTelNum.Text = customer.TelNum;
txtAddress.Text = customer.Address;
txtCustLevel.Text = customer.CustLevel.ToString();
dpBirthDay.SelectedDate = customer.BirthDay;
}
}
}
}

添加和编辑使用同一个界面

<Window x:Class="三层架构.CustomerEditUI"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="CustomerEditUI" Height="400" Width="500" Loaded="Window_Loaded_1">
<Grid>
<TextBlock HorizontalAlignment="Left" Height="36" Margin="41,10,0,0" TextWrapping="Wrap" Text="姓名" VerticalAlignment="Top" Width="89"/>
<TextBlock HorizontalAlignment="Left" Height="36" Margin="41,60,0,0" TextWrapping="Wrap" Text="电话" VerticalAlignment="Top" Width="89"/>
<TextBlock HorizontalAlignment="Left" Height="36" Margin="41,110,0,0" TextWrapping="Wrap" Text="级别" VerticalAlignment="Top" Width="89"/>
<TextBlock HorizontalAlignment="Left" Height="36" Margin="41,160,0,0" TextWrapping="Wrap" Text="生日" VerticalAlignment="Top" Width="89"/>
<TextBlock HorizontalAlignment="Left" Height="36" Margin="41,210,0,0" TextWrapping="Wrap" Text="地址" VerticalAlignment="Top" Width="89"/>
<TextBox x:Name="txtName" HorizontalAlignment="Left" Height="36" Margin="196,10,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="192"/>
<TextBox x:Name="txtTelNum" HorizontalAlignment="Left" Height="36" Margin="196,60,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="192"/>
<TextBox x:Name="txtCustLevel" HorizontalAlignment="Left" Height="36" Margin="196,110,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="192"/>
<TextBox x:Name="txtAddress" HorizontalAlignment="Left" Height="94" Margin="196,210,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="192"/>
<Button x:Name="btnSave" Content="保存" HorizontalAlignment="Left" Height="35" Margin="106,325,0,0" VerticalAlignment="Top" Width="90" Click="btnSave_Click"/>
<Button x:Name="btnCancel" Content="取消" HorizontalAlignment="Left" Height="35" Margin="275,325,0,0" VerticalAlignment="Top" Width="90" Click="btnCancel_Click"/>
<DatePicker x:Name="dpBirthDay" HorizontalAlignment="Left" Height="36" Margin="196,160,0,0" VerticalAlignment="Top" Width="192"/>
</Grid>
</Window>

.cs代码

using Microsoft.Win32;
using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;
using 三层架构.DAL;
using 三层架构.Model;

namespace 三层架构
{
/// <summary>
/// CustomerListUI.xaml 的交互逻辑
/// </summary>
public partial class CustomerListUI : Window
{
public CustomerListUI()
{
InitializeComponent();
}

private void Window_Loaded_1(object sender, RoutedEventArgs e)
{
LoadData();

}

private void LoadData()
{
CustomerDAL dal = new CustomerDAL();
gridCustomers.ItemsSource = dal.GetAll();
}

private void btnInsert_Click(object sender, RoutedEventArgs e)
{
CustomerEditUI editUI = new CustomerEditUI();
editUI.IsInsert = true;
if (editUI.ShowDialog() == true)
{
LoadData();
}
}

private void btnEdit_Click(object sender, RoutedEventArgs e)
{
Customer customer = (Customer)gridCustomers.SelectedItem;
if (customer == null)
{
MessageBox.Show("请选择要编辑的行");
return;
}
CustomerEditUI editUI = new CustomerEditUI();
editUI.IsInsert = false;
editUI.EditingId = customer.Id;
if(editUI.ShowDialog()==true)
{
LoadData();
}
}

private void btnDelete_Click(object sender, RoutedEventArgs e)
{
Customer customer = (Customer)gridCustomers.SelectedItem;
if(customer==null)
{
MessageBox.Show("清选择要删除的行！");
return;
}
if (MessageBox.Show("是否删除？", "警告", MessageBoxButton.YesNo)
== MessageBoxResult.Yes)
{
new CustomerDAL().DeleteById(customer.Id);
LoadData();//刷新数据
}
}

private void btnleading_Click(object sender, RoutedEventArgs e)
{
OpenFileDialog ofd = new OpenFileDialog();
ofd.Filter = "文本文件|*.txt|表格文件|*.xls";
if (ofd.ShowDialog() != true)
{
return;
}
string filename = ofd.FileName;
IEnumerable<string> lines = File.ReadLines(filename,Encoding.Default);
foreach (string line in lines)
{
string[] segs = line.Split('\t');
Customer customer = new Customer();
customer.Name = segs[0];
customer.Name = customer.Name.Trim(' ');
customer.BirthDay = Convert.ToDateTime(segs[1]);
customer.Address = segs[2];
customer.Address = customer.Address.Trim(' ');
customer.TelNum = segs[3];
customer.TelNum = customer.TelNum.Trim(' ');
customer.CustLevel = Convert.ToInt32(segs[4]);

SqlHelper.ExcuteNonQuery(@"Insert into T_Customer (Name,BirthDay,Address,TelNum,CustLevel)
values (@Name,@BirthDay,@Address,@TelNum,@CustLevel)",
new SqlParameter("@Name", customer.Name),
new SqlParameter("@BirthDay", SqlHelper.ToDBValue(customer.BirthDay)),
new SqlParameter("@Address", customer.Address),
new SqlParameter("@TelNum", customer.TelNum),
new SqlParameter("@CustLevel", customer.CustLevel));

}
MessageBox.Show("导入成功，成功导入" + lines.Count() + "条数据");
LoadData();
}

}
}

导入数据这块参照上一篇博文，不过在这一层用了SQL语句确实不好，待改进！

连接数据库字符串配置文件

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
</startup>
<connectionStrings>
<add name ="database" connectionString="data source=.;initial catalog=Mytest;user id=sa;password=46332071"/>
</connectionStrings>
</configuration>

DAL层

SqlHelper

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace 三层架构.DAL
{
class SqlHelper
{
private static string dbStr = ConfigurationManager.ConnectionStrings["database"].ConnectionString;

public static int  ExcuteNonQuery(string sql, params SqlParameter[] parameter)
{
using (SqlConnection conn= new SqlConnection (dbStr))
{
conn.Open();
using (SqlCommand cmd =conn.CreateCommand())
{
cmd.CommandText=sql;
cmd.Parameters.AddRange(parameter);
return cmd.ExecuteNonQuery();

}
}
}
public static object  ExcuteScalar(string sql, params SqlParameter[] parameter)
{
using (SqlConnection conn = new SqlConnection(dbStr))
{
conn.Open();
using (SqlCommand cmd = conn.CreateCommand())
{
cmd.CommandText = sql;
cmd.Parameters.AddRange(parameter);
return cmd.ExecuteScalar();
}
}
}
public static DataTable ExcuteDataTable(string sql, params SqlParameter[] parameter)
{
using (SqlConnection conn = new SqlConnection(dbStr))
{
conn.Open();
using (SqlCommand  cmd = conn.CreateCommand())
{
cmd.CommandText = sql;
cmd.Parameters.AddRange(parameter);
SqlDataAdapter adapter = new SqlDataAdapter(cmd);
DataSet dataset = new DataSet();
adapter.Fill(dataset);
return dataset.Tables[0];
}
}
}
public static object FromDBValue(object value)
{
if (value == DBNull.Value)
{
return null;
}
else
{
return value;
}
}
public static object ToDBValue(object value)
{
if (value == DBNull.Value)
{
return null;
}
else
{
return value;
}
}
}
}

CustomerDAL

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Documents;
using 三层架构.Model;

namespace 三层架构.DAL
{
class CustomerDAL
{
//根据ID获取GetById、Update、DeleteById、GetAll、GetPagedData（分页数据）
//insert （插入新数据）

//把公共的代码封装到一个方法中，这样可以避免重复性的代码，提高代码复用性
private Customer ToCustomer(DataRow row)
{
Customer cust = new Customer();
cust.Id = (long)row["ID"];
cust.Name = (string)row["Name"];
cust.BirthDay = (DateTime?)SqlHelper.FromDBValue(row["BirthDay"]);
cust.Address = (string)row["Address"];
cust.TelNum = (string)row["TelNum"];
cust.CustLevel = (int)row["CustLevel"];
return cust;
}
public Customer GetById(long id)
{
DataTable dt =SqlHelper.ExcuteDataTable("select * from T_Customer where id = @id",
new SqlParameter("@id", id));
if (dt.Rows.Count <= 0)
{
return null;
}
else if (dt.Rows.Count > 1)
{
throw new Exception("严重错误，查出多条数据！");
}
else
{
DataRow row = dt.Rows[0];
//Customer cust = new Customer();
//cust.Id = (long)row["ID"];
//cust.Name = (string )row["Name"];
//cust.BirthDay = (DateTime?)SqlHelper.FromDBValue(row["BirthDay"]);
//cust.Address = (string)row["Address"];
//cust.TelNum = (string)row["TelNum"];
//cust.CustLevel = (int)row["CustLevel"];
//return cust;
return ToCustomer(row);
}
}
public void DeleteById(long id)
{
SqlHelper.ExcuteNonQuery("delete from T_Customer where Id = @Id",
new SqlParameter("@Id", id));
}
public void Insert(Customer customer)
{
SqlHelper.ExcuteNonQuery(@"Insert into T_Customer (Name,BirthDay,Address,TelNum,CustLevel)
values (@Name,@BirthDay,@Address,@TelNum,@CustLevel)",
new SqlParameter("@Name", customer.Name),
new SqlParameter("@BirthDay", SqlHelper.ToDBValue(customer.BirthDay)),
new SqlParameter("@Address", customer.Address),
new SqlParameter("@TelNum", customer.TelNum),
new SqlParameter("@CustLevel", customer.CustLevel));
}
public void Update(Customer customer)
{
SqlHelper.ExcuteNonQuery(@"Update T_Customer Set
Name = @Name,  BirthDay=@BirthDay,  @Address=Address,
TelNum=@TelNum,  @CustLevel=CustLevel   where ID=@ID",
new SqlParameter("@Name", customer.Name),
new SqlParameter("@BirthDay", SqlHelper.ToDBValue(customer.BirthDay)),
new SqlParameter("@Address", customer.Address),
new SqlParameter("@TelNum", customer.TelNum),
new SqlParameter("@CustLevel", customer.CustLevel),
new SqlParameter("@ID",customer.Id));
}
public Customer[] GetAll()
{
DataTable table =  SqlHelper.ExcuteDataTable("select * from T_Customer");
Customer[] customers = new Customer[table.Rows.Count];
for (int i = 0; i < table.Rows.Count; i++)
{
DataRow row = table.Rows[i];
customers[i] = ToCustomer(row);
}
return customers;
}
}
}

然后还有一个MODEL，注意MODEL不能算一层

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace 三层架构.Model
{
class Customer
{
public long Id { get; set; }
public string Name { get; set; }
public DateTime? BirthDay { get; set; }
public string Address { get; set; }
public string TelNum { get; set; }
public int CustLevel { get; set; }
}
}

心得：

初步设计三层架构还是有些头晕，毕竟调用的有点儿复杂，其实这不算是一个真正的三层，还缺一个BLL层，另外还有一个涉及数据库中NULL的问题，SqlParameter 如果值（第二个参数）为NULL，则表示没有提供参数的值，假设用户想保密自己的生日，没有填写生日，保存过数据库会出错，同理数据库中的NULL调用过来也一个道理，所以需要做转换，即DBNull.values。

关于配置文件：

1、app.config是要放到UI项中

2、DAL层通过ConfigurationManager可以读取到这项目中的app.config的配置信息

引用关系：

DAL项目引用MODEL

UI项目引用DAL和MODEL