一、前言
在项目中，我们习惯使用 ConfigurationManager 来读取一些常量。如链接数据库字符串、一些需配置的数据（微信、QQ、支付宝）等的配置。我们需要把这些数据记录在 app.config 或者 web.config 中。接下来我们具体看一下 ConfigurationManager ：
二、介绍
命名空间：System.Configuration
程序集： System.Configuration.dll
引用：在使用中，如果出现“当前上下文中不存在名称：ConfigurationManager ”，你就要检查有没有引用程序集和命名空间了。
ConfigurationManager类： 包含属性（AppSettings、ConnectionStrings ）、方法（GetSection、OpenExeConfiguration、OpenExeConfiguration、OpenMachineConfiguration、OpenMappedExeConfiguration、OpenMappedExeConfiguration、OpenMappedMachineConfiguration、RefreshSection）
三、使用
通过 AppSettings 来获取数据，简单使用案例：
using System;
using System.Configuration;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
ReadAllSettings();
ReadSetting("Setting1");
ReadSetting("NotValid");
AddUpdateAppSettings("NewSetting", "May 7, 2014");
AddUpdateAppSettings("Setting1", "May 8, 2014");
ReadAllSettings();
}
static void ReadAllSettings()
{
try
{
var appSettings = ConfigurationManager.AppSettings;
if (appSettings.Count == 0)
{
Console.WriteLine("AppSettings is empty.");
}
else
{
foreach (var key in appSettings.AllKeys)
{
Console.WriteLine("Key: {0} Value: {1}", key, appSettings[key]);
}
}
}
catch (ConfigurationErrorsException)
{
Console.WriteLine("Error reading app settings");
}
}
static void ReadSetting(string key)
{
try
{
var appSettings = ConfigurationManager.AppSettings;
string result = appSettings[key] ?? "Not Found";
Console.WriteLine(result);
}
catch (ConfigurationErrorsException)
{
Console.WriteLine("Error reading app settings");
}
}
static void AddUpdateAppSettings(string key, string value)
{
try
{
var configFile = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
var settings = configFile.AppSettings.Settings;
if (settings[key] == null)
{
settings.Add(key, value);
}
else
{
settings[key].Value = value;
}
configFile.Save(ConfigurationSaveMode.Modified);
ConfigurationManager.RefreshSection(configFile.AppSettings.SectionInformation.Name);
}
catch (ConfigurationErrorsException)
{
Console.WriteLine("Error writing app settings");
}
}
}
}
在文件 App.config 中配置：
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6.1" />
</startup>
<appSettings>
<add key="Setting1" value="May 5,2018"/>
<add key="Setting2" value="May 5,2017"/>
</appSettings>
</configuration>
2、通过使用 ConnectionStrings 来获取数据，使用案例
using System;
using System.Configuration;
using System.Data.SqlClient;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
ReadUsers();
}
static void ReadUsers()
{
var connectionString = ConfigurationManager.ConnectionStrings["Default"].ConnectionString;
string queryString = "SELECT Id, Name FROM abpusers;";
using (var connection = new SqlConnection(connectionString))
{
var command = new SqlCommand(queryString, connection);
connection.Open();
using (var reader = command.ExecuteReader())
{
while (reader.Read())
{
Console.WriteLine(String.Format("{0}, {1}", reader[0], reader[1]));
}
}
}
}
}
}
在 App.config 中配置数据库链接字符串：
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6.1" />
</startup>
<appSettings>
<add key="Setting1" value="May 5,2018"/>
<add key="Setting2" value="May 5,2017"/>
</appSettings>
<connectionStrings>
<add name="Default" connectionString="Server=127.0.0.1; Database=CityManage; Trusted_Connection=False; Uid=root; pwd=zxx123456;" providerName="System.Data.SqlClient" />
<add name="Abp.Redis.Cache" connectionString="localhost" />
</connectionStrings>
</configuration>
