读写.NET应用程序配置文件

1.读取配置文件

有如下的配置文件

 

<xml version="1.0" encoding="utf-8" ?>
<configuration>
      <appSettings>
            <add key="ApplicationTitle" value="DevAsp Application Configuration Sample" />
            <add key="ApplicationHeaderText" value="DevAsp" />
      </appSettings>

      <connectionStrings>
            <add name="ConnectionString" connectionString="user id=DevAsp;data source=Northwind;persist security info=True;initial catalog=Comments;password=abc"

            providerName="System.Data.SqlClient" />
      </connectionStrings>
</configuration>

读取ApplicationTitle，代码如下：

 

ConfigurationSettings.AppSettings["ApplicationTitle"];

读取连接字符串的代码：

ConfigurationManager.ConnectionStrings["ConnectionString"].ToString()；

 2.写入配置文件

假设有如下配置文件：

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <appSettings>
        <add key="Test1" value="My value 1" />
        <add key="Test2" value="Another value 2" />
    </appSettings>
</configuration>

写配置文件的代码：

using System;
using System.Xml;  
using System.Configuration;
using System.Reflection;
//...


public class ConfigSettings
{
    private ConfigSettings() {}

    public static string ReadSetting(string key)
    {
        return ConfigurationSettings.AppSettings[key];
    }

    public static void WriteSetting(string key, string value)
    {
        // load config document for current assembly
        XmlDocument doc = loadConfigDocument();

        // retrieve appSettings node
        XmlNode node =  doc.SelectSingleNode("//appSettings");

        if (node == null)
            throw new InvalidOperationException("appSettings section not found in config file.");

        try
        {
            // select the 'add' element that contains the key
            XmlElement elem = (XmlElement)node.SelectSingleNode(string.Format("//add[@key='{0}']", key));

            if (elem != null)
            {
                // add value for key
                elem.SetAttribute("value", value);
            }
            else
            {
                // key was not found so create the 'add' element 
                // and set it's key/value attributes 
                elem = doc.CreateElement("add");
                elem.SetAttribute("key", key);
                elem.SetAttribute("value", value); 
                node.AppendChild(elem);
            }
            doc.Save(getConfigFilePath());
        }
        catch
        {
            throw;
        }
    }

    public static void RemoveSetting(string key)
    {
        // load config document for current assembly
        XmlDocument doc = loadConfigDocument();

        // retrieve appSettings node
        XmlNode node =  doc.SelectSingleNode("//appSettings");

        try
        {
            if (node == null)
                throw new InvalidOperationException("appSettings section not found in config file.");
            else
            {
                // remove 'add' element with coresponding key
                node.RemoveChild(node.SelectSingleNode(string.Format("//add[@key='{0}']", key)));
                doc.Save(getConfigFilePath());
            }
        }
        catch (NullReferenceException e)
        {
            throw new Exception(string.Format("The key {0} does not exist.", key), e);
        }
    }

    private static XmlDocument loadConfigDocument()
    {
        XmlDocument doc = null;
        try
        {
            doc = new XmlDocument();
            doc.Load(getConfigFilePath());
            return doc;
        }
        catch (System.IO.FileNotFoundException e)
        {
            throw new Exception("No configuration file found.", e);
        }
    }

    private static string getConfigFilePath()
    {
        return Assembly.GetExecutingAssembly().Location + ".config";
    }
}

例如：

// read the Test1 value from the config file
string test1 = ConfigSettings.ReadSetting("Test1");

 

// write a new value for the Test1 setting
ConfigSettings.WriteSetting("Test1", "This is my new value");

// remove the Test1 setting from the config file
ConfigSettings.RemoveSetting("Test1");




如果想获取web工程的配置：
System.Web.HttpContext.Current.Server.MapPath("web.config");