C#读写config配置文件

现在FrameWork2.0以上使用的是：ConfigurationManager或WebConfigurationManager。
并且AppSettings属性是只读的，并不支持修改属性值．

一、如何使用ConfigurationManager

1、添加引用：添加System.configguration

2、引用空间

3、config配置文件配置节

常用配置节：

（1）普通配置节

</appSettings>

（2）数据源配置节

<connectionStrings>
　　<add name="kyd" connectionString="server=.;database=UFDATA_999_2017;user=sa;pwd=123"/>
</connectionStrings>

（3）自定义配置节

二、config文件读写

1、依据连接串名字connectionName返回数据连接字符串

//依据连接串名字connectionName返回数据连接字符串  
        public static string GetConnectionStringsConfig(string connectionName)
        {
            //指定config文件读取
            string file = System.Windows.Forms.Application.ExecutablePath;
            System.Configuration.Configuration config = ConfigurationManager.OpenExeConfiguration(file);
            string connectionString =
                config.ConnectionStrings.ConnectionStrings[connectionName].ConnectionString.ToString();
            return connectionString;
        }

2、更新连接字符串

///<summary> 
        ///更新连接字符串  
        ///</summary> 
        ///<param name="newName">连接字符串名称</param> 
        ///<param name="newConString">连接字符串内容</param> 
        ///<param name="newProviderName">数据提供程序名称</param> 
        public static void UpdateConnectionStringsConfig(string newName, string newConString, string newProviderName)
        {
            //指定config文件读取
            string file = System.Windows.Forms.Application.ExecutablePath;
            Configuration config = ConfigurationManager.OpenExeConfiguration(file);

            bool exist = false; //记录该连接串是否已经存在  
            //如果要更改的连接串已经存在  
            if (config.ConnectionStrings.ConnectionStrings[newName] != null)
            {
                exist = true;
            }
            // 如果连接串已存在，首先删除它  
            if (exist)
            {
                config.ConnectionStrings.ConnectionStrings.Remove(newName);
            }
            //新建一个连接字符串实例  
            ConnectionStringSettings mySettings =
                new ConnectionStringSettings(newName, newConString, newProviderName);
            // 将新的连接串添加到配置文件中.  
            config.ConnectionStrings.ConnectionStrings.Add(mySettings);
            // 保存对配置文件所作的更改  
            config.Save(ConfigurationSaveMode.Modified);
            // 强制重新载入配置文件的ConnectionStrings配置节  
            ConfigurationManager.RefreshSection("connectionStrings");
        }

3、返回*.exe.config文件中appSettings配置节的value项

///<summary> 
        ///返回*.exe.config文件中appSettings配置节的value项  
        ///</summary> 
        ///<param name="strKey"></param> 
        ///<returns></returns> 
        public static string GetAppConfig(string strKey)
        {
            string file = System.Windows.Forms.Application.ExecutablePath;
            Configuration config = ConfigurationManager.OpenExeConfiguration(file);
            foreach (string key in config.AppSettings.Settings.AllKeys)
            {
                if (key == strKey)
                {
                    return config.AppSettings.Settings[strKey].Value.ToString();
                }
            }
            return null;
        }

4、在*.exe.config文件中appSettings配置节增加一对键值对

///<summary>  
        ///在*.exe.config文件中appSettings配置节增加一对键值对  
        ///</summary>  
        ///<param name="newKey"></param>  
        ///<param name="newValue"></param>  
        public static void UpdateAppConfig(string newKey, string newValue)
        {
            string file = System.Windows.Forms.Application.ExecutablePath;
            Configuration config = ConfigurationManager.OpenExeConfiguration(file);
            bool exist = false;
            foreach (string key in config.AppSettings.Settings.AllKeys)
            {
                if (key == newKey)
                {
                    exist = true;
                }
            }
            if (exist)
            {
                config.AppSettings.Settings.Remove(newKey);
            }
            config.AppSettings.Settings.Add(newKey, newValue);
            config.Save(ConfigurationSaveMode.Modified);
            ConfigurationManager.RefreshSection("appSettings");
        }

5、修改IP地址

修改IP地址

config 读写方法

using System.Configuration;
//省略其他代码
public SalesOrderData()
        {
            string str = "";
            str = ConfigurationManager.ConnectionStrings["kyd"].ToString();
            conn = new SqlConnection(str);
            cmd = conn.CreateCommand();
        }

实际应用：

1、获取配置节的值

button1 点击获取配置节<appSettings>指定key的value值

button2 点击获取配置节<connectionStrings>指定name的connectionString值