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4. 读取与更新 app.config
对于app.config 文件的读写,参照了网络文章:http://www.codeproject.com/csharp/ SystemConfiguration.asp标题为“Read/Write App.Config File with .NET 2.0”一文。
请注意:要使用以下的代码访问app.config文件,除添加引用System.Configuration外,还必须在项目添加对System.Configuration.dll的引用。
4.1 读取connectionStrings配置节
/// <summary>
/// 依据连接串名字connectionName返回数据连接字符串
/// </summary>
/// <param name="connectionName"></param>
/// <returns></returns>
private static string GetConnectionStringsConfig(string connectionName)
{
string connectionString =
ConfigurationManager .ConnectionStrings[connectionName].ConnectionString.ToString();
Console .WriteLine(connectionString);
return connectionString;
}
4.2 更新connectionStrings配置节
/// <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>
private static void UpdateConnectionStringsConfig(string newName,
string newConString,
string newProviderName)
{
bool isModified = 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 (ConfigurationManager .ConnectionStrings[newName] != null )
{
isModified = true ;
}
// 新建一个连接字符串实例
ConnectionStringSettings mySettings =
new ConnectionStringSettings (newName, newConString, newProviderName);
// 打开可执行的配置文件*.exe.config
Configuration config =
ConfigurationManager .OpenExeConfiguration(ConfigurationUserLevel .None);
// 如果连接串已存在,首先删除它
if (isModified)
{
config.ConnectionStrings.ConnectionStrings.Remove(newName);
}
// 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" );
}
4.3 读取appStrings配置节
/// <summary>
/// 返回*.exe.config文件中appSettings配置节的value项
/// </summary>
/// <param name="strKey"></param>
/// <returns></returns>
private static string GetAppConfig(string strKey)
{
foreach (string key in ConfigurationManager .AppSettings)
{
if (key == strKey)
{
return ConfigurationManager .AppSettings[strKey];
}
}
return null ;
}
4.4 更新connectionStrings配置节
/// <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>
private static void UpdateAppConfig(string newKey, string newValue)
{
bool isModified = false ;
foreach (string key in ConfigurationManager .AppSettings)
{
if (key==newKey)
{
isModified = true ;
}
}
// Open App.Config of executable
Configuration config =
ConfigurationManager .OpenExeConfiguration(ConfigurationUserLevel .None);
// You need to remove the old settings object before you can replace it
if (isModified)
{
config.AppSettings.Settings.Remove(newKey);
}
// Add an Application Setting.
config.AppSettings.Settings.Add(newKey,newValue);
// Save the changes in App.config file.
config.Save(ConfigurationSaveMode .Modified);
// Force a reload of a changed section.
ConfigurationManager .RefreshSection("appSettings" );
}
<OutputPath>.\bin\Debug\</OutputPath>
而.vcxproj这个文件中是这样的:
<OutDir>$(SolutionDir)$(Configuration)\</OutDir>
该文件并未找到$(SolutionDir)指向的绝对路径的定义