【发布时间】：2012-05-06 02:20:13
【问题描述】：
我想在应用程序会话之间保留一些数据，并决定使用 .NET 配置 API（System.Configuration 命名空间），事实证明这比我预期的要困难得多。
我已经创建了一个自定义配置部分：
UserMailSourcesSection
public class UserMailSourcesSection : ConfigurationSection
{
[ConfigurationProperty("User", IsRequired = true)]
public string User { get; set; }
[ConfigurationProperty("UserMailSources", IsDefaultCollection = false)]
[ConfigurationCollection(typeof(MailSourceElemet))]
public MailSourceElemetCollection MailSources
{
get
{
return (MailSourceElemetCollection)this["UserMailSources"];
}
set
{
this["UserMailSources"] = value;
}
}
public UserMailSourcesSection()
{
this.User = String.Empty;
}
}
（其余相关代码在题末）
现在实际的问题是，在配置了我想要保留的所有值之后，我从保存本节的代码部分中得到了异常（不是描述性的异常，请注意）。我将其追溯到使用具有一些空值的参数调用的MailSourceElementCollection.Add。该参数是从 Microsoft 的代码传递的。我推断它必须使用默认的无参数构造函数创建参数的新实例。
我虽然解决方案是显式编写一个无参数构造函数，它将用某种默认值（特别是String.Empty）替换空值，这似乎有效。代码运行了，save 方法没有抛出，但出现了一个新问题——即使我在 Main 方法中明确设置了所有内容，实际上也没有保存数据：
PublisherElemet publisher = new PublisherElemet();
publisher.Publisher = "test";
PublisherElementCollection publishers = new PublisherElementCollection();
publishers.Add(publisher);
MailSourceElemet mailSource = new MailSourceElemet();
mailSource.HostName = "test";
mailSource.Port = 0;
mailSource.Username = "test";
mailSource.Password = "test";
mailSource.Publishers = publishers;
MailSourceElemetCollection mailSources = new MailSourceElemetCollection();
mailSources.Add(mailSource);
UserMailSourcesSection userMailSources = new UserMailSourcesSection();
userMailSources.User = Environment.UserName;
userMailSources.MailSources = mailSources;
Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
config.Sections.Add("MailSources", userMailSources);
config.Save(ConfigurationSaveMode.Modified);
在此之后预期的输出是：
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<configSections>
<section name="MailSources" type="Email_To_Rss_V2.Classes.UserMailSourcesSection, Email-To-Rss-V2, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" />
</configSections>
<MailSources User="User">
<UserMailSources>
<add HostName="test" Port="0" Username="test" Password="test">
<Publishers>
<add Publihser="test" />
</Publishers>
</add>
</UserMailSources>
</MailSources>
而实际输出是：
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<configSections>
<section name="MailSources" type="Email_To_Rss_V2.Classes.UserMailSourcesSection, Email-To-Rss-V2, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" />
</configSections>
<MailSources User="">
<UserMailSources>
<add HostName="" Port="0" Username="" Password="">
<Publishers>
<add Publihser="" />
</Publishers>
</add>
</UserMailSources>
</MailSources>
真正奇怪的是，在调试器中数据显示在那里，只是似乎没有输出到文件。
下面是其余的相关代码：
MailSourceElementCollection
public class MailSourceElemetCollection : ConfigurationElementCollection
{
public override ConfigurationElementCollectionType CollectionType
{
get
{
return ConfigurationElementCollectionType.AddRemoveClearMap;
}
}
public MailSourceElemet this[int index]
{
get
{
return (MailSourceElemet)BaseGet(index);
}
set
{
if (BaseGet(index) != null)
{
BaseRemoveAt(index);
}
BaseAdd(0, value);
}
}
protected override object GetElementKey(ConfigurationElement element)
{
if (((MailSourceElemet)element).Username == null)
{
Console.WriteLine("null");
}
return ((MailSourceElemet)element).Username;
}
protected override ConfigurationElement CreateNewElement()
{
return new MailSourceElemet();
}
public void Add(MailSourceElemet mailSource)
{
BaseAdd(mailSource);
}
public void Clear()
{
this.BaseClear();
}
public void Remove(MailSourceElemet element)
{
BaseRemove(element.Username);
}
public void Remove(string name)
{
BaseRemove(name);
}
public void RemoveAt(int index)
{
BaseRemoveAt(index);
}
}
MailSourceElement
public class MailSourceElemet : ConfigurationElement
{
[ConfigurationProperty("HostName", IsRequired = true)]
public string HostName { get; set; }
[ConfigurationProperty("Port", IsRequired = true)]
public int Port { get; set; }
[ConfigurationProperty("Username", IsRequired = true)]
public string Username { get; set; }
[ConfigurationProperty("Password", IsRequired = true)]
public string Password { get; set; }
[ConfigurationProperty("Publishers", IsDefaultCollection = false)]
[ConfigurationCollection(typeof(PublisherElemet))]
public PublisherElementCollection Publishers
{
get
{
return (PublisherElementCollection)this["Publishers"];
}
set
{
this["Publishers"] = value;
}
}
public MailSourceElemet()
{
this.HostName = String.Empty;
this.Port = 0;
this.Username = String.Empty;
this.Password = String.Empty;
}
}
PublisherElementCollection
public class PublisherElementCollection : ConfigurationElementCollection
{
public override ConfigurationElementCollectionType CollectionType
{
get
{
return ConfigurationElementCollectionType.AddRemoveClearMap;
}
}
public PublisherElemet this[int index]
{
get
{
return (PublisherElemet)BaseGet(index);
}
set
{
if (BaseGet(index) != null)
{
BaseRemoveAt(index);
}
BaseAdd(0, (PublisherElemet)value);
}
}
protected override object GetElementKey(ConfigurationElement element)
{
return ((PublisherElemet)element).Publisher;
}
protected override ConfigurationElement CreateNewElement()
{
return new PublisherElemet();
}
public void Add(PublisherElemet publisher)
{
BaseAdd(publisher);
}
public void Clear()
{
this.BaseClear();
}
public void Remove(PublisherElemet publisher)
{
BaseRemove(publisher.Publisher);
}
public void Remove(string name)
{
BaseRemove(name);
}
public void RemoveAt(int index)
{
BaseRemoveAt(index);
}
}
PublisherElement
public class PublisherElemet : ConfigurationElement
{
[ConfigurationProperty("Publihser", IsRequired = true)]
public string Publisher { get; set; }
public PublisherElemet()
{
Publisher = String.Empty;
}
}
提前致谢！
【问题讨论】：
标签： c# .net configuration app-config