访问ConfigurationManager.来自Spring的AppSettings值.. NET xml配置

Question

我有一个需求，要求我使用Spring.net获取一个存储在app.config中的connectionstring，然后将检索到的connectionstring注入到实例化的对象中。

如何使用Spring.net的xml配置?

例如，而不是我的代码这样做:

// Spring.net config:
<object name="myService" type="com.acme.MyService, com.acme">
    <constructor-arg type="System.String" value="myConnectionName"/>
</object>
// Web.config:
<connectionStrings>
    <add name="myConnectionName" connectionString="DB_connectionstring"/>
</connectionStrings>

// Codes:
public class MyService {
    public MyService(string connectionName) {
        var connectionString = ConfigurationManager.AppSettings[connectionName];
        // use connectionString to create a DB connection, etc
    }
}

我想要这样:

 // Spring.net config:
<object name="myService" type="com.acme.MyService, com.acme">
    <constructor-arg type="System.String" ref="retrievedConnectionString"/>
</object>    
// How to make a call similar to "ConfigurationManager.AppSettings[connectionName]" and get the connection string from Web.config and put inside "retrievedConnectionString"?
// Web.config:
<connectionStrings>
    <add name="myConnectionName" connectionString="DB_connectionstring"/>
</connectionStrings>

// Codes:
public class MyService {
    public MyService(string connectionString) {
        // use connectionString to create a DB connection, etc
    }
}

它甚至可能调用ConfigurationManager.AppSettings[..]从Spring.net xml配置?

Answer 1

过去我使用一个表达式来实现这一点，但是通过这个问题和bbaia的回答，我发现更好的方法是使用VariablePlaceholderConfigurer。当你使用VariablePlaceholderConfigurer而不是我的"expression-hack"时，你不会把自己束缚在变量的appSettings / connectionStrings风格配置上:你可以切换到spring.net提供的VariableSources之一，甚至实现你自己的IVariableSource。

开箱即用的,春天。.NET提供了VariablePlaceholderConfigurer来从标准。NET设置(如AppSettings、ConnectionStrings、UserSettings和ApplicationSettings)中检索变量。bbaia的回答部分说明了这一点，您将在下面找到一个完整的示例。

"Expression hack":从xml config中调用ConfigurationManager

所以，我不建议你使用这个，但这是我过去使用的hack，应用到你的配置:

<object object name="myService" type="com.acme.MyService, com.acme">
  <constructor-arg name="Connection" 
                   expression="T(System.Configuration.ConfigurationManager).ConnectionStrings['myConnectionName']" />
</object>

您可以对ConfigurationManager.AppSettings使用相同的方法，例如:

<object object name="myService" type="com.acme.MyService, com.acme">
  <constructor-arg name="AnotherConstructorArgument" 
                   expression="T(System.Configuration.ConfigurationManager).AppSettings['mySetting']" />
</object>

VariablePlaceholderConfigurer:从Spring中引用。net设置。. NET xml config

你可以很容易地配置VariablePlaceholderConfigurer来从标准的。net设置中检索变量，如AppSettings, ConnectionStrings, UserSettings和ApplicationSettings。例如，考虑以下xml配置:

<?xml version="1.0" encoding="utf-8"?>
<objects xmlns="http://www.springframework.net" >
  <object type="Spring.Objects.Factory.Config.VariablePlaceholderConfigurer, Spring.Core">
    <property name="VariableSources">
      <list>
        <object type="Spring.Objects.Factory.Config.ConnectionStringsVariableSource, Spring.Core" />
        <object type="Spring.Objects.Factory.Config.ConfigSectionVariableSource, Spring.Core">
          <!-- Sections to read, sepearated by comma (leave out spaces) -->
          <property name="SectionNames"
                    value="appSettings,applicationSettings/q7991262.Properties.Settings,userSettings/q7991262.Properties.Settings" />
        </object>
      </list>
    </property>
  </object>
  <!-- Note that you have to append '.connectionstring' to the key! -->
  <object id="usingConnectionStringsVariableSource" 
          type="q7991262.MyService, q7991262">
    <property name="Connection" 
              value="${myConnectionName.connectionString}" />
  </object>
  <object id="configSectionVariableSource" 
          type="q7991262.MyService, q7991262">
    <property name="Connection" 
              value="${myConnectionNameAppSettings}" />
  </object>
  <object id="userSettingsSection" 
          type="q7991262.MyService, q7991262">
    <property name="Connection" 
              value="${myConectionNameUserSetting}" />
  </object>
  <object id="applicationSetting" 
          type="q7991262.MyService, q7991262">
    <property name="Connection" 
              value="${myConectionNameApplicationSetting}" />
  </object>
</objects>

从app.config读取设置:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <sectionGroup name="userSettings" type="System.Configuration.UserSettingsGroup, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" >
      <section name="q7991262.Properties.Settings" type="System.Configuration.ClientSettingsSection, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" allowExeDefinition="MachineToLocalUser" requirePermission="false" />
    </sectionGroup>
    <sectionGroup name="applicationSettings" type="System.Configuration.ApplicationSettingsGroup, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" >
      <section name="q7991262.Properties.Settings" type="System.Configuration.ClientSettingsSection, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
    </sectionGroup>
  </configSections>
  <connectionStrings>
    <add name="myConnectionName" 
         connectionString="From connection string section."/>
  </connectionStrings>
  <appSettings>
    <add key="myConnectionNameAppSettings" 
         value="From app setting section." />
  </appSettings>
  <userSettings>
    <q7991262.Properties.Settings>
      <setting name="myConectionNameUserSetting" serializeAs="String">
        <value>My connection from user settings.</value>
      </setting>
    </q7991262.Properties.Settings>
  </userSettings>
  <applicationSettings>
    <q7991262.Properties.Settings>
      <setting name="myConectionNameApplicationSetting" serializeAs="String">
        <value>My connection from application settings.</value>
      </setting>
    </q7991262.Properties.Settings>
  </applicationSettings>
</configuration>

Answer 2

另一个解决方案是使用VariablePlaceholderConfigurer:http://www.springframework.net/doc-latest/reference/html/objects.html objects-variablesource

ConnectionStringsVariableSource实现允许您从配置文件中的ConnectionString部分获取值。

<object type="Spring.Objects.Factory.Config.VariablePlaceholderConfigurer, Spring.Core">
  <property name="VariableSources">
    <list>
      <object type="Spring.Objects.Factory.Config.ConnectionStringsVariableSource, Spring.Core"/>
    </list>
  </property>
</object>
<object name="myService" type="com.acme.MyService, com.acme">
    <constructor-arg type="System.String" value="${myConnectionName.connectionString}"/>
</object>

来自Spring的示例。网论坛:http://forum.springframework.net/showthread.php?3961