如果要实例化的类只有一个构造函数, 则使用方法很简单使用方法如下:
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using (IUnityContainer container = new UnityContainer())
{
UnityConfigurationSection section = (UnityConfigurationSection)ConfigurationManager.GetSection( "unity" );
section.Configure(container); //...
ILogger logger = container.Resolve<ILogger>( "DatabaseLogger" );
return logger;
}
其中配置文件为
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<?xml version= "1.0" encoding= "utf-8" ?>
<configuration>
<configSections>
<section name= "unity" type= "Microsoft.Practices.Unity.Configuration.UnityConfigurationSection,Microsoft.Practices.Unity.Configuration" />
</configSections>
<unity>
<containers>
<container>
<types>
<type type= "Bery.ILogger, UnityStudy" mapTo= "Bery.DatabaseLogger, UnityStudy" name= "DatabaseLogger" >
</type>
</types>
</container>
</containers>
</unity>
</configuration>
如果DatabaseLogger类中的有两个构造函数, 代码如下
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public DatabaseLogger()
{
}
public DatabaseLogger(string name)
{
}
则Unity自动使用参数最多的构造函数进行创建对象, 会抛出以下异常:
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Microsoft.Practices.Unity.ResolutionFailedException: Resolution of the dependency failed, type = "Bery.ILogger" , name = "DatabaseLogger" .
Exception occurred while : while resolving.
Exception is: InvalidOperationException - The type String cannot be constructed. You must configure the container to supply this value.
如果您想让它使用无参的构造函数创建, 则要使用[InjectionConstructor]特性进行修饰无参的构造函数,
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[InjectionConstructor]
public DatabaseLogger()
{
}
若您想使用带参数的构造函数创建对象, 除了在构造函数上使用[InjectionConstructor]外, 还要在创建时传递参数,代码如下
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using (IUnityContainer container = new UnityContainer())
{
UnityConfigurationSection section = (UnityConfigurationSection)ConfigurationManager.GetSection( "unity" );
section.Configure(container);
ILogger logger = container.Resolve<ILogger>( "DatabaseLogger" ,
new ParameterOverrides{
{ "name" , "logName" }
});
return logger;
