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.
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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;
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