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; |