Unity中使用多构造函数

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:
1
2
3
4
5
6
7
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
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
<?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
1
2
3
4
5
6
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:
1
2
3
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,
1
2
3
4
[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
1
2
3
4
5
6
7
8
9
10
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;

引用地址：http://unity3d.9tech.cn/news/2014/0208/39766.html

posted on 2014-07-10 11:04  大木哥  阅读(459)  评论(0)  编辑  收藏  举报

导航