通过例子学Ioc(3)

基于配置文件和.NET反射机制实现IOC 

(相关的DLL参考上篇的代码)
一 配置文件app.config

<? xml version = " 1.0 "  encoding = " utf-8 "   ?>
< configuration >
   < configSections >
     < sectionGroup name = " Ioc " >
       < section name = " objects1 "  type = " Ioc.ConfigHandler, Ioc "   />
     </ sectionGroup >
   </ configSections >
   < Ioc >
     < objects1 >
       < object  name = " SayHello "  assembly = " HelloType.dll "  typeName = " Ioc.EnglishHello " >
       </ object >
       < object  name = " GenerateHello "  assembly = " GenerateHello.dll "  typeName = " Ioc.GenerateHello " >
         < property id = " Param "  value = " cn " ></ property >
       </ object >
     </ objects1 >
   </ Ioc >
</ configuration >

二 处理XML节点的类：ConfigHandler

using  System;
using  System.Collections.Generic;
using  System.Text;
using  System.Xml;
using  System.Configuration;


namespace  Ioc
... {
    class ConfigHandler : IConfigurationSectionHandler
    ...{
        public object Create(object parent, object configContext, System.Xml.XmlNode section)
        ...{
            ObjectInfo info;
            PropertyInfo propInfo;

            ConfigInfo cfgInfo = new ConfigInfo();

            foreach (XmlNode node in section.ChildNodes)
            ...{
                info = new ObjectInfo();
                info.name = node.Attributes["name"].Value;
                info.assemblyName = node.Attributes["assembly"].Value;
                info.typeName = node.Attributes["typeName"].Value;

                foreach (XmlNode prop in node)
                ...{
                    propInfo = new PropertyInfo();
                    propInfo.id = prop.Attributes["id"].Value;
                    propInfo.value = prop.Attributes["value"].Value;
                    info.properties.Add(propInfo);
                }

                cfgInfo.Objects.Add(info);
            }

            return cfgInfo;
        }
    }
}

 

三 与object节点对应的类：ConfigInfo 

using  System;
using  System.Collections;
using  System.Text;

namespace  Ioc
... {
    internal class ConfigInfo
    ...{
        public ArrayList Objects = new ArrayList();

        public ObjectInfo FindByName(string name)
        ...{
            foreach (ObjectInfo o in Objects)
            ...{
                if (o.name == name)
                    return o;
            }

            return null;
        }

    }

    internal class ObjectInfo
    ...{
        public string name;
        public string assemblyName;
        public string typeName;
        public ArrayList properties = new ArrayList();
    }

    internal class PropertyInfo
    ...{
        public string id;
        public string value;
    }
}

四 动态生成对象的类：SayHelloFactory

using  System;
using  System.IO;
using  System.Configuration;
using  System.Reflection;


namespace  Ioc
... {
    class SayHelloFactory
    ...{
        public static object Create(string name)
        ...{
            ConstructorInfo studentConstructor2 = null;

            Assembly assembly;
            object o = null;
            object p;
            string rootPath = Path.GetDirectoryName(Assembly.GetEntryAssembly().Location) +
                              Path.DirectorySeparatorChar;
            //<sectionGroup name="Ioc">
            ConfigInfo cfgInfo = (ConfigInfo)ConfigurationManager.GetSection("Ioc/objects1");
            ObjectInfo info = cfgInfo.FindByName(name);
            if (info != null)
            ...{
                assembly = Assembly.LoadFile(rootPath + info.assemblyName);
                //o = assembly.CreateInstance(info.typeName);
                //Type t = o.GetType();
                Type classSampleType = assembly.GetType(info.typeName);
                studentConstructor2 = classSampleType.GetConstructor(new Type[] ...{ typeof(string) });
                object[] args = new object[info.properties.Count];
                for (int i = 0; i < info.properties.Count; i++)
                ...{
                    PropertyInfo prop = (PropertyInfo)info.properties[i];
                    args[i] = prop.value;
                }
                o = studentConstructor2.Invoke(args);
            }
            return o;
        }
    }
}

五 Main类：

using  System;
using  System.Collections.Generic;
using  System.Text;

namespace  Ioc
... {
    class Program
    ...{
        static void Main(string[] args)
        ...{
            try
            ...{
                GenerateHello genHello = (GenerateHello)SayHelloFactory.Create("GenerateHello");

                if (genHello != null)
                    genHello.Generate("Somebody");                
                   
            }
            catch (Exception ex)
            ...{
                 Console.WriteLine("Got an Error!" + ex.Message);
            }
            finally
            ...{
                Console.Read();
            }
        }
    }
}

六 调试
程序会根据配置，来输出不同的结果。

当<property id="Param" value="cn"></property>时，输出中文
当<property id="Param" value="en"></property>时，输出英文

代码的具体分析，参考http://www.cnblogs.com/zhenyulu/articles/233968.html。我也是看了这篇文章之后，自己动手再写一下。

备注：
在app.config中有点要注意， <section name="objects1" type="Ioc.ConfigHandler, Ioc" />的name="objects1" 必须与下面节点的<objects1>一致