Spring.NET學習筆記9——打造簡易的依賴注入框架(練習篇)

　我們在第三篇中學習裏一個簡易的IoC框架。今天我們接着上次的程序，實現帶參數構造函數對象的實例和屬性的注入 。
　　我們知道可以通過反射獲取類的構造函數及參數(GetConstructors方法)；可以獲取屬性和屬性的類型(GetProperties方法)。通過Activator的CreateInstance(Type type, params object[] args)方法可以創建帶參數構造函數的實例。通過SetValue方法可以給屬性賦值，這樣一來，我們就上次的代碼稍加改造就可以實現屬性的注入了。

　　下面是完成的代碼：

public class Person { public string Name { get; set; } public int Age { get; set; } } public class PersonDao { private int intProp; public PersonDao(int intProp) { this.intProp = intProp; } public Person Entity { get; set; } public override string ToString() { return "構造函數參數intProp爲：" + this.intProp; } }

public class ObjectFactory { private IDictionary<string, object> objectDefine = new Dictionary<string, object>(); private ObjectFactory(string fileName) { InstanceObjects(fileName); // 實例IoC容器 DiObjects(fileName); // 屬性注入 } private static ObjectFactory instance; private static object lockHelper = new object(); public static ObjectFactory Instance(string fileName) { if (instance == null) { lock (lockHelper) { instance = instance ?? new ObjectFactory(fileName); } } return instance; } /**//// <summary> /// 實例IoC容器 /// </summary> /// <param name="fileName"></param> private void InstanceObjects(string fileName) { XElement root = XElement.Load(fileName); var objects = from obj in root.Elements("object") select obj; //無參構造函數 objectDefine = objects.Where(obj => obj.Element("constructor-arg") == null).ToDictionary( k => k.Attribute("id").Value, v => { string typeName = v.Attribute("type").Value; Type type = Type.GetType(typeName); return Activator.CreateInstance(type); } ); //有參構造函數 foreach (XElement item in objects.Where(obj => obj.Element("constructor-arg") != null)) { string id = item.Attribute("id").Value; string typeName = item.Attribute("type").Value; Type type = Type.GetType(typeName); var args = from property in type.GetConstructors()[0].GetParameters() join el in item.Elements("constructor-arg") on property.Name equals el.Attribute("name").Value select Convert.ChangeType(el.Attribute("value").Value, property.ParameterType); object obj = Activator.CreateInstance(type, args.ToArray()); objectDefine.Add(id, obj); } } /**//// <summary> /// 屬性注入 /// </summary> /// <param name="fileName"></param> private void DiObjects(string fileName) { XElement root = XElement.Load(fileName); var objects = from obj in root.Elements("object") select obj; foreach (KeyValuePair<string,object> item in objectDefine) { foreach (var el in objects.Where(e => e.Attribute("id").Value == item.Key).Elements("property")) { Type type = item.Value.GetType(); //獲取屬性 foreach (PropertyInfo property in type.GetProperties()) { if (property.Name == el.Attribute("name").Value) { if (el.Attribute("value") != null) { //設置屬性值 property.SetValue(item.Value, Convert.ChangeType(el.Attribute("value").Value, property.PropertyType), null); } else if (el.Attribute("ref") != null) { object refObject = null; if (objectDefine.ContainsKey(el.Attribute("ref").Value)) { refObject = objectDefine[el.Attribute("ref").Value]; } //設置關聯對象屬性 property.SetValue(item.Value, refObject, null); } } } } } } /**//// <summary> /// 獲取對象 /// </summary> /// <param name="id"></param> /// <returns></returns> public object GetObject(string id) { object result = null; if (objectDefine.ContainsKey(id)) { result = objectDefine[id]; } return result; } }

<?xml version="1.0" encoding="utf-8" ?> <objects> <object id="person" type="SpringNetMyDi.Person, SpringNetMyDi"> <!--屬性值類型注入--> <property name="Name" value="Liu Dong"/> <property name="Age" value="27"/> </object> <object id="personDao" type="SpringNetMyDi.PersonDao, SpringNetMyDi"> <!--構造器注入--> <constructor-arg name="intProp" value="1"/> <property name="Entity" ref="person" /> </object> </objects>

class Program { static void Main(string[] args) { ObjectFactory factory = ObjectFactory.Instance(@"F:/Exercise/SpringNet/Step1/SpringNet_Lesson9/SpringNetMyDi/Objects.xml"); PersonDao dao = (PersonDao)factory.GetObject("personDao"); Console.WriteLine("姓名：" + dao.Entity.Name); Console.WriteLine("年齡：" + dao.Entity.Age); Console.WriteLine(dao); Console.ReadLine(); } }