打造简易的依赖注入框架(下)(此篇与Spring.NET无关，为自己手写IoC框架)
我们知道可以通过反射获取类的构造函数及参数(GetConstructors方法)；可以获取属性和属性的类型(GetProperties方法)。通过Activator的CreateInstance(Type type, params object[] args)方法可以创建带参数构造函数的实例。通过SetValue方法可以给属性赋值，这样一来，我们就上次的代码稍加改造就可以实现属性的注入了。
下面是完成的代码：
Domain
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 "构造函数参数intProp为：" + this.intProp;
}
}
ObjectFactory
public class ObjectFactory
{
private IDictionary<string, object> objectDefine = new Dictionary<string, object>();
private ObjectFactory(string fileName)
{
InstanceObjects(fileName); // 实例IoC容器
DiObjects(fileName); // 属性注入
}
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>
/// 实例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;
//无参构造函数
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);
}
);
//有参构造函数
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>
/// 属性注入
/// </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();
//获取属性
foreach (PropertyInfo property in type.GetProperties())
{
if (property.Name == el.Attribute("name").Value)
{
if (el.Attribute("value") != null)
{
//设置属性值
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];
}
//设置关联对象属性
property.SetValue(item.Value, refObject, null);
}
}
}
}
}
}
/**//// <summary>
/// 获取对象
/// </summary>
/// <param name="id"></param>
/// <returns></returns>
public object GetObject(string id)
{
object result = null;
if (objectDefine.ContainsKey(id))
{
result = objectDefine[id];
}
return result;
}
}