反射的定義:審查元數(shù)據(jù)并收集關(guān)於它的類型信息的能力,元數(shù)據(jù)(編輯后的基本數(shù)據(jù)單元)就是一大堆表,編譯器會(huì)創(chuàng)建一個(gè)類定義表,一個(gè)字段定義表,一個(gè)方法定義表等,System.Reflection命名空間包含的幾個(gè)類,允許你反射(解析)這些元數(shù)據(jù)的代碼
一、反射的作用:
動(dòng)態(tài)的創(chuàng)建類型的實(shí)例,將類型邦定到現(xiàn)有對(duì)象,或從現(xiàn)有對(duì)象中獲取類型
應(yīng)用程序需要在運(yùn)行時(shí)從某個(gè)特定的程序集中載入一個(gè)特定的類型,以便實(shí)現(xiàn)某個(gè)任務(wù)時(shí)可以用到反射
反射主要應(yīng)用於類庫(kù),這些類庫(kù)需要知道一個(gè)類型的定義,以便提供更多的功能
二、應(yīng)用要點(diǎn):
現(xiàn)實(shí)應(yīng)用程序中很少使用到反射
使用反射動(dòng)態(tài)邦定需要犧牲性能
有些元數(shù)據(jù)信息是不能通過(guò)反射獲取的
某些反射類型是專門為那些CLR開發(fā)編輯器開發(fā)使用的,所以你要意思到不是所有反射類型都是可以使用的
三、取得Assembly的方法:
Assembly.Load
Assembly.LoadFile
Assembly.LoadFrom
Type對(duì)象的Assembly方法
四、反射的成員:
MemberInfo-成員
ConstructorInfo-結(jié)構(gòu)
FieldInfo-字段
MethodInfo-方法
PropertyInfo-屬性
EventInfo-事件
五、根據(jù)反射取得對(duì)象的Member信息
private void WriteReflectionInfo()
{
Type testType = typeof(Test);
Assembly assembly = testType.Assembly;
Response.Write("Assembly:" + assembly.FullName + "<br/>");
Type[] typeList = assembly.GetTypes(); // 獲取類型
// 針對(duì)每個(gè)類型獲取詳細(xì)信息
foreach (Type type in typeList)
{
Response.Write("------------------------" + type.Namespace + type.Name + "------------------------<br/>");
// 獲得類型的結(jié)構(gòu)信息
ConstructorInfo[] constructs = type.GetConstructors();
// 獲得類型的字段信息
FieldInfo[] fields = type.GetFields();
Response.Write("<b>類的公共字段信息如下:</b>" + "<br/>");
int a1 = 1;
foreach (FieldInfo field in fields)
{
Response.Write((a1++).ToString() + ". " + field.Name + "<br/>");
}
// 獲得方法信息
MethodInfo[] methods = type.GetMethods();
Response.Write("<b>類的公共方法如下:</b>" + "<br/>");
int a2 = 1;
foreach (MethodInfo method in methods)
{
ParameterInfo[] parameters = method.GetParameters();
ParameterInfo reparam = method.ReturnParameter;
Response.Write((a2++).ToString() + ". " + reparam.ParameterType.Name + " " + method.Name + "(");
int index = 0;
foreach (ParameterInfo para in parameters)
{
if (index++ < parameters.Length - 1)
Response.Write(para.ParameterType.Name + " " + para.Name + ",");
else
Response.Write(para.ParameterType.Name + " " + para.Name);
}
Response.Write(")<br/>");
}
// 獲得屬性的信息
PropertyInfo[] propertys = type.GetProperties();
Response.Write("<b>類的公共屬性如下:</b>" + "<br/>");
int a3 = 1;
foreach (PropertyInfo pro in propertys)
{
Response.Write((a3++).ToString() + ". " + pro.PropertyType.Name + " " + pro.Name + "{");
if (pro.CanRead) Response.Write("get;");
if (pro.CanWrite) Response.Write("set;");
Response.Write("}<br/>");
}
// 獲得事件信息
EventInfo[] events = type.GetEvents();
Response.Write("<b>類的成員如下:</b>" + "<br/>");
// 獲得成員
int a4 = 1;
foreach (MemberInfo mi in type.GetMembers())
{
Response.Write((a4++).ToString() + ". " + mi.MemberType.ToString() + " : " + mi.Name + "<br/>");
}
}
六、動(dòng)態(tài)創(chuàng)建對(duì)象
Assembly對(duì)象的 CreateInstance方法
Activator. CreateInstance方法
Type對(duì)象的 InvokeMember方法
// 使用Assembly的CreateInstance方法來(lái)取得對(duì)象的實(shí)例
private void Assembly_CreateInstance()
{
string assemblyName = "SqlModel";
string className = assemblyName + ".Member";
// 創(chuàng)建無(wú)參數(shù)實(shí)例
IDAL.IMember member = (IDAL.IMember)Assembly.Load(assemblyName).CreateInstance(className);
Response.Write("創(chuàng)建無(wú)參數(shù)實(shí)例:" + member.ID + "<br/>");
// 創(chuàng)建有參數(shù)實(shí)例
Object[] parameters = new Object[1];
parameters[0] = 10000;
IDAL.IMember member1 = (IDAL.IMember)Assembly.Load(assemblyName).CreateInstance(className, false, BindingFlags.Default, null, parameters, null, null);
Response.Write("創(chuàng)建有參數(shù)實(shí)例:" + member1.ID + "<br/>");
}
// 使用Activator的CreateInstance方法來(lái)取得對(duì)象的實(shí)例
private void Activator_CreateInstance()
{
string assemblyName = "SqlModel";
string className = assemblyName + ".Member";
// 創(chuàng)建無(wú)參數(shù)實(shí)例
System.Runtime.Remoting.ObjectHandle obj = Activator.CreateInstance(assemblyName, className);
IDAL.IMember member = (IDAL.IMember)obj.Unwrap();
Response.Write("創(chuàng)建無(wú)參數(shù)實(shí)例:" + member.ID + "<br/>");
// 創(chuàng)建有參數(shù)實(shí)例
Object[] parameters = new Object[1];
parameters[0] = 10000;
System.Runtime.Remoting.ObjectHandle obj1 = Activator.CreateInstance(assemblyName, className, false, BindingFlags.CreateInstance, null, parameters, null, null, null);
IDAL.IMember member1 = (IDAL.IMember)obj1.Unwrap();
Response.Write("創(chuàng)建有參數(shù)實(shí)例:" + member1.ID + "<br/>");
}
// 使用Type的InvokeMember方法來(lái)取得對(duì)象的實(shí)例
private void Type_InvokeMember()
{
string assemblyName = "SqlModel";
string className = assemblyName + ".Member";
Assembly assem = Assembly.Load(assemblyName);
Type type = assem.GetType(className); // 註意這里如果使用Type.GetType來(lái)取得Type的話,那麼assemblyName指定的類一定要是強(qiáng)命名的
// 創(chuàng)建無(wú)參數(shù)實(shí)例
IDAL.IMember member = (IDAL.IMember)type.InvokeMember(className, BindingFlags.CreateInstance, null, null, null);
Response.Write("創(chuàng)建無(wú)參數(shù)實(shí)例:" + member.ID + "<br/>");
// 創(chuàng)建有參數(shù)實(shí)例
Object[] parameters = new Object[1];
parameters[0] = 10000;
IDAL.IMember member1 = (IDAL.IMember)type.InvokeMember(className, BindingFlags.CreateInstance, null, null, parameters);
Response.Write("創(chuàng)建有參數(shù)實(shí)例:" + member1.ID + "<br/>");
}
七、動(dòng)態(tài)調(diào)用對(duì)象方法
Type對(duì)象的 InvokeMember方法
MethodInfo對(duì)象的Invoke方法
// Type對(duì)象的 InvokeMember方法來(lái)動(dòng)態(tài)調(diào)用方法
private void InvokeMember()
{
string assemblyName = "SqlModel";
string className = assemblyName + ".Member";
string methodName = String.Empty;
string result = String.Empty;
Assembly assem = Assembly.Load(assemblyName);
Object obj = assem.CreateInstance(className);
Type type = assem.GetType(className); // 註意這里如果使用Type.GetType來(lái)取得Type的話,那麼assemblyName指定的類一定要是強(qiáng)命名的
// 動(dòng)態(tài)調(diào)用無(wú)參數(shù)的方法
methodName = "GetName";
result = (string)type.InvokeMember(methodName, BindingFlags.InvokeMethod, null, obj, null);
Response.Write(methodName + "方法的返回值:" + result + "<br/>");
// 動(dòng)態(tài)調(diào)用有參數(shù)的方法
methodName = "Update";
Object[] methodParams = new Object[1];
methodParams[0] = DateTime.Now;
result = (string)type.InvokeMember(methodName, BindingFlags.InvokeMethod, null, obj, methodParams);
Response.Write(methodName + "方法的返回值:" + result + "<br/>");
// 動(dòng)態(tài)調(diào)用參數(shù)構(gòu)架函數(shù)的帶有參數(shù)的方法
Object[] parameters = new Object[1];
parameters[0] = 10000;
obj = assem.CreateInstance(className,false,BindingFlags.CreateInstance, null, parameters, null, null);
result = (string)type.InvokeMember(methodName, BindingFlags.InvokeMethod, null, obj, methodParams);
Response.Write(methodName + "方法的返回值:" + result + "<br/>");
}
// MethodInfo對(duì)象的Invoke方法來(lái)動(dòng)態(tài)調(diào)用方法
private void MethodInfo_Invoke()
{
string assemblyName = "SqlModel";
string className = assemblyName + ".Member";
string methodName = String.Empty;
string result = String.Empty;
Assembly assem = Assembly.Load(assemblyName);
Object obj = assem.CreateInstance(className);
Type type = assem.GetType(className); // 註意這里如果使用Type.GetType來(lái)取得Type的話,那麼assemblyName指定的類一定要是強(qiáng)命名的
// 動(dòng)態(tài)調(diào)用無(wú)參數(shù)的方法
methodName = "GetName";
MethodInfo methodInfo = type.GetMethod(methodName);
result = (string)methodInfo.Invoke(obj, null);
Response.Write(methodName + "方法的返回值:" + result + "<br/>");
// 動(dòng)態(tài)調(diào)用有參數(shù)的方法
methodName = "Update";
Object[] methodParams = new Object[1];
methodParams[0] = DateTime.Now;
MethodInfo method = type.GetMethod(methodName);
result = (string)method.Invoke(obj, methodParams);
Response.Write(methodName + "方法的返回值:" + result + "<br/>");
}
--------------------------------------------------------------------------------
以上所使用的SqlModel.Member為:
新建一個(gè)SqlModel類庫(kù),在其下建立一個(gè)Member的類
namespace SqlModel
{
public class Member : IDAL.IMember
{
private int _id = 100;
public int ID
{
get { return _id; }
set { _id = value; }
}
private string _name = "limin";
public string Name
{
get { return _name; }
set { _name = value; }
}
public Member() { }
public Member(int id)
{
_id = id;
}
private void Init()
{ }
public string GetName()
{
return _name;
}
public string Update (DateTime cdate)
{
return "{" + String.Format("ID:{0},Name:{1},CreateDate:{2}",_id,_name,cdate) + "}";
}
}
}
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