通过反射实现Java下的委托机制代码详解

public Class Delegater()//空参构造，该类管理委托实例并实现委托方法 //添加一个静态方法委托，返回整型值ID代表该方法与参数构成的实例。若失败，则返回-1。 public synchronized int addFunctionDelegate(Class<?> srcClass,String methodName,Object... params);//添加一个实例方法委托，返回整型值ID代表该方法与参数构成的实例。若失败，则返回-1。 public synchronized int addFunctionDelegate(Object srcObj,String methodName,Object... params);//根据整型ID从委托实例中删除一个方法委托,返回是否成功 public synchronized Boolean removeMethod(int registerID);//依次执行该委托实例中的所有方法委托（无序） public synchronized void invokeAllMethod();//将参数表转换为参数类型表 private Class<?>[] getParamTypes(Object[] params);//由指定的Class、方法名、参数类型表获得方法实例 private Method getDstMethod(Class<?> srcClass,String methodName,Class<?>[] paramTypes);class DelegateNode(Method refMethod,Object[] params)//DelegateNode类在不使用Object构造时叙述了一个静态方法委托，包括方法实例及参数表 class DelegateNode(Object srcObj,Method refMethod,Object[] params)//DelegateNode类在使用Object构造时叙述了一个实例方法委托，包括类实例、方法实例及参数表 public void invokeMethod();//执行该节点叙述的方法委托

import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import java.util.Hashtable;/**Delegater类使用RTTI及反射实现Java下的委托机制  * @author 三向板砖  * */public class Delegater {	static int register = Integer.MIN_VALUE;	//ID分配变量 	Hashtable<Integer,DelegateNode> nodeTable;	//管理ID与对应委托的容器 	public Delegater() 	  {		nodeTable = new Hashtable<Integer,DelegateNode>();	}	//添加静态方法委托 	public synchronized int addFunctionDelegate(Class<?> srcClass,String methodName,Object... params) 	  {		Class<?>[] paramTypes = getParamTypes(params);		Method refMethod;		if((refMethod = getDstMethod(srcClass,methodName,paramTypes)) != null) 		    {			register++;			nodeTable.put(register,new DelegateNode(refMethod, params));			return register;		} else 		    {			return -1;		}	}	//添加动态方法委托 	public synchronized int addFunctionDelegate(Object srcObj,String methodName,Object... params) 	  {		Class<?>[] paramTypes = getParamTypes(params);		Method refMethod;		if((refMethod = getDstMethod(srcObj.getClass(),methodName,paramTypes)) != null) 		    {			register++;			nodeTable.put(register,new DelegateNode(srcObj,refMethod, params));			return register;		} else 		    {			return -1;		}	}	//删除一个方法委托 	public synchronized Boolean removeMethod(int registerID) 	  {		if(nodeTable.containsKey(registerID)) 		    {			nodeTable.remove(registerID);			return true;		}		return false;	}	//无序地执行委托方法 	public synchronized void invokeAllMethod() 	  {		for (DelegateNode node:nodeTable.values()) 		    {			node.invokeMethod();		}	}	//将参数表转化为参数类型表 	private Class<?>[] getParamTypes(Object[] params) 	  {		Class<?>[] paramTypes = new Class<?>[params.length];		for (int i = 0;i < params.length;i++) 		    {			paramTypes[i] = params[i].getClass();		}		return paramTypes;	}	//根据Class类实例、方法名、参数类型表获得一个Method实例 	private Method getDstMethod(Class<?> srcClass,String methodName,Class<?>[] paramTypes) 	  {		Method result = null;		try {			result = srcClass.getMethod(methodName, paramTypes);			if(result.getReturnType() != void.class) 			      {				System.out.println("Warning,Method:"+methodName+" has a return value!");			}		}		catch (NoSuchMethodException | SecurityException e) {			System.out.println("Can Not Found Method:"+methodName+",ensure it's exist and visible!");		}		return result;	}}class DelegateNode {	Object srcObj;	Method refMethod;	Object[] params;	public DelegateNode(Method refMethod,Object[] params) 	  {		this.refMethod = refMethod;		this.params = params;	}	public DelegateNode(Object srcObj,Method refMethod,Object[] params) 	  {		this.srcObj = srcObj;		this.refMethod = refMethod;		this.params = params;	}	public void invokeMethod() 	  {		try {			refMethod.invoke(srcObj,params);		}		catch (IllegalAccessException | IllegalArgumentException 		        | InvocationTargetException e) {			System.out.println("Method:"+refMethod.toString()+" invoke fail!");		}	}}

public class DelegaterTest {	public void showInfo() 	  {		System.out.println("Hello Delegate!");	}	public void showCustomInfo(String info) 	  {		System.out.println(info);	}	public static void showStaticInfo() 	  {		System.out.println("Static Delegate!");	}	public static void showCustomStaticInfo(String info) 	  {		System.out.println(info);	}	public static void main(String[] args) {		Delegater dele = new Delegater();		DelegaterTest tester = new DelegaterTest();		int ID = dele.addFunctionDelegate(tester,"showInfo");		dele.addFunctionDelegate(tester,"showCustomInfo","Custom!");		dele.addFunctionDelegate(DelegaterTest.class,"showStaticInfo");		dele.addFunctionDelegate(DelegaterTest.class,"showCustomStaticInfo","StaticCustom!");		dele.invokeAllMethod();		dele.removeMethod(ID);		System.out.println("------------------");		dele.invokeAllMethod();	}}