Java 创建动态类和查看方法列表信息

妖狐艹你老母 2022-06-16 20:00 113阅读 0赞

Sample code :

import java.lang.reflect.Constructor;
    import java.lang.reflect.InvocationHandler;
    import java.lang.reflect.Method;
    import java.lang.reflect.Proxy;
    import java.lang.reflect.Type;
    import java.util.ArrayList;
    import java.util.Collection;
    
    public class ProxyTest {
    
    	public static void main(String[] args) throws Exception {
    		// TODO Auto-generated method stub
    		Class clazzProxy = Proxy.getProxyClass(Collection.class.getClassLoader(), Collection.class);
    		System.out.println(clazzProxy);
    		System.out.println("------constructor method list ------");
    		Constructor[] constructors = clazzProxy.getConstructors();
    		for(Constructor constructor:constructors){
    			StringBuilder sb = new StringBuilder(constructor.getName());
    			sb.append("(");
    			Type[] parameterTypes = constructor.getParameterTypes();
    			for(Type parameterType:parameterTypes){
    				sb.append(parameterType.toString()+",");
    			}
    			if(parameterTypes.length>0){
    				sb.deleteCharAt(sb.length()-1);
    			}
    			sb.append(")");
    			System.out.println(sb.toString());
    			
    		}
    		System.out.println("------constructor method list ------\n\n");
    		
    		System.out.println("------ method list ------");
    		Method[] methods = clazzProxy.getMethods();
    		for(Method method:methods){
    			StringBuilder sb2 = new StringBuilder(method.getName());
    			sb2.append("(");
    			Type[] parameterTypes = method.getParameterTypes();
    			for(Type parameterType:parameterTypes){
    				sb2.append(parameterType.toString()+",");
    			}
    			if(parameterTypes.length>0){
    				sb2.deleteCharAt(sb2.length()-1);
    			}
    			sb2.append(")");
    			System.out.println(sb2.toString());
    			
    		}
    		System.out.println("------ method list ------");
    		
    		Constructor proxyConstructor = clazzProxy.getConstructor(InvocationHandler.class);
    		class MyInvocationHandler implements InvocationHandler{
    			ArrayList target = new ArrayList();
    			public Object invoke(Object proxy, Method method, Object[] args)
    					throws Throwable {
    				Object obj = method.invoke(target, args);
    				return obj;
    			}
    			
    		}
    		MyInvocationHandler mih = new MyInvocationHandler();
    		Collection collectionProxy = (Collection) proxyConstructor.newInstance(mih);
    		collectionProxy.add("zhuang");
    		collectionProxy.add("alex");
    		System.out.println("collectionProxy size:"+collectionProxy.size());
    		
    		Collection collectionProxy2 = (Collection)Proxy.newProxyInstance(Collection.class.getClassLoader(),new Class[] {Collection.class},new InvocationHandler(){
    			ArrayList target = new ArrayList();
    			public Object invoke(Object proxy, Method method, Object[] args)
    					throws Throwable {
    				Object obj = method.invoke(target, args);
    				return obj;
    			}
    		});
    		
    		collectionProxy2.add("one");
    		collectionProxy2.add("two");
    		collectionProxy2.add("three");
    		System.out.println("collectionProxy2 size:"+collectionProxy2.size());
    	}

运行结果：

class $Proxy0  
\------constructor method list ------  
$Proxy0(interface java.lang.reflect.InvocationHandler)  
\------constructor method list ------  
  
  
\------ method list ------  
add(class java.lang.Object)  
hashCode()  
equals(class java.lang.Object)  
clear()  
toString()  
contains(class java.lang.Object)  
isEmpty()  
addAll(interface java.util.Collection)  
iterator()  
size()  
toArray(class \[Ljava.lang.Object;)  
toArray()  
remove(class java.lang.Object)  
containsAll(interface java.util.Collection)  
removeAll(interface java.util.Collection)  
retainAll(interface java.util.Collection)  
isProxyClass(class java.lang.Class)  
getProxyClass(class java.lang.ClassLoader,class \[Ljava.lang.Class;)  
newProxyInstance(class java.lang.ClassLoader,class \[Ljava.lang.Class;,interface java.lang.reflect.InvocationHandler)  
getInvocationHandler(class java.lang.Object)  
wait()  
wait(long,int)  
wait(long)  
getClass()  
notify()  
notifyAll()  
\------ method list ------  
collectionProxy size:2  
collectionProxy2 size:3