JAVA反射机制例子

例子：通过一个代理类(Person.java)动态调用两个相似类(Man.java、Woman.java)。其中，代理类用java反射机制实现。参照：http://java.chinaitlab.com/advance/805648.html

Man.java

public class Man
{
	private String name;
	private int age;
	
	public String getName()
	{
		return name;
	}
	public void setName(String name)
	{
		this.name = name;
	}
	public int getAge()
	{
		return age;
	}
	public void setAge(int age)
	{
		this.age = age;
	}
	public void introduce(String name,Integer age){
		System.out.println("name="+name+"& age="+age);
	}
}

 Woman.java

public class Woman
{
	public Woman(){
		
	}
	public Woman(String name,int age){
		this.name = name;
		this.age = age;
	}
	private String name;
	private int age;
	public String getName()
	{
		return name;
	}
	public void setName(String name)
	{
		this.name = name;
	}
	public int getAge()
	{
		return age;
	}
	public void setAge(int age)
	{
		this.age = age;
	}
	public void introduce(){
		System.out.println("name:"+name+" &age:"+age);
	}
}

代理类Person.java

import java.lang.reflect.*;

public class Person
{
	public Person(){
		
	}

	private Object target; // 目标对象
	private String methodName; // 目标方法
	private Object[] params; // 参数数组
	private Method method;
	public Object getTarget()
	{
		return target;
	}
	public void setTarget(Object target)
	{
		this.target = target;
	}
	public String getMethodName()
	{
		return methodName;
	}
	public void setMethodName(String methodName)
	{
		this.methodName = methodName;
	}
	public Object[] getParams()
	{
		return params;
	}
	public void setParams(Object[] params)
	{
		this.params = params;
	}
	public Method getMethod()
	{
		return method;
	}
	public void setMethod(Method method)
	{
		this.method = method;
	}

	/*
	 * 重新设置目标方法
	 */
	public void reSetMethod(String methodName) throws ClassNotFoundException{
		if(params!=null){
			int paramsLength = params.length;
			Class<?>[] paramsTypes = new Class<?>[paramsLength];
			for(int i=0;i<paramsLength;i++){
				paramsTypes[i] = params[i].getClass();
			}//end for
			try{
				method = target.getClass().getMethod(methodName, paramsTypes);
			}catch(Exception e){
				e.printStackTrace();
			}
		}else{
			try{
				method = target.getClass().getMethod(methodName, null);
			}catch(Exception e){
				e.printStackTrace();
			}
		}
	}//end method
	
	/**
	 * 重新设置目标对象和方法
	 * @throws ClassNotFoundException 
	 */
	public void reSetTarget(Object target,String methodName) throws ClassNotFoundException{
		this.target = target;
		this.reSetMethod(methodName);
	}
	
	/**
	 * 动态调用已绑定的方法
	 */
	public void doMethod() throws Exception{
		reSetTarget(target,methodName);
		this.method.invoke(target, params);
	}
	
}

 

调用代理类

import java.lang.reflect.Constructor;
import java.lang.reflect.Method;

public class ProxyTest
{
	
	public void invoke(String className,Class<?>[] calsses,Object[] constructsParams,String methodName,Object[] params)throws Exception{
		Class<?> clazz = Class.forName(className);
		Constructor<?> cons = clazz.getConstructor(calsses);
		Object obj = cons.newInstance(constructsParams);
		Person person = new Person();
		person.setTarget(obj);
		person.setMethodName(methodName);//映射方法名
		person.setParams(params);//映射方法参数
		person.doMethod();//通过反射调用方法
	}

	/**
	 * @throws Exception 
	 * @功能描述  
	 * @输入参数  
	 * @反馈值    
	 */
	public static void main(String[] args) throws Exception
	{
		/**
		 * 运行时动态调用相似类
		 */
		ProxyTest test = new ProxyTest();
		test.invoke("com.sinye.reflect.Man", null, null, "introduce", new Object[]{new String("梁山伯"),25});
		
		test.invoke("com.sinye.reflect.Woman",new Class<?>[]{String.class,int.class}, new Object[]{"祝英台",new Integer(22)}, "introduce", null);
		
		/**
		 * 运行时调用Man类的setName和getName方法
		 */
		Class cc = Class.forName("com.sinye.reflect.Man");
		Object object = cc.newInstance();
		Method m = cc.getDeclaredMethod("setName", new Class[]{String.class});
		m.invoke(object, new Object[]{new String("shanbo")});
		
		m = cc.getDeclaredMethod("getName", null);
		String name = (String) m.invoke(object, null);
		System.out.println(name);
	}
}