Java反射机制

-------------------------TestReflection01.java-------------------------

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Scanner;

@SuppressWarnings("unchecked")
public class TestReflection01 {
	public static void main(String[] args) {
		System.out.println("请输入类型名称：");
		Scanner scan = new Scanner(System.in);
		String className = scan.next();		
		System.out.println("当前类型：" + className);			

		try {
			//获取Class对象
			Class c = Class.forName(className);			
			
			//解析属性信息
			Field[] fs = c.getDeclaredFields();
			for (Field f : fs) {
				System.out.println("----------------------------------------------");
				System.out.println("属性：" + f.toString());
				System.out.println("\t数据类型：" + f.getType());
				System.out.println("\t属性名：" + f.getName());
				int mod = f.getModifiers();				
				System.out.println("\t属性修饰符：" + Modifier.toString(mod));
			}
			
			//解析方法信息
			Method[] ms = c.getDeclaredMethods();
			for(Method m : ms){
				System.out.println("----------------------------------------------");
				System.out.println("方法：" + m.toString());				
				System.out.println("\t方法名：" + m.getName());
				int mod = m.getModifiers();				
				System.out.println("\t方法修饰符：" + Modifier.toString(mod));
				System.out.print("\t方法参数列表：");
				Class pts[] = m.getParameterTypes();
				for (int i = 0; i < pts.length; i++) {
					Class class1 = pts[i];
					if(i != 0 )
						System.out.print(", ");
					System.out.print(class1);
				}	
				System.out.println();
				System.out.println("\t返回值类型：" + m.getReturnType());
			}
			
			//解析构造方法信息
			Constructor[] cs = c.getDeclaredConstructors();
			for (Constructor con : cs) {
				System.out.println("----------------------------------------------");
				System.out.println("构造方法：" + con.toString());				
				System.out.println("\t方法名：" + con.getName());
				int mod = con.getModifiers();				
				System.out.println("\t方法修饰符：" + Modifier.toString(mod));
				System.out.print("\t方法参数列表：");
				Class pts[] = con.getParameterTypes();
				for (int i = 0; i < pts.length; i++) {
					Class class1 = pts[i];
					if(i != 0 )
						System.out.print(", ");
					System.out.print(class1);
				}	
				System.out.println();
			}			
			System.out.println("----------------------------------------------");
			
			//解析当前类类型的父类
			Class superClass = c.getSuperclass();
			System.out.println("当前类的父类:" + superClass.toString());			
			System.out.println("----------------------------------------------");
			
			//解析当前类实现的接口
			Class[] interfaces = c.getInterfaces();
			System.out.print("当前类所实现接口:");
			for (Class class1 : interfaces) {
				System.out.print(class1.toString() + "\t");
			}			
			System.out.println("\n----------------------------------------------");
			
			//解析当前类型所在包信息
			Package p = c.getPackage();
			System.out.println("当前类所在包" + p.toString());
		} catch (ClassNotFoundException e) {			
			e.printStackTrace();
		}
	}
}

-------------------------TestReflection02.java-------------------------

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import p2.User;

@SuppressWarnings("unchecked")
public class TestReflection02 {
	public static void main(String[] a) throws Exception{
		User p1 = new User("张三",18);		
		TestReflection02 t = new TestReflection02();

		System.out.println("----------------------------------------");
		t.mf1(p1,"name","李四");
		t.mf1(p1,"age",30);
		System.out.println(p1);
		
		System.out.println("----------------------------------------");
		t.mf2("p2.User", "total",88);
		
		System.out.println("----------------------------------------");
		Class[] argTypes = {String.class,int.class};
		Object[] args = new Object[]{"王五",99};
		t.mf3(p1, "setAll",argTypes,args);
		System.out.println(p1);
		
		System.out.println("----------------------------------------");
		t.mf4("p2.User", "showTotal",null,null);		
	}
	
	//直接操作对象属性
	public void mf1(Object o,String fieldName,Object newValue) throws  NoSuchFieldException, IllegalAccessException {
		Class c = o.getClass();  
		Field f = c.getField(fieldName);
		Object fv = f.get(o);
		System.out.print("修改前:" + fieldName + "=" + fv);
		f.set(o,newValue);
		System.out.println("\t修改后:" + fieldName + "=" + f.get(o));		
	}
	
	//直接操作类属性
	public void mf2(String className,String fieldName,Object newValue) throws ClassNotFoundException, NoSuchFieldException, IllegalAccessException {
		Class c = Class.forName(className);
		Field f = c.getField(fieldName);
		Object fv = f.get(c);
		System.out.print("修改前:" + fieldName + "=" + fv);
		f.set(c,newValue);
		System.out.println("\t修改后:" + fieldName + "=" + f.get(c));
	}	

	//调用对象成员方法
	public void mf3(Object o,String methodName,Class[]argTypes,Object[] args) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException {
		Class c = o.getClass();
		Method m = c.getMethod(methodName, argTypes);
		Object result = m.invoke(o, args);
		System.out.println(result);
	}	
	
	//调用类成员方法
	public void mf4(String className,String methodName,Class[]argTypes,Object[] args) throws ClassNotFoundException, NoSuchMethodException, IllegalArgumentException, IllegalAccessException, InvocationTargetException {
		Class c = Class.forName(className);
		Method m = c.getMethod(methodName, argTypes);
		Object result = m.invoke(null, args);
		System.out.println("result:" + result);
	}		
}

-------------------------TestReflection03.java-------------------------

/**
 * 
 */
import java.lang.reflect.*;

@SuppressWarnings("unchecked")
public class TestReflection03 {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		Class c;
		try {
			c = Class.forName("p1.Person");
			
			//调用有参数的构造方法
	        Class[] argTypes = {String.class,int.class};
	        Constructor constructor = c.getConstructor(argTypes);
	        Object obj = constructor.newInstance("中国",5000);
	        System.out.println(obj);
	        
	        //调用无参构造方法1
	        constructor = c.getConstructor();	        
	        //constructor = c.getConstructor(new Class[0]);
	        //constructor = c.getConstructor(null);
	        obj = constructor.newInstance();
	        System.out.println(obj);
	        
	        //调用无参构造方法2
	        obj = c.newInstance();
	        System.out.println(obj);
		} catch (Exception e) {
			e.printStackTrace();
		}

	}

}