通过反射调用类中的方法

操作步骤：
1：实例化Class；
2：通过Class类的getMethod()方法取得一个Method的对象，并设置次方法操作时所需的参数类型；
3：使用invoke进行调用，并向方法中传递要设置的参数，但在使用invoke()方法时必须传入一个类的实例化对象

实例1：sayChina()方法中没有参数
package cn.itcast02;

import java.lang.reflect.Method;

//调用Person类中的sayChina()方法，没有参数

public class ClassDemo04 {
     public static void main(String[] args) {
          Class<?> c1 = null;
           try {
              c1 = Class. forName("cn.itcast02.Person");
          } catch (ClassNotFoundException e) {
               // TODO Auto-generated catch block
              e.printStackTrace();
          }
           try {
               //获得一个method对象
              Method method = c1.getMethod( "sayChina");
               //调用方法,必须传递对象实例
              method.invoke(c1.newInstance());
          } catch (Exception e) {
               // TODO Auto-generated catch block
              e.printStackTrace();
          }
     }
}

实例2：sayHello()方法中有参数

package cn.itcast02;

import java.lang.reflect.Method;


//调用Person类中的sayHello()方法，有参数

public class ClassDemo05 {
     public static void main(String[] args) {
          Class<?> c1 = null;
          
           try {
              c1 = Class. forName("cn.itcast02.Person");
          } catch (ClassNotFoundException e) {
               // TODO Auto-generated catch block
              e.printStackTrace();
          }
           try {
              Method method = c1.getMethod( "sayHello", String.class,int .class,char. class);
               //调用方法，必须传递对象实例，同时传递三个参数值
              Object invoke = method.invoke(c1.newInstance(),"侯勇" ,50,‘男‘ );
              System. out.println(invoke);
          } catch (Exception e) {
               // TODO Auto-generated catch block
              e.printStackTrace();
          }
     }
}

实例3：调用getter和setter方法

package cn.itcast02;

import java.lang.reflect.Method;


//调用Person类中的sayChina()方法

public class ClassDemo04 {
     public static void main(String[] args) {
          Class<?> c1 = null;
          Object obj = null;
           try {
              c1 = Class. forName("cn.itcast02.Person");
          } catch (ClassNotFoundException e) {
               // TODO Auto-generated catch block
              e.printStackTrace();
          }
           try {
              obj = c1.newInstance();
          } catch (Exception e) {
               // TODO Auto-generated catch block
              e.printStackTrace();
          }
           try {
              Method method = obj.getClass().getMethod("setName" ,String.class);
              Method method2 = obj.getClass().getMethod("setAge" ,int.class);
              method.invoke(obj, "小红");
              method2.invoke(obj, 30);
          } catch (Exception e) {
               // TODO Auto-generated catch block
              e.printStackTrace();
          }
           try {
              Method method = obj.getClass().getMethod("getName" );
              Method method2 = obj.getClass().getMethod("getAge" );
              System. out.println(method.invoke(obj));
              System. out.println(method2.invoke(obj));
          } catch (Exception e) {
               // TODO Auto-generated catch block
              e.printStackTrace();
          }
     }
}

Person类
package cn.itcast02;

public class Person implements China{
	private String name;
	private int age;
	private char sex;

	public Person() {
		super();
	}

	public Person(String name, int age, char sex) {
		super();
		this.name = name;
		this.age = age;
		this.sex = sex;
	}

	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 char getSex() {
		return sex;
	}

	public void setSex(char sex) {
		this.sex = sex;
	}
	public void eat()
	{
		System.out.println("吃了");
	}

	@Override
	public String toString() {
		return "Person [name=" + name + ", age=" + age + ", sex=" + sex + "]";
	}

	@Override
	public void sayChina() {
		// TODO Auto-generated method stub
		System.out.println("作者："+ AUTHOR + "国籍："+ NATIONAL);
	}

	@Override
	public String sayHello(String name, int age, char sex) {
		// TODO Auto-generated method stub
		return "姓名:" + name +"年龄："+ age +"性别:"+ sex;
	}

}

China接口
package cn.itcast02;

public interface China {
	public static final String NATIONAL = "China";
	public static final String AUTHOR = "成龙";

	public void sayChina();

	public String sayHello(String name, int age, char sex);
}