学步园

我们先创建了一个Person类

package reflect;

public class Person {
	
	public String name = "zhangsan"; 
	
	public Person(){
		System.out.println("person");
	}
	
	public Person(String name){
		System.out.println(name);
	}
	
	public Person(String name,int password){
		System.out.println("person name and password");
	}
	
	private Person(int i){
		System.out.println("person list");
	}
	
}

加载类的方法

package reflect;

public class Demo {

	public static void main(String[] args) throws ClassNotFoundException {
		/*
		 * 反射：加载类，获取类的字节码
		 */
		//方法一
		Class clazz = Class.forName("reflect.Person");
		//方法二
		Class clazz2 = new Person().getClass();
		//方法三
		Class clazz3 = Person.class;
	}

}

反射类的构造函数，可访问Person类，@Test是用junit来测试是否实现的

package reflect;

import java.awt.List;
import java.lang.reflect.Constructor;
import java.util.ArrayList;

import org.junit.Test;

public class Demo2 {
	

	@Test
	public void test() throws ClassNotFoundException, ReflectiveOperationException, SecurityException{
		Class clazz = Class.forName("reflect.Person");
		Constructor c = clazz.getConstructor(null);
		Person p = (Person) c.newInstance(null);
		
		System.out.println(p.name);
	}
	
	@Test
	public void test2() throws Exception{
		Class clazz = Class.forName("reflect.Person");
		Constructor c = clazz.getConstructor(String.class);
		Person p = (Person) c.newInstance("success");	
		System.out.println(p.name);
	}
	
	//访问私有
	@Test
	public void test3() throws Exception{
		Class clazz = Class.forName("reflect.Person");
		Constructor c = clazz.getDeclaredConstructor(int.class);
		c.setAccessible(true);
		Person p = (Person) c.newInstance(13);
		System.out.println(p.name);
	}
	
	//创建对象的另外一种方式
	@Test
	public void test4() throws Exception{
		Class clazz = Class.forName("reflect.Person");
		Person p = (Person) clazz.newInstance();
		System.out.println(p);
	}
		
}