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);

}

}