Java反射《二》获取构造器

 package com.study.reflect;

 import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;

 /**
  * 通过类来反射出构造器。
  * @ClassName: ConstructorDemo
  * @author BlueLake
  * @date 2015年8月13日 下午5:16:07
  */
 public class ConstructorDemo {

     public static void main(String[] args) throws NoSuchMethodException, SecurityException, InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {

         Class c = Student.class;

         //getConstructors()public修饰的构造方法
         Constructor[] cons = c.getConstructors();
         for(Constructor con:cons){
             System.out.println(con);
             /*
              *  public com.study.reflect.Student(java.lang.String,int)
                 public com.study.reflect.Student()
              */
         }

         System.out.println("---------------------------------");

         //getDeclaredConstructors()包括私有的方法
         Constructor[] cons2 = c.getDeclaredConstructors();
         for(Constructor con:cons2){
             System.out.println(con);
             /*
              * private com.study.reflect.Student(java.lang.String)
                 public com.study.reflect.Student(java.lang.String,int)
                 public com.study.reflect.Student()
              */
         }
         System.out.println("------****************-----------");
         //获取指定参数的构造器
         Constructor one = c.getConstructor(int.class);
         System.out.println(one);//public com.study.reflect.Student(int)
         Class[] cls = one.getParameterTypes();
         for(Class cl:cls){
             System.out.println(cl);//int
             System.out.println(cl.getName());//int
             System.out.println(cl.getSimpleName());//int
         }

         Constructor two  = c.getDeclaredConstructor(String.class,int.class);
         Class[] cls2 = two.getParameterTypes();
         for(Class cl:cls2){
             //输出类class标识和类全名。
             System.out.println(cl);//class java.lang.String
             //输出参数的类全名
             System.out.println(cl.getName());//java.lang.String
             //输出参数的类简化名
             System.out.println(cl.getSimpleName());//String
         }

         //通过参数数组来获得构造器
         Class[] params = new Class[2];
         params[0] = String.class;
         params[1] = int.class;
         Constructor three = c.getDeclaredConstructor(params );

         /**
          * 通过获得的构造器来创建对象
          */
         Object objone = one.newInstance(18);
         if(objone instanceof Student){
             Student stu = (Student)objone;
             System.out.println(stu.getAge());
         }

         Object objtwo = two.newInstance("项羽",27);
         if(objtwo instanceof Student){
             Student stu = (Student)objtwo;
             System.out.println(stu.getName()+"..."+stu.getAge());//项羽...27
         }

         Object objthree = three.newInstance("曹操",56);
         if(objthree instanceof Student){
             Student stu = (Student)objthree;
             System.out.println(stu.getName()+"..."+stu.getAge());//曹操...56
         }
     }
 }