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
        }
    }
}