反射机制看自省(探寻类自身的信息--属性/方法/构造方法)

反射机制看自省(探寻类自身的信息--属性/方法/构造方法)

public class TestReflection_1 {
	
	public static void main(String[] args) throws Exception {
		//反射中最常见的方式, 获得类对象
		Class class1 = Class.forName("com.reflection.Student");
		
		//class1.getName();//返回实体的名称
		//class1.getSimpleName//只获得类的名称
		//class1.getName()//获得这个类所在的包名+类名, 比如cn.com.michael.User
		//class1.getSuperClass
		//class1.getInterfaces 获得这个所实现的所有接口，返回一个类对象数组
		//class1.getFields()//获取此类以及此类的父类的所有属性，但不包括此类的私有属性
		//class1.getDeclaredFields()//获取此类的所有属性，包括私有属性，但获取不到父类的属性
		
		//首先，属性
		System.out.println("/**-------------属性-----------------*/");
		Field[] fs1 = class1.getFields();//获取不到本类的私有属性
		Field[] fs2 = class1.getDeclaredFields();
		System.out.println("class " + class1.getSimpleName() +"{");
		for(Field f:fs2){
			System.out.println("\t"+ f.getType().getSimpleName() + " " +f.getName() + ";");
		}
		
		//其次，方法
		System.out.println("/**-------------方法-----------------*/");
		Method[] methods1 = class1.getMethods();
		Method[] methods2 = class1.getDeclaredMethods();
		for(Method method:methods2){
			System.out.print("\t" + method.getReturnType().getSimpleName() + " " + method.getName() + "(");
			Class[] ps = method.getParameterTypes();
			for(Class cls:ps){
				System.out.print(cls.getSimpleName() + ",");
			}
			System.out.println("){}");
		}

		
		//最后，构造方法
		System.out.println("/**-------------构造方法-----------------*/");
		Constructor[] cons = class1.getConstructors();
		for(Constructor c:cons){
			System.out.print("\t" + class1.getSimpleName() +"(");
			Class[] ps = c.getParameterTypes();
			for(Class cls:ps){
				System.out.print(cls.getSimpleName() + ",");
			}
			System.out.println("){}");
		}
		System.out.println("}");
	}
}

class Student{
	private String name;
	private int age;
	public String hobby;
	public Student(){
		
	}
	public Student(String name, int age){
		this.name = name;
		this.age = age;
	}
	public void study(){
		System.out.println("Student " + name +" studies");
	}
	public String study(String course, int time){
		System.out.println("Student " + name +" studies " + course +" times" );
		if(time >=3)return "Good";
		return "Bad";
	}
	public void setName(String name) {
		this.name = name;
	}
	public void setAge(int age) {
		this.age = age;
	}
	public void setHobby(String hobby) {
		this.hobby = hobby;
	}
}