Java之反射--练习

定义Student 类：包含：姓名和年龄等属性，有参和无参构造方法，输出所有信息的方法

1.使用多种方法生成一个Student类的Class对象
2.使用Class类获取Student类的结构信息并输出
3.通过有参(无参)构造方法动态创建Student类的对象
4.使用反射修改和查询Student类的姓名属性
5.使用反射动态执行Student类输出信息的方法

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代码：

Student类

package 敲代码;
//定义Student 类，包含：姓名和年龄等属性，有参和无参构造方法，输出所有信息的方法


public class Student {
    private String name;
    private int age;
    private String sex;

    @Override
    public String toString() {
        return "Student [name=" + name + ", age=" + age + ", sex=" + sex + "]";
    }
    public Student(){}
    public Student(String name,int age,String sex){
        this.name=name;
        this.age=age;
        this.sex=sex;
    }
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public void eat(){
        System.out.println("eat apple!");
    }

    private void run(){
        System.out.println("run and listen to music!");
    }

    public static void play(){
        System.out.println("play game");
    }

}

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测试类：

package 敲代码;

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


public class Test {
    public static void main(String[] args) {
        //1.获取类对象
        //first
        Student student=new Student();
        Class clazz=student.getClass();
        System.out.println(clazz.hashCode());
        //second
        Class clazz2=Student.class;
        System.out.println(clazz2.hashCode());
        //third
        try {
            Class clazz3=Class.forName("敲代码.Student");
            System.out.println(clazz3.hashCode());
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }


        //2.使用Class类获取Student类的结构信息并输出
        try {
            //构造方法
            Constructor[] constructors=clazz.getDeclaredConstructors();
            for (Constructor constructor2 : constructors) {
                System.out.println(constructor2);
            }

            //获取方法对象
            Method[] methods=clazz.getDeclaredMethods();
            for (Method method : methods) {
                System.out.println(method);
            }

            //获取属性
            Field[] fields=clazz.getDeclaredFields();
            for (Field field : fields) {
                System.out.println(field);
            }
        } catch (SecurityException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        //3.通过有参(无参)构造方法动态创建Student类的对象
        try {
            Constructor<Student> constructor=clazz2.getConstructor(String.class,int.class,String.class);
            Student student2=constructor.newInstance("张三",18,"张三");
            System.out.println(student2);


            //4.使用反射修改和查询Student类的姓名属性
            student2.setName("李四");
            System.out.println(student2.getName());

            //5.使用反射动态执行Student类输出信息的方法
            Method method=clazz.getMethod("eat", null);
            method.invoke(student, null);
        } catch (NoSuchMethodException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SecurityException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (InstantiationException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IllegalArgumentException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }   
    }
}

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运行结果：