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：