黑马JAVA P190 反射的作用：绕过编译阶段，做企业级通用框架

package com.itheima.d6_reflect_genericity;

import java.lang.reflect.Method;
import java.util.ArrayList;

public class ReflectDemo {
    public static void main(String[] args) throws Exception {
        //需求：反射实现泛型擦除后，加入其他类型的元素。
        ArrayList list1 = new ArrayList<>();
        ArrayList list2 = new ArrayList<>();

        System.out.println(list1.getClass());
        System.out.println(list2.getClass());

        System.out.println(list1.getClass() == list2.getClass()); //ArrayList.class

        System.out.println("------------");
        ArrayList lists3 = new ArrayList<>();
        lists3.add(23);
        lists3.add(22);
        //list3.add("黑马")

        Class c = lists3.getClass(); //ArrayList.class ===> public boolean add(E e)
        //定位c类中的add方法
        Method add = c.getDeclaredMethod("add",Object.class);
        boolean rs = (boolean) add.invoke(lists3,"黑马");
        System.out.println(rs);

        System.out.println(lists3);

        ArrayList list4 = lists3;
        list4.add("白马");
        list4.add(false);
        System.out.println(lists3);
    }
}

package com.itheima.d7_reflect_framework;

import java.io.FileOutputStream;
import java.io.PrintStream;
import java.lang.reflect.Field;

public class MybatisUtil {
    
    public static void save(Object obj){
        try (
                PrintStream ps = new PrintStream(new FileOutputStream("D:\code\javasepromax\junit-reflect-annotation-proxy-app\src\data.txt",true));

        ){
            //1.提取这个对象的全部 成员变量：只有反射可以解决
            Class c = obj.getClass();//c.getSimpleName() 获取当前类名  c.getName获取全限名：包名+类名
            ps.println("=============" + c.getSimpleName() + "================");

            //2.提取它的全部成员变量
            Field[] fields = c.getDeclaredFields();
            //3.获取成员变量的信息
            for (Field field : fields) {
                String name = field.getName();
                //提取本成员变量在obj对象中的值（取值）
                field.setAccessible(true);
                String value = field.get(obj) + "";
                ps.println(name + "=" + value);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

package com.itheima.d7_reflect_framework;

public class Student {
    private String name;
    private char sex;
    private int age;
    private String className;
    private String hobby;

    public Student() {
    }

    public Student(String name, char sex, int age, String className, String hobby) {
        this.name = name;
        this.sex = sex;
        this.age = age;
        this.className = className;
        this.hobby = hobby;
    }

    public String getName() {
        return name;
    }

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

    public char getSex() {
        return sex;
    }

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

    public int getAge() {
        return age;
    }

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

    public String getClassName() {
        return className;
    }

    public void setClassName(String className) {
        this.className = className;
    }

    public String getHobby() {
        return hobby;
    }

    public void setHobby(String hobby) {
        this.hobby = hobby;
    }
}

package com.itheima.d7_reflect_framework;

public class Teacher {
    private String name;
    private char sex;
    private double salary;

    public Teacher() {
    }

    public Teacher(String name, char sex, double salary) {
        this.name = name;
        this.sex = sex;
        this.salary = salary;
    }

    public String getName() {
        return name;
    }

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

    public char getSex() {
        return sex;
    }

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

    public double getSalary() {
        return salary;
    }

    public void setSalary(double salary) {
        this.salary = salary;
    }
}

package com.itheima.d7_reflect_framework;


public class ReflectDemo {
    public static void main(String[] args) throws Exception {
        Student s = new Student();
        s.setName("猪八戒");
        s.setClassName("西天跑路1班");
        s.setAge(1000);
        s.setHobby("吃，睡");
        s.setSex('男');
        MybatisUtil.save(s);

        Teacher t = new Teacher();
        t.setName("波仔");
        t.setSex('男');
        t.setSalary(6000);
        MybatisUtil.save(t);
    }
}