反射用法总结

缺乏、安全感 2024-04-06 13:17 56阅读 0赞

package com.xch;
    
    import org.junit.jupiter.api.Test;
    import org.springframework.boot.test.context.SpringBootTest;
    
    import java.lang.reflect.Field;
    import java.lang.reflect.Method;
    
    /**
     * @author Chenghe Xu
     * @date 2022/9/21 9:42
     */
    @SpringBootTest
    public class Test01 {
    
        /**
         * 反射用法总结
         */
        @Test
        void test01() throws Exception {
            //非反射创建对象
            Student student1=new Student();
            System.out.println(student1);
            
            //操作对象的public属性
            student1.name="xch1";
            System.out.println(student1.name);
            //操作对象的public方法
            student1.setName("ypy1");
            System.out.println(student1.getName());
            
            //反射创建对象
            //1、获取Class实例
                //1.1、通过类本身.class属性获取
            Class<Student> studentClass1 = Student.class;
                //1.2、通过类的对象获取
            Class<? extends Student> studentClass2 = student1.getClass();
                //1.3、通过Class的静态方法获取
            Class<?> studentClass3 = Class.forName("com.xch.Student");
                //1.4、通过类加载器获取
            ClassLoader classLoader = this.getClass().getClassLoader();
            Class<?> studentClass4 = classLoader.loadClass("com.xch.Student");
            //2、创建Class对应运行时类的对象
                //2.1、默认使用无参构造函数
            Student student2 = studentClass1.newInstance();
                //2.2、指定使用无参构造函数
            Constructor<? extends Student> studentClass2Constructor = studentClass2.getConstructor();
            Student student3 = studentClass2Constructor.newInstance();
                //2.3、指定使用有参构造函数
            Constructor<?> studentClass3Constructor = studentClass3.getConstructor(String.class,Integer.class);
            Student student4 = (Student) studentClass3Constructor.newInstance("XiaoXu", 18);
            System.out.println(student2);
            System.out.println(student3);
            System.out.println(student4);
            
            //操作对象的public属性
            Field name = studentClass1.getField("name");
            name.set(student2, "xch2");
            System.out.println(name.get(student2));
            //操作对象的任何修饰符属性
            Field age = studentClass1.getDeclaredField("age");
            age.setAccessible(true);//强制设置属性可访问
            age.set(student2, 21);
            System.out.println(age.get(student2));
    
            //操作对象的public有参方法
            Method setName = studentClass1.getMethod("setName", String.class);
            setName.invoke(student2, "ypy2");
            //操作对象的任何修饰符有参方法
            Method setAge = studentClass1.getDeclaredMethod("setAge", Integer.class);
            setAge.setAccessible(true);//强制设置属性可访问
            setAge.invoke(student2, 20);
            //操作对象的public无参方法
            Method getName = studentClass1.getMethod("getName");
            System.out.println(getName.invoke(student2));
            //操作对象的任何修饰符无参方法
            Method getAge = studentClass1.getDeclaredMethod("getAge");
            getAge.setAccessible(true);//强制设置属性可访问
            System.out.println(getAge.invoke(student2));
    
        }
        
    }