Java反射机制初尝试

矫情吗；* 2022-05-24 11:25 141阅读 0赞

示例类代码：

package JavaDay_5_26.JavaReflection;
    
    /**
     * @author myvina@qq.com
     * @date 18-5-26  上午9:59
     */
    
    public class Person {
        private String name;
        private int age;
        private String sex;
    
        public Person() {
            name = "";
            age = 0;
            sex = "man";
        }
    
        private Person(String name, int age, String sex) {
            this.name = name;
            this.age = age;
            this.sex = sex;
        }
    
        @Override
        public String toString() {
            return "Person{" +
                    "name='" + name + '\'' +
                    ", age=" + age +
                    ", sex='" + sex + '\'' +
                    '}';
        }
    
        public String getSex() {
            return sex;
        }
    
        public void setSex(String sex) {
            this.sex = sex;
        }
    
        public int getAge() {
    
            return age;
        }
    
        public void setAge(int age) {
            this.age = age;
        }
    
        public String getName() {
    
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    }

Demo类代码：

package JavaDay_5_26.JavaReflection;
    
    import java.lang.reflect.Constructor;
    import java.lang.reflect.Field;
    import java.lang.reflect.InvocationTargetException;
    import java.lang.reflect.Method;
    
    /**
     * @author myvina@qq.com
     * @date 18-5-26  上午9:54
     */
    
    public class Demo1 {
        public static void main(String[] args) {
            String className = "JavaDay_5_26.JavaReflection.Person";
            try {
                //获取Person类对象
                Class classPerson = Class.forName(className);
    
                //通过Person类的无参构造函数创建person1对象
                Object person1 = classPerson.newInstance();
                System.out.println(person1);
    
                //通过Person类的私有有参函数创建person2对象
                Constructor constructor1 = classPerson.getDeclaredConstructor(String.class, int.class, String.class);
                constructor1.setAccessible(true);
                Object person2 = constructor1.newInstance("vina", 21, "man");
                System.out.println(person2);
    
                //获取Person类的toString方法，并调用此方法
                Method method1 = classPerson.getMethod("toString");
                System.out.println(method1.invoke(person2));
    
                //获取Person类的私有字段
                Field nameField = classPerson.getDeclaredField("name");
                nameField.setAccessible(true);
                System.out.println("name = " + nameField.get(person2));
                nameField.set(person2, "myvina");
                System.out.println("name = " + nameField.get(person2));
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            } catch (InstantiationException e) {
                e.printStackTrace();
            } catch (NoSuchMethodException e) {
                e.printStackTrace();
            } catch (InvocationTargetException e) {
                e.printStackTrace();
            } catch (NoSuchFieldException e) {
                e.printStackTrace();
            }
        }
    }

测试结果：

![70][]

总结：初步尝试了Java反射机制的强大，也对反射机制有了初步的认识。Java反射就是动态获取某类的方法、字段和构造函数等，并对其进行调用或访问。

[70]: /images/20220524/49f609db32ce4bc58b9a67bbd05d67b8.png