Java反射机制初尝试

示例类代码：

package JavaDay_5_26.JavaReflection;

/**
 * @author [email protected]
 * @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 [email protected]
 * @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：

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。