7.[练习]反射工具类

需求

通过反射写一个通用的设置，可设置某个对象的某个属性为指定的值

/**
 * 该方法可将obj对象中名为propertyName的属性的值设置为value。
 */
public static void setProperty(Object obj, String propertyName, Object value){
      //TODO
}

实现

class ReflectTool {
    /**
     * 此方法可将obj对象中名为propertyName的属性的值设置为value。
     */
    public static void setProperty(Object obj, String propertyName, Object value) throws Exception {
        //获取字节码对象
        Class clazz = obj.getClass();
        //获取字段，忽略修饰符权限
        Field field = clazz.getDeclaredField(propertyName);
        //设置权限为可访问的
        field.setAccessible(true);
        field.set(obj, value);
    }
}

测试

class Student {
    private String name;
    private int age;
    public Student() {
        super();
    }
    public Student(String name, int age) {
        super();
        this.name = name;
        this.age = age;
    }
    public void setName(String name) {
        this.name = name;
    }
    public void setAge(int age) {
        this.age = age;
    }
    @Override
    public String toString() {
        return "Student [name=" + name + ", age=" + age + "]";
    }
}

public static void main(String[] args) throws Exception {
        Student s = new Student("zhangsan", 18);
        //Student [name=zhangsan, age=18]
        System.out.println(s);
        ReflectTool.setProperty(s, "name", "lisi");
        ReflectTool.setProperty(s, "age", 108);
        //Student [name=lisi, age=108]
        System.out.println(s);
    }