Java属性嵌套获取值的实现方式

public class A{
  private B b;
  //get and set
}
public class B{
  private C c;
    //get and set
}
public class C{
  private String userName;
    //get and set
}

A a = 实例化对象;
if(a ！= null){
 B b = a.getB();
 if(b ！= null){
    C c = b.getC();
    if(c ! = null){
       return c.getUserName();
    }
  }
}

**maven依赖:**
<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.5.6</version>
</dependency>

import org.apache.ibatis.reflection.DefaultReflectorFactory;
import org.apache.ibatis.reflection.MetaObject;
import org.apache.ibatis.reflection.factory.DefaultObjectFactory;
import org.apache.ibatis.reflection.wrapper.DefaultObjectWrapperFactory;


public class FieldUtil {

    /**
     * @param object 具体要查询对象 例如 A
     * @param objectPath 获取对应的值路径 “b.c.userName”
     * @param clazz 返回的实体 
     * @param <T>
     * @return
     */
    public static  <T> T  getObjectValue(Object object,String objectPath,Class<T> clazz){
        if(object == null){
           return null;
        }
        MetaObject metaObject = MetaObject.forObject(object, new DefaultObjectFactory(),new DefaultObjectWrapperFactory(),new DefaultReflectorFactory());
        return  (T)metaObject.getValue(objectPath);
    }
}

String userName = FieldUtil.getObjectValue(a, “b.c.userName”, String.class);