java 反射工具类 ReflectHelper

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package com.util;

import java.lang.reflect.Field;

/**
* @author Administrator
*   反射工具
*/
public class ReflectHelper {
   /**
   * 获取obj对象fieldName的Field
   * @param obj
   * @param fieldName
   * @return
   */
   public static Field getFieldByFieldName(Object obj, String fieldName) {
       for (Class<?> superClass = obj.getClass(); superClass != Object.class; superClass = superClass
               .getSuperclass()) {
           try {
               return superClass.getDeclaredField(fieldName);
           } catch (NoSuchFieldException e) {
           }
       }
       return null;
   }

   /**
   * 获取obj对象fieldName的属性值
   * @param obj
   * @param fieldName
   * @return
   * @throws SecurityException
   * @throws NoSuchFieldException
   * @throws IllegalArgumentException
   * @throws IllegalAccessException
   */
   public static Object getValueByFieldName(Object obj, String fieldName)
           throws SecurityException, NoSuchFieldException,
           IllegalArgumentException, IllegalAccessException {
       Field field = getFieldByFieldName(obj, fieldName);
       Object value = null;
       if(field!=null){
           if (field.isAccessible()) {
               value = field.get(obj);
           } else {
               field.setAccessible(true);
               value = field.get(obj);
               field.setAccessible(false);
           }
       }
       return value;
   }

   /**
   * 设置obj对象fieldName的属性值
   * @param obj
   * @param fieldName
   * @param value
   * @throws SecurityException
   * @throws NoSuchFieldException
   * @throws IllegalArgumentException
   * @throws IllegalAccessException
   */
   public static void setValueByFieldName(Object obj, String fieldName,
           Object value) throws SecurityException, NoSuchFieldException,
           IllegalArgumentException, IllegalAccessException {
       Field field = obj.getClass().getDeclaredField(fieldName);
       if (field.isAccessible()) {
           field.set(obj, value);
       } else {
           field.setAccessible(true);
           field.set(obj, value);
           field.setAccessible(false);
       }
   }

   /**
   * 测试主函数
   * @param args
   */
   public static void main(String[] args) {
       try {
           Class cls = Class.forName("com.flf.entity.User");
           Field field;
           try {
               // 得到一个类的实例
               Object user = cls.newInstance();
               // 调用根据字段名得到字段的方法
               field = ReflectHelper.getFieldByFieldName(user, "loginname");
               System.out.println(field.getName());

               // 根据字段名给字段赋值
               ReflectHelper.setValueByFieldName(user, "loginname","admin");

               // 根据字段名获取到字段值
               Object nameValue = ReflectHelper.getValueByFieldName(user, "loginname");
               System.out.println(nameValue);

           } catch (Exception e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
           }
       } catch (ClassNotFoundException e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
       }

   }

}

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