doc/BUG/后端/BeanUtils报错.md

问题复现

在使用第三方工具类BeanUtils的getProperty方法时候遇见的奇怪的BUG。

• 实体类UserTakeActivity

  @Data
  public class UserTakeActivity {
  /**
   * 自增ID
   */
  private Long id;
  /**
   * 用户ID
   */
  private String uId;
  }
  

• 测试方法报错

  @Test
  public void test_insert() throws Exception {
  UserTakeActivity userTakeActivity = new UserTakeActivity();
  userTakeActivity.setUId("Uhdgkw766120d"); // 1库：Ukdli109op89oi 2库：Ukdli109op811d
  System.out.println(BeanUtils.getProperty(userTakeActivity, "uId"));
  }
  

• 换成UId就不报错

  @Test
  public void test_insert() throws Exception {
  UserTakeActivity userTakeActivity = new UserTakeActivity();
  userTakeActivity.setUId("Uhdgkw766120d"); // 1库：Ukdli109op89oi 2库：Ukdli109op811d
  System.out.println(BeanUtils.getProperty(userTakeActivity, "UId"));
  }
  

问题原因

查看BeanUtils的源码

private BeanIntrospectionData getIntrospectionData(final Class<?> beanClass) {
    if (beanClass == null) {
        throw new IllegalArgumentException("No bean class specified");
    }

    // Look up any cached information for this bean class
    // 获取data元信息
    BeanIntrospectionData data = descriptorsCache.get(beanClass);
    if (data == null) {
        data = fetchIntrospectionData(beanClass);
        descriptorsCache.put(beanClass, data);
    }

    return data;
}

该方法导致获取name为UId，与实际的不一致

public static String decapitalize(String name) {
    if (name == null || name.length() == 0) {
        return name;
    }
    if (name.length() > 1 && Character.isUpperCase(name.charAt(1)) &&
        Character.isUpperCase(name.charAt(0))){
        return name;
    }
    char chars[] = name.toCharArray();
    chars[0] = Character.toLowerCase(chars[0]);
    return new String(chars);
}

BeanUtils.getProperty遵循Java Beans规范的java.beans.Introspectors行为。

以后对变量进行命名不要第一个和第二个字母都是大写。会导致歧义

参考链接

BEANUTILS-369