MyBatis 物理分页foreach 参数失效

最新推荐文章于 2024-04-27 19:28:24 发布

原创最新推荐文章于 2024-04-27 19:28:24 发布 · 519 阅读

1 ·

CC 4.0 BY-SA版权

文章标签：

#java

WEB 专栏收录该内容

16 篇文章

订阅专栏

本文针对MyBatis物理分页中使用foreach时出现的参数失效问题，提供了详细的解决方案。通过反射机制手动设置参数，确保了查询条件正确应用。

场景：MyBatis 物理分页，查询条件中需要用到foreach ，参数失效，查不到结果

分析：把java.sql的debug打开，sql语句正常，参数也正常。debug物理分页代码，setParameters时，boundSql.getAdditionalParameter(propertyName)获取值始终是null，没有拿到参数。但是BoundSql的metaParameters中可以看到相关的参数值。

解决方法：

BoundSql countBS = new BoundSql(configuration, sql, boundSql.getParameterMappings(), parameterObject);
            Field metaParamsField = ReflectUtil.getFieldByFieldName(boundSql, "metaParameters");
            if (metaParamsField != null) {
                MetaObject mo = (MetaObject) ReflectUtil.getValueByFieldName(boundSql, "metaParameters");
                ReflectUtil.setValueByFieldName(countBS, "metaParameters", mo);
            }
            setParameters(prepStat, configuration, countBS, parameterObject);

ReflectUtil 代码：

public class ReflectUtil {
    /**
    * 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 = getFieldByFieldName(obj, fieldName);
        if (field.isAccessible()) {
            field.set(obj, value);
        } else {
            field.setAccessible(true);
            field.set(obj, value);
            field.setAccessible(false);
        }
    }

}