Mybatis将实体转为JSON存储到数据库中和反向序列化读取

最近业务有需要一些页数字段进行传输，考虑到后续可能继续扩展，所以使用了一个实体类来存储，没有在数据库中创建字段；先看一下我的要存的特殊字符：

 

要使用resultMap，来制定typeHandler类型,但是存基本的字段的话只需要用最基本的JSONObkectHander即可（无map、list等前提下），不需要更换，但是读取的话就会自动走我制定了Handler：

        




        select
        a.param_id paramId,
        a.special_word ,
        b.param_name paramName,
        c.id libraryId,
        a.library_id libraryId,
        c.library_name libraryName,
        c.library_sign librarySignÏ
        from
        (select
        id,
        template_id,
        param_id,
        special_word,
        library_id
        from nlu_template_library
        where template_id in
        
            #{templateId}
        ) a
        left join nlu_excute_param b on a.param_id=b.id and b.is_delete=0
        left join nlu_param_library d on d.param_id=b.id
        left join nlu_entity_library c on d.library_id=c.id and c.is_delete=0




        insert into nlu_template_library
        (template_id,param_id,begin,end,special_word)
        values
        
            (#{sp.templateId},#{sp.paramId},#{sp.begin},#{sp.end},#{sp.specialWord,typeHandler=com.liuxy.voiceplatform.typehandler.JsonObjectTypeHandler})
        

typeHandler的内容是指定你的实体类的类型，如果有Map等需要特殊处理重写方法，我在父类中定义了很多方法，正常只需要继承（正常为没有特殊的list和map）

@MappedJdbcTypes({JdbcType.VARCHAR})
@MappedTypes({TransferInfo.class})
public class NluTemplateTypeHandler extends AbstractObjectTypeHandler {

}

最核心的类只需要重写BaseTypeHandler的方法即可

public class AbstractObjectTypeHandler extends BaseTypeHandler {

    @Override
    public void setNonNullParameter(PreparedStatement ps, int i, T parameter, JdbcType jdbcType) throws SQLException {
        ps.setString(i, JsonUtil.getJsonFromObject(ps));
    }

    @Override
    public T getNullableResult(ResultSet rs, String columnName) throws SQLException {
        String data = rs.getString(columnName);
        return StringUtils.isBlank(data) ? null : JsonUtil.getObjectFromString(data,(Class) getRawType());
    }

    @Override
    public T getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
        String data = rs.getString(columnIndex);
        return StringUtils.isBlank(data) ? null : JsonUtil.getObjectFromString(data,(Class) getRawType());
    }

    @Override
    public T getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
        String data = cs.getString(columnIndex);
        return StringUtils.isBlank(data) ? null : JsonUtil.getObjectFromString(data,(Class) getRawType());
    }

public class JsonObjectTypeHandler extends BaseTypeHandler {
    @Override
    public void setNonNullParameter(PreparedStatement preparedStatement, int i, Object o, JdbcType jdbcType) throws SQLException {
        preparedStatement.setString(i, JSONObject.toJSONString(o));
    }

    @Override
    public Object getNullableResult(ResultSet resultSet, String s) throws SQLException {
        return JSONObject.parse(s);
    }

    @Override
    public Object getNullableResult(ResultSet resultSet, int i) throws SQLException {
        return JSONObject.parse(resultSet.getString(i));
    }

    @Override
    public Object getNullableResult(CallableStatement callableStatement, int i) throws SQLException {
        return JSONObject.parse(callableStatement.getString(i));
    }
}

 

public class JsonArrayTypeHandler implements TypeHandler> {
    private List getListByJsonArrayString(String content) {
        if (StringUtils.isEmpty(content)) {
            return new ArrayList<>();
        }
        return JSONObject.parseObject(content, new TypeReference>() {});
    }

    @Override
    public void setParameter(PreparedStatement preparedStatement, int i, List ts, JdbcType jdbcType) throws SQLException {
        preparedStatement.setString(i, JSONObject.toJSONString(ts));
    }

    @Override
    public List getResult(ResultSet resultSet, String s) throws SQLException {
        return getListByJsonArrayString(resultSet.getString(s));
    }

    @Override
    public List getResult(ResultSet resultSet, int i) throws SQLException {
        return getListByJsonArrayString(resultSet.getString(i));
    }

    @Override
    public List getResult(CallableStatement callableStatement, int i) throws SQLException {
        return getListByJsonArrayString(callableStatement.getString(i));
    }
}