单片机开发中的异常处理与Java技术应用

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资源摘要信息: "exceptions.rar_单片机开发_Java_ DATA MINING OF WEBSERVICE" 根据给定的文件信息,我们可以提取出以下知识点: 1. 单片机开发:这是电子工程和计算机工程领域中一个重要的分支,专注于使用单片机(微控制器)进行嵌入式系统的开发。单片机是一种集成电路芯片,它将微处理器、内存(RAM、ROM)、输入/输出端口和其他功能集成到一个单独的芯片上。在单片机开发中,开发者通常需要具备硬件知识,熟悉各种接口(如I2C、SPI、UART等)和外设(如传感器、驱动器、显示器等)的编程和操作。单片机常用于各种控制应用,例如家用电器、工业自动化、汽车电子等。 2. Java编程语言:Java是一种广泛使用的面向对象编程语言,它具有跨平台、对象导向、安全性高等特点。Java通过Java虚拟机(JVM)在不同操作系统上运行,这使得Java编写的程序具有很好的可移植性。Java的开发涉及多方面,包括桌面应用程序、服务器端应用程序、移动应用开发等。在单片机开发中,Java的应用相对较少,因为单片机资源有限,而Java是资源消耗较大的语言。然而,随着物联网的发展,Java在单片机上的应用逐渐增加,特别是在Android Things等平台上。 3. 异常处理(exceptions):在编程中,异常处理是一种重要的机制,用于处理程序执行过程中发生的不正常情况。Java语言提供了强大的异常处理机制,允许开发者通过try-catch-finally语句来捕获和处理运行时的错误。异常通常分为两大类:检查型异常(checked exceptions)和非检查型异常(unchecked exceptions)。检查型异常是那些在编译时必须显式处理的异常,而非检查型异常(如运行时异常)则不需要在编译时显式声明。在单片机编程中,异常处理同样重要,因为错误管理和故障安全措施对于确保嵌入式系统的稳定性和可靠性至关重要。 4. 数据挖掘(DATA MINING):数据挖掘是指从大量数据中提取或“挖掘”知识的过程,这些知识通常具有潜在的价值和意义。数据挖掘在商业智能、科学研究、市场营销等领域非常重要,它涉及的技术包括统计分析、机器学习、模式识别等。在Web服务(WEBSERVICE)中,数据挖掘可以用于分析用户行为、预测市场趋势、改善服务功能等。 5. Web服务(WEBSERVICE):Web服务是一种允许不同软件系统通过网络(通常是互联网)进行通信和数据交换的技术。它们是一种基于Web的分布式计算平台。Web服务通常使用标准协议如SOAP(简单对象访问协议)、REST(表述性状态转移)等进行通信。在Web服务中,数据挖掘可以用来分析用户数据、优化服务流程或提供个性化服务。 综合上述知识点,我们可以看出,此压缩包文件资源可能涉及到使用Java语言进行单片机开发时的异常处理以及在Web服务中应用数据挖掘技术。尽管Java在资源受限的单片机开发中使用不常见,但在某些特定的物联网平台(如Android Things)上,Java的应用正在扩展。而关于异常处理的知识,无论是在单片机开发还是其他类型的Java编程中,都是保证程序稳定运行和错误管理的关键技术。同时,数据挖掘与Web服务的结合,展示了如何在服务端应用数据挖掘技术以增强Web服务的质量和用户体验。

springboot+MyBatis连接MySql数据库遇到问题:### Error querying database. Cause: com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure The last packet successfully received from the server was 11,751 milliseconds ago. The last packet sent successfully to the server was 11,858 milliseconds ago. ### The error may exist in file [/app/tomcat/webapps/project/WEB-INF/classes/mapper/PersonWeekMapper.xml] ### The error may involve com.xmsme.mapper.PersonWeekMapper.selectPersonWeekList-Inline ### The error occurred while setting parameters ### SQL: SELECT count(0) FROM (SELECT WEEK.id, WEEK.sub_time, WEEK.need_thing, WEEK.plan_content, WEEK.target_content, WEEK.sub_time AS update_time, WEEK.create_time, WEEK.week_start, WEEK.user_id, WEEK.week_end, readInfo.id AS readId, readInfo.read_status AS readStatus, updateor.nick_name FROM t_person_weekly AS WEEK LEFT JOIN sys_user sUser ON sUser.user_id = WEEK.user_id LEFT JOIN t_read_info readInfo ON readInfo.business_id = WEEK.id AND readInfo.read_type = 'PER' LEFT JOIN sys_user updateor ON updateor.user_id = WEEK.update_by LEFT JOIN sys_user_role uRole ON uRole.user_id = WEEK.update_by LEFT JOIN sys_user_post uPost ON uPost.user_id = WEEK.user_id LEFT JOIN t_project_person person ON person.user_id = WEEK.user_id LEFT JOIN t_project_person Pperson ON Pperson.project_id = person.project_id WHERE 1 = 1 AND WEEK.is_del = 0 AND WEEK.draft = 'N' AND Pperson.user_id = ? GROUP BY WEEK.id) table_count ### Cause: com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure The last packet successfully received from the server was 11,751 milliseconds ago. The last packet sent successfully to the server was 11,858 milliseconds ago. ; Communications link failure The last packet successfully received from the server was 11,751 milliseconds ago. The last packet sent successfully to the server was 11,858 milliseconds ago.; nested exception is com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure The last packet successfully received from the server was 11,751 milliseconds ago. The last packet sent successfully to the server was 11,858 milliseconds ago.

2023-07-22 上传

UnauthorizedError Traceback (most recent call last) Cell In[162], line 11 9 # 获取上个月的天气情况 10 mgr = owm.weather_manager() ---> 11 observation = mgr.weather_at_place('上海') # 这里以北京为例 12 date_obj = datetime.datetime(last_month.year, last_month.month, 1) 13 one_call = mgr.one_call(lat=observation.weather.location.lat, lon=observation.weather.location.lon, dt=date_obj.timestamp(), exclude='current,minutely,hourly,alerts') File ~/opt/anaconda3/lib/python3.9/site-packages/pyowm/weatherapi25/weather_manager.py:53, in WeatherManager.weather_at_place(self, name) 51 assert isinstance(name, str), "Value must be a string" 52 params = {'q': name} ---> 53 _, json_data = self.http_client.get_json(OBSERVATION_URI, params=params) 54 return observation.Observation.from_dict(json_data) File ~/opt/anaconda3/lib/python3.9/site-packages/pyowm/commons/http_client.py:158, in HttpClient.get_json(self, path, params, headers) 156 except requests.exceptions.Timeout: 157 raise exceptions.TimeoutError('API call timeouted') --> 158 HttpClient.check_status_code(resp.status_code, resp.text) 159 try: 160 return resp.status_code, resp.json() File ~/opt/anaconda3/lib/python3.9/site-packages/pyowm/commons/http_client.py:313, in HttpClient.check_status_code(cls, status_code, payload) 311 raise exceptions.APIRequestError(payload) 312 elif status_code == 401: --> 313 raise exceptions.UnauthorizedError('Invalid API Key provided') 314 elif status_code == 404: 315 raise exceptions.NotFoundError('Unable to find the resource')解释下是什么原因的报错

2023-06-03 上传