ORM、JPA、Spring Data JPA和常用的五种访问数据库方式

朱雀 2023-09-27 08:48 117阅读 0赞

**【ORM】**  
ORM，全称"Object Relational Mapping"，是一种对象关系映射技术，能够用于实现面向对象编程语言里不同类型系统的数据之间的转换。实际上是创建了一个可在编程语言里使用的“虚拟对象数据库”，对象数据库提供了一些查询语言，允许用声明式编程访问对象。  
扩展：面向对象是从软件工程基本原则（如耦合、聚合、封装）的基础上发展起来的，而关系数据库则是从数据理论发展而来的，两套理论存在显著的区别。为了解决这个不匹配的现象，对象关系应映射技术应运而生。  
**【JPA】**  
JPA，是一套ORM规范，Hibernate实现了JPA这种规范。  
**【Spring Data JPA】**  
Spring Data JPA，是Spring提供的一套简化JPA开发的框架，按照约定好的命名规则写DAO层接口（DAO层就是用来访问数据库的，CRUD是增删改查）。特点如下：  
①可以在不写接口实现的情况下，实现对数据库的访问和操作；  
②可以提供基本的CRUD功能，还提供了很多其它功能，如分页、排序、复杂查询等。  
![在这里插入图片描述][3ed2c54d2bcc4aac8d599f421229e60f.png]

**【常见的五种访问数据库方式】**  
（1）原始的Java访问数据库  
特点：开发流程繁琐  
步骤：  
①注册驱动/加载驱动  
②建立连接  
③创建Statement或PreparedStatement（建议这个，有更好的可读性和可维护性）  
④执行SQL语句  
⑤处理结果集  
⑥关闭连接，释放资源  
（2）Apache dbutils框架  
特点：比原始java访问数据库的方式要简单一些  
官网：https://commons.apache.org/proper/commons-dbutils/  
（3）JPA框架  
Spring-data-jpa  
特点：在复杂查询的时候性能不是很好  
（4）Hibernate  
多用于企业级应用，传统OAM企业大都喜欢Hibernate。  
特点：相对简单，没那么灵活。  
（5）Mybatis  
特点：灵活，功能强大，互联网行业主要使用它。  
是一种半ORM，不提供对象关系模型的直接映射，需要自己写sql语句，可以用SQL语句来实现映射，但是很灵活。

**相关链接：**  
[IntelliJ IDEA中构建Spring Boot的项目][IntelliJ IDEA_Spring Boot]  
[Spring Boot中的配置文件（application.properties、application.yml与pom.xml）][Spring Boot_application.properties_application.yml_pom.xml]  
[ORM、JPA、Spring Data JPA和常用的五种访问数据库方式][ORM_JPA_Spring Data JPA]

[SpringBoot–页面显示列表功能][SpringBoot]  
[SpringBoot–列表添加详情功能][SpringBoot 1]  
[SpringBoot–列表添加新增功能][SpringBoot 2]  
[SpringBoot–列表更新功能][SpringBoot 3]  
[SpringBoot–列表删除功能][SpringBoot 4]

[SpringBoot的控制层注解(@Controller与@RestController)][SpringBoot_Controller_RestController]  
[SpringBoot的业务层注解(@Resource、@Autowired与@Qualifier)][SpringBoot_Resource_Autowired_Qualifier]  
[SpringBoot的映射（@RequestMapping、@GetMapping与@PostMapping）][SpringBoot_RequestMapping_GetMapping_PostMapping]  
[SpringBoot的函数参数（JavaBean对象、@RequestParam与@RequestBody）][SpringBoot_JavaBean_RequestParam_RequestBody]  
[SpringBoot的返回数据（@ResponseBody、返回templates下的网页 与 返回公共网页）][SpringBoot_ResponseBody_templates_ _]

[利用postman完成JSON串的发送功能（springboot）][postman_JSON_springboot]  
[利用postman完成数据的分页查询功能（springboot）][postman_springboot]  
[利用postman完成向数据库中添加数据的功能（springboot）][postman_springboot 1]

[Please refer to dump files (if any exist) \[date\].dump, \[date\]-jvmRun\[N\].dump and \[date\].dumpstream.][Please refer to dump files _if any exist_ _date_.dump_ _date_-jvmRun_N_.dump and _date_.dumpstream.]  
[Preparing: insert into user(uuid,username,gender,age,phone,address) values(?,?,?,?,?,?,?)][Preparing_ insert into user_uuid_username_gender_age_phone_address_ values]  
[Could not autowire. No beans of ‘UserMapper‘ type found.][Could not autowire. No beans of _UserMapper_ type found.]  
[Error starting ApplicationContext. To display the conditions report re-run your application with][]  
[Loading class `com.mysql.jdbc.Driver‘. This is deprecated. The new driver class is`com.mysql.cj.jdb][Loading class _com.mysql.jdbc.Driver_. This is deprecated. The new driver class is_com.mysql.cj.jdb]  
[Plugin ‘org.springframework.boot:spring-boot-maven-plugin:‘ not found][Plugin _org.springframework.boot_spring-boot-maven-plugin_ not found]  
[Failed to configure a DataSource: ‘url‘ attribute is not specified and no embedded datasource could][Failed to configure a DataSource_ _url_ attribute is not specified and no embedded datasource could]  
[This application has no explicit mapping for /error, so you are seeing this as a fallback.][This application has no explicit mapping for _error_ so you are seeing this as a fallback.]  
[BootStrap-SpringBoot的使用过程中前端table表格无法加载出数据。][BootStrap-SpringBoot_table]

[3ed2c54d2bcc4aac8d599f421229e60f.png]: https://img-blog.csdnimg.cn/3ed2c54d2bcc4aac8d599f421229e60f.png
[IntelliJ IDEA_Spring Boot]: https://blog.csdn.net/blbyu/article/details/126745392
[Spring Boot_application.properties_application.yml_pom.xml]: https://blog.csdn.net/blbyu/article/details/126747098
[ORM_JPA_Spring Data JPA]: https://blog.csdn.net/blbyu/article/details/126739840
[SpringBoot]: https://blog.csdn.net/blbyu/article/details/126749514
[SpringBoot 1]: https://blog.csdn.net/blbyu/article/details/126749700
[SpringBoot 2]: https://blog.csdn.net/blbyu/article/details/126749722
[SpringBoot 3]: https://blog.csdn.net/blbyu/article/details/126749745
[SpringBoot 4]: https://blog.csdn.net/blbyu/article/details/126760296
[SpringBoot_Controller_RestController]: https://blog.csdn.net/blbyu/article/details/126744746
[SpringBoot_Resource_Autowired_Qualifier]: https://blog.csdn.net/blbyu/article/details/126744825
[SpringBoot_RequestMapping_GetMapping_PostMapping]: https://blog.csdn.net/blbyu/article/details/126744866
[SpringBoot_JavaBean_RequestParam_RequestBody]: https://blog.csdn.net/blbyu/article/details/126744903
[SpringBoot_ResponseBody_templates_ _]: https://blog.csdn.net/blbyu/article/details/126744442
[postman_JSON_springboot]: https://blog.csdn.net/blbyu/article/details/126533207
[postman_springboot]: https://blog.csdn.net/blbyu/article/details/126533491
[postman_springboot 1]: https://blog.csdn.net/blbyu/article/details/126532840
[Please refer to dump files _if any exist_ _date_.dump_ _date_-jvmRun_N_.dump and _date_.dumpstream.]: https://blog.csdn.net/blbyu/article/details/126497411
[Preparing_ insert into user_uuid_username_gender_age_phone_address_ values]: https://blog.csdn.net/blbyu/article/details/126532138
[Could not autowire. No beans of _UserMapper_ type found.]: https://blog.csdn.net/blbyu/article/details/126532911
[Error starting ApplicationContext. To display the conditions report re-run your application with]: https://blog.csdn.net/blbyu/article/details/126468130
[Loading class _com.mysql.jdbc.Driver_. This is deprecated. The new driver class is_com.mysql.cj.jdb]: https://blog.csdn.net/blbyu/article/details/126588912
[Plugin _org.springframework.boot_spring-boot-maven-plugin_ not found]: https://blog.csdn.net/blbyu/article/details/126589582
[Failed to configure a DataSource_ _url_ attribute is not specified and no embedded datasource could]: https://blog.csdn.net/blbyu/article/details/126595381
[This application has no explicit mapping for _error_ so you are seeing this as a fallback.]: https://blog.csdn.net/blbyu/article/details/126595503
[BootStrap-SpringBoot_table]: https://blog.csdn.net/blbyu/article/details/126624043