文章目录
背景
从业十多年Spring JDBC、JPA、Mybatis三种持久层框架都使用过，各有千秋，当下的项目使用Mybatis最多。之前的项目还都是使用xml配置文件的框架，最近两年才用Spring Boot多起来，因为老程序员不干屈居人后的进取心，且不想搞那繁琐而无边际的业务需求，所以利用业余时间扑下心来好好看看官文。随着年龄的增长，精力、记性却不断递减，怕时间长了不知其初心，所以记录之。
在官方文档向导中存在关于JDBC和JPA的资料，我想从实际项目的角度出发去学习并记录，所以我以mysql数据库作为存储，从配置数据源、JDBC访问数据、JPA访问数据、Mybatis访问数据几方面去学习。
配置数据源
引入mysql
新建一个Spring Boot工程，引入mysql驱动。
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
yml文件配置项
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/test
spring.datasource.username=root
spring.datasource.password=mysql3306@118
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
Spring Data JDBC
新建一个web工程，添加jdbc、web等相关依赖包。
添加依赖
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jdbc</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
jar包依赖如下：
新建Entity
public class JdbcUser {
private Integer id;
private String name;
private String email;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
@Override
public String toString() {
return "JpaUser{" +
"id=" + id +
", name='" + name + '\'' +
", email='" + email + '\'' +
'}';
}
}
控制器演示代码
@RestController
public class JdbcController {
protected final static Logger logger = LoggerFactory.getLogger(JdbcController.class);
@Autowired
public JdbcTemplate jdbcTemplate;
@GetMapping("/jdbc/users")
public List<JdbcUser> users() {
return jdbcTemplate.query("select id,name,email from jdbc_user", new RowMapper<JdbcUser>() {
@Override
public JdbcUser mapRow(ResultSet rs, int rowNum) throws SQLException {
JdbcUser jdbcUser = new JdbcUser();
jdbcUser.setId(rs.getInt(1));
jdbcUser.setName(rs.getString(2));
jdbcUser.setEmail(rs.getString(3));
return jdbcUser;
}
});
}
}
浏览器访问结果
http://127.0.0.1:8080/jdbc/users
[{"id":4,"name":"李田","email":"litian@126.com"},{"id":5,"name":"王华","email":"wanghua@126.com"}]
Spring Data JPA
添加依赖
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
新建Entity
@Entity
public class JpaUser {
@Id
private Integer id;
private String name;
private String email;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
@Override
public String toString() {
return "JpaUser{" +
"id=" + id +
", name='" + name + '\'' +
", email='" + email + '\'' +
'}';
}
}
新建Repository接口
public interface UserRepository extends JpaRepository<JpaUser, Integer> {
}
控制器演示代码
@RestController
public class TestController {
protected final static Logger logger = LoggerFactory.getLogger(TestController.class);
@Autowired
private UserRepository userRepository;
@GetMapping("/jpa/users")
public List<JpaUser> users() {
return userRepository.findAll();
}
}
浏览器访问结果
[{"id":4,"name":"赵五","email":"zhaowu@126.com"}]
Mybatis
添加依赖
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>2.2.2</version>
</dependency>
新建Entity
public class Teacher {
private Integer id;
private String name;
private Integer age;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
@Override
public String toString() {
return "Teacher{" +
"id=" + id +
", name='" + name + '\'' +
", age=" + age +
'}';
}
}
新建Mapper接口
@Repository
public interface TeacherMapper {
public int insertTeacher(Teacher teacher);
public List<Teacher> selectList();
}
控制器演示代码
@RestController
public class MybatisController {
protected final static Logger logger = LoggerFactory.getLogger(MybatisController.class);
@Autowired
public TeacherMapper teacherMapper;
@GetMapping("mybatis/teachers")
public List<Teacher> teachers() {
Teacher teacher = new Teacher();
teacher.setName("李继");
teacher.setAge(35);
teacherMapper.insertTeacher(teacher);
return teacherMapper.selectList();
}
}
yml配置项
除了数据源的配置外，添加mybatis的配置，如下：
mybatis.mapper-locations=classpath:config/*Mapper.xml
mybatis.type-aliases-package=com.example.entity
Application启动
@SpringBootApplication
@MapperScan(basePackages = "com.example.dao", annotationClass = Repository.class)
public class MysqlMybatisDemoApplication {
public static void main(String[] args) {
SpringApplication.run(MysqlMybatisDemoApplication.class, args);
}
}
浏览器访问结果
http://127.0.0.1:8080/mybatis/teachers
[{"id":1,"name":"李继","age":35},{"id":2,"name":"李继","age":35},{"id":3,"name":"李继","age":35}]
总结
通过学习，三种框架基本情况如下：
