spring boot写java web和接口
流程:

Springboot开发过程

还有一个是mybatis的依赖
测试接口
@RestController
public class Hello {
    @RequestMapping("/hello")
    public String hello(){
        return "helloworld";
    }
}
***.yml文件配置
spring: datasource: driver-class-name: com.mysql.cj.jdbc.Driver url: jdbc:mysql://localhost:3306/student?useUnicode=true&useSSL=false&characterEncoding=utf8&serverTimezone=Asia/Shanghai username: root password: 123456 mybatis: mapper-locations: classpath:mapper/*.xml
数据库字段:

pojo
@Data
public class User {
    private  int id ;
    private String name;
    private int age;
    private String email;
    *****
剩下的就是get和set方法自行完成
mapper
@Mapper
public interface UserMapper {
    List<User> findAll();
}
如果是springboot,在启动类中使用@MapperScan(“mapper接口所在包全名”)即可,不用一个一个的在Mapper接口中加@Mapper注解。@Mapper注解是识别他为mybatis的mapper接口,会自动的把 加@Mapper 注解的接口生成动态代理类。
让springboot认识你的mapper层,也可以在启动类上面加MapperScan(“mapper层所在包的全名”)
mapper.xml
<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" > <mapper namespace="com.liuyang.mapper.UserMapper"> <select id="findAll" resultType="com.liuyang.entity.User"> SELECT * FROM user </select> </mapper>
controller
@RestController
public class UserController {
    @Autowired
    //把userService实例化
    private UserService userService;
    @RequestMapping("/user")
    public List<User> getUser(){
        return userService.findAll();
    }
}
注意一定要把userService 注入到容器中

数据成功拿到
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