1 连接数据库

第一步

连接数据库，需加入pom.xml

<dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>2.3.0</version></dependency><dependency><groupId>com.alibaba</groupId><artifactId>druid-spring-boot-starter</artifactId><version>1.2.9</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><scope>runtime</scope></dependency>

数据库配置spring.factories

线程池中核心参数有哪些？

1.初始化连接数
2.最小连接数
3.最大连接数
4.最大空闲等待时间

第二步

dao

Data Access Object 数据访问对象

底层可以换任何一个主键

所以需要写student类（在moder中）

package cn.zxy.moder;import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;@Data
@AllArgsConstructor
@NoArgsConstructor
@Builder
public class Student {private Integer id;private String name;private String age;
}

然后写select方法（在resources中建立mapper）

StudentMapper.xml

第三步

Studentcontroller 类在controller文件中写

package cn.zxy.controller;import cn.zxy.dao.StudentDao;
import cn.zxy.moder.Student;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;import java.util.List;@RestController
@RequestMapping("api/student")
public class StudentController {@Autowiredprivate StudentDao studentDao;@GetMappingpublic List<Student> select(){return studentDao.select();}}

注入StudentDao

@Autowiredprivate StudentDao studentDao;

第四步

启动类

package cn.zxy;import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication
@MapperScan
public class Application {public static void main(String[] args) {SpringApplication.run(Application.class, args);}}

第五步

GET做测试http://localhost:8080/api/student/