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使用依赖:web(前后端交互)、mybatis(持久层)、mysql(数据库驱动)
使用更加方便的yml文件,而不是默认的properties文件。删除application.properties,新增application.yml和application-dev.yml,并修改内容。
application.yml:
spring:
profiles:
active: dev
application-dev.yml:
server:
port: 8080
spring:
datasource:
username: root
password: 123456
driver-class-name: com.mysql.cj.jdbc.Driver
url: jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC
自动配置时会将数据库连接相關信息注入到mybatis中.
CREATE TABLE `user` (
`id` int(11) NOT NULL COMMENT 'id',
`username` varchar(50) DEFAULT NULL,
`password` varchar(100) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
该类中跟数据表对应,提供get和set方法。
package com.sxf.demo.model;
public class User {
private Long id;
private String name;
private String pwd;
public Long getId(){
return id;
}
public String getName() {
return name;
}
public String getPwd() {
return pwd;
}
public void setId(Long id) {
this.id = id;
}
public void setName(String name) {
this.name = name;
}
public void setPwd(String pwd) {
this.pwd = pwd;
}
}
SQL的查询语句。
package com.sxf.demo.mapper;
import com.sxf.demo.model.User;
import org.apache.ibatis.annotations.Select;
import java.util.List;
public interface UserMapper {
@Select("select * from user")
List<User> getAllUsers();
@Select("select * from user where id=#{id}")
User getUserById(Long id);
}
UserMapper.java:
package com.sxf.demo.mapper;
import com.sxf.demo.model.User;
import java.util.List;
public interface UserMapper {
User getUserById(Long id);
}
在resource文件夹下新建一个mapper文件夹编写对应的xml
UserMapper.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">
<!-- 此处与接口类地址对应 -->
<mapper namespace="com.sxf.demo.mapper.UserMapper">
<!-- 此处与接口方法名对应 指定参数类型与返回结果类型-->
<select id="getUserById" parameterType="java.lang.Long" resultType="com.sxf.demo.model.User">
select * from user where id = #{id}
</select>
</mapper>
注意: 1.namespace中需要与使用@Mapper的接口对应 2.UserMapper.xml文件名称必须与使用@Mapper的接口一致 3.标签中的id必须与@Mapper的接口中的方法名一致,且参数一致
在application-dev.yml中添加路径,指明映射文件位置:
mybatis:
mapper-locations: classpath:mapper/*Mapper.xml
type-aliases-package: com.sxf.demo.mapper
注意: 1.mybatis中的mapper-locations是mapper的xml文件位置 2.mybatis中的type-aliases-package是为了配置xml文件中resultType返回值的包位置,如果未配置请使用全包名
这里扫描的是接口,不是xml。 启动类DemoApplication.java:
package com.sxf.demo;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
@MapperScan(basePackages = "com.sxf.demo.mapper") // 添加扫描
public class DemoApplication {
public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
}
逻辑代码在这里吧。
package com.sxf.demo.controller;
import com.sxf.demo.mapper.UserMapper;
import com.sxf.demo.model.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import java.util.List;
@Controller
@ResponseBody
public class UserController {
@Autowired(required = false)
private UserMapper userMapper;
@RequestMapping("/getUser")
public User getAllUsers(Long id){
return userMapper.getUserById(id);
}
}
浏览器访问: