springboot学习[版本2.6.2]数据库配置，Druid，Mybatis整合day5-1

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数据访问

数据源自动配置

导入配置

<dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>

关于数据库驱动

由于官方不知道我们使用的是什么数据库，什么版本的数据库所以不帮我们自动导入

导入mysql的驱动（看你自己的版本）

Spring Boot中MySQL的版本仲裁是8.0.22

<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.16</version>
</dependency>

application.yaml配置mysql连接

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=Asia/Shanghai&zeroDateTimeBehavior=CONVERT_TO_NULL&allowPublicKeyRetrieval=true
    username: root
    password: 123456

Druid连接池

<!-- https://mvnrepository.com/artifact/com.alibaba/druid-spring-boot-starter -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid-spring-boot-starter</artifactId>
    <version>1.2.8</version>
</dependency>

application.yaml

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=Asia/Shanghai&zeroDateTimeBehavior=CONVERT_TO_NULL&allowPublicKeyRetrieval=true
    username: root
    password: 123546

    druid:
      stat-view-servlet:
        enabled: true
        login-username: admin
        login-password: 123456
        reset-enable: false

      web-stat-filter:  #监控we'b
        url-pattern: /*
        exclusions: '*.png,/druid/*'
        enabled: true

      filters: stat,wall,slf4j  #底层开启功能，stat：sql监控，wall：防火墙
      filter:
        stat:
          slow-sql-millis: 1000
          log-slow-sql: true
          enabled: true
        wall:
          enabled: true
          config:
            drop-table-allow: false
      aop-patterns: com.example.day3.*

  jdbc:
    template:
      query-timeout: 3

在这里插入图片描述

SpringBoot 整合Mybatis(starter)

文档

mybatis.net.cn/

mybatis配置文件可配置设置

mybatis.net.cn/configurati…

整合步骤

1.导入依赖

<!-- https://mvnrepository.com/artifact/org.mybatis.spring.boot/mybatis-spring-boot-starter -->
<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>2.2.1</version>
</dependency>

2.编写配置全局配置文件位置application.yaml

在这里插入图片描述

#配置mybatis的config和mapper的地址
mybatis:
  config-location: classpath:mybatis/mybatis-config.xml
  mapper-locations: classpath:mybatis/mapper/*.xml

3.编写全局配置文件mybatis-config.xml（可以不写）

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <settings>
    <!--        允许数据库驼峰命名-->
        <setting name="mapUnderscoreToCamelCase" value="true"/>
        <setting name="callSettersOnNulls" value="true"/>
    </settings>
</configuration>

不写全局配置文件就直接在application.yaml里进行配置

mybatis:
  configuration:
    call-setters-on-nulls: true

就等同于

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <settings>
        <setting name="callSettersOnNulls" value="true"/>
    </settings>
</configuration>

4.编写实体类

package com.example.day3.bean;

import lombok.Data;

@Data
public class Stu4 {
    private int stuId;
    private String stuName;
    private int money;
}

5.编写Mapper接口

package com.example.day3.mapper;

import com.example.day3.bean.Stu4;

@Mapper
public interface Stu4Mappper {
    public Stu4 getStu4(int stuId);
}

注意@Mapper注解

6.编写Service

package com.example.day3.service;

import com.example.day3.bean.Stu4;
import com.example.day3.mapper.Stu4Mappper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class Stu4Service {

    @Autowired
    Stu4Mappper stu4Mappper;

    public Stu4 getStu4ById(int id){
        return stu4Mappper.getStu4(id);
    }
}

7.编写Controller类

package com.example.day3.controller;

import com.example.day3.bean.Stu4;
import com.example.day3.bean.User;
import com.example.day3.service.Stu4Service;
import lombok.extern.log4j.Log4j;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.logging.Log;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RequestPart;
import org.springframework.web.servlet.HandlerInterceptor;
import org.thymeleaf.util.StringUtils;

import javax.servlet.http.HttpSession;

@Controller
public class IndexController {

    @Autowired
    JdbcTemplate jdbcTemplate;

    @Autowired
   Stu4Service stu4Service;

    @GetMapping("/stu")
    public Stu4 getById(@RequestParam("id") int id) {
        return stu4Service.getStu4ById(id);
    }
}

8.编写sql映射文件stu4Mapper.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.example.day3.mapper.Stu4Mappper">
<!--    查询-->
    <select id="getStu4" resultType="com.example.day3.bean.Stu4">
       select * from stu4 where id = #{id};
    </select>
</mapper>

文件头部固定写法

<?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="填写你自己项目的Mapper接口路径">
</mapper>

访问http://localhost:8080/stu?id=1

这里的id取决于你数据库里的id

（*）Spring Boot整合Mybatis（纯注解配置式）

创建项目

在这里插入图片描述

数据库准备stu3表

在这里插入图片描述

yaml中的配置同上面

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=Asia/Shanghai&zeroDateTimeBehavior=CONVERT_TO_NULL&allowPublicKeyRetrieval=true
    username: root
    password: 123546

    druid:
      stat-view-servlet:
        enabled: true
        login-username: admin
        login-password: 123456
        reset-enable: false

      web-stat-filter:  #监控we'b
        url-pattern: /*
        exclusions: '*.png,/druid/*'
        enabled: true

      filters: stat,wall,slf4j  #底层开启功能，stat：sql监控，wall：防火墙
      filter:
        stat:
          slow-sql-millis: 1000
          log-slow-sql: true
          enabled: true
        wall:
          enabled: true
          config:
            drop-table-allow: false
      aop-patterns: com.example.day3.*

  jdbc:
    template:
      query-timeout: 3

编写Stu3实体类

package com.example.day5.bean;

import lombok.Data;

@Data
public class Stu3 {
    private int id;
    private String name;
    private int age;
    private String sex;
    private int math;
}

编写Stu3Mapper

package com.example.day5.mapper;

import com.example.day5.bean.Stu3;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;


@Mapper
public interface Stu3Mapper {

    @Select("select * from stu3 where id = #{id}")
    public Stu3 getById(int id);
}

编写Stu3Service

package com.example.day5.service;

import com.example.day5.bean.Stu3;
import com.example.day5.mapper.Stu3Mapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class Stu3Service {

    @Autowired
    Stu3Mapper stu3Mapper;

    public Stu3 getById(int id){
        return stu3Mapper.getById(id);
    }
}

编写Stu3Controller

package com.example.day5.controller;

import com.example.day5.bean.Stu3;
import com.example.day5.service.Stu3Service;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class Stu3Controller {

    @Autowired
    JdbcTemplate jdbcTemplate;

    @Autowired
    Stu3Service stu3Service;

    @ResponseBody
    @GetMapping("/stu")
    public Stu3 getById(@RequestParam("id") int id) {
        return stu3Service.getById(id);
    }
}

访问结果

在这里插入图片描述

推荐使用注解和配置文件混合的方式，注解若过于繁琐就放置在配置文件中，这里指的式Mapper.xml这个配置文件不是全局配置文件

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