关于java:SpringBoot整合Mybatis

新建我的项目

临时只须要勾选webjar包即可

导入jt.sql的数据库

筹备数据库工具~~~~

连贯数据库

增加jar包文件

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.4.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.jt</groupId>
    <artifactId>springboot_demo2_mybatis</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot_demo2_mybatis</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

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

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <!--引入插件lombok 主动的set/get/构造方法插件  -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>

        <!--引入数据库驱动 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>

        <!--springBoot数据库连贯  -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>

        <!--spring整合mybatis  临时  -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.2</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

编辑POJO对象

@Data
@Accessors(chain = true)
public class User implements Serializable {
    private Integer Id;
    private String name;
    private Integer age;
    private String sex;
}

编辑UserDao接口

@Mapper //将接口交给Spring治理
public interface UserDao {

    //查问user表的所有的记录
    @Select("select * from user")
    List<User> findAll();

}

编辑测试类

package com.jt;

import com.jt.dao.UserDao;
import com.jt.pojo.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.util.List;

@SpringBootTest
class SpringbootDemo2MybatisApplicationTests {

    @Autowired
    private UserDao userDao;

    @Test
    public void testFind(){

        List<User> userList = userDao.findAll();
        System.out.println(userList);
    }
}

对于Mybatis配置阐明

前提:Mybatis进行映射时必须满足属性名称统一
业务阐明:
表:      user_id   user_name
对象:     userId   userName

解决方案: 开启mybatis驼峰规定映射
原理:字段名称user_id去除‘——’下滑线userid而后首字母大写userId 属性userId只有名称统一,则能够主动映射.
注意事项: 如果开启驼峰规定,则必须满足要求.
问: 对象的属性user_id 与字段user_id是否映射? 不能映射！

server:
  port: 8090    #定义端口号
 servlet:
    context-path: /   #定义我的项目公布门路
spring:
  datasource:
    #driver-class-name: com.mysql.jdbc.Driver 通知springboot程序采纳默认的配置
 url: jdbc:mysql://127.0.0.1:3306/jtdb?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=utf8&autoReconnect=true&allowMultiQueries=true
    username: root
    password: root
mybatis:
  #定义别名包
 type-aliases-package: com.jt.pojo
  #加载user表的mapper文件
 mapper-locations: classpath:/mybatis/mappers/*.xml
  #开启驼峰映射
 configuration:
    map-underscore-to-camel-case: true

对于数据库url阐明

1.时区设定
serverTimezone=GMT%2B8 %2B= +号
2.编码格局设定
useUnicode=true&characterEncoding=utf8
3.是否主动的从新链接
autoReconnect=true
4.是否容许批量操作
allowMultiQueries=true

对于Mapper注解优化阐明

因为每个接口都须要增加Mapper注解导致代码繁琐.能够采纳包扫描的形式动静导入 代码如下

@SpringBootApplication
/**
*次要通知mapper的包门路,会主动的实现包扫描。
*留神:~~~~这里的参数是要扫描的包门路~~~~
*/
@MapperScan("com.jt.dao") 
public class SpringbootDemo2MybatisApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringbootDemo2MybatisApplication.class, args);
    }

}