MyBatis 学习笔记之 MyBatis 入门开发

作者：fly

2022 年 10 月 02 日
山东
本文字数：5351 字
阅读完需：约 18 分钟

MyBatis 介绍

MyBatis 是一款优秀的持久层框架，它支持定制化 SQL、存储过程以及高级映射。
MyBatis 避免了几乎所有的 JDBC 代码和手动设置参数以及获取结果集。
MyBatis 可以使用简单的 XML 或注解来配置和映射原生信息，将接口和 Java 的 POJOs(Plain Old Java Objects,普通的 Java 对象)映射成数据库中的记录。

mybatis 执行流程

DEMO

POM 依赖

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">    <parent>        <artifactId>mybatis-learn</artifactId>        <groupId>com.fly9</groupId>        <version>1.0-SNAPSHOT</version>    </parent>    <modelVersion>4.0.0</modelVersion>
    <artifactId>mybatis</artifactId>
    <properties>        <maven.compiler.source>8</maven.compiler.source>        <maven.compiler.target>8</maven.compiler.target>    </properties>
    <dependencies>        <!-- https://mvnrepository.com/artifact/ch.qos.logback/logback-classic -->        <!-- 引入以上依赖，会自动引入 logback-classic、 logback-core、 slf4j-api 依赖-->        <dependency>            <groupId>ch.qos.logback</groupId>            <artifactId>logback-classic</artifactId>            <version>1.2.7</version>        </dependency>        <!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->        <dependency>            <groupId>org.projectlombok</groupId>            <artifactId>lombok</artifactId>            <version>1.18.22</version>            <scope>provided</scope>        </dependency>
        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->        <dependency>            <groupId>mysql</groupId>            <artifactId>mysql-connector-java</artifactId>            <version>8.0.28</version>        </dependency>        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->        <dependency>            <groupId>org.mybatis</groupId>            <artifactId>mybatis</artifactId>            <version>3.5.9</version>        </dependency>    </dependencies>
    <build>        <plugins>            <!--https://mvnrepository.com/artifact/org.apache.maven.plugins/maven-compiler-plugin -->            <plugin>                <groupId>org.apache.maven.plugins</groupId>                <artifactId>maven-compiler-plugin</artifactId>                <version>3.8.1</version>                <configuration>                    <source>1.8</source>                    <target>1.8</target>                    <encoding>UTF-8</encoding>                </configuration>            </plugin>        </plugins>
        <!--IDEA是不会编译src的java目录的文件，如果需要读取，则需要手动指定哪些配置文件需要读取-->        <resources>            <resource>                <directory>src/main/java</directory>                <includes>                    <include>**/*.xml</include>                </includes>            </resource>            <resource>                <directory>src/main/resources</directory>                <includes>                    <include>**/*</include>                </includes>            </resource>        </resources>    </build></project>

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配置文件

db-connection.properties

driver=com.mysql.cj.jdbc.Driverurl=jdbc:mysql://192.168.5.129:3306/db_learnusername=rootpassword=123456

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mybatis-config.xml

<?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>    <!-- mybatis 官网配置文档：https://mybatis.org/mybatis-3/zh/configuration.html -->
    <!-- 属性，可以直接赋值，也可以外部进行配置，同一属性名以最后加载的为准    通过方法参数传递的属性具有最高优先级，resource/url 属性中指定的配置文件次之，最低优先级的则是 properties 元素中指定的属性。-->    <properties resource="db-connection.properties">        <property name="driver" value="${driver}"/>        <property name="url" value="${url}"/>        <property name="username" value="${username}"/>        <property name="password" value="${password}"/>    </properties>
    <!-- settings 官网配置：https://mybatis.org/mybatis-3/zh/configuration.html#settings -->    <settings>        <!-- 这是是使用logback的配置，需要在logback配置文件配置dao-->        <setting name="logPrefix" value="dao."/>        <!-- 使用LOG4J打印日志-->        <!--<setting name="logImpl" value="LOG4J"/>-->    </settings>
    <!-- 实体类别名设置 -->    <typeAliases>        <package name="com.fly9.domain"/>    </typeAliases>
    <!-- 类型处理器 https://mybatis.org/mybatis-3/zh/configuration.html#typeHandlers -->    <typeHandlers>            </typeHandlers>
    <!-- 插件(略) https://mybatis.org/mybatis-3/zh/configuration.html#plugins -->
    <!--配置环境，可以配置多个环境，但是每个 SqlSessionFactory 实例只能选择一种环境。-->    <environments default="development">        <environment id="development">            <!--事务管理的配置 -->            <transactionManager type="JDBC"></transactionManager>            <!--数据源的配置-->            <dataSource type="POOLED">                <property name="driver" value="${driver}"/>                <property name="url" value="${url}"/>                <property name="username" value="${username}"/>                <property name="password" value="${password}"/>                <!-- 事务隔离级别，默认数据库事务隔离级别-->                <!--<property name="defaultTransactionIsolationLevel" value=""/>-->            </dataSource>        </environment>    </environments>
    <!--映射器（mappers）-->    <mappers>        <package name="com.fly9.mapper"/>    </mappers></configuration>

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logback.xml

<?xml version="1.0" encoding="UTF-8"?><configuration scan="true" scanPeriod="60 seconds" debug="false">    <appender name="console" class="ch.qos.logback.core.ConsoleAppender">        <encoder>            <pattern>%date{yyyy-MM-dd HH:mm:ss.SSS} %-5level [%thread] %class.%method.%L %msg  %ex{full} %n</pattern>        </encoder>    </appender>
    <logger name="dao" level="DEBUG"/>
    <root level="DEBUG">        <appender-ref ref="console" />    </root>
</configuration>

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代码实现

User.java

package com.fly9.domain;
import lombok.Data;
import java.io.Serializable;import java.time.LocalDateTime;
/** * @author anthony * @date 2022/4/10 */@Datapublic class User implements Serializable {    private static final long serialVersionUID = 6226302148605524294L;
    private Long id;    private String code;    private String username;    private String password;    private String phone;    private String email;    private LocalDateTime birthday;    private String address;    private Byte isEnable;    private Byte isDelete;    private Long version;    private LocalDateTime gmtCreate;    private String creator;    private Long creatorId;    private LocalDateTime gmtModified;    private String modifier;    private Long modifierId;}

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UserMapper.java

package com.fly9.mapper;
import com.fly9.domain.User;
import java.util.List;
/** * @author anthony * @date 2022/4/10 */public interface UserMapper {    /**     * 查询所有     * @return     */    List<User> selectAll();}

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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"><mapper namespace="com.fly9.mapper.UserMapper">    <resultMap id="all" type="com.fly9.domain.User">        <id column="id" jdbcType="BIGINT" property="id"/>        <result column="id" jdbcType="BIGINT" property="id"/>        <result column="code" jdbcType="VARCHAR" property="code"/>        <result column="username" jdbcType="VARCHAR" property="username"/>        <result column="password" jdbcType="VARCHAR" property="password"/>        <result column="phone" jdbcType="VARCHAR" property="phone"/>        <result column="email" jdbcType="VARCHAR" property="email"/>        <result column="birthday" jdbcType="TIMESTAMP" property="birthday"/>        <result column="address" jdbcType="VARCHAR" property="address"/>        <result column="is_enable" jdbcType="TINYINT" property="isEnable"/>        <result column="is_delete" jdbcType="TINYINT" property="isDelete"/>        <result column="version" jdbcType="BIGINT" property="version"/>        <result column="gmt_create" jdbcType="TIMESTAMP" property="gmtCreate"/>        <result column="creator" jdbcType="VARCHAR" property="creator"/>        <result column="creator_id" jdbcType="BIGINT" property="creatorId"/>        <result column="gmt_modified" jdbcType="TIMESTAMP" property="gmtModified"/>        <result column="modifier" jdbcType="VARCHAR" property="modifier"/>        <result column="modifier_id" jdbcType="BIGINT" property="modifierId"/>    </resultMap>
    <select id="selectAll" resultMap="all">        select * from user    </select></mapper>

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执行

package com.fly9;
import com.fly9.domain.User;import com.fly9.mapper.UserMapper;import lombok.extern.slf4j.Slf4j;import org.apache.ibatis.io.Resources;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import java.io.IOException;import java.io.Reader;import java.util.List;
/** * @author anthony * @date 2022/4/10 */@Slf4jpublic class Application {    public static void main(String[] args) {        try {            // 读取配置文件            Reader reader = Resources.getResourceAsReader("mybatis-config.xml");            // 构建SQL会话工厂            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);            // 获取会话            SqlSession sqlSession = sqlSessionFactory.openSession();            // 获取Mapper            UserMapper userMapper = sqlSession.getMapper(UserMapper.class);            // 执行SQL语句，获取结果            List<User> userList = userMapper.selectAll();            userList.forEach(ele -> log.info("{}", ele));            sqlSession.close();        } catch (IOException e) {            log.error("the exception is {}", e.getMessage(), e);        }    }}

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发布于: 刚刚阅读数: 4

原文链接:【http://xie.infoq.cn/article/2cd4cb0acce4036c07aa61065】。

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MyBatis 学习笔记之 MyBatis 入门开发

相关链接

MyBatis 介绍

mybatis 执行流程

DEMO

POM 依赖

配置文件

db-connection.properties

mybatis-config.xml

logback.xml

代码实现

User.java

UserMapper.java

UserMapper.xml

执行

fly

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