MyBatis学习日志

1. 在pom.xml导入依赖

<dependencies>

        <!--导入mysql 驱动jar包-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.32</version>
        </dependency>

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.6</version>
        </dependency>


        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.12</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.1</version>
            <scope>test</scope>
        </dependency>

        <!--添加slf4j日志api-->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.20</version>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.12</version>
            <scope>provided</scope>
        </dependency>

        <!--添加logback-classic依赖-->
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>1.2.9</version>
        </dependency>

        <!--添加logback-core依赖-->
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-core</artifactId>
            <version>1.2.9</version>
        </dependency>

    </dependencies>

在userMapper.xml导入sql语句，进行sql语句的调用

<?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">
<!--
        namespace:名称空间
-->
<!--对应查询语句-->
<mapper namespace="test">
    <select id="selectAll" resultType="com.Ye.User">
        select *from tb_user;
    </select>

</mapper>

在logback.xml, 导入资源包   //用不到也行

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <!--
        CONSOLE ：表示当前的日志信息是可以输出到控制台的。
    -->
    <appender name="Console" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>[%level] %blue(%d{HH:mm:ss.SSS}) %cyan([%thread]) %boldGreen(%logger{15}) - %msg %n</pattern>
        </encoder>
    </appender>

    <logger name="com.Ye" level="DEBUG" additivity="false">
        <appender-ref ref="Console"/>
    </logger>
    <!--
      level:用来设置打印级别，大小写无关：TRACE, DEBUG, INFO, WARN, ERROR, ALL 和 OFF
     ， 默认debug
      <root>可以包含零个或多个<appender-ref>元素，标识这个输出位置将会被本日志级别控制。
      -->
    <root level="DEBUG">
        <appender-ref ref="Console"/>
    </root>
</configuration>

在mybatis-config.xml连接数据库信息。加载映射文件（写sql文件的.xml文件）。

<?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>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>

            <dataSource type="POOLED">
                <!--数据库的链接信息，链接数据库-->
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql:///mybatis?useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>

        </environment>
    </environments>

    <mappers>
        <!--加载sql映射文件-->
        <mapper resource="UserMapper.xml"/>
    </mappers>

</configuration>

在User.java导入关键字信息，用于MyBatisDemo.java文件的数组调用。

package com.Ye;
public class User {
        private Integer id;
        private String username;
        private String password;
        private String gender;
        private String addr;


    public User() {
    }

    public User(Integer id, String username, String password, String gender, String addr) {
        this.id = id;
        this.username = username;
        this.password = password;
        this.gender = gender;
        this.addr = addr;
    }

    /**
     * 获取
     * @return id
     */
    public Integer getId() {
        return id;
    }

    /**
     * 设置
     * @param id
     */
    public void setId(Integer id) {
        this.id = id;
    }

    /**
     * 获取
     * @return username
     */
    public String getUsername() {
        return username;
    }

    /**
     * 设置
     * @param username
     */
    public void setUsername(String username) {
        this.username = username;
    }

    /**
     * 获取
     * @return password
     */
    public String getPassword() {
        return password;
    }

    /**
     * 设置
     * @param password
     */
    public void setPassword(String password) {
        this.password = password;
    }

    /**
     * 获取
     * @return gender
     */
    public String getGender() {
        return gender;
    }

    /**
     * 设置
     * @param gender
     */
    public void setGender(String gender) {
        this.gender = gender;
    }

    /**
     * 获取
     * @return addr
     */
    public String getAddr() {
        return addr;
    }

    /**
     * 设置
     * @param addr
     */
    public void setAddr(String addr) {
        this.addr = addr;
    }

    public String toString() {
        return "User{id = " + id + ", username = " + username + ", password = " + password + ", gender = " + gender + ", addr = " + addr + "}";
    }
}

 在MyBatisDemo.java文件中

1. 加载核心配置文件
2. 获取Sqlsession对象，用它来执行sql语句
3. 执行sql
4. 释放资源

package com.Ye;
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.InputStream;
import java.util.List;

public class MyBatisDemo {
    public static void main(String[] args) throws IOException {
        //1、加载MyBatis核心配置文件
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2、获取SqlSession对象，用它执行sql
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //3、执行sql
        List<User> users = sqlSession.selectList("test.selectAll");//查询所有, 传入sql语句的唯一标识
                                                    //test（id）是唯一标识，selectAll（namespace）名称空间
                                                    //sqlSession.selectOne(); 查询一个
        System.out.println(users);//打印users，显示结果

        //4、释放资源
        sqlSession.close();
    }
}