迦南地
所有文章 标签 分类 实验室 关于
迦南地

目录

mybatis入门

 收录于 技术
   约 1306 字   预计阅读 3 分钟    次阅读  

官方入门演示

HelloWorld

数据准备

 1
 2
 3
 4
 5
 6
 7
 8
 9
10

-- 创建员工表
create table tbl_employee(
	id INT(11) PRIMARY KEY auto_increment,
	last_name VARCHAR(255),
	gender char(1),
	email VARCHAR(255)
);

-- 准备数据
insert into tbl_employee(last_name, gender, email) values('tom', 0, 'tom@gmail.com');

引入maven依赖

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30

<dependencies>
        <!-- mybatis核心包 -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.6</version>
        </dependency>
        <!-- mysql驱动包 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.29</version>
        </dependency>
 			 <!-- 引入日志包 -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.7</version>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-core</artifactId>
            <version>1.1.7</version>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>1.1.7</version>
        </dependency>
    </dependencies>

java代码

  1. employee.java

     1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12

    package com.eh.eden.mybatis.orm.bean;
   
import lombok.Data;
   
@Data
public class Employee {
   
    private Integer id;
    private String lastName;
    private String gender;
    private String email;
}

  2. 日志配置文件 logback.xml

     1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43

    <?xml version="1.0" encoding="UTF-8"?>
<configuration scanPeriod="60 seconds" debug="false">
   
    <property name="APP_NAME" value="java8"/>
    <property name="LOG_HOME" value="/tmp/com.eh"/>
   
    <contextName>${APP_NAME}</contextName>
   
    <timestamp key="dt" datePattern="yyyyMMdd HH:mm:ss"/>
   
    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
   
        <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
            <pattern>${dt} [%thread] %highlight(%-5level) %cyan(%logger{50}) - %msg%n</pattern>
        </encoder>
        <withJansi>true</withJansi>
    </appender>
   
    <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <file>${LOG_HOME}/${APP_NAME}.log</file>
        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <FileNamePattern>${LOG_HOME}/${APP_NAME}.%d.log</FileNamePattern>
            <MaxHistory>30</MaxHistory>
        </rollingPolicy>
        <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
            <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{50} - %msg%n</pattern>
        </encoder>
        <triggeringPolicy class="ch.qos.logback.core.rolling.SizeBasedTriggeringPolicy">
            <MaxFileSize>10MB</MaxFileSize>
        </triggeringPolicy>
    </appender>
   
    <!--myibatis log configure-->
    <logger name="org.apache.ibatis" level="TRACE" />
    <logger name="java.sql.Connection" level="DEBUG"/>
    <logger name="java.sql.Statement" level="DEBUG"/>
    <logger name="java.sql.PreparedStatement" level="DEBUG"/>
   
    <root level="TRACE">
        <appender-ref ref="STDOUT"/>
        <appender-ref ref="FILE"/>
    </root>
</configuration>

  3. mybatis配置文件 mybatis-config.xml

     1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24

    <?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>
   
    <!--引入外部properties文件 必须放在最前面,否则会报错 -->
    <properties resource="db.properties"></properties>
   
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${driver}"/>
                <property name="url" value="${url}"/>
                <property name="username" value="${username}"/>
                <property name="password" value="${password}"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="EmployeeMapper.xml"/>
    </mappers>
</configuration>

  4. db.properties

    1
2
3
4
5

    driver=com.mysql.jdbc.Driver
# 防止乱码
url=jdbc:mysql://localhost:3306/db01?useUnicode=true&characterEncoding=utf8&rewriteBatchedStatements=true
username=root
password=333

  5. sql映射文件 EmployeeMapper.xml

     1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17

    <?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.eh.eden.mybatis.orm.EmployeeMapper">
   
   
    <!--
        id: 唯一标识
        resultType: 返回值类型
        #{id}: 从传递过来的参数中取出id值
    -->
    <select id="selectEmp" resultType="com.eh.eden.mybatis.orm.bean.Employee">
        select id, last_name lastName, gender, email from tbl_employee where id = #{id}
    </select>
   
</mapper>

  6. 测试

     1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33

    package com.eh.eden.mybatis.orm.dao;
   
import com.eh.eden.mybatis.orm.bean.Employee;
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 org.testng.annotations.Test;
   
import java.io.IOException;
import java.io.InputStream;
   
public class EmployeeServiceTest {
   
    @Test
    public void test() throws IOException {
        // 1. 根据xml配置文件（全局配置文件）创建一个SqlSessionFactory对象
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
   
        // 2. 从 SqlSessionFactory 中获取 SqlSession，能直接执行已经映射的sql语句
        try (SqlSession session = sqlSessionFactory.openSession()) {
            Employee employee = session.selectOne("com.eh.eden.mybatis.orm.EmployeeMapper.selectEmp", 1);
            System.out.println(employee);
        }
    }
}
   
// 输出
[TestNG] Running:
  /Users/david/Library/Caches/IntelliJIdea2019.1/temp-testng-customsuite.xml
Employee(id=1, lastName=tom, gender=0, email=tom@gmail.com)

接口式编程

  1. 增加接口

    1
2
3
4
5
6
7
8
9

    package com.eh.eden.mybatis.orm.dao;
   
import com.eh.eden.mybatis.orm.bean.Employee;
   
public interface EmployeeMapper {
   
    Employee getEmployeeById(Integer id);
   
}

  2. 修改sql映射文件

     1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16

    <?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.eh.eden.mybatis.orm.dao.EmployeeMapper">
   
    <!--
        id: 唯一标识
        resultType: 返回值类型
        #{id}: 从传递过来的参数中取出id值
    -->
    <select id="getEmployeeById" resultType="com.eh.eden.mybatis.orm.bean.Employee">
        select id, last_name lastName, gender, email from tbl_employee where id = #{id}
    </select>
   
</mapper>

    namespace 改成接口全限定名

    id改成方法名

  3. 测试

     1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37

    package com.eh.eden.mybatis.orm.dao;
   
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 org.testng.annotations.Test;
   
import java.io.IOException;
import java.io.InputStream;
   
public class EmployeeMapperTest {
   
    public SqlSessionFactory getSqlSessionFactory() throws IOException {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        return new SqlSessionFactoryBuilder().build(inputStream);
    }
   
    @Test
    public void test() throws IOException {
        // 1. 获取SqlSessionFactory
        SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();
   
        // 2. 从 SqlSessionFactory 中获取 SqlSession，能直接执行已经映射的sql语句
        try (SqlSession session = sqlSessionFactory.openSession()) {
            // 3. 获取接口实现类对象
            // mybatis会为接口自动创建一个代理对象，代理对象去执行增删改查方法
            EmployeeMapper employeeMapper = session.getMapper(EmployeeMapper.class);
            System.out.println(employeeMapper.getEmployeeById(1));
        }
    }
}
// 输出
[TestNG] Running:
  /Users/david/Library/Caches/IntelliJIdea2019.1/temp-testng-customsuite.xml
Employee(id=1, lastName=tom, gender=0, email=tom@gmail.com)

总结

  1. 接口式编程

    原生：Dao->DaoImpl

    接口式编程：xxMapper->xxMaper.xml

  2. SqlSession代表和数据库的一次会话，用完必须关闭

  3. SqlSession和connection一样都是非线程安全，每次使用都应该获取新的对象

  4. mapper接口没有实现类，但是mybati会为这个接口生成一个代理对象

    将接口和xml进行绑定

    EmployeeMapper employeeMapper = session.getMapper(EmployeeMapper.class);

  5. 两个重要的配置文件

    1. mybatis的全局配置文件：包含数据库连接池信息，事务管理器信息等系统运行环境信息
    2. sql映射文件：保存了每一个sql语句的映射信息
更新于 2020-06-05
 mybtis
返回 | 主页