spring boot 整合 mybatis 以及原理

同上一篇文章一样，spring boot 整合 mybatis过程中没有看见SqlSessionFactory，sqlsession（sqlsessionTemplate），就连在spring框架整合 mybatis时的SqlSessionFactoryBean都没看到，那spring boot 把这些参数都放在了 mybatis-spring boot autoconfigure.jar 包中的MybatisAutoConfiguration 这个类中，使用 @ConditionalOnMissingBean这个注解，当环境中缺少 sqlsessionFactory sqlsessionTemplate时会自动注入

Example

使用spring boot 的starter pom

需要导入 mybatis-spring-boot-starter 和 数据库连接相关的配置

pom.xml

<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">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.ibigsea</groupId>
    <artifactId>bootdao</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>bootdao</name>
    <url>http://maven.apache.org</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <boot.version>1.3.1.RELEASE</boot.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>${boot.version}</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.1.1</version>
        </dependency>
        <!-- mysql 驱动 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.38</version>
        </dependency>
        <!-- 数据库连接池 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.0.5</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <version>${boot.version}</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

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

</project>

是不是很方便,mybatis的starter pom里面依赖了mybatis和spring相关的jar

只需导入一个就OK了

这里采用的是阿里巴巴的druid数据连接池

为了方便使用 yml配置文件

application.yml

---
spring:
  profiles : dev
  datasource:
    name: mydb
    type: com.alibaba.druid.pool.DruidDataSource
    url: jdbc:mysql://127.0.0.1:3306/mytestdb
    username: root
    password: 123456
    driver-class-name: com.mysql.jdbc.Driver
    minIdle: 1
    maxActive: 2
    initialSize: 1
    timeBetweenEvictionRunsMillis: 3000
    minEvictableIdleTimeMillis: 300000
    validationQuery: SELECT 'ZTM' FROM DUAL
    testWhileIdle: true
    testOnBorrow: false
    testOnReturn: false


mybatis:
  mapperLocations: classpath*:com/ibigsea/bootdao/mapper/*.xml
  typeAliasesPackage: com.ibigsea.bootdao.entity

User.java

package com.ibigsea.bootdao.entity;

import java.io.Serializable;

public class User implements Serializable {

    private static final long serialVersionUID = 8809101560720973267L;

    private Integer id;

    private String userName;

    private Integer age;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "User [id=" + id + ", userName=" + userName + ", age=" + age + "]";
    }


}

UserMapper.java

package com.ibigsea.bootdao.mapper;

import java.util.List;

import org.apache.ibatis.annotations.Mapper;

import com.ibigsea.bootdao.entity.User;

@Mapper
public interface UserMapper {

    int save(User user);

    User selectById(Integer id);

    int updateById(User user);

    int deleteById(Integer id);

    List<User> queryAll();

}

<p>UserMapper.xml</p>

<?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.ibigsea.bootdao.mapper.UserMapper" >

    <insert id="save" parameterType="com.ibigsea.bootdao.entity.User">
        insert into t_user(username,age) values(#{userName,jdbcType=VARCHAR},#{age,jdbcType=NUMERIC})
    </insert>

    <select id="selectById" resultType="com.ibigsea.bootdao.entity.User">
        select * from t_user where id = #{id,jdbcType=NUMERIC}
    </select>

    <update id="updateById" parameterType="com.ibigsea.bootdao.entity.User">
        update t_user set
        username = #{userName,jdbcType=VARCHAR} ,
        age = #{age,jdbcType=NUMERIC}
        where id = #{id,jdbcType=NUMERIC}
    </update>

    <delete id="deleteById">
        delete from t_user where id = #{id,jdbcType=NUMERIC}
    </delete>

    <select id="queryAll" resultType="com.ibigsea.bootdao.entity.User">
        select * from t_user
    </select>

</mapper>

启动类 App.class

package com.ibigsea.bootdao;

import org.springframework.boot.autoconfigure.SpringBootApplication;

/**
 * Hello world!
 *
 */
@SpringBootApplication
//启注解事务管理
@EnableTransactionManagement
public class App {
    public static void main(String[] args) {
        System.out.println("Hello World!");
    }
}

这里使用test来测试

package com.ibigsea.bootdao;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.SpringApplicationConfiguration;
import org.springframework.test.context.ActiveProfiles;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import com.ibigsea.bootdao.entity.User;
import com.ibigsea.bootdao.mapper.UserMapper;

@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = {App.class})
//相当于  --spring.profiles.active=dev
@ActiveProfiles(value="dev")
public class AppTest {

    @Autowired
    private UserMapper mapper;

    @Test
    public void testInsert(){
        User user = new User();
        user.setUserName("张三");
        user.setAge(23);
        mapper.save(user);
        System.out.println("插入用户信息"+user.getUserName());
    }

}

运行结果:

Ok 数据库这边也有数据了

表结构这边就不提供了 , 就一个很简单的表 自己创建一个就可以了

查询:

@Test
    public void testSelect(){
        User user = mapper.selectById(1);
        System.out.println(user);
    }

update

@Test
    public void testUpdate(){
        User user = mapper.selectById(1);
        System.out.println(user);
        user.setAge(24);
        mapper.updateById(user);
        user = mapper.selectById(1);
        System.out.println(user);

    }

Mybatis相关的配置

MybatisAutoConfiguration

Spring boot 在运行的时候会进行自动配置

读取到 mybatis-spring-boot-autoconfigure 里面的spring.factories,然后自动配置

就是下面这个类

这个方法使用了PostConstruct注解,在初始化的时候去加载mybatis的配置文件,然后创建SqlSessionFactory等

Mybatis自动配置会自动创建 sqlSessionFactory和SqlSessionTemplate

这个东西 就是 加载在注解了@Mapper的类

如果不喜欢在mapper上面加注解的话,也可以通过@MapperScan

这样子:

这样就OK啦

关于事务方面

在启动类上面添加

@EnableTransactionManagement注解

然后在类上面或者方法上面添加@Transactional注解

package com.ibigsea.bootdao.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import com.ibigsea.bootdao.entity.User;
import com.ibigsea.bootdao.mapper.UserMapper;

@Service("userService")

//在方法和类上面都可以
@Transactional
public class UserService {

    @Autowired
    private UserMapper mapper;

    public void insetUser() throws Exception {

        User user = new User();
        user.setUserName("李四");
        user.setAge(23);
        mapper.save(user);
        System.out.println("插入用户信息"+user.getUserName());

        if (user.getUserName().equals("李四")) {
            throw new IllegalArgumentException("出现异常QAQ");
        }

        user = new User();
        user.setUserName("李四11111");
        user.setAge(23);
        mapper.save(user);
    }

}

测试类

@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = {App.class})
//相当于  --spring.profiles.active=dev
@ActiveProfiles(value="dev")
@EnableTransactionManagement
public class AppTest {


    @Autowired
    private UserService userService;


    @Test
    public void testTransactional() throws Exception {
        userService.insetUser();
    }

}

数据库结果

我们吧@Transactional注解去掉 或者去掉 @EnableTransactionManagement注解

测试下看看

数据被插入~~~~~