mybatis深入理解

准备工作：

导入依赖pom文件中

<?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>Mybits</artifactId>
        <groupId>com.whz</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>Mybatis-02</artifactId>
    <dependencies>
        <!-- mybatis必备-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.2</version>
        </dependency>
        <!--免写get set 使用注解@data即可，注意需要安装好Lombok插件才有效-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.20</version>
            <scope>provided</scope>
        </dependency>
        <!--Junit-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <!--数据库驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
        <!--处理DataSource需要用到-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.1.9.RELEASE</version>
        </dependency>

        <!--整合mybatis-spring-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>2.0.2</version>
        </dependency>
        <!-- properties的识别需要用到context-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.1.9.RELEASE</version>
        </dependency>
    </dependencies>


    <!--    配置资源过滤，以防止除了resource的xml识别不了，以及每次编译resource下的配置文件更新-->
    <build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
        </resources>
    </build>

</project>

Spring 一起使用 MyBatis，需要在 Spring 应用上下文中定义至少两样东西：一个 SqlSessionFactory 和至少一个数据映射器类。

可使用 SqlSessionFactoryBean来创建 SqlSessionFactory

《spring配置文件中》

配置文件类型：

<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
  <property name="dataSource" ref="dataSource" />
</bean>

注解类型：

@Configuration
public class MyBatisConfig {
  @Bean
  public SqlSessionFactory sqlSessionFactory() throws Exception {
    SqlSessionFactoryBean factoryBean = new SqlSessionFactoryBean();
    factoryBean.setDataSource(dataSource());
    return factoryBean.getObject();
  }
}


所需的datasource:

<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <!-- 配置连接池属性 -->
    <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
    <property name="url" value="jdbc:mysql://localhost:3306/web?characterEncoding=UTF-8&amp;useSSL=false&amp;serverTimezone=GMT"/>
    <property name="username" value="root"/>
    <property name="password" value="1234"/>
</bean>



映射器类必须是一个接口，而不是具体的实现类

假设接口名《mapper的接口》：

配置文件类型：

1 2	`public` `interface` `UserMapper {` `@Select("SELECT * FROM website") <br>　　List<User> selectUser();<br><br> }`

　注解类型：　

<?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.whz.Dao.userMapper">
    <select id="selectUser" resultType="com.whz.pojo">
　　 select * from website 
　　</select> 
</mapper>

Spring 一起使用 MyBatis使用MapperFactoryBean去整合(2)映射器和(1)SqlSessionFactory

《spring配置文件中》加入：

配置文件类型：

<bean id="userMapper" class="org.mybatis.spring.mapper.MapperFactoryBean">
  <property name="mapperInterface" value="org.mybatis.spring.sample.mapper.UserMapper" />
  <property name="sqlSessionFactory" ref="sqlSessionFactory" />
</bean>

注解类型：

@Configuration
public class MyBatisConfig {
  @Bean
  public UserMapper userMapper() throws Exception {
    SqlSessionTemplate sqlSessionTemplate = new SqlSessionTemplate(sqlSessionFactory());
    return sqlSessionTemplate.getMapper(UserMapper.class);
  }
}

　pojo实体类：

package com.whz.pojo;
import lombok.Data;
 
@Data
public class User {
    private String  account;
    private String password;
    private String name;
 
 
}

 测试：

public class test {
    @Test
    public void test01() {
        ApplicationContext app= new ClassPathXmlApplicationContext("spring-dao.xml");
        UserMapper userMapper = (UserMapper) app.getBean("userMapper");
        List<User> users = userMapper.selectUser();
        for (User user: users){
            System.out.println(user.getName());
        }
    }
}