一文吃透Spring集成MyBatis

<dependencies>
    <!--测试-->
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
    <!--spring依赖-->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>5.2.5.RELEASE</version>
    </dependency>
    <!--spring事务依赖-->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-tx</artifactId>
      <version>5.2.5.RELEASE</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-jdbc</artifactId>
      <version>5.2.5.RELEASE</version>
    </dependency>
    <!--mybatis依赖-->
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.5.1</version>
    </dependency>
    <!--mybatis和spring集成-->
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis-spring</artifactId>
      <version>1.3.1</version>
    </dependency>
    <!--mysql驱动-->
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.9</version>
    </dependency>
    <!--阿里的连接池-->
    <dependency>
      <groupId>com.alibaba</groupId>
      <artifactId>druid</artifactId>
      <version>1.1.12</version>
    </dependency>
  </dependencies>
  <build>
    <!--用mybatis就要用到这个插件 编译java目录下，除了java文件，还编译xml和properties文件-->
    <resources>
      <resource>
        <directory>src/main/java</directory>
        <includes>
          <include>**/*.properties</include>
          <include>**/*.xml</include>
        </includes>
        <filtering>false</filtering>
      </resource>
    </resources>
  </build>
</project>

public class Student {
    private Integer id;
    private String name;
    private Integer age;
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Integer getAge() {
        return age;
    }
    public void setAge(Integer age) {
        this.age = age;
    }
    @Override
    public String toString() {
        return "Student{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

public interface StudentDao {
    //添加操作
    int insertStudent(Student student);
    //查询操作
    List<Student> selectStudents();
}

<?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="youfei1_v.Dao.StudentDao">
    <!-- 使用insert，update，select标签写sql -->
    <insert id="insertStudent" >
        insert into student2(name,age) values (#{name},#{age})
    </insert>
    <select id="selectStudents" resultType="youfei1_v.domain.Student">
        select id,name ,age from student2
    </select>
</mapper>

<?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>
    <!--设置日志-->
    <settings>
        <setting name="logImpl" value="STDOUT_LOGGING"/>
    </settings>
    <!--指定其它mapper文件的位置，目的是找到其它文件的sql语句-->
    <mappers>
        <!--使用mapper的resource属性指定mapper文件的路径。
        这个路径是从类路径根目录开始
        使用注意：mapper文件的路径使用 / 分割路径
                 一个mapper resource 指定一个mapper文件
        -->
        <!--<mapper resource="youfei1_v/dao/StudentDao.xml"/>-->
        <!--name：mapper文件所在的包名
        满足要求才能使用这种方式：
        1.mapper文件和dao接口在同一目录
        2.mapper文件和dao接口名称一致
        -->
        <package name="youfei1_v.Dao"/>
    </mappers>
</configuration>

public interface StudentService {
    int addStudent(Student student);
    List<Student> queryStudent();
}

public class StudentServiceImpl implements StudentService {
    private StudentDao studentDao; //创建这个dao对象和set方法
    public void setStudentDao(StudentDao studentDao) {
        this.studentDao = studentDao;
    }
    @Override
    public int addStudent(Student student) {
        int rows = studentDao.insertStudent(student); //方法中调用studentDao对象的方法
        return rows;
    }
    @Override
    public List<Student> queryStudent() {
        List<Student> students = studentDao.selectStudents();
        return students;
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">
    <!--加载外部的属性配置文件-->
    <context:property-placeholder location="classpath:jdbc.properties"/>
    <!--声明数据源DataSource 德鲁伊-->
    <bean id="myDataSource" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close">
        <property name="url" value="jdbc:mysql://localhost:3306/springdb"/>
        <property name="username" value="root"/>
        <property name="password" value="123456"/>
    </bean>
    <!--声明SqlSessionFactoryBean,在这个类的内部，创建SqlSessionFactory bean的id就代表创建SqlSessionFactory对象-->
    <bean id="factory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!--指定数据源-->
        <property name="dataSource" ref="myDataSource" /> <!--用的是什么数据源的id-->
        <!--指定mybatis主配置文件
            Resource可以直接使用 value属性赋值。
        -->
        <property name="configLocation" value="classpath:mybatis.xml" />
    </bean>
    <!--
      相当于：SqlSessionFactory  factory  = new SqlSessonFactoryBuider.build(classpath:mybatis.xml)
    -->
    <!--声明MapperScannerConfigurer
        SqlSession.getMapper(StudentDao.class)
        MapperScannerConfigurer作用是：
        循环basePackage所表示的包，把包中的每个接口都找到，调用SqlSession.getMapper
        把每个dao接口都创建出dao对象 ，dao代理对象放在容器中。
        ApplicationContext ctx = ....
        SqlSessionFactory sqlSessionFactory  = ctx.getBean("factory");
        SqlSession session = sqlSessionFactory.openSession();
        for(接口： com.bjpowernode.dao){
             接口 对象 =  session.getMapper(接口)
             springMap.put(接口名的首字母小写， 对象)  //创建dao代理，这个dao代理的对象的名字是这个接口的首字母小写。也就是bean的id
        }
    -->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <!--指定SqlSessionFactory对象的名称-->
        <property name="sqlSessionFactoryBeanName" value="factory" />
        <!--指定基本包，dao接口所在的包名-->
        <property name="basePackage" value="youfei1_v.Dao" /><!--创建dao代理，这个dao代理的对象的名字是这个接口名的首字母小写。也就是bean的id-->
    </bean>
    <!--声明service-->
    <bean id="studentService" class="youfei1_v.service.impl.StudentServiceImpl">
        <property name="studentDao" ref="studentDao" /> <!--set注入：把dao代理赋值给StudentServiceImpl类中的StudentDao对象-->
    </bean>                         <!--ref用的就是上面的创建出来的dao代理，的id值，这个id值就是接口名的首字母小写-->
    <!--ref="studentDao" :studentDao指的是Student这个接口的代理。上面那个bean，创建出Student接口的代理，这个代理的id就是接口名字小写studentDao-->
</beans>