mybatis-Spring

mybatis-spring

回忆mybatis

• 实体类

  package com.wjj.pojo;
  
  public class User {
      private  Integer id;
      private String name;
      private String pwd;
  
      @Override
      public String toString() {
          return "User{" +
                  "id=" + id +
                  ", name='" + name + '\'' +
                  ", pwd='" + pwd + '\'' +
                  '}';
      }
  }
  

• 核心配置文件 编写 mybatis-config.xml

  <?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核心配置文件-->
  
  
  <configuration>
  
      <typeAliases>
          <package name="com.wjj.pojo"/>
      </typeAliases>
  
      <environments default="development">
          <environment id="development">
              <transactionManager type="JDBC"/>
              <dataSource type="POOLED">
                  <property name="driver" value="com.mysql.jdbc.Driver"/>
                  <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=false&amp;useUnicode=true&amp;characterEncoding=UTF8"/>
                  <property name="username" value="root"/>
                  <property name="password" value="123456"/>
              </dataSource>
          </environment>
      </environments>
  
  
      <mappers>
          <mapper resource="com/wjj/mapper/UserMapper.xml"/>
      </mappers>
  </configuration>
  

• 接口

  import com.wjj.pojo.User;
  
  import java.util.List;
  
  public interface UserMapper {
      public List<User> selectUsers();
  }
  

  绑定到接口

  <?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.wjj.mapper.UserMapper">
      <select id="selectUsers" resultType="User">
          select * from mybatis.user
      </select>
  </mapper>
  

• 编写测试类

  public class MyTest {
      @Test
      public void test() throws IOException {
         String resource="mybatis-config.xml";
         InputStream inputStream= Resources.getResourceAsStream(resource);
         SqlSessionFactory sqlSessionFactory=new SqlSessionFactoryBuilder().build(inputStream);
          SqlSession sqlSession = sqlSessionFactory.openSession(true);
  
          UserMapper mapper = sqlSession.getMapper(UserMapper.class);
          List<User> userList = mapper.selectUsers();
  
          for (User user : userList) {
              System.out.println(user);
          }
      }
  }
  

1.mybatis-spring

• 要和 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。

  在 MyBatis-Spring 中，可使用 SqlSessionFactoryBean来创建 SqlSessionFactory。 mybatis-spring官方文档入门手册

  1. SqlSessionFactory 需要一个 DataSource（数据源）
     

  2. DataSource：使用spring的数据源替换mybatis的配置 c3p0 dbcp druid.
     这里使用spring提供的jdbc
     

  3. <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
         <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
         <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=false&amp;useUnicode=true&amp;characterEncoding=UTF8"/>
         <property name="username" value="root"/>
         <property name="password" value="123456"/>
     </bean>
     

  

  1. 这段操作相当于new故可以替换掉这段

  2. 可以通过application中get出来

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

     

  3. 此时我们sqlssion还没有拿到，就用beas 出来实现SqlSessionTemplate

     

     <!--SqlSessionTemplate 就是我们mybatis中使用的 sqlSession   -->
         <bean id="sqlSessionTemplate" class="org.mybatis.spring.SqlSessionTemplate">
     <!--只能用构造器注入sqlSessionFactory,无set方法-->
             <constructor-arg index="0" ref="sqlSessionFactory"/>
         </bean>
     
     

     实现接口配置类

     import com.wjj.pojo.User;
     import org.mybatis.spring.SqlSessionTemplate;
     
     import java.util.List;
     
     public class UserMapperImpl implements UserMapper{
         private SqlSessionTemplate sqlSessionTemplate;
         public void setSqlSessionTemplate(SqlSessionTemplate sqlSessionTemplate) {
             this.sqlSessionTemplate = sqlSessionTemplate;
         }
         @Override
         public List<User> selectUsers() {
             return sqlSessionTemplate.getMapper(UserMapper.class).selectUsers();
         }
     }
     

  4. 总的代码流程

  编写数据源配置

  <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
      <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
      <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=false&amp;useUnicode=true&amp;characterEncoding=UTF8"/>
      <property name="username" value="root"/>
      <property name="password" value="123456"/>
  </bean>
  
  

      <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
          <property name="dataSource" ref="dataSource" />
          <!--绑定mybatis配置文件-->
          <property name="configLocation" value="classpath:mybatis-config.xml"/>
  <!--        <-同时<property 中也能配置mybatis  例如注册映射器-->
          <property name="mapperLocations" value="com/wjj/mapper/UserMapper.xml"/>
      </bean>
  

  sqlSessionTemplate

      <bean id="sqlSessionTemplate" class="org.mybatis.spring.SqlSessionTemplate">
  <!--只能用构造器注入sqlSessionFactory,无set方法-->
          <constructor-arg index="0" ref="sqlSessionFactory"/>
      </bean>
  

  注入到spring中

  <bean id="userMapperImpl" class="com.wjj.mapper.UserMapperImpl">
      <property name="sqlSessionTemplate" ref="sqlSessionTemplate"/>
  </bean>
  

  测试

  public class MyTest {
      @Test
      public void test() throws IOException {
  
          ApplicationContext Context = new ClassPathXmlApplicationContext("spring-mapper.xml");
          UserMapperImpl UMP = Context.getBean("userMapperImpl", UserMapperImpl.class);
          for (User user : UMP.selectUsers()) {
              System.out.println(user);
          }
      }
  }
  
  

1.2SqlSessionDaoSupport

1. SqlSessionDaoSupport` 是一个抽象的支持类，用来为你提供 `SqlSession`。调用 `getSqlSession()` 方法你会得到一个 `SqlSessionTemplate