mybatis框架快速入门

通过快速入门示例，我们发现使用mybatis 是非常容易的一件事情，因为只需要编写 Dao 接口并且按照

mybatis要求编写两个配置文件，就可以实现功能。远比我们之前的jdbc方便多了。（我们使用注解之后，将变得

更为简单，只需要编写一个mybatis配置文件就够了。）

1.mybatis的环境搭建

第一步：创建maven工程并导入坐标

第二步：创建实体类和dao的接口

第三步：创建Mybatis的主配置文件 SqlMapConifg.xml

第四步：创建映射配置文件  IUserDao.xml

• 创建maven工厂并导入坐标

 <?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">
   <modelVersion>4.0.0</modelVersion>

   <groupId>com.itheima</groupId>
   <artifactId>mybatis_eesy_day01_quickstart</artifactId>
   <version>1.0-SNAPSHOT</version>
   <packaging>jar</packaging>

   <name>mybatis_eesy_day01_quickstart</name>
   <!-- FIXME change it to the project's website -->
   <url>http://www.example.com</url>

   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     <maven.compiler.source>1.8</maven.compiler.source>
     <maven.compiler.target>1.8</maven.compiler.target>
   </properties>

   <dependencies>
       <dependency>
           <groupId>org.mybatis</groupId>
           <artifactId>mybatis</artifactId>
           <version>3.4.5</version>
       </dependency>
     <dependency>
       <groupId>mysql</groupId>
       <artifactId>mysql-connector-java</artifactId>
       <version>5.1.6</version>
     </dependency>
     <dependency>
       <groupId>log4j</groupId>
       <artifactId>log4j</artifactId>
       <version>1.2.17</version>
     </dependency>
     <dependency>
       <groupId>junit</groupId>
       <artifactId>junit</artifactId>
       <version>4.11</version>
       <scope>test</scope>
     </dependency>
   </dependencies>

   <build>
     <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
       <plugins>
         <!-- clean lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#clean_Lifecycle -->
         <plugin>
           <artifactId>maven-clean-plugin</artifactId>
           <version>3.1.0</version>
         </plugin>
         <!-- default lifecycle, jar packaging: see https://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_jar_packaging -->
         <plugin>
           <artifactId>maven-resources-plugin</artifactId>
           <version>3.0.2</version>
         </plugin>
         <plugin>
           <artifactId>maven-compiler-plugin</artifactId>
           <version>3.8.0</version>
         </plugin>
         <plugin>
           <artifactId>maven-surefire-plugin</artifactId>
           <version>2.22.1</version>
         </plugin>
         <plugin>
           <artifactId>maven-jar-plugin</artifactId>
           <version>3.0.2</version>
         </plugin>
         <plugin>
           <artifactId>maven-install-plugin</artifactId>
           <version>2.5.2</version>
         </plugin>
         <plugin>
           <artifactId>maven-deploy-plugin</artifactId>
           <version>2.8.2</version>
         </plugin>
         <!-- site lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#site_Lifecycle -->
         <plugin>
           <artifactId>maven-site-plugin</artifactId>
           <version>3.7.1</version>
         </plugin>
         <plugin>
           <artifactId>maven-project-info-reports-plugin</artifactId>
           <version>3.0.0</version>
         </plugin>
       </plugins>
     </pluginManagement>
   </build>
 </project>

• 创建实体类和dao接口

 public class User implements Serializable {
     private Integer id;
     private String username;
     private Date birthday;
     private String address;
     private String sex;

public interface IUserDao {
//    查询所有用户
    List<User> findAll();
}

• 创建主配置文件

<?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>
    <!--配置mybatis的环境-->
<environments default="mysql">
    <!--配置mysql的环境-->
    <environment id="mysql">
        <!--配置事务的类型-->
        <transactionManager type="JDBC"></transactionManager>
        <!--配置数据库的信息，用的是数据源（连接池技术）-->
        <dataSource type="POOLED">
            <property name="driver" value="com.mysql.jdbc.Driver"/>
            <property name="url" value="jdbc:mysql://localhost:3306/eesy_mybatis"/>
            <property name="username" value="root"/>
            <property name="password" value="123"/>
        </dataSource>
    </environment>
</environments>

    <!--告知mybatis映射文件的位置-->
    <mappers>
        <mapper resource="com/itheima/dao/IUserDao.xml"/>
    </mappers>
</configuration>

• 创建映射文件

<?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.itheima.dao.IUserDao">
    <select id="findAll" resultType="com.itheima.domain.User">
        SELECT * FROM  user
    </select>
</mapper>

编写测试代码

package com.itheima;

import com.itheima.dao.IUserDao;
import com.itheima.domain.User;
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 java.io.IOException;
import java.io.InputStream;
import java.util.List;

public class TestMybatis {
    public static void main(String[] args) throws IOException {
        //1.读取配置文件
        InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2.创建SqlSessionFactory的构建者对象
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        //3.使用构建者创建工厂对象SqlSessionFactory
        SqlSessionFactory factory = builder.build(in);
        //4.使用SqlSessionFactory创建SqlSession对象
        SqlSession sqlSession = factory.openSession();
        //5.使用SqlSession创建dao的代理对象
        IUserDao userDao = sqlSession.getMapper(IUserDao.class);
        //6.使用代理对象执行查询方法
        List<User> userList = userDao.findAll();
        for (User user :userList){
            System.out.println(user.toString());
        }
        //7.释放资源
        sqlSession.close();
        in.close();
    }
}

测试结果

User{id=41, username='老王', birthday=Tue Feb 27 17:47:08 CST 2018, address='北京', sex='男'}
User{id=42, username='小二王', birthday=Fri Mar 02 15:09:37 CST 2018, address='北京金燕龙', sex='女'}
User{id=43, username='小二王', birthday=Sun Mar 04 11:34:34 CST 2018, address='北京金燕龙', sex='女'}
User{id=45, username='传智播客', birthday=Sun Mar 04 12:04:06 CST 2018, address='北京金燕龙', sex='男'}
User{id=46, username='老王', birthday=Wed Mar 07 17:37:26 CST 2018, address='北京', sex='男'}
User{id=48, username='小马宝莉', birthday=Thu Mar 08 11:44:00 CST 2018, address='北京修正', sex='女'}