使用maven创建一个简单的MyBatis例子

MyBatis是一个流行的数据库框架之一，另外一个是hibernate，但是MyBatis是一个班自动映射的框架，它可以解决hibernate全映射的不足。所以MyBatis比hibernate更加的灵活，因此掌握MyBatis是必要的。
这个例子的测试环境
IDE:IntelliJ IDEA + maven + mysql 5.7

一，创建一个maven项目

eclipse也有quickstart这个模板的
填好GroupId与ArtifactId项目就创建好了
以下就是项目的结构

二，在pom.xml文件添加jar包依赖

    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>6.0.6</version>
    </dependency>
    
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.4.4</version>
    </dependency>

依赖图

三，创建User类，以及对应的映射文件

user.java

package per.summer.MyBatis.model;

/**
 * Created by summer on 17-4-16.
 */
public class User{
    private int id;
    private String username;
    private String password;

    public int getId() {
        return id;
    }

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

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

user.xml映射文件
resources以及mapper文件夹自己创建

<?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="per.summer.MyBatis.model.UserMapper">
    <select id="selectUserByID" parameterType="int" resultType="User">
    SELECT * FROM user_inf where id = #{id}
    </select>
</mapper>

四，MyBatis的配置文件

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>
    <!--加载连接数据库的基本信息文件-->
    <properties resource="jdbc.properties"></properties>
    <typeAliases>
    <typeAlias alias="User" type="per.summer.MyBatis.model.User"/>
    </typeAliases>
    <environments default="development">
    <environment id="development">
        <transactionManager type="JDBC"/>
        <dataSource type="POOLED">
            <property name="driver" value="${driver}" />
            <property name="url" value="${url}" />
            <property name="username" value="${username}" />
            <property name="password" value="${password}" />
        </dataSource>
    </environment>
    </environments>
    <mappers>
    <mapper resource="mapper/User.xml"/>
    </mappers>
</configuration>

jdbc.properties

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/user
username=root
password=manager

最后就是测试了

Test.java

package per.summer.MyBatis.test;

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 per.summer.MyBatis.model.User;

import java.io.IOException;
import java.io.Reader;

/**
 * Created by summer on 17-4-16.
 */
public class Test {
    private static SqlSessionFactory sqlSessionFactory;
    private static Reader reader;

    static {
        try {
            reader = Resources.getResourceAsReader("mybatis-config.xml");
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static SqlSessionFactory getSqlSessionFactory() {
        return sqlSessionFactory;
    }

    public static void main(String[] args) {
        SqlSession session = sqlSessionFactory.openSession();
        try {
            User user = (User)session.selectOne("selectUserByID", 2);
            session.commit();
            System.out.println(user.getUsername());
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            session.close();
        }
    }
}