一、下载MyBatis

MyBatis将所有的项目托管到了github上，因此我们在github上搜索下载MyBatis下载

二、创建对应的数据库表和JavaBean类

创建数据表：

CREATE TABLE tab1_employee（
    id     INT(11) PRIMARY KEY AUTO_INCREMENT,
    last_name VARCHAR(255),
    gender CHAR(1),
    email VARCHAR(255)
）

创建对应的JavaBean类

package com.atorg.mybatis.bean;

import org.apache.ibatis.type.Alias;

@Alias("emp")
public class Employee {
    private Integer id;
    private String lastName; //注意此处与数据中的字段并不对应???
    private String email;
    private String gender;
    public Employee() {
        super();
    }
    public Employee(Integer id, String lastName, String email, String gender) {
        super();
        this.id = id;
        this.lastName = lastName;
        this.email = email;
        this.gender = gender;
    }

    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getLastName() {
        return lastName;
    }
    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
    public String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
    public String getGender() {
        return gender;
    }
    public void setGender(String gender) {
        this.gender = gender;
    }
    @Override
    public String toString() {
        return "Employee [id=" + id + ", lastName=" + lastName + ", email=" + email + ", gender=" + gender + "]";
    }
}

三、根据官方文档（下文按照官方文档的步骤实现一个”HelloWorld”）

官方文档在一开始下载的依赖和文档中有，如果没有可以到以下地址下载
官方文档下载链接 提取码：hpaq 内附有Mybatis文档与依赖包

1.导入相关依赖

引入MyBatis的jar包,以及操作数据库驱动的jar包，为显示方便引入log4j日志包，引入log4j时必须要在类路径下放一个log4j.xml文件（在以上的链接中有这些jar包）

2.创建一个xml文件（全局配置文件）[ Building SqlSessionFactory from XML]

创建一个xml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>
  <environments default="development">
    <environment id="development">
      <transactionManager type="JDBC"/>
      <dataSource type="POOLED">//数据源连向我们自己的数据库
        <property name="driver" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/mybatis_plus"/>
        <property name="username" value="root"/>
        <property name="password" value="1234567890"/>
      </dataSource>
    </environment>
  </environments>
  <mappers>
 <!--sql映射文件一定要注册在全局配置文件中(就是此文件中)-->
    <mapper resource="EmployeeMapper.xml"/>
  </mappers>
</configuration>

3.根据xml文件创建一个SqlSessionFactory对象

public class MyBatisTest {
    //此处的resource内容就是上面创建的xml文件的路径名
    public void test() throws IOException{
       String resource = "mybatis-config.xml";
       InputStream inputStream = Resources.getResourceAsStream(resource); 
       SqlSessionFactory sqlSessionFactory =new SqlSessionFactoryBuilder().build(inputStream);
    }
}

4.获取sqlSession实例，能直接执行已经映射的sql语句

       SqlSession openSession = sqlSessionFactory.openSession();

5.用获取的sqlSession调用增删改查的方法 [Acquiring a SqlSession from SqlSessionFactory]

//第一个参数值为sql映射文件中**namespace+具体增删改查对应的唯一id的值**
//第二个参数是执行sql时传入的参数
openSession.selectOne(arg0,arg1);//查询
openSession.delete(arg0,arg1);//删除
openSession.update(arg0,arg1);//更新
openSession.insert(arg0,arg1);//插入
//第一个参数 *statement是一个唯一标识:Unique identifier matching the statement to use.
//第二个参数*parameter是执行sql语句的一个参数:A parameter object to pass to the statement.

6.创建sql映射的xml文件 [Exploring Mapped SQL Statements]

<?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="org.mybatis.example.BlogMapper">   
      <select id="selectEmp" resultType="com.atorg.mybatis.bean.Employee">
           select id,last_name lastName,gender,email from tab1_employee where id = #{id}       <!--给数据库变量起别名解决字段不匹配问题-->
       </select>
</mapper>

【namespace】:名称空间用来映射sql语句的类的全类名
【id】:为select的唯一标识，内容为具体方法的方法名
【resultType】:返回值类型，查询完成之后要返回的类型
【#{id}】:从传递过来的参数中取出id值

7.完整文件

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>
  <environments default="development">
    <environment id="development">
      <transactionManager type="JDBC"/>
      <dataSource type="POOLED"><!--数据库连接池-->
        <property name="driver" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/mybatis_plus"/>
        <property name="username" value="root"/>
        <property name="password" value="1234567890"/>
      </dataSource>
    </environment>
  </environments>

  <mappers>
    <mapper resource="EmployeeMapper.xml"/>
  </mappers>
</configuration>

EmployeeMapper.xml

<?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.atorg.mybatis.EmployeeMapper">
    <!-- 查询数据  -->
   <select id="selectEmp" resultType="com.atorg.mybatis.bean.Employee">
        select * from tab1_emp where id = #{id}
   </select>
   <!-- 插入数据  -->
   <insert id="addEmp" parameterType="com.atorg.mybatis.bean.Employee" useGeneratedKeys="true" keyProperty="id">
        insert into tab1_emp(last_name,email,gender) values(#{lastName},#{email},#{gender})
    </insert>

    <!-- 更新数据  -->
    <update id="updateEmp" parameterType="com.atorg.mybatis.bean.Employee">
        update tab1_emp 
        set last_name=#{lastName},email=#{email},gender=#{gender}
        where id =#{id}
    </update>
    <!-- 删除数据  -->
    <!-- public void deleteEmpByTd(Integer id);  -->
    <delete id="deleteEmp" parameterType="com.atorg.mybatis.bean.Employee">
        delete from tab1_emp where id=#{id}
    </delete>
</mapper>

log4j.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">

<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">

 <appender name="STDOUT" class="org.apache.log4j.ConsoleAppender">
   <param name="Encoding" value="UTF-8" />
   <layout class="org.apache.log4j.PatternLayout">
    <param name="ConversionPattern" value="%-5p %d{MM-dd HH:mm:ss,SSS} %m  (%F:%L) \n" />
   </layout>
 </appender>
 <logger name="java.sql">
   <level value="debug" />
 </logger>
 <logger name="org.apache.ibatis">
   <level value="info" />
 </logger>
 <root>
   <level value="debug" />
   <appender-ref ref="STDOUT" />
 </root>
</log4j:configuration>

四、进行测试

测试类

package com.atorg.mybatis.test;

import java.io.IOException;
import java.io.InputStream;
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 org.junit.Test;
import com.atorg.mybatis.bean.Employee;

public class MyBatisTest {

    @Test
    public void test() throws IOException {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        // 获取sqlsession实例，能直接执行已经映射的sql语句
        SqlSession session = sqlSessionFactory.openSession();
        try {
//            Object employee = session.selectOne("com.atorg.mybatis.EmployeeMapper.selectEmp", 5);
//            System.out.println(employee);

//            session.insert("com.atorg.mybatis.EmployeeMapper.addEmp", new Employee("Jack","Jack@qq.com","1"));
//            session.commit();
//            System.out.println("插入成功");

//            session.delete("com.atorg.mybatis.EmployeeMapper.deleteEmp", 5);
//            session.commit();
//            System.out.println("删除成功");

            session.update("com.atorg.mybatis.EmployeeMapper.updateEmp", new Employee(5,"lucy","lucy@qq.com","0"));
            session.commit();
            System.out.println("更新成功");
        } finally {
            session.close();
        }
    }
}

查看数据库原始状态

测试添加方法（ “Bob”,”Bob@163.com“,”0” ）


测试查询方法（查询5号）


测试删除方法(删除5号)


测试跟新方法（更新1号【”Jack”,”Jack@git.com“,”1”】）

五、升级[Using an interface (e.g. BlogMapper.class) that properly describes the parameter and return value for a given statement]

使用上述代码可以实现对数据库的增删改查操作，但是我们在测试类中传入参数很麻烦，因此我们引进了接口式编程，我们可以创建一个接口，接口来描述我们给定的sql语句的参数和返回值

1.创建一个接口

package com.atorg.mybatis.dao;
import com.atorg.mybatis.bean.Employee;
public interface EmployeeMapper {

    public Employee getEmpByTd(Integer id);

    public void addEmp(Employee employee);

    public void updateEmp(Employee employee);

    public void deleteEmpByTd(Integer id);
}

mybatis提供一个特殊的功能，接口可以与配置文件进行动态绑定
【namespce】:指定为接口的全类名
【id】:增删改查标签的id指定为接口对应的方法名

2.此时的测试类（以查询为例其他类似）

    @Test
    public void test02() throws IOException{
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        // 获取sqlsession实例，能直接执行已经映射的sql语句
        SqlSession openSession = sqlSessionFactory.openSession();
        try{
        EmployeeMapper eMapper=openSession.getMapper(EmployeeMapper.class);
        Employee employee=eMapper.getEmpByTd(1);//直接调用接口的查询员工方法
        System.out.println(employee);
        }finally{
            openSession.close();
        }
    }

【getMapper】：会为接口自动创建一个代理对象，用得到的代理对象去调用接口的增删改查放方法
查询结果