MyBatis框架的使用及源码分析(一) 配置与使用

我们先来看一个例子，简单的了解一下mybatis的mapper接口方式的使用。

 package org.mybatis.spring.sample;

 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 org.mybatis.spring.sample.bean.User;
 import org.mybatis.spring.sample.mapper.UserMapper;

 import java.io.IOException;

 public class MybatisTest {

     /**
      * 读取mybatis的配置文件，生成SqlSessionFactory
      *
      * @return
      */
     private static SqlSessionFactory getSessionFactory() {
         SqlSessionFactory sessionFactory = null;
         String resource = "mybatisConfig.xml";
         try {
             sessionFactory = new SqlSessionFactoryBuilder().build(Resources
                     .getResourceAsReader(resource));
         } catch (IOException e) {
             e.printStackTrace();
         }
         return sessionFactory;
     }

     @Test
     public void findUserById() {
         SqlSessionFactory sqlSessionFactory = getSessionFactory();
         SqlSession sqlSession = sqlSessionFactory.openSession();
         UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
         User user = userMapper.selectByPrimaryKey(1l);
         System.out.println(user.getId() + " /  " + user.getName());
     }

 }

输出结果

1 /  赵大

数据库表 user

User.java

 /*
  * User.java
  * Copyright(C) 2015-2017 Jstudio.org
  * All rights reserved.
  * --------------------------------------
  * 2017-09-17 Created.
  */
 package org.mybatis.spring.sample.bean;

 import java.io.Serializable;

 /**
  *
  * This class was generated by MyBatis Generator.
  * This class corresponds to the database table user
  *
  * @mbg.generated do_not_delete_during_merge 2017-09-17
  */
 public class User implements Serializable {
     /**
      * 主键
      */
     private Long id;

     /**
      * 用户名
      */
     private String name;

     /**
      * 密码
      */
     private String password;

     /**
      * 电子邮件
      */
     private String email;

     /**
      * 年龄
      */
     private Integer age;

     private static final long serialVersionUID = 1L;

     /**
      * 获取主键
      *
      * @return id - 主键
      */
     public Long getId() {
         return id;
     }

     /**
      * 设置主键
      *
      * @param id 主键
      */
     public void setId(Long id) {
         this.id = id;
     }

     /**
      * 获取用户名
      *
      * @return name - 用户名
      */
     public String getName() {
         return name;
     }

     /**
      * 设置用户名
      *
      * @param name 用户名
      */
     public void setName(String name) {
         this.name = name == null ? null : name.trim();
     }

     /**
      * 获取密码
      *
      * @return password - 密码
      */
     public String getPassword() {
         return password;
     }

     /**
      * 设置密码
      *
      * @param password 密码
      */
     public void setPassword(String password) {
         this.password = password == null ? null : password.trim();
     }

     /**
      * 获取电子邮件
      *
      * @return email - 电子邮件
      */
     public String getEmail() {
         return email;
     }

     /**
      * 设置电子邮件
      *
      * @param email 电子邮件
      */
     public void setEmail(String email) {
         this.email = email == null ? null : email.trim();
     }

     /**
      * 获取年龄
      *
      * @return age - 年龄
      */
     public Integer getAge() {
         return age;
     }

     /**
      * 设置年龄
      *
      * @param age 年龄
      */
     public void setAge(Integer age) {
         this.age = age;
     }
 }

UserMapper.java

 /*
  * UserMapper.java
  * Copyright(C) 2015-2017 Jstudio.org
  * All rights reserved.
  * --------------------------------------
  * 2017-09-17 Created.
  */
 package org.mybatis.spring.sample.mapper;

 import org.mybatis.spring.sample.bean.User;

 import java.util.List;

 public interface UserMapper {

     int insert(User entity);

     int insertSelective(User entity);

     int deleteByPrimaryKey(Long id);

     int updateByPrimaryKeySelective(User entity);

     int updateByPrimaryKey(User entity);

     User selectByPrimaryKey(Long id);

 }

UserMapper.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="org.mybatis.spring.sample.mapper.UserMapper">
   <!--  This is automatically generated by MyBatis Generator on 2017-09-17. -->
   <resultMap id="BaseResultMap" type="org.mybatis.spring.sample.bean.User">
     <!--  WARNING - This element is automatically generated by MyBatis Generator, modify carefully. -->
     <id column="id" jdbcType="BIGINT" property="id" />
     <result column="name" jdbcType="VARCHAR" property="name" />
     <result column="password" jdbcType="VARCHAR" property="password" />
     <result column="email" jdbcType="VARCHAR" property="email" />
     <result column="age" jdbcType="INTEGER" property="age" />
   </resultMap>
   <sql id="Base_Column_List">
     <!--  WARNING - This element is automatically generated by MyBatis Generator, modify carefully. -->
     id, name, password, email, age
   </sql>
   <select id="selectByPrimaryKey" parameterType="java.lang.Long" resultMap="BaseResultMap">
     <!--  WARNING - This element is automatically generated by MyBatis Generator, modify carefully. -->
     select
     <include refid="Base_Column_List" />
     from user
     where id = #{id,jdbcType=BIGINT}
   </select>
   <delete id="deleteByPrimaryKey" parameterType="java.lang.Long">
     <!--  WARNING - This element is automatically generated by MyBatis Generator, modify carefully. -->
     delete from user
     where id = #{id,jdbcType=BIGINT}
   </delete>
   <insert id="insert" parameterType="org.mybatis.spring.sample.bean.User">
     <!--  WARNING - This element is automatically generated by MyBatis Generator, modify carefully. -->
     <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Long">
       SELECT LAST_INSERT_ID()
     </selectKey>
     insert into user (name, password, email,
       age)
     values (#{name,jdbcType=VARCHAR}, #{password,jdbcType=VARCHAR}, #{email,jdbcType=VARCHAR},
       #{age,jdbcType=INTEGER})
   </insert>
   <insert id="insertSelective" parameterType="org.mybatis.spring.sample.bean.User">
     <!--  WARNING - This element is automatically generated by MyBatis Generator, modify carefully. -->
     <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Long">
       SELECT LAST_INSERT_ID()
     </selectKey>
     insert into user
     <trim prefix="(" suffix=")" suffixOverrides=",">
       <if test="name != null">
         name,
       </if>
       <if test="password != null">
         password,
       </if>
       <if test="email != null">
         email,
       </if>
       <if test="age != null">
         age,
       </if>
     </trim>
     <trim prefix="values (" suffix=")" suffixOverrides=",">
       <if test="name != null">
         #{name,jdbcType=VARCHAR},
       </if>
       <if test="password != null">
         #{password,jdbcType=VARCHAR},
       </if>
       <if test="email != null">
         #{email,jdbcType=VARCHAR},
       </if>
       <if test="age != null">
         #{age,jdbcType=INTEGER},
       </if>
     </trim>
   </insert>
   <update id="updateByPrimaryKeySelective" parameterType="org.mybatis.spring.sample.bean.User">
     <!--  WARNING - This element is automatically generated by MyBatis Generator, modify carefully. -->
     update user
     <set>
       <if test="name != null">
         name = #{name,jdbcType=VARCHAR},
       </if>
       <if test="password != null">
         password = #{password,jdbcType=VARCHAR},
       </if>
       <if test="email != null">
         email = #{email,jdbcType=VARCHAR},
       </if>
       <if test="age != null">
         age = #{age,jdbcType=INTEGER},
       </if>
     </set>
     where id = #{id,jdbcType=BIGINT}
   </update>
   <update id="updateByPrimaryKey" parameterType="org.mybatis.spring.sample.bean.User">
     <!--  WARNING - This element is automatically generated by MyBatis Generator, modify carefully. -->
     update user
     set name = #{name,jdbcType=VARCHAR},
       password = #{password,jdbcType=VARCHAR},
       email = #{email,jdbcType=VARCHAR},
       age = #{age,jdbcType=INTEGER}
     where id = #{id,jdbcType=BIGINT}
   </update>
  </mapper>

mybatisConfig.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">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://127.0.0.1:3306/test"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <mapper resource="sqlmapping/UserMapper.xml"/>
    </mappers>
</configuration>

后继我们将继续讲解Mybatis如何加载配置，解析Mappper的xml,创建和使用Mapper。