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spring boot ---优雅的使用mybatis

mybatis-spring-boot-starter

官方说明：MyBatis Spring-Boot-Starter will help you use MyBatis with Spring Boot
其实就是myBatis看spring boot这么火热也开发出一套解决方案来凑凑热闹,但这一凑确实解决了很多问题，使用起来确实顺畅了许多。mybatis-spring-boot-starter主要有两种解决方案，一种是使用注解解决一切问题，一种是简化后的老传统。

当然任何模式都需要首先引入mybatis-spring-boot-starter的pom文件,现在最新版本是1.1.1（刚好快到双11了 :)）

<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>1.1.1</version>
</dependency>

好了下来分别介绍两种开发模式

无配置文件注解版

就是一切使用注解搞定。

1 添加相关maven文件

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>1.1.1</version>
    </dependency>
     <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
    </dependency>
     <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <optional>true</optional>
    </dependency>
</dependencies>

完整的pom包这里就不贴了，大家直接看源码

2、application.properties 添加相关配置

mybatis.type-aliases-package=com.neo.entity

spring.datasource.driverClassName = com.mysql.jdbc.Driver

spring.datasource.url = jdbc:mysql://localhost:3306/test1?useUnicode=true&characterEncoding=utf-8

spring.datasource.username = root

spring.datasource.password = root

springboot会自动加载spring.datasource.*相关配置，数据源就会自动注入到sqlSessionFactory中，sqlSessionFactory会自动注入到Mapper中，对了你一切都不用管了，直接拿起来使用就行了。

在启动类中添加对mapper包扫描@MapperScan

@SpringBootApplication

@MapperScan("com.neo.mapper")

public class Application {


<span>public</span> <span>static</span> <span>void</span> <span>main</span><span>(</span><span>String</span><span>[]</span> <span>args</span><span>)</span> <span>{</span>
    <span>SpringApplication</span><span>.</span><span>run</span><span>(</span><span>Application</span><span>.</span><span>class</span><span>,</span> <span>args</span><span>);</span>
<span>}</span>



}

或者直接在Mapper类上面添加注解@Mapper,建议使用上面那种，不然每个mapper加个注解也挺麻烦的

3、开发Mapper

第三步是最关键的一块，sql生产都在这里

public interface UserMapper {


<span>@Select</span><span>(</span><span>"SELECT * FROM users"</span><span>)</span>
<span>@Results</span><span>({</span>
    <span>@Result</span><span>(</span><span>property</span> <span>=</span> <span>"userSex"</span><span>,</span>  <span>column</span> <span>=</span> <span>"user_sex"</span><span>,</span> <span>javaType</span> <span>=</span> <span>UserSexEnum</span><span>.</span><span>class</span><span>),</span>
    <span>@Result</span><span>(</span><span>property</span> <span>=</span> <span>"nickName"</span><span>,</span> <span>column</span> <span>=</span> <span>"nick_name"</span><span>)</span>
<span>})</span>
<span>List</span><span>&lt;</span><span>UserEntity</span><span>&gt;</span> <span>getAll</span><span>();</span>

<span>@Select</span><span>(</span><span>"SELECT * FROM users WHERE id = #{id}"</span><span>)</span>
<span>@Results</span><span>({</span>
    <span>@Result</span><span>(</span><span>property</span> <span>=</span> <span>"userSex"</span><span>,</span>  <span>column</span> <span>=</span> <span>"user_sex"</span><span>,</span> <span>javaType</span> <span>=</span> <span>UserSexEnum</span><span>.</span><span>class</span><span>),</span>
    <span>@Result</span><span>(</span><span>property</span> <span>=</span> <span>"nickName"</span><span>,</span> <span>column</span> <span>=</span> <span>"nick_name"</span><span>)</span>
<span>})</span>
<span>UserEntity</span> <span>getOne</span><span>(</span><span>Long</span> <span>id</span><span>);</span>

<span>@Insert</span><span>(</span><span>"INSERT INTO users(userName,passWord,user_sex) VALUES(#{userName}, #{passWord}, #{userSex})"</span><span>)</span>
<span>void</span> <span>insert</span><span>(</span><span>UserEntity</span> <span>user</span><span>);</span>

<span>@Update</span><span>(</span><span>"UPDATE users SET userName=#{userName},nick_name=#{nickName} WHERE id =#{id}"</span><span>)</span>
<span>void</span> <span>update</span><span>(</span><span>UserEntity</span> <span>user</span><span>);</span>

<span>@Delete</span><span>(</span><span>"DELETE FROM users WHERE id =#{id}"</span><span>)</span>
<span>void</span> <span>delete</span><span>(</span><span>Long</span> <span>id</span><span>);</span>



}

为了更接近生产我特地将user_sex、nick_name两个属性在数据库加了下划线和实体类属性名不一致，另外user_sex使用了枚举

  • @Select 是查询类的注解，所有的查询均使用这个
  • @Result 修饰返回的结果集，关联实体类属性和数据库字段一一对应，如果实体类属性和数据库属性名保持一致，就不需要这个属性来修饰。
  • @Insert 插入数据库使用，直接传入实体类会自动解析属性到对应的值
  • @Update 负责修改，也可以直接传入对象
  • @delete 负责删除

了解更多属性参考这里

注意，使用#符号和$符号的不同：

// This example creates a prepared statement, something like select * from teacher where name = ?;

@Select("Select * from teacher where name = #")

Teacher selectTeachForGivenName(@Param("name") String name);


// This example creates n inlined statement, something like select * from teacher where name = 'someName';

@Select("Select * from teacher where name = '$'")

Teacher selectTeachForGivenName(@Param("name") String name);

4、使用

上面三步就基本完成了相关dao层开发，使用的时候当作普通的类注入进入就可以了

@RunWith(SpringRunner.class)

@SpringBootTest

public class UserMapperTest {


<span>@Autowired</span>
<span>private</span> <span>UserMapper</span> <span>UserMapper</span><span>;</span>

<span>@Test</span>
<span>public</span> <span>void</span> <span>testInsert</span><span>()</span> <span>throws</span> <span>Exception</span> <span>{</span>
    <span>UserMapper</span><span>.</span><span>insert</span><span>(</span><span>new</span> <span>UserEntity</span><span>(</span><span>"aa"</span><span>,</span> <span>"a123456"</span><span>,</span> <span>UserSexEnum</span><span>.</span><span>MAN</span><span>));</span>
    <span>UserMapper</span><span>.</span><span>insert</span><span>(</span><span>new</span> <span>UserEntity</span><span>(</span><span>"bb"</span><span>,</span> <span>"b123456"</span><span>,</span> <span>UserSexEnum</span><span>.</span><span>WOMAN</span><span>));</span>
    <span>UserMapper</span><span>.</span><span>insert</span><span>(</span><span>new</span> <span>UserEntity</span><span>(</span><span>"cc"</span><span>,</span> <span>"b123456"</span><span>,</span> <span>UserSexEnum</span><span>.</span><span>WOMAN</span><span>));</span>

    <span>Assert</span><span>.</span><span>assertEquals</span><span>(</span><span>3</span><span>,</span> <span>UserMapper</span><span>.</span><span>getAll</span><span>().</span><span>size</span><span>());</span>
<span>}</span>

<span>@Test</span>
<span>public</span> <span>void</span> <span>testQuery</span><span>()</span> <span>throws</span> <span>Exception</span> <span>{</span>
    <span>List</span><span>&lt;</span><span>UserEntity</span><span>&gt;</span> <span>users</span> <span>=</span> <span>UserMapper</span><span>.</span><span>getAll</span><span>();</span>
    <span>System</span><span>.</span><span>out</span><span>.</span><span>println</span><span>(</span><span>users</span><span>.</span><span>toString</span><span>());</span>
<span>}</span>

<span>@Test</span>
<span>public</span> <span>void</span> <span>testUpdate</span><span>()</span> <span>throws</span> <span>Exception</span> <span>{</span>
    <span>UserEntity</span> <span>user</span> <span>=</span> <span>UserMapper</span><span>.</span><span>getOne</span><span>(</span><span>3</span><span>l</span><span>);</span>
    <span>System</span><span>.</span><span>out</span><span>.</span><span>println</span><span>(</span><span>user</span><span>.</span><span>toString</span><span>());</span>
    <span>user</span><span>.</span><span>setNickName</span><span>(</span><span>"neo"</span><span>);</span>
    <span>UserMapper</span><span>.</span><span>update</span><span>(</span><span>user</span><span>);</span>
    <span>Assert</span><span>.</span><span>assertTrue</span><span>((</span><span>"neo"</span><span>.</span><span>equals</span><span>(</span><span>UserMapper</span><span>.</span><span>getOne</span><span>(</span><span>3</span><span>l</span><span>).</span><span>getNickName</span><span>())));</span>
<span>}</span>



}

源码中controler层有完整的增删改查，这里就不贴了
源码在这里spring-boot-mybatis-annotation

极简xml版本

极简xml版本保持映射文件的老传统，优化主要体现在不需要实现dao的是实现层，系统会自动根据方法名在映射文件中找对应的sql.

1、配置

pom文件和上个版本一样，只是application.properties新增以下配置

mybatis.config-locations=classpath:mybatis/mybatis-config.xml

mybatis.mapper-locations=classpath:mybatis/mapper/*.xml

指定了mybatis基础配置文件和实体类映射文件的地址

mybatis-config.xml 配置

<configuration>

<typeAliases>

<typeAlias alias="Integer" type="java.lang.Integer" />

<typeAlias alias="Long" type="java.lang.Long" />

<typeAlias alias="HashMap" type="java.util.HashMap" />

<typeAlias alias="LinkedHashMap" type="java.util.LinkedHashMap" />

<typeAlias alias="ArrayList" type="java.util.ArrayList" />

<typeAlias alias="LinkedList" type="java.util.LinkedList" />

</typeAliases>

</configuration>

这里也可以添加一些mybatis基础的配置

2、添加User的映射文件

<mapper namespace="com.neo.mapper.UserMapper" >

<resultMap id="BaseResultMap" type="com.neo.entity.UserEntity" >

<id column="id" property="id" jdbcType="BIGINT" />

<result column="userName" property="userName" jdbcType="VARCHAR" />

<result column="passWord" property="passWord" jdbcType="VARCHAR" />

<result column="user_sex" property="userSex" javaType="com.neo.enums.UserSexEnum"/>

<result column="nick_name" property="nickName" jdbcType="VARCHAR" />

</resultMap>


<span>&lt;sql</span> <span>id=</span><span>"Base_Column_List"</span> <span>&gt;</span>
    id, userName, passWord, user_sex, nick_name
<span>&lt;/sql&gt;</span>

<span>&lt;select</span> <span>id=</span><span>"getAll"</span> <span>resultMap=</span><span>"BaseResultMap"</span>  <span>&gt;</span>
   SELECT 
   <span>&lt;include</span> <span>refid=</span><span>"Base_Column_List"</span> <span>/&gt;</span>
   FROM users
<span>&lt;/select&gt;</span>

<span>&lt;select</span> <span>id=</span><span>"getOne"</span> <span>parameterType=</span><span>"java.lang.Long"</span> <span>resultMap=</span><span>"BaseResultMap"</span> <span>&gt;</span>
    SELECT 
   <span>&lt;include</span> <span>refid=</span><span>"Base_Column_List"</span> <span>/&gt;</span>
   FROM users
   WHERE id = #{id}
<span>&lt;/select&gt;</span>

<span>&lt;insert</span> <span>id=</span><span>"insert"</span> <span>parameterType=</span><span>"com.neo.entity.UserEntity"</span> <span>&gt;</span>
   INSERT INTO 
        users
        (userName,passWord,user_sex) 
    VALUES
        (#{userName}, #{passWord}, #{userSex})
<span>&lt;/insert&gt;</span>

<span>&lt;update</span> <span>id=</span><span>"update"</span> <span>parameterType=</span><span>"com.neo.entity.UserEntity"</span> <span>&gt;</span>
   UPDATE 
        users 
   SET 
    <span>&lt;if</span> <span>test=</span><span>"userName != null"</span><span>&gt;</span>userName = #{userName},<span>&lt;/if&gt;</span>
    <span>&lt;if</span> <span>test=</span><span>"passWord != null"</span><span>&gt;</span>passWord = #{passWord},<span>&lt;/if&gt;</span>
    nick_name = #{nickName}
   WHERE 
        id = #{id}
<span>&lt;/update&gt;</span>

<span>&lt;delete</span> <span>id=</span><span>"delete"</span> <span>parameterType=</span><span>"java.lang.Long"</span> <span>&gt;</span>
   DELETE FROM
         users 
   WHERE 
         id =#{id}
<span>&lt;/delete&gt;</span>



</mapper>

其实就是把上个版本中mapper的sql搬到了这里的xml中了

3、编写Dao层的代码

public interface UserMapper {


<span>List</span><span>&lt;</span><span>UserEntity</span><span>&gt;</span> <span>getAll</span><span>();</span>

<span>UserEntity</span> <span>getOne</span><span>(</span><span>Long</span> <span>id</span><span>);</span>

<span>void</span> <span>insert</span><span>(</span><span>UserEntity</span> <span>user</span><span>);</span>

<span>void</span> <span>update</span><span>(</span><span>UserEntity</span> <span>user</span><span>);</span>

<span>void</span> <span>delete</span><span>(</span><span>Long</span> <span>id</span><span>);</span>



}

对比上一步这里全部只剩了接口方法

4、使用

使用和上个版本没有任何区别，大家就看代码吧

xml配置版本

如何选择

两种模式各有特点，注解版适合简单快速的模式，其实像现在流行的这种微服务模式，一个微服务就会对应一个自已的数据库，多表连接查询的需求会大大的降低，会越来越适合这种模式。

老传统模式比适合大型项目，可以灵活的动态生成SQL，方便调整SQL，也有痛痛快快，洋洋洒洒的写SQL的感觉。


作者：纯洁的微笑

出处：http://www.ityouknow.com/


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