Spring Boot 整合MyBatis

經過一個小例子來實現Spring Boot 與MyBatis的整合。

加入maven依賴

<!-- mybatis整合spring boot的starter -->
<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>1.3.0</version>
</dependency>

<dependency>
    <groupId>com.h2database</groupId>
    <artifactId>h2</artifactId>
    <scope>runtime</scope>
</dependency>

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
</dependency>

Spring Boot官方提供的starter是這樣的：spring-boot-starter-* 而其餘第三方提供的starter是這樣的：*-spring-boot-starter

開發實體類

public class Emp {

    private Long id;
    private String name;
    private Date birthday;
    private Double salary;

    public Emp() {
    }

    public Emp(String name, Date birthday, Double salary) {
        this.name = name;
        this.birthday = birthday;
        this.salary = salary;
    }

    //getter and setter
}

開發持久層

public interface EmpMapper {
    List<Emp> findAll();
    Emp findById(Long id);
    void save(Emp emp);
    void update(Emp emp);
    void delete(Long id);
}

開發Spring Boot的啓動類

@MapperScan("org.yun.mapper")  //這裏指定要掃描的mapper包
@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

@MapperScan指定要掃描的mapper包

在src/main/resources/下建立包 org.yun.mapper（與EmpMapper.java的包同名）。而後，創建EmpMapper.xml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="org.yun.mapper.EmpMapper">

    <sql id="baseSql">
        id,name,birthday,salary
    </sql>

    <select id="findAll" resultType="org.yun.domain.Emp">
        select
        <include refid="baseSql"/>
        from emp
    </select>

    <select id="findById" parameterType="long" resultType="org.yun.domain.Emp">
        select
        <include refid="baseSql"/>
        from emp
        where id = #{id}
    </select>

    <insert id="save" parameterType="org.yun.domain.Emp" keyProperty="id" useGeneratedKeys="true">
        insert into emp(name,birthday,salary)values(#{name},#{birthday},#{salary})
    </insert>

    <update id="update" parameterType="org.yun.domain.Emp">
        update emp set name = #{name},birthday = #{birthday},salary = #{salary}
        where id = #{id}
    </update>

    <delete id="delete" parameterType="long">
        delete from emp where id = #{id}
    </delete>

</mapper>

關於 MyBatis 這部分，使用 MBG 或 MyBatis Plus會更方便。

配置 application.properties

#指定實體類的名別包
mybatis.type-aliases-package=org.yun.domain

#指定XxxMapper.xml的位置
#mybatis.mapper-locations=classpath:org/yun/mapper/*Mapper.xml

建立數據表schema.sql

CREATE TABLE emp (
  id       BIGINT  AUTO_INCREMENT,
  name     VARCHAR(30),
  birthday DATE,
  salary   DOUBLE,
  PRIMARY KEY(id)
);

初始化數據data.sql

insert into emp(name,birthday,salary)values('admin','1999-09-09',9000);

將schema.sql、data.sql（名字固定）文件放置在src/main/resources下目錄，Spring Boot啓動的時候會自動執行。

單元測試

@RunWith(SpringRunner.class)
@SpringBootTest
public class ApplicationTests {

    @Autowired
    private EmpMapper empMapper;

    @Test
    public void contextLoads() {
        assertNotNull(empMapper);

        Emp emp1 = new Emp("tom", new Date(), 5000D);
        Emp emp2 = new Emp("bill", new Date(), 6000D);
        empMapper.save(emp1);
        empMapper.save(emp2);

        assertTrue(empMapper.findAll().size() == 3);

        Emp emp = empMapper.findById(2L);
        emp.setSalary(8000D);
        empMapper.update(emp);
        assertTrue(emp.getSalary() == 8000D);

        empMapper.delete(2L);
        assertTrue(empMapper.findAll().size() == 2);
    }
}

參考資料：

• https://github.com/mybatis/spring-boot-starter/wiki/Quick-Start

• http://www.mybatis.org/spring-boot-starter/mybatis-spring-boot-autoconfigure/index.html

補充：

在實際項目中通常都會使用Mybatis Generator來實現實體類、映射文件的生成。

那具體怎麼操做呢？以MySQL數據庫爲例。

<!--
 <dependency>
    <groupId>com.h2database</groupId>
    <artifactId>h2</artifactId>
    <scope>runtime</scope>
</dependency>
-->

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.41</version>
    <scope>runtime</scope>
</dependency>

取消h2內存數據庫驅動的依賴，加入MySQL數據庫驅動的依賴。

同時添加以一個Mybatis Generator插件

<plugin>
	<groupId>org.mybatis.generator</groupId>
	<artifactId>mybatis-generator-maven-plugin</artifactId>
	<version>1.3.2</version>
	<dependencies>
		<dependency>
		<groupId>mysql</groupId>
		<artifactId>mysql-connector-java</artifactId>
		<version>5.1.41</version>
		</dependency>
	</dependencies>
</plugin>

編寫mybatis的文件生成配置文件：generatorConfig.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE generatorConfiguration
          PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
          "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">

<generatorConfiguration>

    <!--加載jdbc屬性文件-->
    <properties resource="application.properties"/>

    <context id="DB2Tables" targetRuntime="MyBatis3" defaultModelType="flat">
        <!--緩存 暫時不加-->
        <!--<plugin type="org.mybatis.generator.plugins.CachePlugin"/>-->
        <!--重寫equals()和hashCode()-->
        <plugin type="org.mybatis.generator.plugins.EqualsHashCodePlugin"/>
        <!-- 分頁 -->
        <plugin type="org.mybatis.generator.plugins.RowBoundsPlugin"/>
        <!--序列化-->
        <plugin type="org.mybatis.generator.plugins.SerializablePlugin"/>
        <!--重寫toString()-->
        <plugin type="org.mybatis.generator.plugins.ToStringPlugin"/>
        <!-- 註釋 -->
        <commentGenerator>
            <!-- 是否取消註釋 -->
            <property name="suppressAllComments" value="true"/>
            <!-- 是否生成註釋代時間戳-->
            <property name="suppressDate" value="true"/>
        </commentGenerator>
        <!--數據庫連接URL，用戶名、密碼 -->
        <jdbcConnection driverClass="${spring.datasource.driver-class-name}"
                        connectionURL="${spring.datasource.url}"
                        userId="${spring.datasource.username}"
                        password="${spring.datasource.password}"/>
        <!-- 類型解析器 -->
        <!--  默認false：把JDBC DECIMAL 和 NUMERIC 類型解析爲java.lang.Integer
                  true：把JDBC DECIMAL 和 NUMERIC 類型解析爲java.math.BigDecimal
        -->
        <javaTypeResolver>
            <property name="forceBigDecimals" value="false"/>
        </javaTypeResolver>
        <!-- 生成model的包名和位置 -->
        <javaModelGenerator targetPackage="org.yun.domain"
                            targetProject="src\main\java">
            <!-- 是否讓schema做爲包的後綴 -->
            <property name="enableSubPackages" value="true"/>
            <!-- 從數據庫返回的值被清理先後的空格  -->
            <property name="trimStrings" value="true"/>
        </javaModelGenerator>
        <!-- 生成 xxxMapper.xml文件的包名和位置 -->
        <sqlMapGenerator targetPackage="org.yun.mapper"
                         targetProject="src\main\resources"> <!-- 這裏必定是src/main/resources目錄 -->
            <property name="enableSubPackages" value="true"/>
        </sqlMapGenerator>
        <!-- 生成xxxMapper的包名和位置 -->
        <javaClientGenerator type="XMLMAPPER"
                             targetPackage="org.yun.mapper"
                             targetProject="src\main\java">
            <property name="enableSubPackages" value="true"/>
        </javaClientGenerator>
        <!-- 要生成哪些表 -->
        <table tableName="emp" domainObjectName="Emp"/>
    </context>
</generatorConfiguration>

使用IDA右鍵執行，便可實現代碼生成。

會生成以下代碼