SpringBoot之持久化框架

在之前的 Spring学习之旅(十二)--持久化框架 中我们介绍了 JPA 的使用，今天我们就来了解下另一种持久化框架 Mybatis。

一、集成 Mybatis

1.1 准备工作

新建用户表

CREATE TABLE `sys_user` (
  `user_id` bigint(21) NOT NULL COMMENT '用户编码',
  `user_name` varchar(50) DEFAULT NULL COMMENT '用户名',
  `age` int(3) DEFAULT NULL COMMENT '年龄',
  `email` varchar(100) DEFAULT NULL COMMENT '邮箱',
  PRIMARY KEY (`user_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

添加依赖

<dependencies>
	......
	<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-data-jpa</artifactId>
	</dependency>

	<dependency>
		<groupId>mysql</groupId>
		<artifactId>mysql-connector-java</artifactId>
		<scope>runtime</scope>
	</dependency>
    
    <dependency>
		<groupId>org.projectlombok</groupId>
		<artifactId>lombok</artifactId>
		<version>1.18.10</version>
		<scope>provided</scope>
	</dependency>
</dependencies>

新建实体类:

@Data
public class SysUser {
    private Long userId;
    private String userName;
    private int age;
    private String email;
}

1.2注解形式

@Mapper
public interface SysUserAnnotationMapper {

    @Insert("INSERT INTO sys_user VALUES(#{userId},#{userName},#{age},#{email})")
    int add(SysUser sysUser);


    @Select("SELECT * FROM sys_user")
    @Results({
            @Result(property = "userId",  column = "user_id", javaType = Long.class),
            @Result(property = "userName", column = "user_name"),
            @Result(property = "age", column = "age"),
            @Result(property = "email", column = "email")
    })
    
    List<SysUser> getAll();
}

新建测试类：

@SpringBootTest
public class AnnotationMapperTest {

    @Autowired
    private SysUserAnnotationMapper userMapper;

    // JUnit5 开始 @Before 和@After被 @BeforeEach 和 @AfterEach给替代
    @BeforeEach
    public void setUp() {
        testDelete();
    }

    @Test
    public void test() {
        testAdd();
        testGetList();
    }

    private void testDelete() {
        userMapper.delete();
        List<SysUser> result = userMapper.getAll();
        Assert.assertTrue(result.size() == 0);
    }

    private void testAdd() {
        SysUser user = getOneUser();
        int result = userMapper.add(user);
        Assert.assertEquals(1, result);
    }

    private void testGetList() {
        SysUser user = getOneUser();
        List<SysUser> userList = userMapper.getAll();
        Assert.assertTrue(userList.size() > 0);
        Assert.assertEquals(user, userList.get(0));
    }


    private SysUser getOneUser() {
        SysUser user = new SysUser();
        user.setUserId(new Long("1572228567336"));
        user.setUserName("MarkLogZhu");
        user.setAge(26);
        user.setEmail("marklogzhu@163.com");
        return user;
    }
}

1.3 传统 XML 形式

在 application.yml 文件中指定 XML 和配置文件文件位置

mybatis:
  config-location: classpath:mybatis/mybatis-config.xml
  mapper-locations: classpath:mybatis//mapper/*.xml

在 resources/mybatis 目录下新建配置文件

<?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>
    <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>

在 resources/mybatis/mapper 目录下新建 SysUserXmlMapper.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="com.learm.springboot.dao.SysUserXmlMapper">
    <resultMap id="BaseResultMap" type="com.learm.springboot.domain.entity.SysUser">
        <id     column="user_id" property="userId" jdbcType="BIGINT"/>
        <result column="user_name" property="userName" jdbcType="VARCHAR"/>
        <result column="age" property="age" jdbcType="INTEGER"/>
        <result column="email" property="email" jdbcType="VARCHAR"/>
    </resultMap>

    <select id="getAll" resultMap="BaseResultMap">
        SELECT * FROM sys_user
    </select>

    <insert id="add" parameterType="com.learm.springboot.domain.entity.SysUser">
        INSERT INTO sys_user
            VALUES(#{userId},#{userName},#{age},#{email})
    </insert>
    
    <delete id="delete">
        DELETE FROM sys_user
    </delete>
    
</mapper>

新建 SysUserXmlMapper.java 文件

@Mapper
public interface SysUserXmlMapper {
    int add(SysUser sysUser);

    List<SysUser> getAll();

    int delete();
}

新建测试类：

@SpringBootTest
public class XmlMapperTest {
    @Autowired
    private SysUserXmlMapper userMapper;

    // JUnit5 开始 @Before 和@After被 @BeforeEach 和 @AfterEach给替代
    @BeforeEach
    public void setUp() {
        testDelete();
    }

    @Test
    public void test() {
        testAdd();
        testGetList();
    }

    private void testDelete() {
        userMapper.delete();
        List<SysUser> result = userMapper.getAll();
        Assert.assertTrue(result.size() == 0);
    }

    private void testAdd() {
        SysUser user = getOneUser();
        int result = userMapper.add(user);
        Assert.assertEquals(1, result);
    }

    private void testGetList() {
        SysUser user = getOneUser();
        List<SysUser> userList = userMapper.getAll();
        Assert.assertTrue(userList.size() > 0);
        Assert.assertEquals(user, userList.get(0));
    }


    private SysUser getOneUser() {
        SysUser user = new SysUser();
        user.setUserId(new Long("1572228567336"));
        user.setUserName("MarkLogZhu");
        user.setAge(26);
        user.setEmail("marklogzhu@163.com");
        return user;
    }
}

1.4 两种方式选择

单表操作可以直接使用注解形式，多表操作采用 XML 形式。

二、通用 Mapper

2.1 为什么使用通用 Mapper

原生的 mybatis 就算最基本的单表 CRUD 也需要我们先手工生成大量的文件，如 pojo 类 、 mapper文件以及dao类 。Mybati 为了方便我们特地提供了 mybatis generator 工具来自动生成这些文件，而 通用 Mapper 是对mybatis generator 升级改造，解决了使用 mybatis-generator 可能需要大量重构的问题，并且在这个基础上加入了一些新的功能。 另一种改造方向的技术是 Mybatis-Plus, 它不仅能够根据数据库表快速生成 pojo 实体类，还封装了大量 CRUD 方法，使用 Wrapper 解决了复杂条件构造等问题，更是根据开发中常见的问题给出了一系列解决方案。

2.2 集成 通用 Mapper

导入依赖

<dependencies>
	......
	<!-- 通用 mybatis 依赖-->
	<dependency>
		<groupId>tk.mybatis</groupId>
		<artifactId>mapper-spring-boot-starter</artifactId>
		<version>2.1.5</version>
	</dependency>
</dependencies>

设置扫描注解

@SpringBootApplication
@MapperScan("com.learm.springboot")
public class SpringbootApplication extends SpringBootServletInitializer {
 ......   
}

2.3 通用 Mapper 专用代码生成器

通用 Mapper 支持 Java 代码和插件两种形式生成文件，我们这边采用插件的形式。

1.在 pom.xml 文件中添加插件

<build>
    <finalName>SpringBoot</finalName>
    <plugins>
		......

        <!--通用 Mapper 代码生成插件-->
        <plugin>
            <groupId>org.mybatis.generator</groupId>
            <artifactId>mybatis-generator-maven-plugin</artifactId>
            <version>1.3.6</version>
            <configuration>
                <configurationFile>
                    ${basedir}/src/main/resources/generator/generatorConfig.xml
                </configurationFile>
                <overwrite>true</overwrite>
                <verbose>true</verbose>
            </configuration>
            <dependencies>
                <dependency>
                    <groupId>mysql</groupId>
                    <artifactId>mysql-connector-java</artifactId>
                    <version>8.0.18</version>
                </dependency>
                <dependency>
                    <groupId>tk.mybatis</groupId>
                    <artifactId>mapper</artifactId>
                    <version>4.1.5</version>
                </dependency>
    		    <dependency>
                	<groupId>tk.mybatis</groupId>
                    <artifactId>mapper-generator</artifactId>
                    <version>1.1.5</version>
                </dependency>	
            </dependencies>
        </plugin>
    </plugins>
</build>

2.在 resources/generator 目录下新建 generatorConfig.xml 文件

<!DOCTYPE generatorConfiguration
        PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
        "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">

<generatorConfiguration>

    <!--配置文件-->
    <properties resource="generator/config.properties"/>

    <context id="Mysql" targetRuntime="MyBatis3Simple" defaultModelType="flat">
        <property name="beginningDelimiter" value="`"/>
        <property name="endingDelimiter" value="`"/>

        <plugin type="tk.mybatis.mapper.generator.MapperPlugin">
            <property name="mappers" value="tk.mybatis.mapper.common.Mapper"/>
            <property name="caseSensitive" value="true"/>
            <!--增加 lombok 注解-->
            <property name="lombok" value="Getter,Setter,ToString"/>
        </plugin>

        <!--数据库连接-->
        <jdbcConnection driverClass="${jdbc.driverClass}"
                        connectionURL="${jdbc.url}"
                        userId="${jdbc.user}"
                        password="${jdbc.password}">
        </jdbcConnection>

        <!--实体-->
        <javaModelGenerator targetPackage="${packageName}.domain.entity.${moduleName}"
                            targetProject="src/main/java"/>

        <!--mapper.xml 文件-->
        <sqlMapGenerator targetPackage="mybatis/mapper/${moduleName}"
                         targetProject="src/main/resources"/>

        <!--mapper.Dao-->
        <javaClientGenerator targetPackage="${packageName}.dao.${moduleName}"
                             targetProject="src/main/java"
                             type="XMLMAPPER"/>

        <!--要生成的表-->
        <table tableName="${tableName}">
            <generatedKey column="id" sqlStatement="JDBC"/>
        </table>
    </context>
</generatorConfiguration>

3.在resources/generator 目录下新建 config.properties 文件

jdbc.driverClass=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/test?characterEncoding=utf8&serverTimezone=GMT%2B8&nullCatalogMeansCurrent=true
jdbc.user=root
jdbc.password=sa000
packageName=com.learm.springboot
moduleName=system
tableName=sys_user

4.执行 Mavne 插件,生成文件

2.3 测试

@SpringBootTest
public class MapperTest {

    @Autowired
    private SysUserMapper sysUserMapper;


    @Test
    public void testAdd() {
        SysUser user = new SysUser();
        user.setUserId(new Long(new Date().getTime()));
        user.setAge(25);
        user.setUserName("lulu");
        user.setEmail("lulu@163.com");
        int result = sysUserMapper.insertSelective(user);
        Assert.assertTrue(result > 0);
    }


    @Test
    public void testSelectAll() {
        List<SysUser> userList = sysUserMapper.selectAll();
        Assert.assertNotNull(userList);
        Assert.assertTrue(userList.size() > 0);
    }
    
}