SpringBoot之持久化框架

2023-03-04 22:48:37

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);

    }

}

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