SpringBoot 系列教程 Mybatis+注解整合篇

SpringBoot 系列教程 Mybatis+注解整合篇

上一篇博文介紹了 SpringBoot 整合 mybatis 的過程，但是 xml 的方式，總感覺讓人有點蛋疼；本文將介紹一種 noxml 的使用姿勢，純用注解的方式來支持 CURD

I. 環境

本文使用 SpringBoot 版本為 2.2.1.RELEASE， mybatis 版本為1.3.2，數據庫為 mysql 5+

1. 項目搭建

推薦是用官方的教程來創建一個 SpringBoot 項目； 如果直接創建一個 maven 工程的話，將下面配置內容，拷貝到你的pom.xml中

• 主要引入的是mybatis-spring-boot-starter，可以減少令人窒息的配置

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.2.1.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    <java.version>1.8</java.version>
</properties>

<dependencies>
    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>1.3.2</version>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
    </dependency>
</dependencies>

<build>
    <pluginManagement>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </pluginManagement>
</build>
<repositories>
    <repository>
        <id>spring-snapshots</id>
        <name>Spring Snapshots</name>
        <url>https://repo.spring.io/libs-snapshot-local</url>
        <snapshots>
            <enabled>true</enabled>
        </snapshots>
    </repository>
    <repository>
        <id>spring-milestones</id>
        <name>Spring Milestones</name>
        <url>https://repo.spring.io/libs-milestone-local</url>
        <snapshots>
            <enabled>false</enabled>
        </snapshots>
    </repository>
    <repository>
        <id>spring-releases</id>
        <name>Spring Releases</name>
        <url>https://repo.spring.io/libs-release-local</url>
        <snapshots>
            <enabled>false</enabled>
        </snapshots>
    </repository>
</repositories>

2. 配置信息

在 application.yml 配置文件中，加一下 db 的相關配置

spring:
  datasource:
    url: jdbc:mysql://127.0.0.1:3306/story?useUnicode=true&characterEncoding=UTF-8&useSSL=false
    username: root
    password:

接下來准備一個測試表(依然借用之前 db 操作系列博文中的表結構)，用於后續的 CURD；表結果信息如下

DROP TABLE IF EXISTS `money`;

CREATE TABLE `money` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(20) NOT NULL DEFAULT '' COMMENT '用戶名',
  `money` int(26) NOT NULL DEFAULT '0' COMMENT '有多少錢',
  `is_deleted` tinyint(1) NOT NULL DEFAULT '0',
  `create_at` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '創建時間',
  `update_at` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '更新時間',
  PRIMARY KEY (`id`),
  KEY `name` (`name`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

II. 實例整合

在前一篇的基礎上進行擴展，重點在於干掉了 xml 文件，在 DAO 接口上通過注解來實現 CURD

1. PO

創建表對應的 PO 對象: MoneyPo

@Data
public class MoneyPo {
    private Integer id;

    private String name;

    private Long money;

    private Integer isDeleted;

    private Timestamp createAt;

    private Timestamp updateAt;
}

2. DAO 接口

表的操作接口，下面簡單的寫了四個接口，分別對應 CRUID 四種操作

@Mapper
public interface MoneyMapper {

    // 支持主鍵寫回到po

    @Options(useGeneratedKeys = true, keyProperty = "po.id", keyColumn = "id")
    @Insert("insert into money (name, money, is_deleted) values (#{po.name}, #{po.money}, #{po.isDeleted})")
    int savePo(@Param("po") MoneyPo po);

    @Select("select * from money where name=#{name}")
    @Results({@Result(property = "id", column = "id", id = true, jdbcType = JdbcType.INTEGER),
            @Result(property = "name", column = "name", jdbcType = JdbcType.VARCHAR),
            @Result(property = "money", column = "money", jdbcType = JdbcType.INTEGER),
            @Result(property = "isDeleted", column = "is_deleted", jdbcType = JdbcType.TINYINT),
            @Result(property = "createAt", column = "create_at", jdbcType = JdbcType.TIMESTAMP),
            @Result(property = "updateAt", column = "update_at", jdbcType = JdbcType.TIMESTAMP)})
    List<MoneyPo> findByName(@Param("name") String name);

    @Update("update money set money=money+#{money} where id=#{id}")
    int addMoney(@Param("id") int id, @Param("money") int money);

    @Delete("delete from money where id = #{id,jdbcType=INTEGER}")
    int delPo(@Param("id") int id);

    @Select("<script> select * from money " +
            "<trim prefix=\"WHERE\" prefixOverrides=\"AND | OR\">" +
            "   <if test=\"id != null\">" +
            "       id = #{id}" +
            "   </if>" +
            "   <if test=\"name != null\">" +
            "       AND name=#{name}" +
            "   </if>" +
            "   <if test=\"money != null\">" +
            "       AND money=#{money}" +
            "   </if>" +
            "</trim>" +
            "</script>")
    @Results({@Result(property = "id", column = "id", id = true, jdbcType = JdbcType.INTEGER),
                @Result(property = "name", column = "name", jdbcType = JdbcType.VARCHAR),
                @Result(property = "money", column = "money", jdbcType = JdbcType.INTEGER),
                @Result(property = "isDeleted", column = "is_deleted", jdbcType = JdbcType.TINYINT),
                @Result(property = "createAt", column = "create_at", jdbcType = JdbcType.TIMESTAMP),
                @Result(property = "updateAt", column = "update_at", jdbcType = JdbcType.TIMESTAMP)})
    List<MoneyPo> findByPo(MoneyPo po);
}

從 mapper 的實現上，也可以看出來，通過 @Insert, @Select, @Update, @Delete 四個注解來實現 CURD，使用上面這種方式時，有幾個點需要注意

• insert: 當我們希望插入的主鍵寫回到 PO 時，可以配置@Options(useGeneratedKeys = true, keyProperty = "po.id", keyColumn = "id")
• 動態 sql: 在注解中，通過<script>來包裝動態 sql
• @Results 實現<resultMap>的映射關系

5. 測試

接下來簡單測試一下上面的四個接口，看是否可以正常工作

啟動類

@SpringBootApplication
public class Application {

    public Application(MoneyRepository repository) {
        repository.testMapper();
    }

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

測試類

@Repository
public class MoneyRepository {
    @Autowired
    private MoneyMapper moneyMapper;

    private Random random = new Random();

    public void testMapper() {
        MoneyPo po = new MoneyPo();
        po.setName("mybatis noxml user");
        po.setMoney((long) random.nextInt(12343));
        po.setIsDeleted(0);

        moneyMapper.savePo(po);
        System.out.println("add record: " + po);
        moneyMapper.addMoney(po.getId(), 200);
        System.out.println("after update: " + moneyMapper.findByName(po.getName()));
        moneyMapper.delPo(po.getId());
        System.out.println("after delete: " + moneyMapper.findByName(po.getName()));
    }
}

輸出結果

II. 其他

0. 項目

• 工程：https://github.com/liuyueyi/spring-boot-demo
• 項目源碼: https://github.com/liuyueyi/spring-boot-demo/tree/master/spring-boot/104-mybatis-noxml

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