Mybatis Plus代码生成器

HYF Lv3
  2023-05-21 13:46:32 2023-05-21 13:46:32 创建   2024-07-27 21:21:51 2024-07-27 21:21:51 更新    2.2k 字  11 分钟  

在使用 Spring Boot开发项目时，需要手动创建Controller, Entity, Service, ServiceImpl, Mapper, Mapper XML 文件，效率实在太慢，本文介绍如何使用Mybatis Plus代码生成器去自动生成各个模块代码。
MyBatis Plus 的代码生成器，通过 AutoGenerator 可以快速生成 Controller, Entity, Service, ServiceImpl, Mapper, Mapper XML 各个模块的代码，极大的提升了开发效率。

1 引入依赖

初始化一个Spring Boot 项目,在引入所需业务依赖下，额外引入以下Mybatis Plus相关依赖

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<!--        Mybatis Plus-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.5.3.1</version>
        </dependency>
<!--        代码生成器-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-generator</artifactId>
            <version>3.2.0</version>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-extension</artifactId>
            <version>3.5.3.1</version>
        </dependency>
<!--        生成器所需模板引擎-->
        <dependency>
            <groupId>org.apache.velocity</groupId>
            <artifactId>velocity-engine-core</artifactId>
            <version>2.3</version>
        </dependency>

2 数据库建表

2.1 user 表结构：

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MariaDB [test]> desc user;
+------------+--------------+------+-----+---------+-------+
| Field      | Type         | Null | Key | Default | Extra |
+------------+--------------+------+-----+---------+-------+
| userid     | char(19)     | NO   | PRI | NULL    |       |
| username   | varchar(255) | YES  |     | NULL    |       |
| password   | varchar(255) | YES  |     | NULL    |       |
| createtime | datetime     | YES  |     | NULL    |       |
| updatetime | datetime     | YES  |     | NULL    |       |
+------------+--------------+------+-----+---------+-------+
5 rows in set (0.001 sec)

2.2 file 表结构

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MariaDB [test]> desc file;
+------------+--------------+------+-----+---------+-------+
| Field      | Type         | Null | Key | Default | Extra |
+------------+--------------+------+-----+---------+-------+
| fileid     | char(19)     | NO   | PRI | NULL    |       |
| filename   | varchar(255) | YES  |     | NULL    |       |
| createtime | datetime     | YES  |     | NULL    |       |
| updatetime | datetime     | YES  |     | NULL    |       |
| type       | varchar(255) | YES  |     | NULL    |       |
| collection | varchar(255) | YES  |     | NULL    |       |
| logicdel   | tinyint(1)   | YES  |     | NULL    |       |
+------------+--------------+------+-----+---------+-------+
7 rows in set (0.001 sec)

3 启动生成器代码

使用生成器之前代码结构:

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---com.youfeng.CodeGenerator:
    ---utils:
        ---CodeGenerator.java
    ---Application.java

在 com/youfeng/CodeGenerator 下新建 utils/CodeGenerator.java 类

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/**
 * @author -侑枫
 * @date 2023/5/21 15:38:22
 */
public class CodeGenerator {
    public static void main(String[] args) {
        //1.获取代码生成器的对象
        AutoGenerator autoGenerator = new AutoGenerator();

        //设置数据库相关配置
        DataSourceConfig dataSource = new DataSourceConfig();

        dataSource.setDriverName("com.mysql.cj.jdbc.Driver");
        dataSource.setUrl("jdbc:mysql://47.120.5.13:3306/test?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=Asia/Shanghai");
        dataSource.setUsername("['you databases username']");
        dataSource.setPassword("['you databases password']");
        autoGenerator.setDataSource(dataSource);

        //设置全局配置
        GlobalConfig globalConfig = new GlobalConfig();
        //设置代码生成位置
        globalConfig.setOutputDir(System.getProperty("user.dir")+"\\src\\main\\java");
        //设置生成完毕后是否打开生成代码所在的目录
        globalConfig.setOpen(false);
        //设置作者
        globalConfig.setAuthor("-无心");
        //设置是否覆盖原始生成的文件
        globalConfig.setFileOverride(true);
        //设置数据层接口名，%s为占位符，指代模块名称
        //globalConfig.setMapperName("%sMapper");
        //设置Id生成策略
        globalConfig.setIdType(IdType.ASSIGN_ID);
        autoGenerator.setGlobalConfig(globalConfig);

        //设置包名相关配置
        PackageConfig packageInfo = new PackageConfig();
        //设置生成的包名，与代码所在位置不冲突，二者叠加组成完整路径
        packageInfo.setParent("com.youfeng.CodeGenerator");
        //设置实体类包名
        packageInfo.setEntity("entity");
        //设置数据层包名
        packageInfo.setMapper("mapper");
        autoGenerator.setPackageInfo(packageInfo);

        //策略设置
        StrategyConfig strategyConfig = new StrategyConfig();
        //设置当前参与生成的表名，参数为可变参数
        strategyConfig.setInclude("user","file");
        //设置数据库表的前缀名称，模块名 = 数据库表名 - 前缀名  例如： User = tbl_user - tbl_
//        strategyConfig.setTablePrefix("tbl_");
        //设置是否启用Rest风格
        strategyConfig.setRestControllerStyle(true);
        //设置乐观锁字段名
//        strategyConfig.setVersionFieldName("version");
        //设置逻辑删除字段名
        strategyConfig.setLogicDeleteFieldName("logicDel");
        //设置是否启用lombok
        strategyConfig.setEntityLombokModel(true);
        autoGenerator.setStrategy(strategyConfig);
        //2.执行生成操作
        autoGenerator.execute();
    }
}

生成后的代码机构为:

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---com.youfeng.CodeGenerator:
    ---controller:
        ---FileController.java
        ---UserController.java
    ---mapper:
        ---xml:
            ---FileMapper.xml
            ---UserMapper.xml
        ---FileMapper.java
        ---UserMapper.java
    ---entity:
        ---File.java
        ---User.java
    ---service：
        ---impl：
            ---FileServiceImpl.java
            ---UserServiceImpl.java
        ---IFileService.java
        ---IUserService.java
    ---utils:
        ---CodeGenerator.java
    ---Application.java

4 代码展示

4.1 UserController.java

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/**
 * <p>
 *  前端控制器
 * </p>
 *
 * @author -侑枫
 * @since 2023-05-21
 */
@RestController
@RequestMapping("/user")
public class UserController {

}

4.2 UserMapper.xml

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<?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.youfeng.CodeGenerator.mapper.UserMapper">

</mapper>

4.3 UserMapper.java

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/**
 * <p>
 *  Mapper 接口
 * </p>
 *
 * @author -侑枫
 * @since 2023-05-21
 */
public interface UserMapper extends BaseMapper<User> {

}

4.4 User.java

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/**
 * <p>
 *  实体类
 * </p>
 *
 * @author -侑枫
 * @since 2023-05-21
 */
@Data
@EqualsAndHashCode(callSuper = false)
@Accessors(chain = true)
public class User implements Serializable {

    private static final long serialVersionUID=1L;

    @TableId(value = "userid", type = IdType.ASSIGN_ID)
    private String userid;

    private String username;

    private String password;

    private LocalDateTime createTime;

    private LocalDateTime updateTime;


}

4.5 IUserService.java

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/**
 * <p>
 *  服务类
 * </p>
 *
 * @author -侑枫
 * @since 2023-05-21
 */
public interface IUserService extends IService<User> {

}

4.6 UserServiceImpl.java

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/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author -侑枫
 * @since 2023-05-21
 */
@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements IUserService {

}

5 代码测试

5.1 完善 application.yml 配置

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server:
  port: 8081
spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: "jdbc:mysql://47.120.5.13:3306/test?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=Asia/Shanghai"
    username: "['you databases username']"
    password: "['you databases password']"

logging:
  level:
    root: warn
    com.scaffold.test.mapper: trace

5.2 XML 增加 sql 语句 mapper/userMapper.xml

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<?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.youfeng.CodeGenerator.mapper.UserMapper">
    <insert id="insert">
        insert into user
            (username, password)
            value
            (#{username}, #{password})
    </insert>
</mapper>

5.3 Mapper接口 com/youfeng/CodeGenerator/mapper/UserMapper.java

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/**
 * <p>
 * Mapper 接口
 * </p>
 *
 * @author -侑枫
 * @since 2023-05-21
 */
public interface UserMapper extends BaseMapper<User> {

    /**
     * 添加用户
     *
     * @param user 用户信息
     * @return 添加结果 >0 表示插入成功
     */
    int insert(User user);

}

5.4 Service接口和实现方法

5.4.1 com/youfeng/CodeGenerator/service/IUserService.java

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/**
 * <p>
 * 服务类
 * </p>
 *
 * @author -侑枫
 * @since 2023-05-21
 */
public interface IUserService extends IService<User> {
    
    /**
     * 添加用户
     *
     * @param user 用户信息
     * @return 添加结果
     */
    String addUser(User user);
}

5.4.2 com/youfeng/CodeGenerator/service/impl/UserServiceImpl.java

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/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author -侑枫
 * @since 2023-05-21
 */
@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements IUserService {

    @Resource
    private UserMapper mapper;

    @Override
    public String addUser(User user) {
        return mapper.insert(user) > 0 ? "添加成功" : "添加失败";
    }
}

5.5 Controller层：com/youfeng/CodeGenerator/controller/UserController.java

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/**
 * <p>
 * 前端控制器
 * </p>
 *
 * @author -侑枫
 * @since 2023-05-21
 */
@RestController
@RequestMapping("/users")
public class UserController {
    @Resource
    private IUserService userService;

    @PostMapping("/add")
    public String add() {
        User user = new User();
        user.setUsername("-wuxin");
        user.setPassword("456");
        return userService.addUser(user);
    }

    @PostMapping("/insert")
    public String insert() {
        User user = new User();
        user.setUsername("-snow");
        user.setPassword("123");
        return userService.save(user) ? "添加成功" : "添加失败";
    }

}

5.6 启动项目

项目启动发现一个报错

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***************************
APPLICATION FAILED TO START
***************************

Description:

A component required a bean of type 'com.youfeng.CodeGenerator.mapper.UserMapper' that could not be found.


Action:

Consider defining a bean of type 'com.youfeng.CodeGenerator.mapper.UserMapper' in your configuration.


Process finished with exit code 1

问题原因：

遗漏自动注入，Spring没有扫描到UserMapper这个bean

解决办法:

方法一：在每个mapper接口上添加上注解@Mapper

方法二：在Application.java文件中添加注解@MapperScan(“这里填入mapper接口的路径”)

如果使用@Mapper这个注解的话,每个dao都需要添加，有些麻烦。

而解决方法二使用@MapperScan就可以很好的解决该问题的。

在启动类Application.java添加@MapperScan注解

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/**
 * @author -侑枫
 */
@MapperScan("com.youfeng.CodeGenerator.mapper")
@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

项目成功启动

5.7 PostMan测试

使用add()方法添加后的结果：

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MariaDB [test]> select * from user;
+---------------------+----------+----------+------------+------------+
| userid              | username | password | createtime | updatetime |
+---------------------+----------+----------+------------+------------+
| 1642912163666333697 | -wuxin   | 123      | NULL       | NULL       |
+---------------------+----------+----------+------------+------------+
1 row in set (0.000 sec)

使用insert()方法添加后的结果:

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MariaDB [test]> select * from user;
+---------------------+----------+----------+------------+------------+
| userid              | username | password | createtime | updatetime |
+---------------------+----------+----------+------------+------------+
| 1642912163666333697 | -wuxin   | 123      | NULL       | NULL       |
| 1642912299863773185 | -snow    | 123      | NULL       | NULL       |
+---------------------+----------+----------+------------+------------+
2 rows in set (0.000 sec)

项目测试完毕

6 代码优化

测试结果我们可以发现一个问题，createtime和updatetime为NULL，这显然不符合我们的需求

6.1 修改User实体类

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/**
 * <p>
 *
 * </p>
 *
 * @author -侑枫
 * @since 2023-05-21
 */
@Data
@EqualsAndHashCode(callSuper = false)
@Accessors(chain = true)
public class User implements Serializable {

    private static final long serialVersionUID = 1L;

    @TableId(value = "userid", type = IdType.ASSIGN_ID)
    private String userid;

    private String username;

    private String password;
    
    @TableField(value = "createtime", fill = FieldFill.INSERT)
    private String createTime;

    @TableField(value = "updatetime", fill = FieldFill.INSERT_UPDATE)
    private String updateTime;
    
}

6.2 在 config 包下创建 MyMetaObjectHandler.java 类

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/**
 * @author -侑枫
 * @date 2023/5/21 15:54:45
 */
@Component
public class MyMetaObjectHandler implements MetaObjectHandler {
    SimpleDateFormat simp = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    @Override
    public void insertFill(MetaObject metaObject) {
        this.setFieldValByName("createTime", simp.format(new Date()), metaObject);
        this.setFieldValByName("updateTime", simp.format(new Date()), metaObject);
    }

    @Override
    public void updateFill(MetaObject metaObject) {
        this.setFieldValByName("updateTime", simp.format(new Date()), metaObject);
    }
}

6.3 修改controller后重新使用 PostMan 测试

UserController.java

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/**
 * <p>
 * 前端控制器
 * </p>
 *
 * @author -侑枫
 * @since 2023-05-21
 */
@RestController
@RequestMapping("/users")
public class UserController {
    @Resource
    private IUserService userService;

    @PostMapping("/add")
    public String add() {
        User user = new User();
        user.setUsername("-wuxin");
        user.setPassword("456");
        return userService.addUser(user);
    }

    @PostMapping("/insert")
    public String insert() {
        User user = new User();
        user.setUsername("-snow");
        user.setPassword("456");
        return userService.save(user) ? "添加成功" : "添加失败";
    }

}

使用add()方法和insert()方法添加后的结果：
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MariaDB [test]> select * from user;
+---------------------+----------+----------+---------------------+---------------------+
| userid              | username | password | createtime          | updatetime          |
+---------------------+----------+----------+---------------------+---------------------+
| 1642912163666333697 | -wuxin   | 123      | NULL                | NULL                |
| 1642912299863773185 | -snow    | 123      | NULL                | NULL                |
| 1642912649085755393 | -wuxin   | 456      | 2023-04-03 23:31:14 | 2023-04-03 23:31:14 |
| 1642912717310304257 | -snow    | 456      | 2023-04-03 23:31:30 | 2023-04-03 23:31:30 |
+---------------------+----------+----------+---------------------+---------------------+
4 rows in set (0.000 sec)

代码优化完成，最后附上本文所写源代码：Mybatis Plus代码生成器使用

  • 标题: Mybatis Plus代码生成器
  • 作者: HYF
  • 创建于 : 2023-05-21 13:46:32
  • 更新于 : 2024-07-27 21:21:51
  • 链接: https://youfeng.ink/generator-0cf176b7f99d/
  • 版权声明: 本文章采用 CC BY-NC-SA 4.0 进行许可。
此页目录
Mybatis Plus代码生成器
  1. 1 引入依赖
  2. 2 数据库建表
    1. 2.1 user 表结构：
    2. 2.2 file 表结构
  3. 3 启动生成器代码
  4. 4 代码展示
    1. 4.1 UserController.java
    2. 4.2 UserMapper.xml
    3. 4.3 UserMapper.java
    4. 4.4 User.java
    5. 4.5 IUserService.java
    6. 4.6 UserServiceImpl.java
  5. 5 代码测试
    1. 5.1 完善 application.yml 配置
    2. 5.2 XML 增加 sql 语句 mapper/userMapper.xml
    3. 5.3 Mapper接口 com/youfeng/CodeGenerator/mapper/UserMapper.java
    4. 5.4 Service接口和实现方法
      1. 5.4.1 com/youfeng/CodeGenerator/service/IUserService.java
      2. 5.4.2 com/youfeng/CodeGenerator/service/impl/UserServiceImpl.java
    5. 5.5 Controller层：com/youfeng/CodeGenerator/controller/UserController.java
    6. 5.6 启动项目
      1. 项目启动发现一个报错
      2. 问题原因：
      3. 解决办法:
    7. 5.7 PostMan测试
      1. 项目测试完毕
  6. 6 代码优化
    1. 6.1 修改User实体类
    2. 6.2 在 config 包下创建 MyMetaObjectHandler.java 类
    3. 6.3 修改controller后重新使用 PostMan 测试
      1. UserController.java
    4. 使用add()方法和insert()方法添加后的结果：12345678910MariaDB [test]> select * from user;+---------------------+----------+----------+---------------------+---------------------+| userid | username | password | createtime | updatetime |+---------------------+----------+----------+---------------------+---------------------+| 1642912163666333697 | -wuxin | 123 | NULL | NULL || 1642912299863773185 | -snow | 123 | NULL | NULL || 1642912649085755393 | -wuxin | 456 | 2023-04-03 23:31:14 | 2023-04-03 23:31:14 || 1642912717310304257 | -snow | 456 | 2023-04-03 23:31:30 | 2023-04-03 23:31:30 |+---------------------+----------+----------+---------------------+---------------------+4 rows in set (0.000 sec)