Mybatis-Plus 真好用（乡村爱情加持）

写在前面MyBatis的增强方案确实有不少，甚至有种感觉是现在如果只用 “裸MyBatis”，不来点增强插件都不好意思了。这不，在上一篇文章《Spring Boot项目利用MyBatis Generator进行数据层代码自动生成》 中尝试了一下 MyBatis Generator。这次来点更加先进的 Mybatis-Plus，SQL语句都不用写了，分页也是自动完成，嗯，真香！数据库准备CREATE TABLE tbl_user( user_id BIGINT(20) NOT NULL COMMENT ‘主键ID’, user_name VARCHAR(30) NULL DEFAULT NULL COMMENT ‘姓名’, user_age INT(11) NULL DEFAULT NULL COMMENT ‘年龄’, PRIMARY KEY (user_id)) charset = utf8;MyBatis-Plus加持工程搭建 （不赘述了）依赖引入<dependency> <groupId>com.baomidou</groupId> <artifactId>mybatis-plus-boot-starter</artifactId> <version>3.1.0</version></dependency><dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId></dependency><dependency> <groupId>com.alibaba</groupId> <artifactId>druid-spring-boot-starter</artifactId> <version>1.1.9</version></dependency><dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <scope>runtime</scope> <version>8.0.12</version></dependency>主要是 Mybatis Plus、Lombok（不知道Lombok干嘛的？可以看这里）、Druid连接池 等依赖。MyBatis Plus配置项目配置mybatis-plus: mapper-locations: classpath:/mapper/*Mapper.xml新增 MyBatis Plus配置类@Configuration@MapperScan(“cn.codesheep.springbtmybatisplus.mapper”)public class MyBatisConfig {}看到没，几乎零配置啊，下面就可以写业务逻辑了业务编写实体类@Data@TableName(“tbl_user”)public class User { @TableId(value = “user_id”) private Long userId; private String userName; private Integer userAge;}Mapper类public interface UserMapper extends BaseMapper<User> {}这里啥接口方法也不用写，就可以实现增删改查了！Service类Service接口：public interface UserService extends IService<User> { int insertUser( User user ); int updateUser( User user ); int deleteUser( User user ); User findUserByName( String userName ); IPage getUserPage( Page page, User user );}Service实现：@Service@AllArgsConstructorpublic class UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService { // 增 @Override public int insertUser(User user) { return baseMapper.insert( user ); } // 改 @Override public int updateUser(User user) { return baseMapper.updateById( user ); } // 删 @Override public int deleteUser(User user) { return baseMapper.deleteById( user.getUserId() ); } // 查 @Override public User findUserByName( String userName ) { return baseMapper.getUserByName( userName ); }}Controller类@RestController@RequestMapping("/user")public class UserContorller { @Autowired private UserService userService; // 增 @PostMapping( value = “/insert”) public Object insert( @RequestBody User user ) { return userService.insertUser( user ); } // 改 @PostMapping( value = “/update”) public Object update( @RequestBody User user ) { return userService.updateUser( user ); } // 删 @PostMapping( value = “/delete”) public Object delete( @RequestBody User user ) { return userService.deleteUser( user ); } // 查 @GetMapping( value = “/getUserByName”) public Object getUserByName( @RequestParam String userName ) { return userService.findUserByName( userName ); }}通过以上几个简单的步骤，我们就实现了 tbl_user表的增删改查，传统 MyBatis的 XML文件一个都不需要写！实际实验【《乡爱》加持】启动项目很牛批的 logo就会出现接下来通过 Postman来发送增删改查的请求插入记录通过 Postman随便插入几条记录 POST localhost:8089/user/insert{“userId”:3,“userName”:“刘能”,“userAge”:“58”}{“userId”:4,“userName”:“赵四”,“userAge”:“58”}{“userId”:5,“userName”:“谢广坤”,“userAge”:“58”}{“userId”:6,“userName”:“刘大脑袋”,“userAge”:“58”}修改记录修改记录时需要带用户ID，比如我们修改 赵四 那条记录的名字为 赵四（Zhao Four）删除记录修改记录时同样需要带用户ID，比如删除ID=6 那条 刘大脑袋的记录查询记录（普通查询，下文讲分页查询）比如，按照名字来查询：GET localhost:8089/user/getUserByName?userName=刘能最关心的分页问题首先装配分页插件@Beanpublic PaginationInterceptor paginationInterceptor() { return new PaginationInterceptor();}Mapper类public interface UserMapper extends BaseMapper<User> { // 普通查询 User getUserByName( String userName ); // 分页查询 IPage<List<User>> getUsersPage( Page page, @Param(“query”) User user );}Service类@Service@AllArgsConstructorpublic class UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService { // 查：普通查 @Override public User findUserByName( String userName ) { return baseMapper.getUserByName( userName ); } // 分页查 @Override public IPage getUserPage(Page page, User user) { return baseMapper.getUsersPage( page, user ); }}Controller类@GetMapping( value = “/page”)public Object getUserPage( Page page, User user ) { return userService.getUserPage( page, user );}实际实验一下，我们分页查询 年龄 = 58 的多条记录：可以看到结果数据中，除了给到当前页数据，还把总记录条数，总页数等一并返回了，很是优雅呢 ！写在最后由于能力有限，若有错误或者不当之处，还请大家批评指正，一起学习交流！My Personal Blog：CodeSheep 程序羊