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无侵入:只做增强不做改变,引入它不会对现有工程产生影响,如丝般顺滑
损耗小:启动即会自动注入基本 CURD,性能基本无损耗,直接面向对象操作
强大的 CRUD 操作:内置通用 Mapper、通用 Service,仅仅通过少量配置即可实现单表大部分 CRUD 操作,更有强大的条件构造器,满足各类使用需求
支持 Lambda 形式调用:通过 Lambda 表达式,方便的编写各类查询条件,无需再担心字段写错
支持主键自动生成:支持多达 4 种主键策略(内含分布式唯一 ID 生成器 - Sequence),可自由配置,完美解决主键问题
支持 ActiveRecord 模式:支持 ActiveRecord 形式调用,实体类只需继承 Model 类即可进行强大的 CRUD 操作
支持自定义全局通用操作:支持全局通用方法注入( Write once, use anywhere )
内置代码生成器:采用代码或者 Maven 插件可快速生成 Mapper 、 Model 、 Service 、 Controller 层代码,支持模板引擎,更有超多自定义配置等您来使用
内置分页插件:基于 MyBatis 物理分页,开发者无需关心具体操作,配置好插件之后,写分页等同于普通 List 查询
分页插件支持多种数据库:支持 MySQL、MariaDB、Oracle、DB2、H2、HSQL、SQLite、Postgre、SQLServer 等多种数据库
内置性能分析插件:可输出 SQL 语句以及其执行时间,建议开发测试时启用该功能,能快速揪出慢查询
内置全局拦截插件:提供全表 delete 、 update 操作智能分析阻断,也可自定义拦截规则,预防误操作
1.快速入门
1.添加依赖
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| <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.6.5</version> <relativePath/> </parent>
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| <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>com.baomidou</groupId> <artifactId>mybatis-plus-boot-starter</artifactId> <version>3.5.1</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> </dependency> </dependencies>
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2.配置数据库连接
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| spring: datasource: username: root password: password url: jdbc:mysql:///mybatis_plus?userUnicode=true&characterEncoding=utf-8 driver-class-name: com.mysql.cj.jdbc.Driver
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3.在spring boot启动类中添加@MapperScan注解,扫描Mapper文件夹:
一定要用MapperScan不要用ComponentScan
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| @SpringBootApplication @MapperScan("com.wen.mybatis_plus.mapper") public class MybatisPlusApplication { public static void main(String[] args) { SpringApplication.run(MybatisPlusApplication.class, args); } }
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4.配置实体类
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| import lombok.Data;
@Data public class User { private Long id; private String name; private Integer age; private String email; }
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5.编写Mapper包下的UserMapper接口
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| import com.baomidou.mybatisplus.core.mapper.BaseMapper; import com.wen.mybatis_plus.pojo.User; import org.apache.ibatis.annotations.Mapper;
@Mapper public interface UserMapper extends BaseMapper<User> { }
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6.测试
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| @SpringBootTest class MybatisPlusApplicationTests {
@Autowired private UserMapper userMapper;
@Test public void testSelect(){ System.out.println("--------selectAll method test-------"); List<User> userList = userMapper.selectList(null); userList.forEach(System.out::println); }
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2.Iservice
1.继承接口
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| #Userservice.java package com.richu.iorichu1.Service;
import com.baomidou.mybatisplus.extension.service.IService; import com.richu.iorichu1.domain.po.User;
public interface Userservice extends IService<User>{ }
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2.实现类
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| package com.richu.iorichu1.Service.impl;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl; import com.richu.iorichu1.Mapper.UserMapper; import com.richu.iorichu1.Service.Userservice; import com.richu.iorichu1.domain.po.User; import org.springframework.stereotype.Service;
@Service public class Userserviceimpl extends ServiceImpl<UserMapper, User> implements Userservice{
}
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3.测试
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| @Autowired private Userservice userservice;
@Test public void testsaveUser(){ User user = new User(); user.setId(7L); user.setUsername("李磊"); user.setPassword("123"); user.setPhone("18688990011"); user.setBalance(200); user.setInfo("{\"age\": 24, \"intro\": \"数学老师\", \"gender\": \"female\"}"); user.setCreateTime(LocalDateTime.now()); user.setUpdateTime(LocalDateTime.now()); userservice.save(user); }
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3.自定义SQL
1.测试类
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| @Test public void CustomTest() { List<Long> ids = List.of(1L, 2L, 3L, 4L); int amount=200; QueryWrapper<User> queryWrapper = new QueryWrapper<User>().in("id",ids); userMapper.updateblance(queryWrapper,amount); }
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2.Mapper
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| @Mapper public interface UserMapper extends BaseMapper<User> { void updateblance(@Param("ew") QueryWrapper<User> queryWrapper,@Param("amount") int amount); }
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3.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.richu.iorichu1.Mapper.UserMapper">
<update id="updateblance"> update user set balance = balance- #{amount} ${ew.customSqlSegment} </update> </mapper>
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4.DB静态工具
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| List<Address> addresses=Db.lambdaQuery(Address.class) .eq(Address::getUserId,user.getId()).list();
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5.逻辑删除支持
配置全局逻辑删除属性
在 application.yml
中配置 MyBatis-Plus 的全局逻辑删除属性:
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| mybatis-plus: global-config: db-config: logic-delete-field: deleted # 全局逻辑删除字段名 logic-delete-value: 1 # 逻辑已删除值 logic-not-delete-value: 0 # 逻辑未删除值
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步骤 2: 在实体类中使用 @TableLogic
注解
在实体类中,对应数据库表的逻辑删除字段上添加 @TableLogic
注解:
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| import com.baomidou.mybatisplus.annotation.TableLogic;
public class User { // 其他字段...
@TableLogic private Integer deleted; }
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6.枚举处理器
方式一:注解标记
枚举属性使用 @EnumValue
注解,指定枚举值在数据库中存储的实际值。支持枚举类中的任意字段,如序号或编码。
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| @Getter @AllArgsConstructor public enum GradeEnum { PRIMARY(1, "小学"), SECONDARY(2, "中学"), HIGH(3, "高中");
@EnumValue private final int code; }
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| mybatis-plus: configuration: default-enum-type-handler: xx.xx.xx.MyEnumTypeHandler
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7.JSON处理器
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| @Data @TableName(value = "user",autoResultMap = true) public class UserVo {
private Long id;
private String username; @TableField(typeHandler = JacksonTypeHandler.class) private UserInfo info; private Integer status;
private String balance;
public List<AddressVo> addresses; }
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7.配置分页插件
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| package com.richu.iorichu1.Config;
import com.baomidou.mybatisplus.annotation.DbType; import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor; import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration;
@Configuration public class MybatisConfig {
@Bean public MybatisPlusInterceptor mybatisPlusInterceptor() { MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
PaginationInnerInterceptor paginationInnerInterceptor = new PaginationInnerInterceptor(DbType.MYSQL); paginationInnerInterceptor.setMaxLimit(1000L);
interceptor.addInnerInterceptor(paginationInnerInterceptor); return interceptor; } }
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实现复杂业务
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| @Override public PageDto<UserVo> pagelist(UserQuery query) { String name = query.getName(); Integer status = query.getStatus(); Page<User> page = Page.of(query.getPageNo(),query.getPageSize()); if (StrUtil.isNotBlank(query.getSortBy())){ page.addOrder(new OrderItem(query.getSortBy(),query.getIsAsc())); }else{ page.addOrder(new OrderItem("update_time",false)); } Page<User> pagelist = lambdaQuery().like(name != null,User::getUsername,name) .eq(status != null,User::getStatus,status) .page(page); PageDto<UserVo> dto = new PageDto<>(); dto.setPage((int) pagelist.getPages()); dto.setTotal((int) pagelist.getTotal()); if (CollUtil.isEmpty(pagelist.getRecords())){ dto.setList(Collections.emptyList()); return dto; } List<User> p = pagelist.getRecords(); dto.setList(BeanUtil.copyToList(p,UserVo.class)); return dto; }
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8.通用分页实体