微服务开发与实战Day01 - MyBatisPlus

本文主要是介绍微服务开发与实战Day01 - MyBatisPlus，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

一、微服务

概念：微服务是一种软件架构风格，它是以专注于单一职责的很多小型项目为基础，组合除复杂的大型应用。

课程安排：

https://www.bilibili.com/video/BV1S142197x7/?spm_id_from=333.1007.top_right_bar_window_history.content.click&vd_source=26bfae91aa8be97ba3634570e2041c28

二、MybatisPlus

MyBatis-Plus 🚀 为简化开发而生

1. 快速入门

1.1 入门案例

需求：基于课前资料提供的项目，实现下列功能：

• ①新增用户功能
• ②根据id查询用户
• ③根据id批量查询用户
• ④根据id更新用户
• ⑤根据id删除用户

(1)导入项目到IDEA

（2）执行SQL脚本

①启动SQL服务

②打开SQL命令行窗口，复制粘贴资料里的SQL脚本，执行

③在IDEA中打开数据库表

这里记得把项目中application.yaml中的数据库连接密码也改成自己的

（3）安装插件 - MyBatisx 

点击左侧的小鸟可以快速切换到XML文档

使用步骤：

1. 引入MyBatisPlus的起步依赖 - pom.xml

MyBatisPlus官方提供了starter，其中集成了MyBatis和MyBatisPlus的所有功能，并且实现了自动装配效果。因此，我们可以使用MyBatisPlus的starter代替MyBatis的starter：

<!--<dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>2.3.1</version>
</dependency>-->
<dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId><version>3.5.3.1</version>
</dependency>

2. 定义Mapper - userMapper.java

自定义的Mapper继承MyBatisPlus提供的BaseMapper，注意要指定泛形

package com.itheima.mp.mapper;import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.itheima.mp.domain.po.User;
import org.apache.ibatis.annotations.Mapper;@Mapper  // 不要忘记加上@Mapper注解
public interface UserMapper extends BaseMapper<User> {// ... ...   
}

如果在测试时遇到下面的问题，把pom.xml中的lombok依赖版本改为1.18.30(因为JDK22对应的lombok版本为1.18.30)

java: java.lang.NoSuchFieldError: Class com.sun.tools.javac.tree.JCTree$JCImport does not have member field 'com.sun.tools.javac.tree.JCTree qualid'

<dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.18.30</version>
</dependency>

3. 删除src/main/resources/mapper/UserMapper.xml里的内容如下

4. 把UserMapperTest.java改成如下，亲测全部测试通过

package com.itheima.mp.mapper;import com.itheima.mp.domain.po.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;import java.time.LocalDateTime;
import java.util.List;@SpringBootTest
class UserMapperTest {@Autowiredprivate UserMapper userMapper;@Testvoid testInsert() {User user = new User();user.setId(5L);user.setUsername("Lucy");user.setPassword("123");user.setPhone("18688990011");user.setBalance(200);user.setInfo("{\"age\": 24, \"intro\": \"英文老师\", \"gender\": \"female\"}");user.setCreateTime(LocalDateTime.now());user.setUpdateTime(LocalDateTime.now());userMapper.insert(user);}@Testvoid testSelectById() {User user = userMapper.selectById(5L);System.out.println("user = " + user);}@Testvoid testQueryByIds() {List<User> users = userMapper.selectBatchIds(List.of(1L, 2L, 3L, 4L));users.forEach(System.out::println);}@Testvoid testUpdateById() {User user = new User();user.setId(5L);user.setBalance(20000);userMapper.updateById(user);}@Testvoid testDeleteUser() {userMapper.deleteById(5L);}
}

1.2 常见注解

注解配置 | MyBatis-Plus

MyBatisPlus通过扫描实体类，并基于反射获取实体类信息作为数据库信息。

MyBatisPlus中比较常用的几个注解如下：

• @TableName：用来指定表名
• @TableId：用来指定表中的主键字段信息
• @TableField：用来指定表中的普通字段信息

1.3 常见配置

使用配置 | MyBatis-Plus

MyBatisPlus的配置项继承了MyBatis原生配置和一些自己特有的配置。例如：

①修改application.yaml

spring:datasource:url: jdbc:mysql://127.0.0.1:3306/mp?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&serverTimezone=Asia/Shanghaidriver-class-name: com.mysql.cj.jdbc.Driverusername: rootpassword: 123456
logging:level:com.itheima: debugpattern:dateformat: HH:mm:ss
mybatis-plus:type-aliases-package: com.itheima.mp.domain.poglobal-config:db-config:id-type: auto

2. 核心功能

2.1 条件构造器

MyBatisPlus支持各种复杂的where条件，可以满足日常开发的所有需求。

案例1：基于QueryWrapper的查询

需求：

①查询出名字中带o的，存款大于等于1000元的人的id、username、info、balance字段

SELECT id, username, info, balance
FROM user
WHERE username LIKE ? > AND balance >= ?

    // 基于QueryWrapper@Testvoid testQueryWrapper() {// 1. 构建查询条件QueryWrapper<User> wrapper = new QueryWrapper<User>().select("id", "username", "info", "balance").like("username", "o").ge("balance", 1000);List<User> users = userMapper.selectList(wrapper);users.forEach(System.out::println);}

    // 基于LambdaQueryWrapper@Testvoid testLambdaQueryWrapper() {// 1. 构建查询条件LambdaQueryWrapper<User> wrapper = new LambdaQueryWrapper<User>().select(User::getId, User::getUsername, User::getInfo, User::getBalance).like(User::getUsername, "o").ge(User::getBalance, 1000);List<User> users = userMapper.selectList(wrapper);users.forEach(System.out::println);}

②更新用户名为jack的用户的余额为2000

UPDATE userSET balance = 2000WHERE username = "jack"

    @Testvoid testUpdateByQueryWrapper() {// 1. 要更新的数据User user = new User();user.setBalance(2000);// 2. 更新的条件QueryWrapper<User> wrapper = new QueryWrapper<User>().eq("username", "jack");// 3. 执行更新userMapper.update(user, wrapper);}

案例2：基于UpdateWrapper的更新

需求：更新id为1，2，4的用户余额，扣200

UPDATE userSET balance = balance - 200WHERE id in (1, 2, 4)

    @Testvoid testUpdateWrapper() {List<Long> ids = List.of(1L, 2L, 4L);UpdateWrapper<User> wrapper = new UpdateWrapper<User>().setSql("balance = balance - 200").in("id", ids);userMapper.update(null, wrapper);}

总结

条件构造器的用法：

• QueryWrapper和LambdaQueryWrapper通常用来构建select、delete、update的where条件部分
• UpdateWrapper和LambdaUpdateWrapper通常只有在set语句比较特殊才使用
• 尽量使用LambdaQueryWrapper和LambdaUpdateWrapper，避免硬编码

2.2 自定义SQL

我们可以利用MyBatisPlus的Wrapper来构建复杂的Where条件，然后自己定义SQL语句中剩下的部分。

案例1：自定义SQL

需求：将id在指定范围内的用户（如1、2、4）的余额扣减指定值

①基于Wrapper构建where条件

②在mapper方法参数中用Param注解声明wrapper变量名称，必须是ew

③自定义SQL，并使用Wrapper条件

2.3 Service接口

使用示例：

①自定义service接口继承 IService接口

IUserService.java

package com.itheima.mp.service;import com.baomidou.mybatisplus.extension.service.IService;
import com.itheima.mp.domain.po.User;public interface IUserService extends IService<User> {
}

②自定义Service实现类，实现自定义接口并继承 ServiceImpl类

UserServiceImpl.java

package com.itheima.mp.service.impl;import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.itheima.mp.domain.po.User;
import com.itheima.mp.mapper.UserMapper;
import com.itheima.mp.service.IUserService;
import org.springframework.stereotype.Service;@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements IUserService {
}

IUserServiceTest.java

package com.itheima.mp.service;import com.itheima.mp.domain.po.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;import java.time.LocalDateTime;
import java.util.List;import static org.junit.jupiter.api.Assertions.*;@SpringBootTest
class IUserServiceTest {@Autowiredprivate IUserService userService;// 新增@Testvoid testSaveUser() {User user = new User();user.setUsername("Lily");user.setPassword("123");user.setPhone("18358995031");user.setBalance(20000);user.setInfo("{\"age\": 24, \"intro\": \"物理老师\", \"gender\": \"female\"}");user.setCreateTime(LocalDateTime.now());user.setUpdateTime(LocalDateTime.now());userService.save(user);}// 查询@Testvoid testQuery() {List<User> users = userService.listByIds((List.of(1L, 2L, 4L)));users.forEach(System.out::println);}}

案例1：基于Restful风格实现下列接口

需求：基于Restful风格实现下面的接口：

文档地址：Docs

①在项目中引入依赖 - pom.xml

<!--swagger-->
<dependency><groupId>com.github.xiaoymin</groupId><artifactId>knife4j-openapi2-spring-boot-starter</artifactId><version>4.1.0</version>
</dependency>
<!--web-->
<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId>
</dependency>

②配置swagger信息 - application.yaml

knife4j:enable: trueopenapi:title: 用户管理接口文档description: "用户管理接口文档"email: zhanghuyi@itcast.cnconcat: 虎哥url: https://www.itcast.cnversion: v1.0.0group:default:group-name: defaultapi-rule: packageapi-rule-resources:- com.itheima.mp.controller

③UserController.java

package com.itheima.mp.controller;import cn.hutool.core.bean.BeanUtil;
import com.itheima.mp.domain.dto.UserFormDTO;
import com.itheima.mp.domain.po.User;
import com.itheima.mp.domain.vo.UserVO;
import com.itheima.mp.service.IUserService;
import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
import io.swagger.annotations.ApiParam;
import lombok.RequiredArgsConstructor;
import org.springframework.web.bind.annotation.*;import java.util.List;@Api(tags = "用户管理接口")
@RequestMapping("/users")
@RestController
@RequiredArgsConstructor
public class UserController {private final IUserService userService;@ApiOperation("新增用户接口")@PostMappingpublic void saveUser(@RequestBody UserFormDTO userDTO) {// 1. 把DTO拷贝到PO（hutool）User user = BeanUtil.copyProperties(userDTO, User.class);// 新增userService.save(user);}@ApiOperation("删除用户接口")@DeleteMapping("{id}")public void deleteUserById(@ApiParam("用户id") @PathVariable("id") Long id) {userService.removeById(id);}@ApiOperation("根据id查询用户接口")@GetMapping("{id}")public UserVO queryUserById(@ApiParam("用户id") @PathVariable("id") Long id) {// 1. 查询用户POUser user = userService.getById(id);// 2. 把PO拷贝到VOreturn BeanUtil.copyProperties(user, UserVO.class);}@ApiOperation("根据id批量查询用户接口")@GetMappingpublic List<UserVO> queryUserByIds(@ApiParam("用户id集合") @RequestParam("ids") List<Long> ids) {// 1. 查询用户POList<User> users = userService.listByIds(ids);// 2. 把PO拷贝到VOreturn BeanUtil.copyToList(users, UserVO.class);}@ApiOperation("扣减用户余额接口")@PutMapping("/{id}/deduction/{money}")public void deductBalance(@ApiParam("用户id") @PathVariable("id") Long id,@ApiParam("扣减的金额") @PathVariable("money") Integer money) {userService.deductBalance(id, money);}
}

④IUserService.java

package com.itheima.mp.service;import com.baomidou.mybatisplus.extension.service.IService;
import com.itheima.mp.domain.po.User;public interface IUserService extends IService<User> {void deductBalance(Long id, Integer money);
}

⑤UserServiceImpl.java

package com.itheima.mp.service.impl;import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.itheima.mp.domain.po.User;
import com.itheima.mp.mapper.UserMapper;
import com.itheima.mp.service.IUserService;
import org.springframework.stereotype.Service;@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements IUserService {@Overridepublic void deductBalance(Long id, Integer money) {// 1. 查询用户User user = getById(id);// 2. 校验用户状态if(user == null || user.getStatus() == 2) {throw new RuntimeException("用户状态异常！");}// 3. 校验用户余额是否充足if(user.getBalance() < money) {throw new RuntimeException("用户余额不足！");}// 4. 扣减余额baseMapper.deductBalance(id, money);}
}

⑥UserMapper.java

package com.itheima.mp.mapper;import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.itheima.mp.domain.po.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Update;import java.util.List;@Mapper  // 不要忘记加上@Mapper注解
public interface UserMapper extends BaseMapper<User> {@Update("UPDATE tb_user SET balance = balance - #{money} WHERE id = #{id}")void deductBalance(@Param("ew") Long id, @Param("money") Integer money);
}

http://localhost:8080/doc.html#/home

案例2：IServiced的Lambda查询

需求：实现一个根据复杂条件查询用户的接口，查询条件如下：

• name：用户名关键字，可以为空
• status：用户状态，可以为空
• minBalance：最小余额，可以为空
• maxBalance：最大余额，可以为空

UserController.java

import com.itheima.mp.query.UserQuery;// ... ...@ApiOperation("根据复杂条件查询用户接口")@GetMapping("/list")public List<UserVO> queryUsers(UserQuery query) {// 1. 查询用户POList<User> users = userService.queryUsers(query.getName(), query.getStatus(), query.getMinBalance(), query.getMaxBalance());// 2. 把PO拷贝到VOreturn BeanUtil.copyToList(users, UserVO.class);}

UserQuery.java

package com.itheima.mp.query;import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;@Data
@ApiModel(description = "用户查询条件实体")
public class UserQuery {@ApiModelProperty("用户名关键字")private String name;@ApiModelProperty("用户状态：1-正常，2-冻结")private Integer status;@ApiModelProperty("余额最小值")private Integer minBalance;@ApiModelProperty("余额最大值")private Integer maxBalance;
}

IUserService.java

package com.itheima.mp.service;import com.baomidou.mybatisplus.extension.service.IService;
import com.itheima.mp.domain.po.User;import java.util.List;public interface IUserService extends IService<User> {List<User> queryUsers(String name, Integer status, Integer minBalance, Integer maxBalance);
}

UserServiceImpl.java

    @Overridepublic List<User> queryUsers(String name, Integer status, Integer minBalance, Integer maxBalance) {return lambdaQuery().like(name != null, User::getUsername, name).eq(status != null, User::getStatus, status).ge(minBalance != null, User::getBalance, minBalance).le(maxBalance != null, User::getBalance, maxBalance).list();}

案例2：IService的Lambda更新

需求：改造根据id修改用户余额的接口，要求如下

①完成对用户状态校验

②完成对用户余额校验

③如果扣减后余额为0，则将用户status修改为冻结状态

UserServiceImpl.java

    @Override@Transactionalpublic void deductBalance(Long id, Integer money) {// 1. 查询用户User user = getById(id);// 2. 校验用户状态if(user == null || user.getStatus() == 2) {throw new RuntimeException("用户状态异常！");}// 3. 校验用户余额是否充足if(user.getBalance() < money) {throw new RuntimeException("用户余额不足！");}// 4. 扣减余额// baseMapper.deductBalance(id, money);int remainBalance = user.getBalance() - money;lambdaUpdate().set(User::getBalance, remainBalance).set(remainBalance == 0, User::getStatus, 2).eq(User::getId, id).eq(User::getBalance, user.getBalance())  // 乐观锁.update();}

案例3：IService批量新增

需求：批量插入1万条用户数据，并作出对比：

• 普通for循环插入
• IService的批量插入

    private User buildUser(int i) {User user = new User();user.setUsername("user_" + i);user.setPassword("123");user.setPhone("" + (18688190000L + i));user.setBalance(2000);user.setInfo("{\"age\": 24, \"intro\": \"语文老师\", \"gender\": \"female\"}");user.setCreateTime(LocalDateTime.now());user.setUpdateTime(LocalDateTime.now());return user;}@Testvoid testSaveOneByOne() {long b = System.currentTimeMillis();for (int i = 1; i <= 100000; i++) {userService.save(buildUser(i));}long e = System.currentTimeMillis();System.out.println("耗时：" + (e - b));}@Testvoid testSaveBatch() {// 我们每次批量插入1000条件，插入100次，即10万条数据// 1. 准备一个容量为1000的集合List<User> list = new ArrayList<>(1000);long b = System.currentTimeMillis();for (int i = 1; i <= 100000; i++) {// 2. 添加一个userlist.add(buildUser(i));// 3. 每隔1000条批量插入一次if(i % 1000 == 0) {userService.saveBatch(list);// 4. 清空集合，准备下一批数据list.clear();}}long e = System.currentTimeMillis();System.out.println("耗时：" + (e - b));}

测试完记得删除测试数据

开启rewriteBatchedStatements=true参数  - application.yaml

spring:datasource:url: jdbc:mysql://127.0.0.1:3306/mp?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&serverTimezone=Asia/Shanghai&rewriteBatchedStatements=truedriver-class-name: com.mysql.cj.jdbc.Driverusername: rootpassword: 123456

3. 扩展功能

3.1 代码生成

代码生成器 | MyBatis-Plus

Mybatis X 插件 | MyBatis-Plus

MyBatisPlus插件装不了的直接进官网安装：MyBatisPlus - IntelliJ IDEs Plugin | Marketplace

①测试连接

②代码生成

注：在AddressServiceImpl里加上@Service注解

效果：

3.2 静态工具

案例1：静态工具查询

需求：

• ①改造根据id查询用户的接口，查询用户的同时，查询除用户对应的所有地址
• ②改造根据id批量查询用户的接口，查询用户的同时，查询出用户对应的所有地址

（1）改造根据id查询用户的接口，查询用户的同时，查询除用户对应的所有地址

出现service相互调用的情况。

①从Day01的资料里拷贝AddressVO.java到vo文件夹下，在UserVO.java中添加地址属性：

@ApiModelProperty("用户的收货地址")
private List<AddressVO> addresses;

②改写UserController.java下的 queryUserById方法

    @ApiOperation("根据id查询用户接口")@GetMapping("{id}")public UserVO queryUserById(@ApiParam("用户id") @PathVariable("id") Long id) {return userService.queryUserAndAddressById(id);}

③IUserService.java

UserVO queryUserAndAddressById(Long id);

④UserServiceImpl.java

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.collection.CollUtil;
import com.baomidou.mybatisplus.extension.toolkit.Db;// ... ...   @Overridepublic UserVO queryUserAndAddressById(Long id) {// 1. 查询用户User user = getById(id);if(user == null || user.getStatus() == 2) {throw new RuntimeException("用户状态异常!");}// 2. 查询地址List<Address> addresses = Db.lambdaQuery(Address.class).eq(Address::getUserId, id).list();// 3. 封装VO// 3.1 转User的PO为VOUserVO userVO = BeanUtil.copyProperties(user, UserVO.class);// 3.2 转地址VOif(CollUtil.isNotEmpty(addresses)) {userVO.setAddresses(BeanUtil.copyToList(addresses, AddressVO.class));}return userVO;}

（2）改造根据id批量查询用户的接口，查询用户的同时，查询出用户对应的所有地址

①UserController.java

    @ApiOperation("根据id批量查询用户接口")@GetMappingpublic List<UserVO> queryUserByIds(@ApiParam("用户id集合") @RequestParam("ids") List<Long> ids) {return userService.queryUserAndAddressByIds(ids);}

②IUserService.java

List<UserVO> queryUserAndAddressByIds(List<Long> ids);

③UserServiceImpl.java

    @Overridepublic List<UserVO> queryUserAndAddressByIds(List<Long> ids) {// 1. 查询用户List<User> users = listByIds(ids);if(CollUtil.isEmpty(users)) {return Collections.emptyList();}// 2. 查询地址// 2.1 获取用户id集合List<Long> userIds = users.stream().map(User::getId).collect(Collectors.toList());// 2.2 根据用户id查询地址List<Address> addresses = Db.lambdaQuery(Address.class).in(Address::getUserId, userIds).list();// 2.3 转换地址voList<AddressVO> addressVOList = BeanUtil.copyToList(addresses, AddressVO.class);// 2.4 用户地址集合分组处理，相同用户的放入一个集合（组）中Map<Long, List<AddressVO>> addressMap = new HashMap<>(0);if(CollUtil.isNotEmpty(addressVOList)) {addressMap = addressVOList.stream().collect(Collectors.groupingBy(AddressVO::getUserId));}// 3. 转VO返回List<UserVO> list = new ArrayList<>(users.size());for (User user : users) {// 3.1 转换user的po为voUserVO vo = BeanUtil.copyProperties(user, UserVO.class);list.add(vo);// 3.2 转换地址vovo.setAddresses(addressMap.get(user.getId()));}return list;}

3.3 逻辑删除

逻辑删除就是基于代码逻辑模拟删除效果，但并不会真正删除数据。思路如下：

• 在表中添加一个字段标记数据是否被删除
• 当删除数据时把标记置为1
• 查询时只查询标记为0的数据

例如，逻辑删除字段为deleted：

• 删除操作：

UPDATE user SET deleted = 1 WHERE id = 1 AND deleted = 0

• 查询操作：

SELECT * FROM user WHERE deleted = 0

MyBatisPlus提供了逻辑删除功能，无需改变方法调应的方式，而是在底层帮我们自动修改CRUD的语句。我们要做的就是在application.yaml文件中配置逻辑删除的字段名称和值即可：

mybatis-plus:global-config:db-config:id-type: autologic-delete-field: deleted  # 全局逻辑删除的实体字段名，字段类型可以是boolean、integerlogic-delete-value: 1  # 逻辑已删除值（默认为1）logic-not-delete-value: 0  # 逻辑未删除值（默认为0）

IAddressServiceTest.java

package com.itheima.mp.service;import com.itheima.mp.domain.po.Address;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;import static org.junit.jupiter.api.Assertions.*;@SpringBootTest
class IAddressServiceTest {@Autowiredprivate IAddressService addressService;@Testvoid testLogicDelete() {// 1. 删除addressService.removeById(59L);// 2. 查询Address address = addressService.getById(59L);System.out.println("address = " + address);  // null}
}

注意：逻辑删除本身也有自己的问题，比如：

• 会导致数据库表垃圾数据越来越多，影响查询效率
• SQL中全都需要对逻辑删除字段做判断，影响查询效率

因此，不太推荐采用逻辑删除功能，如果数据不能删除，可以采用把数据迁移到其他表的方法。

3.4 枚举处理器

User类中有一个用户状态字段：

通用枚举

在application.yaml中配置全局枚举处理器，实现类型转换：

mybatis-plus:type-aliases-package: com.itheima.mp.domain.poconfiguration:default-enum-type-handler: com.baomidou.mybatisplus.core.handlers.MybatisEnumTypeHandler

UserStatus.java

package com.itheima.mp.enums;import com.baomidou.mybatisplus.annotation.EnumValue;
import com.fasterxml.jackson.annotation.JsonValue;
import lombok.Getter;@Getter
public enum UserStatus {NORMAL(1, "正常"),FROZEN(2, "冻结"),;@EnumValueprivate final int value;@JsonValueprivate final String desc;UserStatus(int value, String desc) {this.value = value;this.desc = desc;}
}

User.java

import com.itheima.mp.enums.UserStatus;/*** 账户余额*/private UserStatus balance;

UserVO.java

@ApiModelProperty("使用状态（1正常 2冻结）")
private UserStatus status;

把用到账户状态值的地方改成枚举变量 - UserServiceImpl.java

package com.itheima.mp.service.impl;import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.collection.CollUtil;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.baomidou.mybatisplus.extension.toolkit.Db;
import com.itheima.mp.domain.po.Address;
import com.itheima.mp.domain.po.User;
import com.itheima.mp.domain.vo.AddressVO;
import com.itheima.mp.domain.vo.UserVO;
import com.itheima.mp.enums.UserStatus;
import com.itheima.mp.mapper.UserMapper;
import com.itheima.mp.service.IUserService;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;import java.util.*;
import java.util.stream.Collectors;@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements IUserService {@Override@Transactionalpublic void deductBalance(Long id, Integer money) {// 1. 查询用户User user = getById(id);// 2. 校验用户状态if (user == null || user.getStatus() == UserStatus.FROZEN) {throw new RuntimeException("用户状态异常！");}// 3. 校验用户余额是否充足if (user.getBalance() < money) {throw new RuntimeException("用户余额不足！");}// 4. 扣减余额// baseMapper.deductBalance(id, money);int remainBalance = user.getBalance() - money;lambdaUpdate().set(User::getBalance, remainBalance).set(remainBalance == 0, User::getStatus, UserStatus.FROZEN).eq(User::getId, id).eq(User::getBalance, user.getBalance())  // 乐观锁.update();}@Overridepublic List<User> queryUsers(String name, Integer status, Integer minBalance, Integer maxBalance) {return lambdaQuery().like(name != null, User::getUsername, name).eq(status != null, User::getStatus, status).ge(minBalance != null, User::getBalance, minBalance).le(maxBalance != null, User::getBalance, maxBalance).list();}@Overridepublic UserVO queryUserAndAddressById(Long id) {// 1. 查询用户User user = getById(id);if(user == null || user.getStatus() == UserStatus.FROZEN) {throw new RuntimeException("用户状态异常!");}// 2. 查询地址List<Address> addresses = Db.lambdaQuery(Address.class).eq(Address::getUserId, id).list();// 3. 封装VO// 3.1 转User的PO为VOUserVO userVO = BeanUtil.copyProperties(user, UserVO.class);// 3.2 转地址VOif(CollUtil.isNotEmpty(addresses)) {userVO.setAddresses(BeanUtil.copyToList(addresses, AddressVO.class));}return userVO;}@Overridepublic List<UserVO> queryUserAndAddressByIds(List<Long> ids) {// 1. 查询用户List<User> users = listByIds(ids);if(CollUtil.isEmpty(users)) {return Collections.emptyList();}// 2. 查询地址// 2.1 获取用户id集合List<Long> userIds = users.stream().map(User::getId).collect(Collectors.toList());// 2.2 根据用户id查询地址List<Address> addresses = Db.lambdaQuery(Address.class).in(Address::getUserId, userIds).list();// 2.3 转换地址voList<AddressVO> addressVOList = BeanUtil.copyToList(addresses, AddressVO.class);// 2.4 用户地址集合分组处理，相同用户的放入一个集合（组）中Map<Long, List<AddressVO>> addressMap = new HashMap<>(0);if(CollUtil.isNotEmpty(addressVOList)) {addressMap = addressVOList.stream().collect(Collectors.groupingBy(AddressVO::getUserId));}// 3. 转VO返回List<UserVO> list = new ArrayList<>(users.size());for (User user : users) {// 3.1 转换user的po为voUserVO vo = BeanUtil.copyProperties(user, UserVO.class);list.add(vo);// 3.2 转换地址vovo.setAddresses(addressMap.get(user.getId()));}return list;}
}

总结：

如何实现PO类中的枚举类型变量与数据库字段的转换？

①给枚举中的与数据库对应value值添加@EnumValue注解

②在配置文件中配置统一的枚举处理器，实现类型转换。

3.5 JSON处理器

①userInfo.java

package com.itheima.mp.domain.po;import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;@Data
@NoArgsConstructor
@AllArgsConstructor(staticName = "of")
public class UserInfo {private Integer age;private String intro;private String gender;
}

②User.java

package com.itheima.mp.domain.po;import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import com.baomidou.mybatisplus.extension.handlers.JacksonTypeHandler;
import com.itheima.mp.enums.UserStatus;
import lombok.Data;import java.time.LocalDateTime;@Data
@TableName(value = "tb_user", autoResultMap = true)
public class User {// ... .../*** 详细信息*/@TableField(typeHandler = JacksonTypeHandler.class)private UserInfo info;// ... ...
}

③设置用户信息改成

// user.setInfo("{\"age\": 24, \"intro\": \"英文老师\", \"gender\": \"female\"}");
user.setInfo(UserInfo.of(24,"英文老师","female"));

④UserVO.java

@ApiModelProperty("详细信息")
private UserInfo info;

⑤UserFormDTO.java

@ApiModelProperty("详细信息，JSON风格")
private UserInfo info;

如果有出现下面的问题，把UserMapper.xml里的SQL语句改成如下，删除parameterType="com.itheima.mp.domain.po.User"

    <insert id="saveUser">INSERT INTO `tb_user` (`id`, `username`, `password`, `phone`, `info`, `balance`)VALUES (#{id}, #{username}, #{password}, #{phone}, #{info}, #{balance});</insert>

4. 插件功能

MyBatisPlus提供的内置拦截器有下面这些：

拦截器	描述
TenantLineInnerInterceptor	多租户插件
DynamicTableNameInnerInterceptor	动态表名插件
PaginationInnerInterceptor	分页插件
OptimisticLockerInnerInterceptor	乐观锁插件
IllegalSQLInnerInterceptor	SQL性能规范插件，检测并拦截垃圾SQL
BlockAttackInnerInterceptor	防止全表更新和删除的插件

4.1 分页插件

①在配置类中注册MyBatisPlus的核心插件，同时添加分页插件：

package com.itheima.mp.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 {@Beanpublic MybatisPlusInterceptor mybatisPlusInterceptor() {MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();// 1. 创建分页插件PaginationInnerInterceptor paginationInnerInterceptor = new PaginationInnerInterceptor(DbType.MYSQL);paginationInnerInterceptor.setMaxLimit(1000L);  // 设置分页上限// 2. 添加分页插件interceptor.addInnerInterceptor(paginationInnerInterceptor);return interceptor;}
}

②使用分页的API

IUserServiceTest.java

    @Testvoid testPageQuery() {int pageNo = 1, pageSize = 2;// 1. 准备分页条件// 1.1 分页条件Page<User> page = Page.of(pageNo, pageSize);// 1.2 排序条件page.addOrder(new OrderItem("balance", true));page.addOrder(new OrderItem("id", true));// 2. 分页查询Page<User> p = userService.page(page);// 3. 解析long total = p.getTotal();System.out.println("total = " + total);long pages = p.getPages();System.out.println("pages = " + pages);List<User> users = p.getRecords();users.forEach(System.out::println);}

4.2 通用分页实体

案例1：简单分页查询案例

需求：遵循下面的接口规范，编写一个UserController接口，实现User的分页查询

①PageQuery.java

package com.itheima.mp.query;import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;@Data
@ApiModel(description = "分页查询实体")
public class PageQuery {@ApiModelProperty("页码")private Integer pageNo;@ApiModelProperty("页大小")private Integer pageSize;@ApiModelProperty("排序字段")private String sortBy;@ApiModelProperty("是否升序")private Boolean isAsc;
}

②UserQuery继承PageQuery

package com.itheima.mp.query;import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;
import lombok.EqualsAndHashCode;@EqualsAndHashCode(callSuper = true)
@Data
@ApiModel(description = "用户查询条件实体")
public class UserQuery extends PageQuery{@ApiModelProperty("用户名关键字")private String name;@ApiModelProperty("用户状态：1-正常，2-冻结")private Integer status;@ApiModelProperty("余额最小值")private Integer minBalance;@ApiModelProperty("余额最大值")private Integer maxBalance;
}

③PageDTO.java

package com.itheima.mp.domain.dto;import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;import java.util.List;@Data
@ApiModel(description = "分页结果")
public class PageDTO<T> {@ApiModelProperty("总条数")private Long total;@ApiModelProperty("总页数")private Long pages;@ApiModelProperty("集合")private List<T> list;
}

④UserController.java

    @ApiOperation("根据复杂条件分页查询用户接口")@GetMapping("/page")public PageDTO<UserVO> queryUsersPage(UserQuery query) {return userService.queryUsersPage(query);}

⑤IUserService.java

PageDTO<UserVO> queryUsersPage(UserQuery query);

⑥UserSeerviceImpl.java

package com.itheima.mp.service.impl;import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.collection.CollUtil;
import cn.hutool.core.util.StrUtil;
import com.baomidou.mybatisplus.core.metadata.OrderItem;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.baomidou.mybatisplus.extension.toolkit.Db;
import com.itheima.mp.domain.dto.PageDTO;
import com.itheima.mp.domain.po.Address;
import com.itheima.mp.domain.po.User;
import com.itheima.mp.domain.vo.AddressVO;
import com.itheima.mp.domain.vo.UserVO;
import com.itheima.mp.enums.UserStatus;
import com.itheima.mp.mapper.UserMapper;
import com.itheima.mp.query.UserQuery;
import com.itheima.mp.service.IUserService;
import org.springframework.stereotype.Service;import java.util.*;
import java.util.stream.Collectors;@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements IUserService {// ... ...@Overridepublic PageDTO<UserVO> queryUsersPage(UserQuery query) {String name = query.getName();Integer status = query.getStatus();Integer minBalance = query.getMinBalance();Integer maxBalance = query.getMaxBalance();// 1. 构建查询条件// 1.1 分页条件Page<User> page = Page.of(query.getPageNo(), query.getPageSize());// 1.2 排序条件if(StrUtil.isNotBlank(query.getSortBy())) {// 排序字段不为空，按照排序字段排序page.addOrder(new OrderItem(query.getSortBy(), query.getIsAsc()));} else {// 排序字段为空，默认按照更新时间排序page.addOrder(new OrderItem("update_time", false));}// 2. 分页查询Page<User> p = lambdaQuery().like(name != null, User::getUsername, name).eq(status != null, User::getStatus, status).ge(minBalance != null, User::getBalance, minBalance).le(maxBalance != null, User::getBalance, maxBalance).page(page);// 3. 封装VO结果PageDTO<UserVO> dto = new PageDTO<>();// 3.1 总条数dto.setTotal(p.getTotal());// 3.2 总页数dto.setPages(p.getPages());// 3.3 当前页数据List<User> records = p.getRecords();if(CollUtil.isEmpty(records)) {dto.setList(Collections.emptyList());return dto;}// 3.4 拷贝user的VOdto.setList(BeanUtil.copyToList(records, UserVO.class));// 4. 返回return dto;}
}

案例2：通用分页实体

需求：

• 在PageQuery中定义方法，将PageQuery对象转为MyBatisPlus中的page对象
• 在PageDTO中定义方法，将MyBatisPlus中的Page结果转为PageDTO结果

①PageQuery.java

package com.itheima.mp.query;import cn.hutool.core.util.StrUtil;
import com.baomidou.mybatisplus.core.metadata.OrderItem;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.itheima.mp.domain.po.User;
import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;@Data
@ApiModel(description = "分页查询实体")
public class PageQuery {@ApiModelProperty("页码")private Integer pageNo = 1;@ApiModelProperty("页大小")private Integer pageSize = 5;@ApiModelProperty("排序字段")private String sortBy;@ApiModelProperty("是否升序")private Boolean isAsc = true;public <T> Page<T> toMpPage(OrderItem ... items) {// 1 分页条件Page<T> page = Page.of(pageNo, pageSize);// 2 排序条件if(StrUtil.isNotBlank(sortBy)) {// 排序字段不为空，按照排序字段排序page.addOrder(new OrderItem(sortBy, isAsc));} else if(items != null) {// 排序字段为空，默认排序page.addOrder(items);}return page;}public <T> Page<T> toMpPage(String defaultSortBy, Boolean defaultAsc) {return toMpPage(new OrderItem(defaultSortBy, defaultAsc));}public <T> Page<T> toMpPageDefaultSortByCreateTime() {return toMpPage(new OrderItem("create_time", false));}public <T> Page<T> toMpPageDefaultSortByUpdateTime() {return toMpPage(new OrderItem("update_time", false));}
}

②PageDTO.java

package com.itheima.mp.domain.dto;import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.collection.CollUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.itheima.mp.domain.po.User;
import com.itheima.mp.domain.vo.UserVO;
import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;import java.util.Collections;
import java.util.List;
import java.util.function.Function;
import java.util.stream.Collectors;@Data
@ApiModel(description = "分页结果")
public class PageDTO<T> {@ApiModelProperty("总条数")private Long total;@ApiModelProperty("总页数")private Long pages;@ApiModelProperty("集合")private List<T> list;public static <PO, VO> PageDTO<VO> of(Page<PO> p, Class<VO> clazz) {PageDTO<VO> dto = new PageDTO<>();// 1 总条数dto.setTotal(p.getTotal());// 2 总页数dto.setPages(p.getPages());// 3 当前页数据List<PO> records = p.getRecords();if(CollUtil.isEmpty(records)) {dto.setList(Collections.emptyList());return dto;}// 4 拷贝user的VOdto.setList(BeanUtil.copyToList(records, clazz));// 5. 返回return dto;}public static <PO, VO> PageDTO<VO> of(Page<PO> p, Function<PO, VO> convertor) {PageDTO<VO> dto = new PageDTO<>();// 1 总条数dto.setTotal(p.getTotal());// 2 总页数dto.setPages(p.getPages());// 3 当前页数据List<PO> records = p.getRecords();if(CollUtil.isEmpty(records)) {dto.setList(Collections.emptyList());return dto;}// 4 拷贝user的VOdto.setList(records.stream().map(convertor).collect(Collectors.toList()));// 5. 返回return dto;}
}

③UserServiceImpl.java

package com.itheima.mp.service.impl;import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.collection.CollUtil;
import cn.hutool.core.util.StrUtil;
import com.baomidou.mybatisplus.core.metadata.OrderItem;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.baomidou.mybatisplus.extension.toolkit.Db;
import com.itheima.mp.domain.dto.PageDTO;
import com.itheima.mp.domain.po.Address;
import com.itheima.mp.domain.po.User;
import com.itheima.mp.domain.vo.AddressVO;
import com.itheima.mp.domain.vo.UserVO;
import com.itheima.mp.enums.UserStatus;
import com.itheima.mp.mapper.UserMapper;
import com.itheima.mp.query.UserQuery;
import com.itheima.mp.service.IUserService;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;import java.util.*;
import java.util.stream.Collectors;@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements IUserService {@Overridepublic List<UserVO> queryUserAndAddressByIds(List<Long> ids) {// 1. 查询用户List<User> users = listByIds(ids);if(CollUtil.isEmpty(users)) {return Collections.emptyList();}// 2. 查询地址// 2.1 获取用户id集合List<Long> userIds = users.stream().map(User::getId).collect(Collectors.toList());// 2.2 根据用户id查询地址List<Address> addresses = Db.lambdaQuery(Address.class).in(Address::getUserId, userIds).list();// 2.3 转换地址voList<AddressVO> addressVOList = BeanUtil.copyToList(addresses, AddressVO.class);// 2.4 用户地址集合分组处理，相同用户的放入一个集合（组）中Map<Long, List<AddressVO>> addressMap = new HashMap<>(0);if(CollUtil.isNotEmpty(addressVOList)) {addressMap = addressVOList.stream().collect(Collectors.groupingBy(AddressVO::getUserId));}// 3. 转VO返回List<UserVO> list = new ArrayList<>(users.size());for (User user : users) {// 3.1 转换user的po为voUserVO vo = BeanUtil.copyProperties(user, UserVO.class);list.add(vo);// 3.2 转换地址vovo.setAddresses(addressMap.get(user.getId()));}return list;}@Overridepublic PageDTO<UserVO> queryUsersPage(UserQuery query) {String name = query.getName();Integer status = query.getStatus();Integer minBalance = query.getMinBalance();Integer maxBalance = query.getMaxBalance();// 1. 构建查询条件Page<User> page = query.toMpPageDefaultSortByUpdateTime();// 2. 分页查询Page<User> p = lambdaQuery().like(name != null, User::getUsername, name).eq(status != null, User::getStatus, status).ge(minBalance != null, User::getBalance, minBalance).le(maxBalance != null, User::getBalance, maxBalance).page(page);// 3. 封装VO结果// return PageDTO.of(p, UserVO.class);// return PageDTO.of(p, user -> BeanUtil.copyProperties(user, UserVO.class));return PageDTO.of(p, user -> {// 1. 拷贝基础属性UserVO vo = BeanUtil.copyProperties(user, UserVO.class);// 2. 处理特殊逻辑vo.setUsername(vo.getUsername().substring(0, vo.getUsername().length() - 2) + "**");return vo;});}
}

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