Reactor 响应式编程（第三篇：R2DBC）

系列文章目录

Reactor 响应式编程（第一篇：Reactor核心）
Reactor 响应式编程（第二篇：Spring Webflux）
Reactor 响应式编程（第三篇：R2DBC）
Reactor 响应式编程（第四篇：Spring Security Reactive）

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1. R2DBC 介绍

Web、网络、IO（存储）、中间件（Redis、MySQL）

应用开发：

• 网络
• 存储：MySQL、Redis
• Web：Webflux
• 前端； 后端：Controller – Service – Dao（r2dbc；mysql）

数据库：

• 导入驱动：以前：JDBC（jdbc、各大驱动mysql-connector）； 现在：r2dbc（r2dbc-spi、各大驱动 r2dbc-mysql）
• 驱动
  • 获取连接
  • 发送SQL、执行
  • 封装数据库返回结果

今日任务：

• r2dbc原生API
• boot整合spring data r2dbc：spring-boot-starter-data-r2dbc
• 三大组件：R2dbcRepository、R2dbcEntityTemplate 、DatabaseClient
• RBAC权限模型导入，基础CRUD练习；SQL文件在附录
• 1-1，1-N 关系处理；
• 扩展：导入接口文档进行测试： 访问 项目/doc.html

<dependency><groupId>org.springdoc</groupId><artifactId>springdoc-openapi-starter-webflux-ui</artifactId><version>2.0.2</version>
</dependency>
<dependency><groupId>com.github.xiaoymin</groupId><artifactId>knife4j-openapi3-ui</artifactId><version>4.0.0</version>
</dependency>

用法：

• 导入驱动: 导入连接池（r2dbc-pool）、导入驱动（r2dbc-mysql ）
• 使用驱动提供的API操作

        <dependency><groupId>io.asyncer</groupId><artifactId>r2dbc-mysql</artifactId><version>1.0.5</version></dependency>

        //0、MySQL配置MySqlConnectionConfiguration configuration = MySqlConnectionConfiguration.builder().host("localhost").port(3306).username("root").password("123456").database("test").build();//1、获取连接工厂MySqlConnectionFactory connectionFactory = MySqlConnectionFactory.from(configuration);//2、获取到连接，发送sql// JDBC： Statement： 封装sql的//3、数据发布者Mono.from(connectionFactory.create()).flatMapMany(connection ->connection.createStatement("select * from t_author where id=?id and name=?name").bind("id",1L) //具名参数.bind("name","张三").execute()).flatMap(result -> {return result.map(readable -> {Long id = readable.get("id", Long.class);String name = readable.get("name", String.class);return new TAuthor(id, name);});}).subscribe(tAuthor -> System.out.println("tAuthor = " + tAuthor));

2. Spring Data R2DBC

2.1 整合

2.1.1 导入依赖

        <!-- https://mvnrepository.com/artifact/io.asyncer/r2dbc-mysql --><dependency><groupId>io.asyncer</groupId><artifactId>r2dbc-mysql</artifactId><version>1.0.5</version></dependency><!--        响应式 Spring Data R2dbc--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-r2dbc</artifactId></dependency>

2.1.2 编写配置

spring:r2dbc:password: 123456username: rooturl: r2dbc:mysql://localhost:3306/testname: test

2.2 声明式接口：R2dbcRepository

2.2.1 Repository接口

@Repository
public interface AuthorRepositories extends R2dbcRepository<TAuthor,Long> {//默认继承了一堆CRUD方法； 像mybatis-plus//QBC： Query By Criteria//QBE： Query By Example//成为一个起名工程师  where id In () and name like ?//仅限单表复杂条件查询Flux<TAuthor> findAllByIdInAndNameLike(Collection<Long> id, String name);//多表复杂查询@Query("select * from t_author") //自定义query注解，指定sql语句Flux<TAuthor> findHaha();// 1-1：关联// 1-N：关联//场景：// 1、一个图书有唯一作者； 1-1// 2、一个作者可以有很多图书： 1-N
}

2.2.2 自定义Converter

package com.atguigu.r2dbc.config.converter;import com.atguigu.r2dbc.entity.TAuthor;
import com.atguigu.r2dbc.entity.TBook;
import io.r2dbc.spi.Row;
import org.springframework.core.convert.converter.Converter;
import org.springframework.data.convert.ReadingConverter;import java.time.Instant;/*** @author lfy* @Description* @create 2023-12-23 22:04** 告诉Spring Data 怎么封装Book对象*/
@ReadingConverter //读取数据库数据的时候,把row转成 TBook
public class BookConverter implements Converter<Row, TBook> {@Overridepublic TBook convert(Row source) {if(source == null) return null;//自定义结果集的封装TBook tBook = new TBook();tBook.setId(source.get("id", Long.class));tBook.setTitle(source.get("title", String.class));Long author_id = source.get("author_id", Long.class);tBook.setAuthorId(author_id);//        tBook.setPublishTime(source.get("publish_time", Instant.class));TAuthor tAuthor = new TAuthor();tAuthor.setId(author_id);tAuthor.setName(source.get("name", String.class));tBook.setAuthor(tAuthor);return null;}
}

2.2.3 配置生效

@EnableR2dbcRepositories //开启 R2dbc 仓库功能；jpa
@Configuration
public class R2DbcConfiguration {@Bean //替换容器中原来的@ConditionalOnMissingBeanpublic R2dbcCustomConversions conversions(){//把我们的转换器加入进去； 效果新增了我们的 Converterreturn R2dbcCustomConversions.of(MySqlDialect.INSTANCE,new BookConverter());}
}

2.3 编程式组件

• R2dbcEntityTemplate
• DatabaseClient

3. RBAC-SQL练习

3.1 1-1

自定义 Converter<Row，Bean> 方式

    @BeanR2dbcCustomConversions r2dbcCustomConversions(){List<Converter<?, ?>> converters = new ArrayList<>();converters.add(new BookConverter());return R2dbcCustomConversions.of(MySqlDialect.INSTANCE, converters);}//1-1： 结合自定义 Converter
bookRepostory.hahaBook(1L).subscribe(tBook -> System.out.println("tBook = " + tBook));

编程式封装方式: 使用DatabaseClient

//1-1：第二种方式
databaseClient.sql("select b.*,t.name as name from t_book b " +"LEFT JOIN t_author t on b.author_id = t.id " +"WHERE b.id = ?").bind(0, 1L).fetch().all().map(row-> {String id = row.get("id").toString();String title = row.get("title").toString();String author_id = row.get("author_id").toString();String name = row.get("name").toString();TBook tBook = new TBook();tBook.setId(Long.parseLong(id));tBook.setTitle(title);TAuthor tAuthor = new TAuthor();tAuthor.setName(name);tAuthor.setId(Long.parseLong(author_id));tBook.setAuthor(tAuthor);return tBook;}).subscribe(tBook -> System.out.println("tBook = " + tBook));

3.2 1-N

使用底层API DatabaseClient；

    @Testvoid oneToN() throws IOException {//        databaseClient.sql("select a.id aid,a.name,b.* from t_author a  " +
//                "left join t_book b on a.id = b.author_id " +
//                "order by a.id")
//                .fetch()
//                .all(row -> {
//
//                })// 1~6// 1：false 2：false 3:false 4: true 8:true 5:false 6:false 7:false 8:true 9:false 10:false// [1,2,3]// [4,8]// [5,6,7]// [8]// [9,10]// bufferUntilChanged：// 如果下一个判定值比起上一个发生了变化就开一个新buffer保存，如果没有变化就保存到原buffer中//        Flux.just(1,2,3,4,8,5,6,7,8,9,10)
//                .bufferUntilChanged(integer -> integer%4==0 )
//                .subscribe(list-> System.out.println("list = " + list));; //自带分组Flux<TAuthor> flux = databaseClient.sql("select a.id aid,a.name,b.* from t_author a  " +"left join t_book b on a.id = b.author_id " +"order by a.id").fetch().all().bufferUntilChanged(rowMap -> Long.parseLong(rowMap.get("aid").toString())).map(list -> {TAuthor tAuthor = new TAuthor();Map<String, Object> map = list.get(0);tAuthor.setId(Long.parseLong(map.get("aid").toString()));tAuthor.setName(map.get("name").toString());//查到的所有图书List<TBook> tBooks = list.stream().map(ele -> {TBook tBook = new TBook();tBook.setId(Long.parseLong(ele.get("id").toString()));tBook.setAuthorId(Long.parseLong(ele.get("author_id").toString()));tBook.setTitle(ele.get("title").toString());return tBook;}).collect(Collectors.toList());tAuthor.setBooks(tBooks);return tAuthor;});//Long 数字缓存 -127 - 127；// 对象比较需要自己写好equals方法flux.subscribe(tAuthor -> System.out.println("tAuthor = " + tAuthor));System.in.read();}

4. 最佳实践

最佳实践： 提升生产效率的做法

• Spring Data R2DBC，基础的CRUD用 R2dbcRepository 提供好了
• 自定义复杂的SQL（单表）： @Query；
• 多表查询复杂结果集： DatabaseClient 自定义SQL及结果封装；
  • @Query + 自定义 Converter 实现结果封装

经验：

• 1-1:1-N 关联关系的封装都需要自定义结果集的方式
  • Spring Data R2DBC：
    • 自定义Converter指定结果封装
    • DatabaseClient：贴近底层的操作进行封装; 见下面代码
  • MyBatis： 自定义 ResultMap 标签去来封装

        databaseClient.sql("select b.*,t.name as name from t_book b " +"LEFT JOIN t_author t on b.author_id = t.id " +"WHERE b.id = ?").bind(0, 1L).fetch().all().map(row-> {String id = row.get("id").toString();String title = row.get("title").toString();String author_id = row.get("author_id").toString();String name = row.get("name").toString();TBook tBook = new TBook();tBook.setId(Long.parseLong(id));tBook.setTitle(title);TAuthor tAuthor = new TAuthor();tAuthor.setName(name);tAuthor.setId(Long.parseLong(author_id));tBook.setAuthor(tAuthor);return tBook;}).subscribe(tBook -> System.out.println("tBook = " + tBook));

5. 附录

RBAC SQL文件

-- 用户表
DROP TABLE IF EXISTS `t_user`;
CREATE TABLE `t_user`(`id` bigint(20) NOT NULL AUTO_INCREMENT,`username` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL COMMENT '用户名',`password` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL COMMENT '密码',`email` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL COMMENT '邮箱',`phone` char(11) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL COMMENT '电话',`create_time` datetime(0) NOT NULL COMMENT '创建时间',`update_time` datetime(0) NOT NULL COMMENT '更新时间',PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB  CHARACTER SET = utf8mb4 COLLATE = utf8mb4_0900_ai_ci ROW_FORMAT = Dynamic;-- 角色表
DROP TABLE IF EXISTS `t_roles`;
CREATE TABLE `t_roles`(`id` bigint(20) NOT NULL AUTO_INCREMENT,`name` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL COMMENT '角色名',`value` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL COMMENT '角色的英文名',`create_time` datetime(0) NOT NULL,`update_time` datetime(0) NOT NULL,PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB  CHARACTER SET = utf8mb4 COLLATE = utf8mb4_0900_ai_ci ROW_FORMAT = Dynamic;-- 权限表（资源表）
DROP TABLE IF EXISTS `t_perm`;
CREATE TABLE `t_perm`(`id` bigint(20) NOT NULL AUTO_INCREMENT,`value` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL COMMENT '权限字段',`uri` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL COMMENT '资源路径',`description` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL COMMENT '资源描述',`create_time` datetime(0) NOT NULL,`update_time` datetime(0) NOT NULL,PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB  CHARACTER SET = utf8mb4 COLLATE = utf8mb4_0900_ai_ci ROW_FORMAT = Dynamic;-- 用户角色关系表
DROP TABLE IF EXISTS `t_user_role`;
CREATE TABLE `t_user_role`(`id` bigint(20) NOT NULL AUTO_INCREMENT,`user_id` bigint(20) NOT NULL,`role_id` bigint(20) NOT NULL,`create_time` datetime(0) NOT NULL,`update_time` datetime(0) NOT NULL,PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB  CHARACTER SET = utf8mb4 COLLATE = utf8mb4_0900_ai_ci ROW_FORMAT = Dynamic;-- 角色权限关系表
DROP TABLE IF EXISTS `t_role_perm`;
CREATE TABLE `t_role_perm`(`id` bigint(20) NOT NULL AUTO_INCREMENT,`role_id` bigint(20) NOT NULL,`perm_id` bigint(20) NOT NULL,`create_time` datetime(0) NOT NULL,`update_time` datetime(0) NOT NULL,PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_0900_ai_ci ROW_FORMAT = Dynamic;-- 图书&作者表
CREATE TABLE `t_book`(`id` bigint(20) NOT NULL AUTO_INCREMENT,`title` varchar(255) NOT NULL,`author_id` bigint(20) NOT NULL,`publish_time` datetime(0) NOT NULL,PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_0900_ai_ci ROW_FORMAT = Dynamic;CREATE TABLE `t_author`(`id` bigint(20) NOT NULL AUTO_INCREMENT,`name` varchar(255) NOT NULL,PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_0900_ai_ci ROW_FORMAT = Dynamic;