开源中国的Markdown居然不渲染mermaid画的图！！访问原文：： http://kanng.cn/reactor-gateway/
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我基于Spring-Cloud-Gateway做响应式的API网关开发工作也有1年多的时间了，做了很多扩展性的工作， 可以说对Spring-Cloud-Gateway的设计思想和源码细节有不错的了解了，但是我个人其实不太喜欢Spring-Cloud-Gateway， 或者说是因为不太喜欢Spring-Boot和Spring-Framework，因为我觉的它太重了，诚然，它很好用（写业务），提供了很多开箱即用的功能， 可以很大的提高业务团队写业务的效率，但是一想到它往我的内存里塞了那么多我可能根本就不需要的东西， 构建出来的包那么大，启动的那么慢，我就有点不舒服。另外，我个人喜欢对代码的执行有更好的掌控感，能不用框架解决的问题就不用框架。 所以，最终，我决定吸收Spring-Cloud-Gateway的部分思想自己写一个响应式API网关。 目的倒不是做一个多么成功的项目，主要是做一个笔记，和自己所学的沉淀。
技术选型
API网关类型的项目，确实是适合用响应式的库来开发，这个可以看Spring-Cloud-Gateway和Spring-WebFlux的文档上相关的说明。 Spring-Cloud-Gateway其实就是建立在Spring自己推出的响应式Web框架Spring-WebFlux之上， 而Spring-WebFlux底层的Http服务实现是一个叫reactor-netty, 这个项目其实也是Spring的团队出的，它其实就是结合了2个项目[netty]和[project-reactor]，前者是众所周知的高性能网络库， 后者是Spring推出的响应式库，二者结合起来，就是“高性能的响应式网络库”。
所以，整个以依赖的层级关系就是：
flowchart TD
id1[Spring-Cloud-Gateway]
id2[Spring-Boot]
id3[Spring-WebFlux]
id4[reactor-netty]
id5[netty]
id6[project-reactor]
id7[reactive-streams]
style id5 fill:#f9f,stroke:#333,stroke-width:2px
style id7 fill:#f9f,stroke:#333,stroke-width:2px
id1 --> id2
id1 --> id3
id3 --> id4
id4 --> id5
id4 --> id6
id6 --> id7
除了netty和reactive-streams其他的其实都是Spring团队出的东西。
响应式宣言reactive-streams的实现，除了Spring的亲儿子project-reactor， 其他的主要还有RxJava和Vert.x。其实也许用Vert.x来实现响应式API网关是一个更加不错的选择，它号称比较优雅，但是考虑到我自己还是对project-reactor的 Mono和Flux那一套API更加的熟悉。所以我们开发响应式API网关还是以project-reactor作为基础，因此，最底层的HTTP服务还是由reactor-netty来实现。
现在，我们就抛弃和Spring-Framework相关的东西，直接基于reactor-netty来实现我们自己的响应式API网关。
项目的名字就叫做reactor-gateway，依赖关系图现在简单一些了：
flowchart TD
id[reactor-gateway]
id4[reactor-netty]
id5[netty]
id6[project-reactor]
id7[reactive-streams]
style id5 fill:#f9f,stroke:#333,stroke-width:2px
style id7 fill:#f9f,stroke:#333,stroke-width:2px
style id fill:#7CCD7C,stroke:#333,stroke-width:2px
id --> id4
id4 --> id5
id4 --> id6
id6 --> id7
项目启动
Talk is cheap, show me the code!
Talk is cheap, show me the code!
现在就建立一个空的git项目开始写代码吧：
-
新建一个空的git项目
-
配置好
.gitignore -
一个简单的
README.md -
一个开源协议文件，开源协议用Apache License V2
mkdir reactor-gateway
cd reactor-gateway
git init
touch .gitignore
touch README.md
touch LICENSE
.gitignore
# IDEA ignore
.idea
*.iml
*.ipr
*.iws
# vs code ingore
.vscode
*.suo
*.njsproj
**/bin/main/
# vim ingore
*.swp
*.swo
# eclipse ingore
.project
.settings
.classpath
# Mac OS ingore
.DS_Store
# gradle project ingore
.gradle
build
qa/format/java-format.xml
qa/format/java.importorder
README.md
基于Reactor-Netty实现的响应式API网关
LICENSE
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最后，执行我们的第一个提交：
git add .
git commit -m '初始化空项目'
新项目启动！！
说明
此系列博文后面还会出现很多贴大段代码的地方，会比较影响阅读体验，网页要是能折叠代码就看起来体验会好点。其实这是我特意如此的，因为我想读者自己跟着动手，而不是只动眼。我自己的想法是做一个“菜单”，而不是直接端出一盘做好的菜。“菜单”是一个可以重复的过程，而不是单单只有结果。好比你去看kafka的源码，直接丢给你几十万行的代码，你根本把握不住它的核心思想，但是如果kafka的作者，把他从0到1做kafka的过程展示给你，你肯定把kafka学的更好。如果你想要看githug的代码，也是有的，感兴趣可以瞅瞅：https://github.com/tmzk1005/reactor-gateway， https://github.com/tmzk1005/fornax， 后者是插件化比较弱的版本，前者是正在弄的插件化的重构版，还处于比较初始的阶段，不过，不妨碍理解设计思想。
如果能给个Star鼓励鼓励就更好了~~!
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