開源中國的Markdown居然不渲染mermaid畫的圖！！訪問原文：： http://kanng.cn/reactor-gateway/
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我基於Spring-Cloud-Gateway做響應式的API網關開發工作也有1年多的時間了，做了很多擴展性的工作， 可以說對Spring-Cloud-Gateway的設計思想和源碼細節有不錯的瞭解了，但是我個人其實不太喜歡Spring-Cloud-Gateway， 或者說是因爲不太喜歡Spring-Boot和Spring-Framework，因爲我覺的它太重了，誠然，它很好用（寫業務），提供了很多開箱即用的功能， 可以很大的提高業務團隊寫業務的效率，但是一想到它往我的內存裏塞了那麼多我可能根本就不需要的東西， 構建出來的包那麼大，啓動的那麼慢，我就有點不舒服。另外，我個人喜歡對代碼的執行有更好的掌控感，能不用框架解決的問題就不用框架。 所以，最終，我決定吸收Spring-Cloud-Gateway的部分思想自己寫一個響應式API網關。 目的倒不是做一個多麼成功的項目，主要是做一個筆記，和自己所學的沉澱。
技術選型
API網關類型的項目，確實是適合用響應式的庫來開發，這個可以看Spring-Cloud-Gateway和Spring-WebFlux的文檔上相關的說明。 Spring-Cloud-Gateway其實就是建立在Spring自己推出的響應式Web框架Spring-WebFlux之上， 而Spring-WebFlux底層的Http服務實現是一個叫reactor-netty, 這個項目其實也是Spring的團隊出的，它其實就是結合了2個項目[netty]和[project-reactor]，前者是衆所周知的高性能網絡庫， 後者是Spring推出的響應式庫，二者結合起來，就是“高性能的響應式網絡庫”。
所以，整個以依賴的層級關係就是：
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其他的其實都是Spring團隊出的東西。
響應式宣言reactive-streams的實現，除了Spring的親兒子project-reactor， 其他的主要還有RxJava和Vert.x。其實也許用Vert.x來實現響應式API網關是一個更加不錯的選擇，它號稱比較優雅，但是考慮到我自己還是對project-reactor的 Mono和Flux那一套API更加的熟悉。所以我們開發響應式API網關還是以project-reactor作爲基礎，因此，最底層的HTTP服務還是由reactor-netty來實現。
現在，我們就拋棄和Spring-Framework相關的東西，直接基於reactor-netty來實現我們自己的響應式API網關。
項目的名字就叫做reactor-gateway，依賴關係圖現在簡單一些了：
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
項目啓動
Talk is cheap, show me the code!
Talk is cheap, show me the code!
現在就建立一個空的git項目開始寫代碼吧：
-
新建一個空的git項目
-
配置好
.gitignore -
一個簡單的
README.md -
一個開源協議文件，開源協議用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
基於Reactor-Netty實現的響應式API網關
LICENSE
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最後，執行我們的第一個提交：
git add .
git commit -m '初始化空項目'
新項目啓動！！
說明
此係列博文後面還會出現很多貼大段代碼的地方，會比較影響閱讀體驗，網頁要是能摺疊代碼就看起來體驗會好點。其實這是我特意如此的，因爲我想讀者自己跟着動手，而不是隻動眼。我自己的想法是做一個“菜單”，而不是直接端出一盤做好的菜。“菜單”是一個可以重複的過程，而不是單單隻有結果。好比你去看kafka的源碼，直接丟給你幾十萬行的代碼，你根本把握不住它的核心思想，但是如果kafka的作者，把他從0到1做kafka的過程展示給你，你肯定把kafka學的更好。如果你想要看githug的代碼，也是有的，感興趣可以瞅瞅：https://github.com/tmzk1005/reactor-gateway， https://github.com/tmzk1005/fornax， 後者是插件化比較弱的版本，前者是正在弄的插件化的重構版，還處於比較初始的階段，不過，不妨礙理解設計思想。
如果能給個Star鼓勵鼓勵就更好了~~!
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