OpenApi自動生成client.md

前言

之前沒有覺得OpenApi有什麼特別了不得的，直到參加了花旗銀行的一次面試，對方部門老總對OpenApi是非常重視，認爲可以極大提升效率；後來在eBay，隨着微服務化的推行，應用之間RESTful調用指數級增長，應用內調用接口的代碼佔了很大一部分，複用程度不高，比如一個基礎應用A被10個上層應用調用，各寫各的後果如下：

• 10個應用有的用okHttp有的用apache http，不統一
• 單元測試覆蓋率要達到80%，意味着相同功能加10倍UT
• 缺乏重試、異常處理等機制

後來試用了OpenApi，將如上10個應用的代碼，代替爲OpenApi生成的jar包（jar包可以統一管理，10個應用引入即可），採用的技術統一，UT只要一份，代碼質量有保證！

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OpenApi和swagger

OpenApi解析swagger的接口的規程，自動生成java類庫，非常方便！

網易鏈接口調用關係.md 裏面用到了自己編寫的okHttpClient，但是如果能夠自動生成，豈不是很方便？
swagger.md 原理是利用swagger.json，裏面有詳細的返回的類及哪些接口

20190924： 跑通了整體流程，最大改動：submitTime原來是offsetTime類型的，後來我改爲string還是不過，後來乾脆取消對這個字段的讀取，就通過了；另外發現一個jobType的問題，是haowen在qm上遺漏了，已經fix了

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具體操作 hands-on

1. 先把swagger.json 下載下來
2. 在運行

$ java -jar modules/openapi-generator-cli/target/openapi-generator-cli.jar generate -i workswagger.json -g java -o /var/tmp/javaClient4Workflow

上傳到ebay的qa庫中，小竅門是1.0-SNAPSHOT，否則報錯

[INFO] --- maven-deploy-plugin:2.7:deploy (default-deploy) @ openapi-workflow-client ---
Downloading: https://ebaycentral.qa.ebay.com/content/repositories/snapshots/com/ebay/marketing/opclients/openapi-workflow-client/1.0-SNAPSHOT/maven-metadata.xml
Uploading: https://ebaycentral.qa.ebay.com/content/repositories/snapshots/com/ebay/marketing/opclients/openapi-workflow-client/1.0-SNAPSHOT/openapi-workflow-client-1.0-20190918.062345-1.jar
Uploaded: https://ebaycentral.qa.ebay.com/content/repositories/snapshots/com/ebay/marketing/opclients/openapi-workflow-client/1.0-SNAPSHOT/openapi-workflow-client-1.0-20190918.062345-1.jar (102 KB at 45.3 KB/sec)
Uploading: https://ebaycentral.qa.ebay.com/content/repositories/snapshots/com/ebay/marketing/opclients/openapi-workflow-client/1.0-SNAPSHOT/openapi-workflow-client-1.0-20190918.062345-1.pom
Uploaded: https://ebaycentral.qa.ebay.com/content/repositories/snapshots/com/ebay/marketing/opclients/openapi-workflow-client/1.0-SNAPSHOT/openapi-workflow-client-1.0-20190918.062345-1.pom (11 KB at 15.3 KB/sec)

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平常做spring-boot項目在服務間相互調用時一般都是RestTemplate，有了這個就不用了，可以生成client端的jar包，直接調用jar包中的方法就會進行服務調用

命令

git clone https://github.com/openapitools/openapi-generator.git
cd openapi-generator
mvn clean install
java -jar modules/openapi-generator-cli/target/openapi-generator-cli.jar generate \
  -i modules/openapi-generator/src/test/resources/2_0/petstore.yaml \
  -l jaxrs-cxf-client \
  -o /var/tmp/openapi-generator/jaxrs-cxf-client

openapi-generator-cli help
用list命令嘗試

config-help

meta

validate (先驗證一下給的petstore的例子)

openapi-generator validate -i petstore-v3.0.yaml

$ java -jar openapi-generator-cli.jar help
usage: openapi-generator-cli <command> [<args>]

The most commonly used openapi-generator-cli commands are:
    config-help Config help for chosen lang
    generate Generate code with the specified generator.
    help Display help information
    list Lists the available generators
    meta MetaGenerator. Generator for creating a new template set and configuration for Codegen. The output will be based on the language you specify, and includes default templates to include.
    validate Validate specification
    version Show version information