OpenApi自动生成client.md_openapi转换md

前言

之前没有觉得OpenApi有什么特别了不得的，直到参加了花旗银行的一次面试，对方部门老总对OpenApi是非常重视，认为可以极大提升效率；后来在eBay，随着微服务化的推行，应用之间RESTful调用指数级增长，应用内调用接口的代码占了很大一部分，复用程度不高，比如一个基础应用A被10个上层应用调用，各写各的后果如下：

• 10个应用有的用okHttp有的用apache http，不统一
• 单元测试覆盖率要达到80%，意味着相同功能加10倍UT
• 缺乏重试、异常处理等机制

后来试用了OpenApi，将如上10个应用的代码，代替为OpenApi生成的jar包（jar包可以统一管理，10个应用引入即可），采用的技术统一，UT只要一份，代码质量有保证！

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OpenApi和swagger

OpenApi解析swagger的接口的规程，自动生成java类库，非常方便！

网易链接口调用关系.md 里面用到了自己编写的okHttpClient，但是如果能够自动生成，岂不是很方便？
swagger.md 原理是利用swagger.json，里面有详细的返回的类及哪些接口

20190924： 跑通了整体流程，最大改动：submitTime原来是offsetTime类型的，后来我改为string还是不过，后来干脆取消对这个字段的读取，就通过了；另外发现一个jobType的问题，是haowen在qm上遗漏了，已经fix了

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具体操作 hands-on

1. 先把swagger.json 下载下来
2. 在运行

$ java -jar modules/openapi-generator-cli/target/openapi-generator-cli.jar generate -i workswagger.json -g java -o /var/tmp/javaClient4Workflow
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上传到ebay的qa库中，小窍门是1.0-SNAPSHOT，否则报错

[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项目在服务间相互调用时一般都是RestTemplate，有了这个就不用了，可以生成client端的jar包，直接调用jar包中的方法就会进行服务调用

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
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openapi-generator-cli help
用list命令尝试

config-help

meta

validate (先验证一下给的petstore的例子)

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