java - 使用外部 java 类作为 AVRO 模式中的类型

Question

是否可以在 avsc 文件中引用已实现的 Java 类？

我的想法是:

{
    "namespace": "com.myCompany.myProject.schemas",
    "type": "record",
    "name": "SimpleTest",
    "fields": [
      {"name": "text","type": "string"},
      {"name": "myOtherObj","type": "com.myCompany.myProject.MyClass"}
      ]
}

其中字段 myOtherObj 的类型是已定义的已构建的 java 类 MyClass。

Answer 1

我的解决方案是:我定义了一个文件夹，通过 MyClass.avsc 在其中定义基本类型 MyClass 的虚拟版本:

{
  "namespace": "com.myCompany.myProject.basicTypes",
  "type": "record",
  "name": "MyClass",
  "doc": "This is only a place-holder needed to let Avro compile correctly the schemas. The real implementation is provided in the java project",
  "fields": [
        {"name": "value", "type": "string"}
    ]
}

然后，使用gradle插件:https://github.com/commercehub-oss/gradle-avro-plugin ，我与此一起构建了 avro 类 SimpleTest 。通过这种方式，Avro 将创建 SimpleTest.java 和 MyClass.java 并正确解析它们的依赖关系。最后，我从类路径中删除 Avro 插件创建的 MyClass.java 实现。

//remove the basicTypes as these are only place holder while the real implementation is somewhere else.
task removeBasicTypes {
    dependsOn compileJava
    doLast {
        println "Removing java files of all the basic types."
        //cleanup the generated java classes
        delete fileTree(dir: 'src/main/java/com/myCompany/myProject/basicTypes' , include: '**/*.java')
        //cleanup also the build folder that will be used to generate the jar file
        delete fileTree(dir: 'build/classes/java/main/com/myCompany/myProject/basicTypes' , include: '**/*.class')
    }
}

task generateAvro(type: com.commercehub.gradle.plugin.avro.GenerateAvroJavaTask) {
    source("$rootDir/basicTypes", "src/main/avro")
    outputDir = file("src/main/java")

    finalizedBy('removeBasicTypes')
}

此 MyClass 的实际实现将作为依赖项提供，或者在我包含此生成 SimpleTest.java 文件的项目中提供。