我尝试使用 JDO 将一个谷歌云项目从端点 v1 迁移到 v2。我已经按照迁移指南和此处的一些解决方案尝试使 datanucleous 插件增强我的类，并将它们上传到谷歌云，但没有运气。

我将发布 build.gradle，然后在客户端尝试连接到端点时返回服务器错误，这是一个 NoClassFound 错误。

build.gradle:

buildscript {
    repositories {
        mavenCentral()
        mavenLocal()
    }
    dependencies {
        // App Engine Gradle plugin
        classpath 'com.google.cloud.tools:appengine-gradle-plugin:1.3.3'

        // Endpoints Frameworks Gradle plugin
        classpath 'com.google.cloud.tools:endpoints-framework-gradle-plugin:1.0.2'

    }
}

repositories {
    mavenCentral();
    jcenter()
}

apply plugin: 'java'
apply plugin: 'war'

// [START apply_plugins]
apply plugin: 'com.google.cloud.tools.appengine'
apply plugin: 'com.google.cloud.tools.endpoints-framework-server'
// [END apply_plugins]

dependencies {
    compile ('com.google.endpoints:endpoints-framework:2.0.8') {
        exclude group: 'com.google.guava', module: 'guava-jdk5'
    }

    compile 'javax.servlet:servlet-api:2.5'
    compile 'com.ganyo:gcm-server:1.0.2'
    compile 'javax.jdo:jdo-api:3.0.1'
    compile 'org.datanucleus:datanucleus-core:3.1.3'
    compile 'org.datanucleus:datanucleus-api-jdo:3.1.3'
    compile 'org.datanucleus:datanucleus-accessplatform-jdo-rdbms:4.1.1'
    compile 'com.google.appengine.orm:datanucleus-appengine:2.1.2'
    compile 'com.google.code.gson:gson:2.2.4'
    compile 'org.apache.commons:commons-lang3:3.5'
}

sourceCompatibility = JavaVersion.VERSION_1_7
targetCompatibility = JavaVersion.VERSION_1_7

appengine {  // App Engine tasks configuration
    deploy {   // deploy configuration
        version = findProperty("appengine.deploy.version")

        def promoteProp = findProperty("appengine.deploy.promote")
        if (promoteProp != null) {
            promote = new Boolean(promoteProp)
        }

    }
}

endpointsServer {
    // Endpoints Framework Plugin server-side configuration
    hostname = "komilibro.appspot.com"
}

task datanucleusEnhance {
    description "Enhance JDO model classes using DataNucleus Enhancer"
    dependsOn processResources

    doLast {
        // define the entity classes
        def entityFiles = fileTree(sourceSets.main.output.classesDir).matching {
            include 'com/meanwhile/komi/head/**/*.class'
        }

        println "Enhancing with DataNucleus the following files"
        entityFiles.getFiles().each {
            println it
        }

        // define Ant task for DataNucleus Enhancer
        ant.taskdef(
                name : 'datanucleusenhancer',
                classpath : sourceSets.main.runtimeClasspath.asPath,
                classname : 'org.datanucleus.enhancer.EnhancerTask'
                // the below is for DataNucleus Enhancer 3.1.1
                //classname : 'org.datanucleus.enhancer.tools.EnhancerTask'
        )

        // run the DataNucleus Enhancer as an Ant task
        ant.datanucleusenhancer(
                classpath: sourceSets.main.runtimeClasspath.asPath,
                verbose: true,
                api: "JDO") {
            entityFiles.addToAntBuilder(ant, 'fileset', FileCollection.AntType.FileSet)
        }
    }
}

classes.dependsOn(datanucleusEnhance)

在用户请求后查看服务器日志，我可以看到两个错误: 第一:

    org.datanucleus.store.types.TypeManagerImpl loadJavaTypes: User-defined type
 mapping class "org.datanucleus.store.types.sco.simple.Collection" was not found.
 Please check the mapping file class specifications and your CLASSPATH. The class
 must be in the CLASSPATH. 

这是第二个。 PMF 只是一个用于加载和实例化 PersistenceManager 的类。

com.google.api.server.spi.SystemService invokeServiceMethod: exception occurred while calling backend method (SystemService.java:375)
java.lang.NoClassDefFoundError: Could not initialize class com.meanwhile.komi.head.PMF

所以，似乎所需的类没有到位，而且 TypeManagerImpl 也没有找到 Collection 类(在端点中使用默认的 java Collection)。我在这里有点迷路，所以非常欢迎帮助。

谢谢!

最佳答案

将此添加到您的 gradle 构建文件中:

task datanucleusEnhance {
  description "Enhance JDO model classes using DataNucleus Enhancer"
  dependsOn compileJava

  doLast {    
      // define the entity classes
      def entityFiles = fileTree(sourceSets.main.output.classesDir).matching {
          include 'com/mycom/*.class', 'org/myorg/*.class'
      }

      println "Enhancing with DataNucleus the following files"
      entityFiles.getFiles().each {
          println it
      }

      // define Ant task for DataNucleus Enhancer
      ant.taskdef(
          name : 'datanucleusenhancer',
          classpath : sourceSets.main.runtimeClasspath.asPath,
          classname : 'org.datanucleus.enhancer.EnhancerTask'
          // the below is for DataNucleus Enhancer 3.1.1
          //classname : 'org.datanucleus.enhancer.tools.EnhancerTask'
      )

      // run the DataNucleus Enhancer as an Ant task
      ant.datanucleusenhancer(
          classpath: sourceSets.main.runtimeClasspath.asPath,
          verbose: true,
          api: "JDO") {
          entityFiles.addToAntBuilder(ant, 'fileset', FileCollection.AntType.FileSet)
      }
  }
}

classes.dependsOn(datanucleusEnhance)

entityFiles 是您配置 JPA 实体注释类的地方。

关于java - 将 JDO 项目迁移到 google cloud endpoints v2，服务器返回 NoClassDefFoundError，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/51808819/