使用Datanucleus中的错误

Question

当我在本地Appengine开发服务器中对Datanucleus资源执行Http POST时，服务器将引发以下错误：

Caused by: java.lang.ClassNotFoundException: org.datanucleus.NucleusContext
    at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
    at com.google.appengine.tools.development.IsolatedAppClassLoader.loadClass(IsolatedAppClassLoader.java:176)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
    ... 37 more

从表面上看，平台不允许在应用程序引擎上使用数据核素Rest？

编辑:pom中的数据核：

<dependency>
    <groupId>com.google.appengine.orm</groupId>
    <artifactId>datanucleus-appengine</artifactId>
    <version>2.0.0</version>
</dependency>
<dependency>
    <groupId>org.datanucleus</groupId>
    <artifactId>datanucleus-core</artifactId>
    <version>3.0.0-release</version>
</dependency>

<dependency>
    <groupId>org.datanucleus</groupId>
    <artifactId>datanucleus-api-jpa</artifactId>
    <version>3.0.0-release</version>
</dependency>
<dependency>
    <groupId>org.apache.geronimo.specs</groupId>
    <artifactId>geronimo-jpa_2.0_spec</artifactId>
    <version>1.0</version>
</dependency>

        <!-- Required by Datanucleus REST API -->
        <dependency>
            <groupId>org.datanucleus</groupId>
            <artifactId>datanucleus-rest</artifactId>
            <version>2.0.0-release</version>
        </dependency>
        <dependency>
            <groupId>net.sf.flexjson</groupId>
            <artifactId>flexjson</artifactId>
            <version>2.1</version>
        </dependency>
        <dependency>
            <groupId>org.datanucleus</groupId>
            <artifactId>datanucleus-json</artifactId>
            <version>2.0.0-release</version>
        </dependency>

这里是WEB/lib文件夹中与DN相关的jars：

• datanucleus-rest-2.0.0-release.jar
• datanucleus-json-2.0.0-release.jar
• datanucleus-core-3.0.0-release.jar
• datanucleus-appengine-2.0.0.jar
• datanucleus-api-jpa-3.0.0-release.jar

编辑：

通过使用v3.0DN依赖项修正了最初的问题。

但是，现在当我尝试从DN servlet访问REST资源时，它会抛出以下错误：

Error : An error occurred trying to instantiate an instance of the API adapter "org.datanucleus.api.jdo.JDOAdapter" (perhaps you dont have the requisite datanucleus-api-XXX jar in the CLASSPATH?) : {1}
org.datanucleus.exceptions.NucleusUserException: Error : An error occurred trying to instantiate an instance of the API adapter "org.datanucleus.api.jdo.JDOAdapter" (perhaps you dont have the requisite datanucleus-api-XXX jar in the CLASSPATH?) : {1}

Answer 1

因此，您使用某些版本的datanucleus api-rest(大概是3.x)，并且没有必要版本的datanucleus core(也是3.x)。这通常是ClassNotFoundException的意思。