java - 使用 Datanucleus Rest API 时出现错误

Question

当我对本地 Appengine 开发服务器中的 Datanucleus Rest 资源执行 Http POST 时，服务器会抛出此错误:

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 appengine 上使用 Datnuclues Rest API？

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>

以下是 WEB-INF/lib 文件夹中与 DN 相关的 jar:

• 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:

使用 v3.0 DN 依赖项修复了最初的问题。

但是，现在当我尝试从 DN servlet 访问 REST 资源时，它会抛出此错误:

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)。这通常就是 ClassNotFoundException 的含义