Datanucleus 编程 API 类增强

Question

我使用的是 Eclipse 3.7 (OSGI)，我可以进行手动增强（将 Datanucleus Eclipse 插件和 datanucleus-enhancer-2.1.0-release 作为插件依赖项导入）

我现在正在尝试使用 API 类增强功能：http://www.datanucleus.org/products/accessplatform/jpa/enhancer.html#api

在类路径中使用 ASM 3.1 和此代码：

DataNucleusEnhancer enhancer=new DataNucleusEnhancer("JDO","ASM");
enhancer.setVerbose(true);
enhancer.addClasses(...);
enhancer.enhance();

我明白了：

You have selected to use ClassEnhancer "ASM" yet the JAR for that enhancer does not seem to be in the CLASSPATH!
org.datanucleus.enhancer.NucleusEnhanceException: You have selected to use ClassEnhancer "ASM" yet the JAR for that enhancer does not seem to be in the CLASSPATH!
    at org.datanucleus.enhancer.DataNucleusEnhancer.init(DataNucleusEnhancer.java:224)
    at org.datanucleus.enhancer.DataNucleusEnhancer.addClasses(DataNucleusEnhancer.java:406)

使用教程中建议的代码：

JDOEnhancer enhancer = JDOHelper.getEnhancer();
enhancer.setVerbose(true);
enhancer.addClasses(...);
enhancer.enhance();

我明白了：

javax.jdo.JDOFatalUserException: There are 0 services entries for the JDOEnhancer; there were no valid JDOEnhancer implementations found in the CLASSPATH. The file META-INF/services/javax.jdo.JDOEnhancer should name the implementation class.

有没有办法实现 API 类增强？

Answer 1

查看此链接http://www.datanucleus.org/products/accessplatform_3_0/enhancer.html#runtime

特别是一句：“运行时增强需要以下运行时依赖项：ASM 和 DataNucleus 核心库。”

所以您可能缺少 ASM 依赖项。

尝试添加此依赖项：

    <dependency>
      <groupId>org.ow2.asm</groupId>
      <artifactId>asm</artifactId>
      <version>4.2</version>
    </dependency>