写耶拿内置插件 [英] writing Jena built-ins

问题描述

我正在尝试编写 Jena内置以返回值从我给出的算法开始，然后对该值进行比较，例如，

I'm trying to write a Jena built-in to return a value from an algorithm I have been given and then do a comparison against that value, e.g.,

String rule = "[exRule: (?d rdf:type ex:abc)" +
              "<-" +
              // ...extract ?a, ?b to use as inputs to the rule
          "greaterThan(myBuiltIn(?a, ?b), 1)" +  // Is return value greater than 1
      "]";

首先， Jena文档说最简单的实验方法是查看builtins目录中的示例，但是我的安装中似乎没有这个，我在Windows 7上使用Jena 2.6.4。我在哪里可以找到它？我是否需要从其他地方下载？

So, first the Jena documentation says that the easiest way to experiment with this is to look at the examples in the builtins directory, however I don't seem to have this in my installation, I'm using Jena 2.6.4 on Windows 7. Where can I find this? Do I need to download it from elsewhere?

其次，我不确定如何从我的内置中获取返回值。如果我只是使用硬连线值调用 myBuiltIn（2,1）我知道它被调用，因为我已经添加到内置的 bodyCall中的一些调试输出（）方法。但是，如果我将它传递给 greaterThan（），那么我就不会再看到这个了。还在被叫吗？

Secondly, I'm unsure how to pick up the return value from my builtin. If I simply call myBuiltIn(2, 1) using hardwired values I know it's being called due to some debug output I've added to the builtin's bodyCall() method. However, if I pass it to greaterThan(), then I no longer see this. Is it still being called?

推荐答案

@Joshua

我找到了如何实现这一点。

I found how to implement this.

首先，你应该创建一个从 BaseBuiltin 扩展的新类，如下所示 http://sadl.sourceforge.net/CustomJenaBuiltins.html

First of all, you should create a new class that extend from BaseBuiltin like this http://sadl.sourceforge.net/CustomJenaBuiltins.html

然后将其添加到builtinRegistry类

and then add it into builtinRegistry class

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