java – 一旦我编写了内置函数,我需要做些什么才能让reasoners知道它？

我已经在我的项目中编写了一个自定义内置程序,但我真的不知道如何使用它.
我写过两节课.在其中一个中有我使用的内置(使用BaseBuiltin),另一个我注册了新的内置(使用BuiltinRegistry).

我已经尝试使用默认的内置函数,编写在使用Java从Eclipse可读的文本文件中使用它们的规则.在这种情况下,我没有任何问题.我怎样才能使用我建的内置？我应该在某些文件中导入(或包含)某些内容吗？

解决方法:

首先定义一个Builtin,通常通过扩展BaseBuiltin,然后使用BuiltinRegistry.theRegistry.register(Builtin)使其可用于基于Jena规则的推理.

完成后,您需要实际使用一个引用您的Builtin的规则来触发它.

BuiltinRegistry.theRegistry.register( new BaseBuiltin() {
    @Override
    public String getName() {
        return "example";
    }
    @Override
    public void headAction( final Node[] args, final int length, final RuleContext context ) {
        System.out.println("Head Action: "+Arrays.toString(args));
    }
} );

final String exampleRuleString =
    "[mat1: (?s ?p ?o)\n\t-> print(?s ?p ?o),\n\t   example(?s ?p ?o)\n]"+
    "";
System.out.println(exampleRuleString);

/* I tend to use a fairly verbose syntax for parsing out my rules when I construct them
 * from a string. You can read them from whatever other sources.
 */
final List<Rule> rules;
try( final BufferedReader src = new BufferedReader(new InputStreamReader(new ByteArrayInputStream(exampleRuleString.getBytes()))) ) {
    rules = Rule.parseRules(Rule.rulesParserFromReader(src));
}

/* Construct a reasoner and associate the rules with it  */
final GenericRuleReasoner reasoner = (GenericRuleReasoner) GenericRuleReasonerFactory.theInstance().create(null);
reasoner.setRules(rules);

/* Create & Prepare the InfModel. If you don't call prepare, then
 * rule firings and inference may be deferred until you query the
 * model rather than happening at insertion. This can make you think
 * that your Builtin is not working, when it is.
 */
final InfModel infModel = ModelFactory.createInfModel(reasoner, ModelFactory.createDefaultModel());
infModel.prepare();

/* Add a triple to the graph: 
* [] rdf:type rdfs:Class
*/
infModel.createResource(RDFS.Class);

此代码的输出将是：

>前向链规则的字符串
>调用print Builtin的结果
>调用示例Builtin的结果

……这正是我们所看到的：

[mat1: (?s ?p ?o)
    -> print(?s ?p ?o),
       example(?s ?p ?o)
]
-2b47400d:14593fc1564:-7fff rdf:type rdfs:Class 
Head Action: [-2b47400d:14593fc1564:-7fff, http://www.w3.org/1999/02/22-rdf-syntax-ns#type, http://www.w3.org/2000/01/rdf-schema#Class]

标签：jena,jena-rules,java,eclipse,rdf
来源： https://codeday.me/bug/20190928/1825285.html