版權(quán)聲明：本文為博主原創(chuàng)文章，轉(zhuǎn)載請寫明出處。 https://blog.csdn.net/wo541075754/article/details/76566016

在《Drools7.0.0.Final規(guī)則引擎教程》之Springboot集成中介紹了怎樣將Drools與Springboot進(jìn)行集成，本篇博客介紹一下集成之后，如何實現(xiàn)從數(shù)據(jù)庫讀取規(guī)則并重新加載規(guī)則的簡單demo。因本章重點介紹的是Drools相關(guān)操作的API，所以將查詢數(shù)據(jù)庫部分的操作省略，直接使用數(shù)據(jù)庫查詢出的規(guī)則代碼來進(jìn)行規(guī)則的重新加載。另外，此示例采用訪問一個http請求來進(jìn)行重新加載，根據(jù)實際需要可考慮定時任務(wù)進(jìn)行加載等擴展方式。最終的使用還是要結(jié)合具體業(yè)務(wù)場景來進(jìn)行分析擴展。

整體項目結(jié)構(gòu)

上圖是基于intellij maven的項目結(jié)構(gòu)。其中涉及到springboot的Drools集成配置類，重新加載規(guī)則類。一些實體類和工具類。下面會抽出比較重要的類進(jìn)行分析說明。

DroolsAutoConfiguration

@Configuration
public class DroolsAutoConfiguration {

    private static final String RULES_PATH = "rules/";

    @Bean
    @ConditionalOnMissingBean(KieFileSystem.class)
    public KieFileSystem kieFileSystem() throws IOException {
        KieFileSystem kieFileSystem = getKieServices().newKieFileSystem();
        for (Resource file : getRuleFiles()) {
            kieFileSystem.write(ResourceFactory.newClassPathResource(RULES_PATH + file.getFilename(), "UTF-8"));
        }
        return kieFileSystem;
    }

    private Resource[] getRuleFiles() throws IOException {
        ResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();
        return resourcePatternResolver.getResources("classpath*:" + RULES_PATH + "**/*.*");
    }

    @Bean
    @ConditionalOnMissingBean(KieContainer.class)
    public KieContainer kieContainer() throws IOException {
        final KieRepository kieRepository = getKieServices().getRepository();

        kieRepository.addKieModule(new KieModule() {
            public ReleaseId getReleaseId() {
                return kieRepository.getDefaultReleaseId();
            }
        });

        KieBuilder kieBuilder = getKieServices().newKieBuilder(kieFileSystem());
        kieBuilder.buildAll();

        KieContainer kieContainer = getKieServices().newKieContainer(kieRepository.getDefaultReleaseId());
        KieUtils.setKieContainer(kieContainer);
        return getKieServices().newKieContainer(kieRepository.getDefaultReleaseId());
    }

    private KieServices getKieServices() {
        return KieServices.Factory.get();
    }

    @Bean
    @ConditionalOnMissingBean(KieBase.class)
    public KieBase kieBase() throws IOException {
        return kieContainer().getKieBase();
    }

    @Bean
    @ConditionalOnMissingBean(KieSession.class)
    public KieSession kieSession() throws IOException {
        KieSession kieSession = kieContainer().newKieSession();
        KieUtils.setKieSession(kieSession);
        return kieSession;
    }

    @Bean
    @ConditionalOnMissingBean(KModuleBeanFactoryPostProcessor.class)
    public KModuleBeanFactoryPostProcessor kiePostProcessor() {
        return new KModuleBeanFactoryPostProcessor();
    }
}
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此類主要用來初始化Drools的配置，其中需要注意的是對KieContainer和KieSession的初始化之后都將其設(shè)置到KieUtils類中。

KieUtils

KieUtils類中存儲了對應(yīng)的靜態(tài)方法和靜態(tài)屬性，供其他使用的地方獲取和更新。

public class KieUtils {

    private static KieContainer kieContainer;

    private static KieSession kieSession;

    public static KieContainer getKieContainer() {
        return kieContainer;
    }

    public static void setKieContainer(KieContainer kieContainer) {
        KieUtils.kieContainer = kieContainer;
        kieSession = kieContainer.newKieSession();
    }

    public static KieSession getKieSession() {
        return kieSession;
    }

    public static void setKieSession(KieSession kieSession) {
        KieUtils.kieSession = kieSession;
    }
}
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ReloadDroolsRules

提供了reload規(guī)則的方法，也是本篇博客的重點之一，其中從數(shù)據(jù)庫讀取的規(guī)則代碼直接用字符串代替，讀者可自行進(jìn)行替換為數(shù)據(jù)庫操作。

@Service
public class ReloadDroolsRules {

    public void reload() throws UnsupportedEncodingException {
        KieServices kieServices = KieServices.Factory.get();
        KieFileSystem kfs = kieServices.newKieFileSystem();
        kfs.write("src/main/resources/rules/temp.drl", loadRules());
        KieBuilder kieBuilder = kieServices.newKieBuilder(kfs).buildAll();
        Results results = kieBuilder.getResults();
        if (results.hasMessages(Message.Level.ERROR)) {
            System.out.println(results.getMessages());
            throw new IllegalStateException("### errors ###");
        }

        KieUtils.setKieContainer(kieServices.newKieContainer(getKieServices().getRepository().getDefaultReleaseId()));
        System.out.println("新規(guī)則重載成功");
    }

    private String loadRules() {
        // 從數(shù)據(jù)庫加載的規(guī)則
        return "package plausibcheck.adress\n\n import com.neo.drools.model.Address;\n import com.neo.drools.model.fact.AddressCheckResult;\n\n rule \"Postcode 6 numbers\"\n\n    when\n  then\n        System.out.println(\"規(guī)則2中打印日志：校驗通過!\");\n end";

    }

    private KieServices getKieServices() {
        return KieServices.Factory.get();
    }

}
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TestController

提供了驗證入口和reload入口。

@RequestMapping("/test")
@Controller
public class TestController {


    @Resource
    private ReloadDroolsRules rules;

    @ResponseBody
    @RequestMapping("/address")
    public void test(){
        KieSession kieSession = KieUtils.getKieSession();

        Address address = new Address();
        address.setPostcode("994251");

        AddressCheckResult result = new AddressCheckResult();
        kieSession.insert(address);
        kieSession.insert(result);
        int ruleFiredCount = kieSession.fireAllRules();
        System.out.println("觸發(fā)了" + ruleFiredCount + "條規(guī)則");

        if(result.isPostCodeResult()){
            System.out.println("規(guī)則校驗通過");
        }

    }


    @ResponseBody
    @RequestMapping("/reload")
    public String reload() throws IOException {
        rules.reload();
        return "ok";
    }
}
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其他

其他類和文件內(nèi)容參考springboot集成部分或demo源代碼。

操作步驟如下：啟動項目訪問http://localhost:8080/test/address 會首先觸發(fā)默認(rèn)加載的address.drl中的規(guī)則。當(dāng)調(diào)用reload之后，再次調(diào)用次方法會發(fā)現(xiàn)觸發(fā)的規(guī)則已經(jīng)變成重新加載的規(guī)則了。

CSDN demo下載地址：http://download.csdn.net/detail/wo541075754/9918297
GitHub demo下載地址：https://github.com/secbr/drools/tree/master/springboot-drools-reload-rules

后語

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