上一篇文章講了 規則引擎的簡單版本,可以說 是 drl配置檔案版本,現在將一下資料庫版本,這樣資料就可以共享,靈活性更加大一些吧,.
規則引擎版本1
其實原理和上一篇一樣,都是一樣的模式,今天簡單介紹一下,

private KieContainer loadKieContainerDao() throws IOException {

        KieServices kieService = KieServices.Factory.get();
        final KieRepository kieRepository = kieService.getRepository
 
();
        kieRepository.addKieModule(kieRepository::getDefaultReleaseId);
        KieFileSystem kfs = kieService.newKieFileSystem();
        String[] files = listRulesDao();

        for (String file : files) {
            String myString = IOUtils.toString(new ByteArrayInputStream(file.getBytes()), "UTF-8"
 
);
            String path = "src/main/resources/xxx.drl";
            kfs.write(path, myString );
        }
        KieBuilder kieBuilder = kieService.newKieBuilder(kfs);
        kieBuilder.buildAll(); // kieModule is automatically deployed to KieRepository if successfully built.
        return kieService.newKieContainer
 
(kieRepository.getDefaultReleaseId());
    }

本demo用string代替,讀者課自行處理,得到自己想要的類容;

private String[] listRulesDao() {
        String s = "package drools;\n" +
                "import com.sdingba.Drools.demo1.person;\n" +
                "\n" +
                "rule showdemo\n" +
                "when\n" +
                "    $person : person(age>3)\n" +
                "//    System.out.println(\"xxxxx\");\n" +
                "then\n" +
                "    $person.toString(\"sdfsdf\");\n" +
                "    $person.setName(\"xxxxxx\");\n" +
                "end";
        return new String[]{s};
    }

 @Bean
    @ConditionalOnMissingBean(KieSession.class)
    public KieSession kieSession() throws IOException {
        return loadKieContainerDao().newKieSession();
    }

其他原理同上一篇部落格一樣,以及測試程式碼,這兒不多說…