前言：

Drools是一款基于Java的開源規則引擎

實現了將業務決策從應用程序中分離出來。

優點：

1、簡化系統架構，優化應用

2、提高系統的可維護性和維護成本

3、方便系統的整合

4、減少編寫“硬代碼”業務規則的成本和風險

不多說，直接low代碼，此例是使用springboot項目為基礎：

1.需添加maven依賴 使用7.x：

org.drools

drools-core

7.4.1.Final

org.drools

drools-compiler

7.4.1.Final

2.main方法測試

//執行的主類

public class Application {

public static void test1() throws Exception {

KieSession kieSession = check(getRule());

IrssetDroolsVo drools = new IrssetDroolsVo();

drools.setSurpDayCnt(2);

kieSession.insert(drools);

int i = kieSession.fireAllRules();

System.out.println("命中： " + i +"返回結果：" + drools.getMsg());

}

/**

* 不進行檢查

* @param rule

* @return

*/

public static KieSession getSession(String rule) {

KieSession kieSession = null;

try {

KnowledgeBuilder builder = KnowledgeBuilderFactory.newKnowledgeBuilder();

builder.add(ResourceFactory.newByteArrayResource(rule.getBytes("UTF-8")),ResourceType.DRL);

InternalKnowledgeBase knowledgeBase = KnowledgeBaseFactory.newKnowledgeBase();

Collection packages = builder.getKnowledgePackages();

knowledgeBase.addPackages(packages);

kieSession = knowledgeBase.newKieSession();

} catch (Exception e) {

e.printStackTrace();

}

return kieSession;

}

/**

* 檢查

* @param sq

* @return

* @throws Exception

*/

private static KieSession check(String sq) throws Exception {

KieSessionRepo kieSession = new KieSessionRepo();

KieServices kieServices = KieServices.Factory.get();

KieFileSystem kfs = kieServices.newKieFileSystem();

kfs.write("src/main/resources/test.drl", sq );

KieBuilder kieBuilder = kieServices.newKieBuilder(kfs).buildAll();

Results results = kieBuilder.getResults();

if (results.hasMessages(Message.Level.ERROR)) {

for (Message msg : results.getMessages()) {

System.out.println("drools script error info : " + msg.getText());

}

throw new Exception("drools script error");

}

kieSession.setKieContainer("test", kieServices.newKieContainer(KieServices.Factory.get().getRepository().getDefaultReleaseId()));

return kieSession.getKieSession("test");

}

public static String getRule() {

StringBuffer ruleSb = new StringBuffer();

ruleSb.append(" package rule_10001;\n");

ruleSb.append("import com.learn.rule.model.IrssetDroolsVo\n");

ruleSb.append("rule rule_10001 \n");

ruleSb.append("when \n");

ruleSb.append("$riskDroolsVo : IrssetDroolsVo(surpDayCnt>=2 && surpDayCnt<=10); \n");

ruleSb.append("then \n");

ruleSb.append("$riskDroolsVo.setMsg(\"命中了\"); \n");

ruleSb.append("end");

System.out.println(ruleSb.toString());

return ruleSb.toString();

}

public static void main(String[] args) throws Exception {

test1();

}

3.執行的實體類：

public class IrssetDroolsVo implements Serializable {

private Integer surpDayCnt = null;

private boolean mBlack = false;

private String msg;

public String getMsg() {

return msg;

}

public void setMsg(String msg) {

this.msg = msg;

}

public IrssetDroolsVo() {

}

private static final long serialVersionUID = 1L;

public Integer getSurpDayCnt() {

return surpDayCnt;

}

public void setSurpDayCnt(Integer surpDayCnt) {

this.surpDayCnt = surpDayCnt;

}

public boolean ismBlack() {

return mBlack;

}

public void setmBlack(boolean mBlack) {

this.mBlack = mBlack;

}

}

4. KieSeesionRepo:

public class KieSessionRepo {

private static Map kieContainerMap = new ConcurrentHashMap();

private static Map kieSessionMap= new ConcurrentHashMap();

public static void setKieContainer(String key,KieContainer kieContainer) {

KieSession newKieSession = kieContainer.newKieSession();

kieContainerMap.put(key, kieContainer);

kieSessionMap.put(key,newKieSession);

}

public KieSession getKieSession(String key) {

return kieSessionMap.get(key);

}

}

最終執行的結果:

總結

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