基于drools创建自己的关系操作符

我们知道drools提供了12种关系操作符

但是有些时候这12种操作符依然不能满足我们的业务需求，我们可以扩展自己的操作符，下面是为某一航空公司做项目时扩展了操作符，在这分享下

首先，我们要实现的逻辑是对航班记录
frFfpTravelDetail的票价级别etFareBasis属性做比配(逻辑：票价级别
去除非英文和数字字符后，第二位开始包含“ID**”或“DG**”或“AD**”（**为数字）)，这个逻辑太复杂，用以上12种关系操作符都不能满足，为此要进行扩展。

第一步：新增CsairEvaluatorDefinition类

package com.csair.cbd.rules.drools.services.impl;

import java.io.IOException;

import java.io.ObjectInput;

import java.io.ObjectOutput;

import org.drools.base.ValueType;

import org.drools.base.evaluators.EvaluatorDefinition;

import org.drools.base.evaluators.Operator;

import org.drools.spi.Evaluator;

public class CsairEvaluatorDefinition implements EvaluatorDefinition {

public static final Operator STR_COMPARE = Operator.addOperatorToRegistry(


"csair", false);


public static final Operator NOT_STR_COMPARE = Operator


.addOperatorToRegistry("csair", true);


private static final String[] SUPPORTED_IDS = { STR_COMPARE


.getOperatorString() };

public enum Operations {


FbInculde


}

private Evaluator[] evaluator;

public Evaluator getEvaluator(ValueType type, Operator operator) {


return this.getEvaluator(type, operator.getOperatorString(), operator


.isNegated(), null);


}

public Evaluator getEvaluator(ValueType type, Operator operator,


String parameterText) {


return this.getEvaluator(type, operator.getOperatorString(), operator


.isNegated(), parameterText);


}

public Evaluator getEvaluator(ValueType type, String operatorId,


boolean isNegated, String parameterText) {


return getEvaluator(type, operatorId, isNegated, parameterText,


Target.FACT, Target.FACT);


}

public Evaluator getEvaluator(ValueType type, String operatorId,


boolean isNegated, String parameterText, Target leftTarget,


Target rightTarget) {


CsairEvaluator evaluator = new CsairEvaluator(type, isNegated);


evaluator.setParameterText(parameterText);


return evaluator;


}

public String[] getEvaluatorIds() {


return SUPPORTED_IDS;


}

public Target getTarget() {


return Target.FACT;


}

public boolean isNegatable() {


return true;


}

public boolean supportsType(ValueType arg0) {


return true;


}

public void readExternal(ObjectInput in) throws IOException,


ClassNotFoundException {


evaluator = (Evaluator[]) in.readObject();

}

public void writeExternal(ObjectOutput out) throws IOException {


out.writeObject(evaluator);


}

}

第二步骤，新增CsairEvaluator类

package com.csair.cbd.rules.drools.services.impl;

import org.drools.base.BaseEvaluator;

import org.drools.base.ValueType;

import org.drools.common.InternalWorkingMemory;

import org.drools.rule.VariableRestriction.VariableContextEntry;

import org.drools.spi.FieldValue;

import org.drools.spi.InternalReadAccessor;

import com.csair.cbd.rules.drools.services.impl.CsairEvaluatorDefinition.Operations;

public class CsairEvaluator extends BaseEvaluator {

private Operations parameter;

public void setParameterText(String parameterText) {


this.parameter = Operations.valueOf(parameterText);


}

public Operations getParameter() {


return parameter;


}

public CsairEvaluator(final ValueType type, final boolean isNegated) {


  super(type, isNegated ?  CsairEvaluatorDefinition.NOT_STR_COMPARE: CsairEvaluatorDefinition.STR_COMPARE);


}

public boolean evaluate(InternalWorkingMemory workingMemory,


InternalReadAccessor extractor, Object object, FieldValue value) {


final Object objectValue = extractor.getValue(workingMemory, object);


switch (parameter) {


case FbInculde:


String sObjectValue = String.valueOf(objectValue);


String sObjectValueTrim = sObjectValue.replaceAll("[^a-zA-Z0-9]","");


String sFieldvalue  = String.valueOf(value.getValue());


boolean ret =sObjectValueTrim.substring(1).matches("^.*["+sFieldvalue+"][0-9]+.*$");


return  ret;


default:


throw new IllegalAccessError("Illegal str comparison parameter");


}


}

public boolean evaluate(InternalWorkingMemory arg0,


InternalReadAccessor arg1, Object arg2, InternalReadAccessor arg3,


Object arg4) {


return false;


}

public boolean evaluateCachedLeft(InternalWorkingMemory arg0,


VariableContextEntry arg1, Object arg2) {


return false;


}

public boolean evaluateCachedRight(InternalWorkingMemory arg0,


VariableContextEntry arg1, Object arg2) {


return false;


}

}

第三步骤，配置使drools规则引擎能够识别你定制的逻辑操作符

    System.setProperty("drools.dateformat", "yyyy-MM-dd");


            System.setProperty("drools.dialect.java.compiler", "JANINO");

//修改默认Java Dialect编译器

Properties props = new Properties();

//set default java compiler

//TODO use a file property to allow configuration

props.setProperty("drools.dialect.java.compiler", "JANINO");

PackageBuilderConfiguration pkgBuilderCfg = new PackageBuilderConfiguration(props);


//扩展csair条件比配操作符,caozhiping
pkgBuilderCfg.setOption(EvaluatorOption.get("csair",new CsairEvaluatorDefinition()));

// 声明新的KnowledgeBuilder对象

KnowledgeBuilder kbuilder = KnowledgeBuilderFactory

.newKnowledgeBuilder(pkgBuilderCfg);

经过以上三步后，你就可以正常使用你自己的关系操作符csair[FBInculde]了,这里贴上项目中的规则

rule "MingZhuKa-KeDuiHuanLiCheng-500000000001751-p20130727013"
salience 1          
no-loop false 
activation-group "1" 
ruleflow-group "1" 
 
    when 
        mileages : ArrayList() 
        mileageRuleMiddleValue : MileageRuleMiddleValue() 
        and frFfpTravelDetail : FrFfpTravelDetail(cumulateCabin == "E") 
        and FrFfpTravelDetail(this == frFfpTravelDetail &&
etFareBasis csair[FbInculde] "(ID)|(DG)|(AD)"
) 
 
    then 
        Date[] dates = ruleGlobalUtil.getMileageRuleCalculate().getValidBeginEndDatesFromTheDate(55,mileageRuleMiddleValue.getBeginValidDate());
        Mileage mileage = new Mileage("000001", "000001", mileageRuleMiddleValue.getBaseMileage()*44*0.01, mileageRuleMiddleValue.getRemark(),"ruleId", dates[0], dates[1], "travel-basic-award-1");
        mileages.add(mileage); 
end 
 

参考资料http://blog.athico.com/2010/06/creating-pluggable-oprators.html