基于drools创建自己的关系操作符

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);

作者：czp11210 发表于2013-7-27 13:07:10 原文链接

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