1、前言
Drools（JBoss
Rules ）具有一个易于访问企业策略、易于调整以及易于管理的开源业务规则引擎，符合业内标准，速度快、效率高。本文一个简单的例子讲解从java规则转化为规则引擎调用。
2、drtools规则
rule：定义一个规则。rule "ruleName"。一个规则可以包含三个部分：
属性部分：定义当前规则执行的一些属性等，比如是否可被重复执行、过期时间、生效时间等。
条件部分，即LHS，定义当前规则的条件，如 when Message(); 判断当前workingMemory中是否存在Message对象。
结果部分，即RHS，这里可以写普通java代码，即当前规则条件满足后执行的操作，可以直接调用Fact对象的方法来操作应用。
规则事例：
详细文法见：http://www.360doc.com/content/07/0705/18/7147_596025.shtml
3、使用例子
3.1需要转化的java代码
public int statusProcess(int faceStatus, double faceProbability, int tuStatus, double tuProbability) {
if (faceStatus == 0 || tuStatus == 0) {
return 0;
}
if (faceStatus == 1 || tuStatus == 1) {
return 0;
}
if (faceStatus == 2 && tuStatus == 2) {
double probability = tuProbability + faceProbability;
if (probability>0.85 && tuProbability >= 0.85) {
return 1;
} else if (tuProbability > 0.4 && tuProbability < 0.85 && probability >= 1.3) {
return 1;
} else if (probability >= 0.8 && probability < 1.3) {
return 2;
} else if (probability < 0.8) {
return 0;
}
}
return 2;
}
3.2 对应的规则文件
package com.feinno.drools
import com.feinno.drools.HelloWorldExample.ResultRate;
rule "1"
dialect "mvel"
when
m : ResultRate((faceStatus == -1 && tuStatus== -1 && status == -1 ), resultStatus : resultStatus )
then
System.out.println( resultStatus );
modify ( m ) {
status = 1,
resultStatus = 0
};
end
rule "2"
dialect "mvel"
when
m : ResultRate((faceStatus == 0 && tuStatus== 0 && status == -1 ), resultStatus : resultStatus )
then
System.out.println( resultStatus );
modify ( m ) {
status = 1,
resultStatus = 0
};
end
rule "3"
dialect "mvel"
when
m : ResultRate((faceStatus == 2 && tuStatus== 2&&tuProbability >= 0.85 && status == -1 ), resultStatus : resultStatus )
then
System.out.println( resultStatus );
modify ( m ) {
status = 1,
resultStatus =1
};
end
rule "4"
dialect "mvel"
when
m : ResultRate((faceStatus == 2 && tuStatus== 2&& tuProbability > 0.4 && tuProbability < 0.85 && probability>= 1.3 && status == -1 ), resultStatus : resultStatus )
then
System.out.println( resultStatus );
modify ( m ) {
status = 1,
resultStatus =1
};
end
rule "5"
dialect "mvel"
when
m : ResultRate((faceStatus == 2 && tuStatus== 2&& probability>= 0.8 && probability< 1.3 && status == -1 ), resultStatus : resultStatus )
then
System.out.println( resultStatus );
modify ( m ) {
status = 9,
resultStatus = 2
};
end
rule "51"
dialect "mvel"
when
m : ResultRate((faceStatus == 2 && tuStatus== 2&&tuProbability >= 0.85&& status == 9 ), resultStatus : resultStatus )
then
System.out.println( resultStatus );
modify ( m ) {
status = 1,
resultStatus = 1
};
end
rule "6"
dialect "mvel"
when
m : ResultRate((faceStatus == 2 && tuStatus== 2&& probability< 0.8 && status == -1 ), resultStatus : resultStatus )
then
System.out.println( resultStatus );
modify ( m ) {
status = 1,
resultStatus = 0
};
end
注意：
1、规则不能嵌套
2、规则不支持a+b，增加一个中间变量probability
3.3 对应的java对象
public static class ResultRate{
int faceStatus;
double faceProbability;
int tuStatus;
double tuProbability;
int status;
int resultStatus;
double probability;
public ResultRate(){
status = -1;
}
public int getFaceStatus() {
return faceStatus;
}
public void setFaceStatus(int faceStatus) {
this.faceStatus = faceStatus;
}
public double getFaceProbability() {
return faceProbability;
}
public void setFaceProbability(double faceProbability) {
this.faceProbability = faceProbability;
}
public int getTuStatus() {
return tuStatus;
}
public void setTuStatus(int tuStatus) {
this.tuStatus = tuStatus;
}
public double getTuProbability() {
return tuProbability;
}
public void setTuProbability(double tuProbability) {
this.tuProbability = tuProbability;
}
public int getStatus() {
return status;
}
public void setStatus(int status) {
this.status = status;
}
public int getResultStatus() {
return resultStatus;
}
public void setResultStatus(int resultStatus) {
this.resultStatus = resultStatus;
}
public double getProbability() {
return probability;
}
public void setProbability(double probability) {
this.probability = probability;
}
public void computeProbability(){
probability = faceProbability+tuProbability;
}
}
3.4 测试程序
public static void testRate()throws Exception {
String filepath = "C:\\目标路径\\ResultRate.drl";
final Reader source = new FileReader(filepath);
final PackageBuilder builder = new PackageBuilder();
//新建规则
builder.addPackageFromDrl(source);
if (builder.hasErrors()) {
System.out.println(builder.getErrors().toString());
throw new RuntimeException("Unable to compile ResultRate.drl");
}
// get the compiled package (which is serializable)
final Package pkg = builder.getPackage();
// add the package to a rulebase (deploy the rule package).
final RuleBase ruleBase = RuleBaseFactory.newRuleBase();
ruleBase.addPackage(pkg);
final StatefulSession session = ruleBase.newStatefulSession();
session.addEventListener(new DebugAgendaEventListener());
session.addEventListener(new DebugWorkingMemoryEventListener());
//测试
ResultRate rusultRate = new ResultRate();
rusultRate.setFaceStatus(2);
rusultRate.setFaceProbability(0.3);
rusultRate.setTuStatus(2);
rusultRate.setTuProbability(0.90);
rusultRate.computeProbability();
session.insert(rusultRate);
session.fireAllRules();
System.out.println("======================================");
//规则库后测试
Package[] packs = ruleBase.getPackages();
for(int i = 0;i<packs.length;i++){
System.out.println(packs[i].getName());
ruleBase.removePackage(packs[i].getName());
}
ResultRate rusultRate2 = new ResultRate();
rusultRate2.setFaceStatus(2);
rusultRate2.setFaceProbability(0.3);
rusultRate2.setTuStatus(2);
rusultRate2.setTuProbability(0.90);
rusultRate2.computeProbability();
System.out.println(rusultRate2.getResultStatus());
//消除相关的处理
session.dispose();
}
4、参考文档
http://blog.csdn.net/kevin_darkelf/article/details/50728137
http://www.360doc.com/content/07/0705/18/7147_596025.shtml
时间： 2024-08-08 20:59:49