Drools学习 入门实例

http://blog.sina.com.cn/s/blog_67d6d5df0100jyqk.html

在Eclipse新建Drools工程就可以导入自带的例子进行学习。





接下来：




如此，就可以对实例进行学习了。


下面只是参照HelloWorld写的一个小例子，当做笔记。

设计场景是银行借贷，当借贷款额小于1000时，直接借出，否则，需交由总经理处理。

1 新建工程，命名：drools,导入Drools相关jar包。

2 新建Package,命名：aaron.loan，在此包中建立class文件：pojo.java
pojo.java

package aaron.loan;
public class pojo {

int moneycount;
public int getMoneycount() {

return moneycount;

}
public void setMoneycount(int moneycount) {

this.moneycount = moneycount;

}

}

3 新建规则文件：DecisionRule.drl
Decision.drl

import aaron.loan.pojo;

rule "A"

when

$m:pojo(moneycount<1000);

then

System.out.println("Done!");

end
rule "B"

when

$m:pojo(moneycount>=1000);

then

System.out.println("Pass it to the management!");

end

4 在aaron.loan包中新建class文件：deploy.java
deploy.java

package aaron.loan;
import org.drools.KnowledgeBase;

import org.drools.KnowledgeBaseFactory;

import org.drools.builder.KnowledgeBuilder;

import org.drools.builder.KnowledgeBuilderError;

import org.drools.builder.KnowledgeBuilderErrors;

import org.drools.builder.KnowledgeBuilderFactory;

import org.drools.builder.ResourceType;

import org.drools.io.ResourceFactory;

import org.drools.logger.KnowledgeRuntimeLogger;

import org.drools.logger.KnowledgeRuntimeLoggerFactory;

import org.drools.runtime.StatefulKnowledgeSession;

public class deploy {

public void loanrool(int moneycount) throws Exception {

// TODO Auto-generated method stub

pojo p=new pojo();

try {

KnowledgeBase kbase = readKnowledgeBase();

StatefulKnowledgeSession ksession = kbase.newStatefulKnowledgeSession();

KnowledgeRuntimeLogger logger = KnowledgeRuntimeLoggerFactory

.newFileLogger(ksession, "test");

p.setMoneycount(moneycount);

ksession.insert(p);

ksession.fireAllRules();

System.out.print("moneycount:"+p.getMoneycount());

logger.close();

} catch (Throwable t) {

t.printStackTrace();

}

}

private KnowledgeBase readKnowledgeBase() throws Exception {

KnowledgeBuilder kbuilder = KnowledgeBuilderFactory

.newKnowledgeBuilder();

kbuilder.add(ResourceFactory.newClassPathResource("DecisionRule.drl"), ResourceType.DRL);

KnowledgeBuilderErrors errors = kbuilder.getErrors();

if (errors.size() > 0) {

for (KnowledgeBuilderError error : errors) {

System.err.println(error);

}

throw new IllegalArgumentException("Could not parse knowledge.");

}

KnowledgeBase kbase = KnowledgeBaseFactory.newKnowledgeBase();

kbase.addKnowledgePackages(kbuilder.getKnowledgePackages());

return kbase;

}
}

5 建立测试文件：test.java
test.java

package aaron.loan;

public class test {

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

// TODO Auto-generated method stub

deploy dp=new deploy();

pojo pj=new pojo();

pj.setMoneycount(900); //此处900是任意设的值。

int mc=pj.getMoneycount();

dp.loanrool(mc);

}
}

运行test.java文件，控制台结果如下：
Done!

moneycount:900

到此，Drools小实例就运行成功了

。

another drl example：

#ident "%W%"

#created on: Nov 4, 2011

package rules.com.citi.gcd.ptrs

#list any import classes here.

import com.citi.apollo.fmk.limit2.LimitRequest;

import java.util.List;

import java.util.ArrayList;

import com.citi.apollo.fmk.limit.PortfolioLimitResult;

import com.citi.apollo.fmk.limit.PortfolioLimitStatus;

import com.citi.apollo.fmk.util.aggregation.Aggregate;

import com.citi.apollo.fmk.limit.LimitAggregate;

import com.citi.apollo.fmk.limit.LimitRange;

# functions

import function com.citi.apollo.fmk.limit2.Limit2Util.setDefaultResult;

import function com.citi.apollo.fmk.limit2.Limit2Util.totalOf;

function void calcSomething(LimitRequest req, Double value, Double total) {

List<Aggregate> l = new ArrayList<Aggregate>();

LimitAggregate a = new LimitAggregate(new Aggregate(value, total));

a.setPercentValue(total/total);

l.add(a);

req.result.addAggregates(l);

req.result.setStatus(PortfolioLimitStatus.PASS);

LimitRange lr = new LimitRange(req.getLimit().getMinValue(),

req.getLimit().getMaxValue(),

req.getLimit().getMinPerValue(),

req.getLimit().getMaxPerValue());

lr.setExcessConcentration(false);

req.result.setLimitRange(lr);

}

#declare any global variables here

rule "Commitment"

no-loop true

when

$req : LimitRequest ( limit.limitName == "Commitment" )

then

double total = totalOf($req, "commitmentamount");

calcSomething($req, total, total);

setDefaultResult($req, total, total);

end