比较日期在Drools中，如下

Question

我的规则文件，

import com.springapp.mvc.model.Person; 
dialect "java" 
rule "4" 
    when 
     $person:Person(((date > "20-Jan-2015") && (date < "20-Dec-2015")) && (call_count >= "299")) 
    then 
     System.out.println("Beep"); 
end 

我加了下面的人对象，如下消防规则，

Person person = new Person(); 
person.date = "20-Feb-2015"; 
person.call_count = 400; 
kSession.insert(person); 
int fires = kSession.fireAllRules(); 

但它并没有打印出“哔”。我认为条件不匹配，但我不明白为什么会发生这种情况。我如何比较口水中的日期？

我的实际规则集，

package Customer_Loyalty_Categorization; 
import com.springapp.mvc.model.Person; 
dialect "java" 

rule "4" 
    when 
     $person:Person(((date > "10-Nov-2015") && (date < "10-Dec-2015")) && (call_count >= "299")) 
     $person:Person(((date > "10-Nov-2015")&&(date < "30-Dec-2015")) && (call_count >= "299")) 
    then 
     System.out.println("Point rule runs."); 
     $person.points = ($person.call_count)*0.2; 
end 

rule "6" 
    when 
     $person:Person(call_count >= "599") 
    then 
     System.out.println("Category rule runs."); 
     $person.setCategory('PLATINUM'); 
end 

并改变人的日期变量的类型后，我得到了以下异常，

java.lang.RuntimeException: Unable to Analyse Expression date > "20-Nov-2015": 
[Error: Comparison operation requires compatible types. Found class java.util.Date and class java.lang.String] 
[Near : {... date > "20-Nov-2015" ....}] 
        ^
[Line: 8, Column: 8] : [Rule name='4'] 

Unable to Analyse Expression date < "20-Dec-2015": 
[Error: Comparison operation requires compatible types. Found class java.util.Date and class java.lang.String] 
[Near : {... date < "20-Dec-2015" ....}] 
        ^
[Line: 8, Column: 8] : [Rule name='4'] 

Unable to Analyse Expression date > "01-Jan-2015": 
[Error: Comparison operation requires compatible types. Found class java.util.Date and class java.lang.String] 
[Near : {... date > "01-Jan-2015" ....}] 
        ^
[Line: 40, Column: 8] : [Rule name='1'] 

Unable to Analyse Expression date < "07-Jan-2015": 
[Error: Comparison operation requires compatible types. Found class java.util.Date and class java.lang.String] 
[Near : {... date < "07-Jan-2015" ....}] 
        ^
[Line: 40, Column: 8] : [Rule name='1'] 

Unable to Analyse Expression date > "01-Jan-2015": 
[Error: Comparison operation requires compatible types. Found class java.util.Date and class java.lang.String] 
[Near : {... date > "01-Jan-2015" ....}] 
        ^
[Line: 48, Column: 8] : [Rule name='2'] 

Unable to Analyse Expression date < "07-Jan-2015": 
[Error: Comparison operation requires compatible types. Found class java.util.Date and class java.lang.String] 
[Near : {... date < "07-Jan-2015" ....}] 
        ^
[Line: 48, Column: 8] : [Rule name='2'] 

Unable to Analyse Expression date > "05-Jan-2015": 
[Error: Comparison operation requires compatible types. Found class java.util.Date and class java.lang.String] 
[Near : {... date > "05-Jan-2015" ....}] 
        ^
[Line: 48, Column: 8] : [Rule name='2'] 

Unable to Analyse Expression date < "10-Jan-2015": 
[Error: Comparison operation requires compatible types. Found class java.util.Date and class java.lang.String] 
[Near : {... date < "10-Jan-2015" ....}] 
        ^
[Line: 48, Column: 8] : [Rule name='2'] 

我生成规则的字符串设定和转换他们使用以下功能进入知识库，

public void createKnowledgeBase(){ 
     String ruleSet = loadRuleSet();//generate rules as strings. 
     try { 
      System.out.println(ruleSet); 
      long start = System.currentTimeMillis(); 
      if(ruleSet!=null){ 
       KnowledgeBuilder knowledgeBuilder = KnowledgeBuilderFactory.newKnowledgeBuilder(); 
       Resource myResource = ResourceFactory.newReaderResource(new StringReader(ruleSet)); 
       knowledgeBuilder.add(myResource, ResourceType.DRL); 
       if (knowledgeBuilder.hasErrors()) { 
        throw new RuntimeException(knowledgeBuilder.getErrors().toString()); 
       } 
       knowledgeBase = KnowledgeBaseFactory.newKnowledgeBase(); 
       knowledgeBase.addKnowledgePackages(knowledgeBuilder.getKnowledgePackages()); 
      } 
      long finish = System.currentTimeMillis(); 
      System.out.println("Execution time = " + (finish-start) + " milliseconds."); 
     } 
     catch (Exception e) { 
      e.printStackTrace(); 
     } 
    } 

Answer 1

显然，你有

class Person { 
    String date; 
    // ... 
} 

这样

when 
    $person:Person(((date > "20-Jan-2015") ... 

结果在一个字符串（！）的

"20-Feb-2015" > "20-Jan-2015" && "20-Feb-2015" < "20-Dec-2015" 

比较甚至可能有时工作，但主要是它不会。您应该使用

class Person { 
    java.util.Date date; 
    // ... 
} 

您需要更改

person.date = new Date(115, 1, 20); // or, preferably, parse a string 

，但你可以离开规则，因为它是; Drools会将字符串转换为日期值（只要它对应于您的区域设置）。

后来经过一些实验后，我发现在编译java.util.Date到String的比较时，6.3.0（可能更早的版本）有一个相当奇怪的行为。

rule x1 when 
    Person(date > "10-Jan-2000")    // OK 
    Person($date:date, date > "10-Jan-2000") // OK 
    Person($date:date, $date > "10-Jan-2000") // Error (types incompatible) 

当程序员可能不依赖于绑定变量的行为与绑定的属性相同时，这是非常令人困惑的。

最后： 不要在您的事实类中使用公共字段。留在Java Beans模型中并声明getter和setter。事实证明，当由于缺少getter而访问（公共）实例变量本身时，Drools没有使用从String到java.util.Date的自动转换。

Answer 2

您可以试用org.apache.commons.lang.time.DateUtils。我遇到了同样的问题，这一个为我工作，可能会在你的工作。

import org.apache.commons.lang.time.DateUtils; 

$person: Person((date > DateUtils.parseDate("20-01-2015", "dd-MM-yyyy") && date < DateUtils.parseDate("20-12-2015", "dd-MM-yyyy")) && (call_count >= "299"));