rulebook 简单记录

总体：

最后发版为2018年
相比EASY RULE，不支持jexl等脚本语言
支持Spring
内部执行都是使用jdk proxy模式，无论是annotation还是builder模式
可以使用CoRRuleBook 实现chain模式，在chain内按order进行执行
一个rule里面可以有多个action（@Then），多个fact（@Given），多个condition（@When），但注意When只有一个会执行
支持将一个java package的所有rule类组成一个Chain-CoRRuleBook
支持audit

核心概念

Much like the Given-When-Then language for defining tests that was popularized by BDD, RuleBook uses a Given-When-Then language for defining rules. The RuleBook Given-When-Then methods have the following meanings.

Given some Fact(s)
When a condition evaluates to true
Then an action is triggered

核心类及示意代码

rule执行类：GoldenRule

/**
A standard implementation of {@link Rule}.
@param the fact type
@param the Result type
*/
public class GoldenRule<T, U> implements Rule<T, U> {

action 识别代码

public List<Object> getActions() {if (_rule.getActions().size() < 1) {List<Object> actionList = new ArrayList<>();for (Method actionMethod : getAnnotatedMethods(Then.class, _pojoRule.getClass())) {actionMethod.setAccessible(true);Object then = getThenMethodAsBiConsumer(actionMethod).map(Object.class::cast).orElse(getThenMethodAsConsumer(actionMethod).orElse(factMap -> { }));actionList.add(then);}_rule.getActions().addAll(actionList);}return _rule.getActions();
}

condition 设置和获取，可以手工指定condition 如：auditableRule.setCondition(condition);
如果没有设置，使用如下代码识别

@Override
@SuppressWarnings("unchecked")
public Predicate<NameValueReferableMap> getCondition() {//Use what was set by then() first, if it's thereif (_rule.getCondition() != null) {return _rule.getCondition();}//If nothing was explicitly set, then convert the method in the class_rule.setCondition(Arrays.stream(_pojoRule.getClass().getMethods()).filter(method -> method.getReturnType() == boolean.class || method.getReturnType() == Boolean.class).filter(method -> Arrays.stream(method.getDeclaredAnnotations()).anyMatch(When.class::isInstance)).findFirst()

注意findFirst，代表只有一个生效

Chain 管理类 CoRRuleBook 使用Reflections 识别package下所有rule类的核心代码如下：

/*** Gets the POJO Rules to be used by the RuleBook via reflection of the specified package.* @return  a List of POJO Rules*/protected List<Class<?>> getPojoRules() {Reflections reflections = new Reflections(_package);List<Class<?>> rules = reflections.getTypesAnnotatedWith(com.deliveredtechnologies.rulebook.annotation.Rule.class).stream().filter(rule -> _package.equals(rule.getPackage().getName())) // Search only within package, not subpackages.filter(rule -> rule.getAnnotatedSuperclass() != null) // Include classes only, exclude interfaces, etc..collect(Collectors.toList());rules.sort(comparingInt(aClass ->getAnnotation(com.deliveredtechnologies.rulebook.annotation.Rule.class, aClass).order()));return rules;}

Fact管理

/*** A Fact is a single piece of data that can be supplied to a {@link Rule}.* Facts are not immutable; they may be changed by rules and used to derive a result state.*/
public class Fact<T> implements NameValueReferable<T> {private String _name;private T _value;/*** A FactMap decorates {@link Map}; it stores facts by their name and provides convenience methods for* accessing {@link Fact} objects.*/
public class FactMap<T> implements NameValueReferableMap<T> {private Map<String, NameValueReferable<T>> _facts;public FactMap(Map<String, NameValueReferable<T>> facts) {_facts = facts;}

实际上有点key重复的感觉，每个fact 本身还有name和value

Then/action 的执行核心代码在goldenRule里面

//invoke the actionStream.of(action.getClass().getMethods()).filter(method -> method.getName().equals("accept")).findFirst().ifPresent(method -> {try {method.setAccessible(true);method.invoke(action,ArrayUtils.combine(new Object[]{new TypeConvertibleFactMap<>(usingFacts)},new Object[]{getResult().orElseGet(() -> result)},method.getParameterCount()));if (result.getValue() != null) {_result = result;}} catch (IllegalAccessException | InvocationTargetException err) {LOGGER.error("Error invoking action on " + action.getClass(), err);if (_actionType.equals(ERROR_ON_FAILURE)) {throw err.getCause() == null ? new RuleException(err) :err.getCause() instanceof RuleException ? (RuleException)err.getCause() :new RuleException(err.getCause());}}});facts.putAll(usingFacts);
}

多fact示意

fact 通过@Given进行命名

@Rule
public class HelloWorld {@Given("hello")private String hello;@Given("world")private String world;

然后复制

facts.setValue("hello", "Hello");
facts.setValue("world", "World");

Spring 使用

@Configuration
@ComponentScan("com.example.rulebook.helloworld")
public class SpringConfig {@Bean
public RuleBook ruleBook() {RuleBook ruleBook = new SpringAwareRuleBookRunner("com.example.rulebook.helloworld");
return ruleBook;
}
}

扩展

可以扩展rule类，参考RuleAdapter

public RuleAdapter(Object pojoRule, Rule rule) throws InvalidClassException {com.deliveredtechnologies.rulebook.annotation.Rule ruleAnnotation =getAnnotation(com.deliveredtechnologies.rulebook.annotation.Rule.class, pojoRule.getClass());if (ruleAnnotation == null) {throw new InvalidClassException(pojoRule.getClass() + " is not a Rule; missing @Rule annotation");}_actionType = ruleAnnotation.ruleChainAction();_rule = rule == null ? new GoldenRule(Object.class, _actionType) : rule;_pojoRule = pojoRule;
}

扩展RuleBook（The RuleBook interface for defining objects that handle the behavior of rules chained together.）

/*** Creates a new RuleBookRunner using the specified package and the supplied RuleBook.* @param ruleBookClass the RuleBook type to use as a delegate for the RuleBookRunner.* @param rulePackage   the package to scan for POJO rules.*/public RuleBookRunner(Class<? extends RuleBook> ruleBookClass, String rulePackage) {super(ruleBookClass);_prototypeClass = ruleBookClass;_package = rulePackage;}

当然chain类也可以自己写。

其它

使用predicate的test 来判断condition 来
boolean test(T t)
Evaluates this predicate on the given argument.
Parameters:
t - the input argument
Returns:
true if the input argument matches the predicate, otherwise false

使用isAssignableFrom 来判断输入的fact 是否满足rule类里面的定义
isAssignableFrom是用来判断子类和父类的关系的，或者接口的实现类和接口的关系的，默认所有的类的终极父类都是
Object。如果
A.isAssignableFrom(B)结果是true，证明
B可以转换成为
A,也就是
A可以由
B转换而来