Java 8中的策略模式

这是两个有关如何使用Java 8功能样式以及Cyclops模式匹配和Hamcrest库来实现策略模式设计的示例。

PrintDependingOnInput方法是一种策略，该策略将根据传递的日志在System.println中显示一些消息。

AddPrefix是另一种策略，它将根据邮件内容为邮件添加前缀。

package com.marco.patternmatching; import static org.hamcrest.Matchers.containsString;
import static org.hamcrest.Matchers.not;
import static org.hamcrest.Matchers.startsWith;
import static org.hamcrest.core.AllOf.allOf;
import java.util.ArrayList;
import java.util.List;
import com.aol.cyclops.matcher.builders.Matching; public class FunctionalStrategy {public static void main(String[] args) {List<String> toTest = new ArrayList<>();toTest.add("INFO everything is fine");toTest.add("WARN something weird happened");toTest.add("ERROR NullPointerException");toTest.add("ERROR IOException");toTest.stream().forEach(FunctionalStrategy::printDependingOnInput);System.out.println("--------------------");List<String> messages = new ArrayList<>();messages.add("everything is fine");messages.add("something weird happened");messages.add("NullPointerException");messages.add("IOException");messages.stream().map(FunctionalStrategy::addPrefix).forEach(System.out::println);}public static void printDependingOnInput(String log) {Matching.when().isMatch(startsWith("INFO")).thenConsume(System.out::println).when().isMatch(startsWith("WARN")).thenConsume(message -> System.out.println("Found one warning : " + message)).when().isMatch(allOf(startsWith("ERROR"), containsString("NullPointerException"))).thenConsume(message -> System.err.println(message)).when().isMatch(allOf(startsWith("ERROR"), containsString("IOException"))).thenConsume(message -> System.err.println(message + " Retrying a couple of times")).match(log);}public static String addPrefix(String log) {return Matching.when().isMatch(allOf(not(containsString("Exception")), not(containsString("weird")))).thenApply(message -> "INFO " + message).when().isMatch(containsString("weird")).thenApply(message -> "WARN " + message).when().isMatch(containsString("Exception")).thenApply(message -> "ERROR " + message).match(log).get();}
}

干净整洁;）