initial commit

lottery-module/src/application.properties

@@ -0,0 +1 @@
+random.service=CHEAP

lottery-module/src/com/example/lottery/application/LotteryApp.java

@@ -1,16 +1,31 @@
 package com.example.lottery.application;
 
+import java.io.File;
+import java.io.FileInputStream;
+import java.util.Properties;
 import java.util.ServiceLoader;
+import java.util.ServiceLoader.Provider;
 
 import com.example.lottery.service.business.StandardLotterService;
+import com.example.random.service.QoS;
+import com.example.random.service.QualityLevel;
 import com.example.random.service.RandomNumberService;
 
 public class LotteryApp {
 
-	public static void main(String[] args) {
+	public static void main(String[] args) throws Exception {
+		var props = new Properties();
+		props.load(new FileInputStream(new File("src","application.properties")));
+		var qualityLevel = QualityLevel.valueOf(props.getProperty("random.service"));
 		var lotteryService = new StandardLotterService();
 		var services = ServiceLoader.load(RandomNumberService.class);
-		lotteryService.setRandomNumberService(services.findFirst().get());
+		var service = services.stream()
+				              .map(Provider::get)
+				              .filter(srv -> srv.getClass().isAnnotationPresent(QoS.class))
+				              .filter(srv -> srv.getClass().getAnnotation(QoS.class).value()==qualityLevel)
+				              .findFirst()
+				              .orElseThrow();
+		lotteryService.setRandomNumberService(service);
 		lotteryService.getLotteryNumbers(60, 6, 10)
 		              .forEach(System.out::println);
 	}

random-module/src/com/example/random/service/QoS.java

@@ -0,0 +1,12 @@
+package com.example.random.service;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface QoS {
+	QualityLevel value();
+}

random-module/src/com/example/random/service/QualityLevel.java

@@ -0,0 +1,5 @@
+package com.example.random.service;
+
+public enum QualityLevel {
+	FAST, SECURE, CHEAP
+}

random-module/src/com/example/random/service/business/CheapRandomNumberService.java

@@ -0,0 +1,17 @@
+package com.example.random.service.business;
+
+import com.example.random.service.QoS;
+import com.example.random.service.QualityLevel;
+import com.example.random.service.RandomNumberService;
+
+@QoS(QualityLevel.CHEAP)
+public class CheapRandomNumberService implements RandomNumberService {
+	private static int counter = 0;
+	@Override
+	public int generate(int min, int max) {
+		System.err.println("CheapRandomNumberService::generate");
+		counter++;
+		return min + (counter % (max-min+1) );
+	}
+
+}

random-module/src/com/example/random/service/business/FastRandomNumberService.java

@@ -2,12 +2,16 @@
 
 import java.util.concurrent.ThreadLocalRandom;
 
+import com.example.random.service.QoS;
+import com.example.random.service.QualityLevel;
 import com.example.random.service.RandomNumberService;
 
+@QoS(QualityLevel.FAST)
 public class FastRandomNumberService implements RandomNumberService {
 
 	@Override
 	public int generate(int min, int max) {
+		System.err.println("FastRandomNumberService::generate");
 		return ThreadLocalRandom.current().nextInt(min, max);
 	}
 

random-module/src/com/example/random/service/business/SecureRandomNumberService.java

@@ -2,14 +2,18 @@
 
 import java.security.SecureRandom;
 
+import com.example.random.service.QoS;
+import com.example.random.service.QualityLevel;
 import com.example.random.service.RandomNumberService;
 
+@QoS(QualityLevel.SECURE)
 public class SecureRandomNumberService implements RandomNumberService {
 
 	private SecureRandom random = new SecureRandom();
 
 	@Override
 	public int generate(int min, int max) {
+		System.err.println("SecureRandomNumberService::generate");
 		return random.nextInt(min, max);
 	}
 

random-module/src/module-info.java

@@ -1,8 +1,9 @@
 import com.example.random.service.RandomNumberService;
+import com.example.random.service.business.CheapRandomNumberService;
 import com.example.random.service.business.FastRandomNumberService;
 import com.example.random.service.business.SecureRandomNumberService;
 
 module com.example.random {
 	exports com.example.random.service;
-	provides RandomNumberService with FastRandomNumberService,SecureRandomNumberService;
+	provides RandomNumberService with FastRandomNumberService,SecureRandomNumberService,CheapRandomNumberService;
 }