added chain of responsibility sample

chain/pom.xml

+<?xml version="1.0"?>
+<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+  <modelVersion>4.0.0</modelVersion>
+  <parent>
+    <groupId>com.iluwatar</groupId>
+    <artifactId>java-design-patterns</artifactId>
+    <version>1.0-SNAPSHOT</version>
+  </parent>
+  <groupId>com.iluwatar</groupId>
+  <artifactId>chain</artifactId>
+  <version>1.0-SNAPSHOT</version>
+  <name>chain</name>
+  <url>http://maven.apache.org</url>
+  <dependencies>
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <version>3.8.1</version>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+</project>

chain/src/main/java/com/iluwatar/App.java

+package com.iluwatar;
+
+public class App 
+{
+    public static void main( String[] args )
+    {
+
+    	OrcKing king = new OrcKing();
+    	king.makeRequest(new Request(RequestType.DEFEND_CASTLE, "defend castle"));
+    	king.makeRequest(new Request(RequestType.TORTURE_PRISONER, "torture prisoner"));
+    	king.makeRequest(new Request(RequestType.COLLECT_TAX, "collect tax"));
+        
+    }
+}

chain/src/main/java/com/iluwatar/OrcCommander.java

+package com.iluwatar;
+
+public class OrcCommander extends RequestHandler {
+
+	public OrcCommander(RequestHandler handler) {
+		super(handler);
+	}
+	
+	@Override
+	public void handleRequest(Request req) {
+		if (req.getRequestType().equals(RequestType.DEFEND_CASTLE)) {
+			printHandling(req);
+		} else {
+			super.handleRequest(req);
+		}
+	}
+
+	@Override
+	public String toString() {
+		return "Orc commander";
+	}
+}

chain/src/main/java/com/iluwatar/OrcKing.java

+package com.iluwatar;
+
+public class OrcKing {
+
+	RequestHandler chain;
+	
+	public OrcKing() {
+		buildChain();
+	}
+	
+	private void buildChain() {
+		chain = new OrcCommander(new OrcOfficer(new OrcSoldier(null)));
+	}
+	
+	public void makeRequest(Request req) {
+		chain.handleRequest(req);
+	}
+	
+}

chain/src/main/java/com/iluwatar/OrcOfficer.java

+package com.iluwatar;
+
+public class OrcOfficer extends RequestHandler {
+
+	public OrcOfficer(RequestHandler handler) {
+		super(handler);
+	}
+	
+	@Override
+	public void handleRequest(Request req) {
+		if (req.getRequestType().equals(RequestType.TORTURE_PRISONER)) {
+			printHandling(req);
+		} else {
+			super.handleRequest(req);
+		}
+	}
+
+	@Override
+	public String toString() {
+		return "Orc officer";
+	}
+
+}

chain/src/main/java/com/iluwatar/OrcSoldier.java

+package com.iluwatar;
+
+public class OrcSoldier extends RequestHandler {
+
+	public OrcSoldier(RequestHandler handler) {
+		super(handler);
+	}
+
+	@Override
+	public void handleRequest(Request req) {
+		if (req.getRequestType().equals(RequestType.COLLECT_TAX)) {
+			printHandling(req);
+		} else {
+			super.handleRequest(req);
+		}
+	}
+
+	@Override
+	public String toString() {
+		return "Orc soldier";
+	}
+}

chain/src/main/java/com/iluwatar/Request.java

+package com.iluwatar;
+
+public class Request {
+
+	private String requestDescription;
+	private RequestType requestType;
+
+	public Request(RequestType requestType, String requestDescription) {
+		this.setRequestType(requestType);
+		this.setRequestDescription(requestDescription);
+	}
+
+	public String getRequestDescription() {
+		return requestDescription;
+	}
+
+	public void setRequestDescription(String requestDescription) {
+		this.requestDescription = requestDescription;
+	}
+
+	public RequestType getRequestType() {
+		return requestType;
+	}
+
+	public void setRequestType(RequestType requestType) {
+		this.requestType = requestType;
+	}
+
+	@Override
+	public String toString() {
+		return getRequestDescription();
+	}
+}

chain/src/main/java/com/iluwatar/RequestHandler.java

+package com.iluwatar;
+
+public abstract class RequestHandler {
+	
+	private RequestHandler next;
+
+	public RequestHandler(RequestHandler next) {
+		this.next = next;
+	}
+	
+	public void handleRequest(Request req) {
+		if (next != null) {
+			next.handleRequest(req);
+		}
+	}
+
+	protected void printHandling(Request req) {
+		System.out.println(this + " handling request \"" + req + "\"");
+	}
+
+	@Override
+	public abstract String toString();
+}

chain/src/main/java/com/iluwatar/RequestType.java

+package com.iluwatar;
+
+public enum RequestType {
+
+	DEFEND_CASTLE,
+	TORTURE_PRISONER,
+	COLLECT_TAX
+	
+}

pom.xml

@@ -30,6 +30,7 @@
     <module>facade</module>
     <module>flyweight</module>
     <module>proxy</module>
+    <module>chain</module>
   </modules>
   
 <build>