Proxy pattern: Improve the example

proxy/README.md

@@ -18,24 +18,24 @@ Surrogate
 Provide a surrogate or placeholder for another object to control
 access to it.
 
-![alt text](./etc/proxy_1.png "Proxy")
+![alt text](./etc/proxy.png "Proxy")
 
 ## Applicability
 Proxy is applicable whenever there is a need for a more
 versatile or sophisticated reference to an object than a simple pointer. Here
 are several common situations in which the Proxy pattern is applicable
 
-* a remote proxy provides a local representative for an object in a different address space.
+* Remote proxy provides a local representative for an object in a different address space.
-* a virtual proxy creates expensive objects on demand.
+* Virtual proxy creates expensive objects on demand.
-* a protection proxy controls access to the original object. Protection proxies are useful when objects should have different access rights.
+* Protection proxy controls access to the original object. Protection proxies are useful when objects should have different access rights.
 
 ## Typical Use Case
 
-* control access to another object
+* Control access to another object
-* lazy initialization
+* Lazy initialization
-* implement logging
+* Implement logging
-* facilitate network connection
+* Facilitate network connection
-* to count references to an object
+* Count references to an object
 
 ## Real world examples
 

proxy/etc/proxy.ucls

@@ -1,9 +1,10 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<class-diagram version="1.1.8" icons="true" automaticImage="PNG" always-add-relationships="false" generalizations="true" 
+<class-diagram version="1.1.11" icons="true" automaticImage="PNG" always-add-relationships="false" 
-  realizations="true" associations="true" dependencies="false" nesting-relationships="true">  
+  generalizations="true" realizations="true" associations="true" dependencies="false" nesting-relationships="true" 
+  router="FAN">  
   <class id="1" language="java" name="com.iluwatar.proxy.WizardTowerProxy" project="proxy" 
     file="/proxy/src/main/java/com/iluwatar/proxy/WizardTowerProxy.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="142" width="214" x="260" y="438"/>    
+    <position height="149" width="191" x="388" y="271"/>    
     <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
       sort-features="false" accessors="true" visibility="true">      
       <attributes public="true" package="true" protected="true" private="true" static="true"/>      
@@ -12,26 +13,56 @@
   </class>  
   <class id="2" language="java" name="com.iluwatar.proxy.Wizard" project="proxy" 
     file="/proxy/src/main/java/com/iluwatar/proxy/Wizard.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="124" width="117" x="187" y="274"/>    
+    <position height="113" width="102" x="619" y="271"/>    
     <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
       sort-features="false" accessors="true" visibility="true">      
       <attributes public="true" package="true" protected="true" private="true" static="true"/>      
       <operations public="true" package="true" protected="true" private="true" static="true"/>    
     </display>  
   </class>  
-  <class id="3" language="java" name="com.iluwatar.proxy.WizardTower" project="proxy" 
+  <interface id="3" language="java" name="com.iluwatar.proxy.WizardTower" project="proxy" 
     file="/proxy/src/main/java/com/iluwatar/proxy/WizardTower.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="106" width="130" x="344" y="274"/>    
+    <position height="77" width="116" x="388" y="460"/>    
+    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
+      <operations public="true" package="true" protected="true" private="true" static="true"/>    
+    </display>  
+  </interface>  
+  <class id="4" language="java" name="com.iluwatar.proxy.IvoryTower" project="proxy" 
+    file="/proxy/src/main/java/com/iluwatar/proxy/IvoryTower.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="113" width="116" x="761" y="271"/>    
     <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
       sort-features="false" accessors="true" visibility="true">      
       <attributes public="true" package="true" protected="true" private="true" static="true"/>      
       <operations public="true" package="true" protected="true" private="true" static="true"/>    
     </display>  
   </class>  
-  <generalization id="4">    
+  <class id="5" language="java" name="com.iluwatar.proxy.App" project="proxy" 
+    file="/proxy/src/main/java/com/iluwatar/proxy/App.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="95" width="114" x="917" y="271"/>    
+    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
+      <operations public="true" package="true" protected="true" private="true" static="true"/>    
+    </display>  
+  </class>  
+  <association id="6">    
+    <end type="SOURCE" refId="1" navigable="false">      
+      <attribute id="7" name="tower"/>      
+      <multiplicity id="8" minimum="0" maximum="1"/>    
+    </end>    
+    <end type="TARGET" refId="3" navigable="true"/>    
+    <display labels="true" multiplicity="true"/>  
+  </association>  
+  <realization id="9">    
+    <end type="SOURCE" refId="4"/>    
+    <end type="TARGET" refId="3"/>  
+  </realization>  
+  <realization id="10">    
     <end type="SOURCE" refId="1"/>    
     <end type="TARGET" refId="3"/>  
-  </generalization>  
+  </realization>  
   <classifier-display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
     sort-features="false" accessors="true" visibility="true">    
     <attributes public="true" package="true" protected="true" private="true" static="true"/>    

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

@@ -35,7 +35,7 @@ package com.iluwatar.proxy;
  * functionality to the object of interest without changing the object's code.
  * <p>
  * In this example the proxy ({@link WizardTowerProxy}) controls access to the actual object (
- * {@link WizardTower}).
+ * {@link IvoryTower}).
  * 
  */
 public class App {
@@ -45,12 +45,12 @@ public class App {
    */
   public static void main(String[] args) {
 
-    WizardTowerProxy tower = new WizardTowerProxy();
+    WizardTowerProxy proxy = new WizardTowerProxy(new IvoryTower());
-    tower.enter(new Wizard("Red wizard"));
+    proxy.enter(new Wizard("Red wizard"));
-    tower.enter(new Wizard("White wizard"));
+    proxy.enter(new Wizard("White wizard"));
-    tower.enter(new Wizard("Black wizard"));
+    proxy.enter(new Wizard("Black wizard"));
-    tower.enter(new Wizard("Green wizard"));
+    proxy.enter(new Wizard("Green wizard"));
-    tower.enter(new Wizard("Brown wizard"));
+    proxy.enter(new Wizard("Brown wizard"));
 
   }
 }

proxy/src/main/java/com/iluwatar/proxy/IvoryTower.java

@@ -0,0 +1,41 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.proxy;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * 
+ * The object to be proxyed.
+ * 
+ */
+public class IvoryTower implements WizardTower {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(IvoryTower.class);
+
+  public void enter(Wizard wizard) {
+    LOGGER.info("{} enters the tower.", wizard);
+  }
+
+}

proxy/src/main/java/com/iluwatar/proxy/Wizard.java

@@ -29,7 +29,7 @@ package com.iluwatar.proxy;
  */
 public class Wizard {
 
-  private String name;
+  private final String name;
 
   public Wizard(String name) {
     this.name = name;

proxy/src/main/java/com/iluwatar/proxy/WizardTower.java

@@ -1,41 +1,9 @@
-/**
- * The MIT License
- * Copyright (c) 2014 Ilkka Seppälä
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
 package com.iluwatar.proxy;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 /**
- * 
+ * WizardTower interface
- * The object to be proxyed.
- * 
  */
-public class WizardTower {
+public interface WizardTower {
-
-  private static final Logger LOGGER = LoggerFactory.getLogger(WizardTower.class);
-
-  public void enter(Wizard wizard) {
-    LOGGER.info("{} enters the tower.", wizard);
-  }
 
+  void enter(Wizard wizard);
 }

proxy/src/main/java/com/iluwatar/proxy/WizardTowerProxy.java

@@ -27,10 +27,10 @@ import org.slf4j.LoggerFactory;
 
 /**
  * 
- * The proxy controlling access to the {@link WizardTower}.
+ * The proxy controlling access to the {@link IvoryTower}.
  * 
  */
-public class WizardTowerProxy extends WizardTower {
+public class WizardTowerProxy implements WizardTower {
 
   private static final Logger LOGGER = LoggerFactory.getLogger(WizardTowerProxy.class);
 
@@ -38,10 +38,16 @@ public class WizardTowerProxy extends WizardTower {
 
   private int numWizards;
 
+  private final WizardTower tower;
+
+  public WizardTowerProxy(WizardTower tower) {
+    this.tower = tower;
+  }
+
   @Override
   public void enter(Wizard wizard) {
     if (numWizards < NUM_WIZARDS_ALLOWED) {
-      super.enter(wizard);
+      tower.enter(wizard);
       numWizards++;
     } else {
       LOGGER.info("{} is not allowed to enter!", wizard);

proxy/src/test/java/com/iluwatar/proxy/IvoryTowerTest.java

@@ -27,21 +27,21 @@ import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
 
+import java.util.Arrays;
+
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 
 /**
- * Date: 12/28/15 - 9:18 PM
+ * Tests for {@link IvoryTower}
- *
- * @author Jeroen Meulemeester
  */
-public class WizardTowerTest {
+public class IvoryTowerTest {
 
   private InMemoryAppender appender;
 
   @Before
   public void setUp() {
-    appender = new InMemoryAppender(WizardTower.class);
+    appender = new InMemoryAppender(IvoryTower.class);
   }
 
   @After
@@ -58,8 +58,8 @@ public class WizardTowerTest {
         new Wizard("Merlin")
     };
 
-    final WizardTower tower = new WizardTower();
+    IvoryTower tower = new IvoryTower();
-    for (final Wizard wizard : wizards) {
+    for (Wizard wizard : wizards) {
       tower.enter(wizard);
     }
 
@@ -69,5 +69,4 @@ public class WizardTowerTest {
     assertTrue(appender.logContains("Merlin enters the tower."));
     assertEquals(4, appender.getLogSize());
   }
-
 }

proxy/src/test/java/com/iluwatar/proxy/WizardTest.java

@@ -27,18 +27,15 @@ import org.junit.Test;
 import static org.junit.Assert.assertEquals;
 
 /**
- * Date: 12/28/15 - 9:02 PM
+ * Tests for {@link Wizard}
- *
- * @author Jeroen Meulemeester
  */
 public class WizardTest {
 
   @Test
   public void testToString() throws Exception {
     final String[] wizardNames = {"Gandalf", "Dumbledore", "Oz", "Merlin"};
-    for (final String name : wizardNames) {
+    for (String name : wizardNames) {
       assertEquals(name, new Wizard(name).toString());
     }
   }
-
 }

proxy/src/test/java/com/iluwatar/proxy/WizardTowerProxyTest.java

@@ -31,9 +31,7 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 
 /**
- * Date: 12/28/15 - 9:18 PM
+ * Tests for {@link WizardTowerProxy}
- *
- * @author Jeroen Meulemeester
  */
 public class WizardTowerProxyTest {
 
@@ -58,9 +56,9 @@ public class WizardTowerProxyTest {
         new Wizard("Merlin")
     };
 
-    final WizardTowerProxy tower = new WizardTowerProxy();
+    final WizardTowerProxy proxy = new WizardTowerProxy(new IvoryTower());
-    for (final Wizard wizard : wizards) {
+    for (Wizard wizard : wizards) {
-      tower.enter(wizard);
+      proxy.enter(wizard);
     }
 
     assertTrue(appender.logContains("Gandalf enters the tower."));
@@ -69,5 +67,4 @@ public class WizardTowerProxyTest {
     assertTrue(appender.logContains("Merlin is not allowed to enter!"));
     assertEquals(4, appender.getLogSize());
   }
-
 }