From 06c57000c7fd3408d2974d38f7f61f4f602547ae Mon Sep 17 00:00:00 2001
From: Markus Geiss <mgeiss@mifos.org>
Date: Sun, 26 Apr 2015 17:08:07 +0200
Subject: [PATCH] Added autodiscovery for command handlers.

---
 .../provider/CommandHandlerProvider.java      | 45 ++++++++++++-------
 .../handler/CreateClientCommandHandler.java   |  4 +-
 .../resources/META-INF/spring/appContext.xml  |  1 +
 .../provider/CommandHandlerProviderTest.java  | 31 ++++++-------
 .../provider/InvalidCommandHandler.java       | 23 ----------
 .../provider/ValidCommandHandler.java         |  5 ++-
 6 files changed, 48 insertions(+), 61 deletions(-)
 delete mode 100644 mifosng-provider/src/test/java/org/mifosplatform/commands/provider/InvalidCommandHandler.java

diff --git a/mifosng-provider/src/main/java/org/mifosplatform/commands/provider/CommandHandlerProvider.java b/mifosng-provider/src/main/java/org/mifosplatform/commands/provider/CommandHandlerProvider.java
index ce6375248..850e38a81 100644
--- a/mifosng-provider/src/main/java/org/mifosplatform/commands/provider/CommandHandlerProvider.java
+++ b/mifosng-provider/src/main/java/org/mifosplatform/commands/provider/CommandHandlerProvider.java
@@ -6,10 +6,14 @@
 package org.mifosplatform.commands.provider;
 
 import com.google.common.base.Preconditions;
+import org.apache.commons.lang3.ArrayUtils;
 import org.apache.commons.lang3.StringUtils;
 import org.mifosplatform.commands.annotation.CommandType;
 import org.mifosplatform.commands.exception.UnsupportedCommandException;
 import org.mifosplatform.commands.handler.NewCommandSourceHandler;
+import org.springframework.beans.BeansException;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.ApplicationContextAware;
 import org.springframework.context.annotation.Scope;
 import org.springframework.stereotype.Component;
 
@@ -30,28 +34,17 @@ import java.util.HashMap;
  */
 @Component
 @Scope("singleton")
-public class CommandHandlerProvider {
+public class CommandHandlerProvider implements ApplicationContextAware {
 
-    private final HashMap<String, NewCommandSourceHandler> registeredHandlers = new HashMap<>();
+    private ApplicationContext applicationContext;
+    private HashMap<String, String> registeredHandlers;
 
     CommandHandlerProvider() {
         super();
     }
 
     /**
-     * Registers a {@link NewCommandSourceHandler} using the annotation {@link CommandType} to register the handler.<br/>
-     * <br/>
-     * @param handler the {@link NewCommandSourceHandler} to be added, must be given
-     */
-    public <C extends NewCommandSourceHandler> void registerHandler(@Nonnull final C handler) {
-        Preconditions.checkArgument(handler != null, "A handler must be given!");
-
-        final CommandType commandType = handler.getClass().getAnnotation(CommandType.class);
-        this.registeredHandlers.put(commandType.entity() + "|" + commandType.action(), handler);
-    }
-
-    /**
-     * Returns a handler gor the given entity and action.<br/>
+     * Returns a handler for the given entity and action.<br/>
      * <br/>
      * Throws an {@link UnsupportedCommandException} if no handler
      * for the given entity, action combination can be found.
@@ -67,6 +60,26 @@ public class CommandHandlerProvider {
         if (!this.registeredHandlers.containsKey(key)) {
             throw new UnsupportedCommandException(key);
         }
-        return this.registeredHandlers.get(entity + "|" + action);
+        return (NewCommandSourceHandler)this.applicationContext.getBean(this.registeredHandlers.get(key));
+    }
+
+    private void initializeHandlerRegistry() {
+        if (this.registeredHandlers == null) {
+            this.registeredHandlers = new HashMap<>();
+
+            final String[] commandHandlerBeans = this.applicationContext.getBeanNamesForAnnotation(CommandType.class);
+            if (ArrayUtils.isNotEmpty(commandHandlerBeans)) {
+                for (final String commandHandlerName : commandHandlerBeans) {
+                    final CommandType commandType = this.applicationContext.getType(commandHandlerName).getAnnotation(CommandType.class);
+                    this.registeredHandlers.put(commandType.entity() + "|" + commandType.action(), commandHandlerName);
+                }
+            }
+        }
+    }
+
+    @Override
+    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
+        this.applicationContext = applicationContext;
+        this.initializeHandlerRegistry();
     }
 }
diff --git a/mifosng-provider/src/main/java/org/mifosplatform/portfolio/client/handler/CreateClientCommandHandler.java b/mifosng-provider/src/main/java/org/mifosplatform/portfolio/client/handler/CreateClientCommandHandler.java
index 17a864746..3b4526175 100644
--- a/mifosng-provider/src/main/java/org/mifosplatform/portfolio/client/handler/CreateClientCommandHandler.java
+++ b/mifosng-provider/src/main/java/org/mifosplatform/portfolio/client/handler/CreateClientCommandHandler.java
@@ -22,10 +22,8 @@ public class CreateClientCommandHandler implements NewCommandSourceHandler {
     private final ClientWritePlatformService clientWritePlatformService;
 
     @Autowired
-    public CreateClientCommandHandler(final ClientWritePlatformService clientWritePlatformService,
-                                      final CommandHandlerProvider commandHandlerProvider) {
+    public CreateClientCommandHandler(final ClientWritePlatformService clientWritePlatformService) {
         this.clientWritePlatformService = clientWritePlatformService;
-        commandHandlerProvider.registerHandler(this);
     }
 
     @Transactional
diff --git a/mifosng-provider/src/main/resources/META-INF/spring/appContext.xml b/mifosng-provider/src/main/resources/META-INF/spring/appContext.xml
index 422d368b4..26e8abead 100644
--- a/mifosng-provider/src/main/resources/META-INF/spring/appContext.xml
+++ b/mifosng-provider/src/main/resources/META-INF/spring/appContext.xml
@@ -27,6 +27,7 @@
 
 	<context:component-scan
 		base-package="org.mifosplatform.accounting.*,
+									      org.mifosplatform.commands.provider.*,
 									      org.mifosplatform.commands.handler.*,
 										  org.mifosplatform.commands.service.*,
 										  org.mifosplatform.commands.*,
diff --git a/mifosng-provider/src/test/java/org/mifosplatform/commands/provider/CommandHandlerProviderTest.java b/mifosng-provider/src/test/java/org/mifosplatform/commands/provider/CommandHandlerProviderTest.java
index 132dbb8b1..c618c3260 100644
--- a/mifosng-provider/src/test/java/org/mifosplatform/commands/provider/CommandHandlerProviderTest.java
+++ b/mifosng-provider/src/test/java/org/mifosplatform/commands/provider/CommandHandlerProviderTest.java
@@ -7,30 +7,35 @@ package org.mifosplatform.commands.provider;
 
 import org.junit.Assert;
 import org.junit.Test;
+import org.junit.runner.RunWith;
 import org.mifosplatform.commands.exception.UnsupportedCommandException;
 import org.mifosplatform.commands.handler.NewCommandSourceHandler;
+import org.mifosplatform.infrastructure.configuration.spring.TestsWithoutDatabaseAndNoJobsConfiguration;
 import org.mifosplatform.infrastructure.core.api.JsonCommand;
 import org.mifosplatform.infrastructure.core.data.CommandProcessingResult;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.test.context.web.WebAppConfiguration;
 
+@RunWith(SpringJUnit4ClassRunner.class)
+@WebAppConfiguration
+@ContextConfiguration(classes = TestsWithoutDatabaseAndNoJobsConfiguration.class)
 public class CommandHandlerProviderTest {
 
+    @Autowired
+    private CommandHandlerProvider commandHandlerProvider;
+
     public CommandHandlerProviderTest() {
         super();
     }
 
     @Test
     public void shouldRegisterHandler() {
-        final CommandHandlerProvider provider = new CommandHandlerProvider();
-        try {
-            new ValidCommandHandler(provider);
-        } catch (NullPointerException pex) {
-            Assert.fail();
-        }
-
         try {
             final Long testCommandId = 815L;
 
-            final NewCommandSourceHandler registeredHandler = provider.getHandler("HUMAN", "UPDATE");
+            final NewCommandSourceHandler registeredHandler = this.commandHandlerProvider.getHandler("HUMAN", "UPDATE");
 
             final CommandProcessingResult result =
                     registeredHandler.processCommand(
@@ -41,16 +46,8 @@ public class CommandHandlerProviderTest {
         }
     }
 
-    @Test(expected = NullPointerException.class)
-    public void shouldNotRegisterHandlerAndThrowNullPointerException() {
-        final CommandHandlerProvider provider = new CommandHandlerProvider();
-        new InvalidCommandHandler(provider);
-    }
-
     @Test(expected = UnsupportedCommandException.class)
     public void shouldThrowUnsupportedCommandException() {
-        final CommandHandlerProvider provider = new CommandHandlerProvider();
-        provider.getHandler("WHATEVER", "DOSOMETHING");
-
+        this.commandHandlerProvider.getHandler("WHATEVER", "DOSOMETHING");
     }
 }
diff --git a/mifosng-provider/src/test/java/org/mifosplatform/commands/provider/InvalidCommandHandler.java b/mifosng-provider/src/test/java/org/mifosplatform/commands/provider/InvalidCommandHandler.java
deleted file mode 100644
index 3ff9e6819..000000000
--- a/mifosng-provider/src/test/java/org/mifosplatform/commands/provider/InvalidCommandHandler.java
+++ /dev/null
@@ -1,23 +0,0 @@
-/**
- * This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this file,
- * You can obtain one at http://mozilla.org/MPL/2.0/.
- */
-package org.mifosplatform.commands.provider;
-
-import org.mifosplatform.commands.handler.NewCommandSourceHandler;
-import org.mifosplatform.infrastructure.core.api.JsonCommand;
-import org.mifosplatform.infrastructure.core.data.CommandProcessingResult;
-
-public class InvalidCommandHandler implements NewCommandSourceHandler {
-
-    public InvalidCommandHandler(final CommandHandlerProvider commandHandlerProvider) {
-        super();
-        commandHandlerProvider.registerHandler(this);
-    }
-
-    @Override
-    public CommandProcessingResult processCommand(JsonCommand command) {
-        return CommandProcessingResult.commandOnlyResult(command.commandId());
-    }
-}
diff --git a/mifosng-provider/src/test/java/org/mifosplatform/commands/provider/ValidCommandHandler.java b/mifosng-provider/src/test/java/org/mifosplatform/commands/provider/ValidCommandHandler.java
index b5c3ef828..0aac8d8b7 100644
--- a/mifosng-provider/src/test/java/org/mifosplatform/commands/provider/ValidCommandHandler.java
+++ b/mifosng-provider/src/test/java/org/mifosplatform/commands/provider/ValidCommandHandler.java
@@ -9,13 +9,14 @@ import org.mifosplatform.commands.annotation.CommandType;
 import org.mifosplatform.commands.handler.NewCommandSourceHandler;
 import org.mifosplatform.infrastructure.core.api.JsonCommand;
 import org.mifosplatform.infrastructure.core.data.CommandProcessingResult;
+import org.springframework.stereotype.Component;
 
+@Component
 @CommandType(entity = "HUMAN", action = "UPDATE")
 public class ValidCommandHandler implements NewCommandSourceHandler {
 
-    public ValidCommandHandler(final CommandHandlerProvider commandHandlerProvider) {
+    public ValidCommandHandler() {
         super();
-        commandHandlerProvider.registerHandler(this);
     }
 
     @Override