id prefixes are now done at the very last moment instead of when an item is added.

[xmlrouter] / impl / src / main / java / org / wamblee / xmlrouter / impl / IdentifiablePrefixProxyFactory.java

diff --git a/impl/src/main/java/org/wamblee/xmlrouter/impl/IdentifiablePrefixProxyFactory.java b/impl/src/main/java/org/wamblee/xmlrouter/impl/IdentifiablePrefixProxyFactory.java
new file mode 100644 (file)
index 0000000..c787c7b
--- /dev/null
+++ b/impl/src/main/java/org/wamblee/xmlrouter/impl/IdentifiablePrefixProxyFactory.java
@@ -0,0 +1,83 @@
+/*
+ * Copyright 2005-2011 the original author or authors.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.wamblee.xmlrouter.impl;
+
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+
+import org.wamblee.xmlrouter.common.Id;
+import org.wamblee.xmlrouter.config.Identifiable;
+
+/**
+ * This proxy factory creates proxies for identifiable objects that add a prefix
+ * to the ids.
+ * 
+ * @author Erik Brakkee
+ * 
+ * @param <T>
+ */
+public class IdentifiablePrefixProxyFactory<T> {
+
+    public static final class IdPrefixInvocationHandler<T> implements
+        InvocationHandler {
+
+        private String prefix;
+        private T service;
+
+        public IdPrefixInvocationHandler(String aPrefix, T aService) {
+            prefix = aPrefix;
+            service = aService;
+        }
+
+        @Override
+        public Object invoke(Object aProxy, final Method aMethod,
+            final Object[] aArgs) throws Throwable {
+            try {
+                if (aMethod.getDeclaringClass().equals(Identifiable.class)) {
+                    if (!aMethod.getName().equals("getId")) {
+                        throw new RuntimeException(
+                            "Programming error, Identifiable interface was modified");
+                    }
+                    Id id = (Id) aMethod.invoke(service, aArgs);
+                    return new Id(prefix + id.getId());
+                }
+                return aMethod.invoke(service, aArgs);
+            } catch (InvocationTargetException e) {
+                throw e.getCause();
+            }
+        }
+    }
+
+    public static <T> T getProxy(String aPrefix, T aService,
+        Class... aInterfaces) {
+        InvocationHandler handler = new IdPrefixInvocationHandler<T>(aPrefix,
+            aService);
+        Class proxyClass = Proxy.getProxyClass(aService.getClass()
+            .getClassLoader(), aInterfaces);
+        T proxy;
+        try {
+            proxy = (T) proxyClass.getConstructor(
+                new Class[] { InvocationHandler.class }).newInstance(
+                new Object[] { handler });
+            return proxy;
+        } catch (Exception e) {
+            throw new RuntimeException("Could not create proxy for " +
+                aService.getClass().getName(), e);
+        }
+    }
+}