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Diffstat (limited to 'qpid/java/perftests/src/main/java/org/apache/qpid/disttest/Visitor.java')
-rw-r--r-- | qpid/java/perftests/src/main/java/org/apache/qpid/disttest/Visitor.java | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/qpid/java/perftests/src/main/java/org/apache/qpid/disttest/Visitor.java b/qpid/java/perftests/src/main/java/org/apache/qpid/disttest/Visitor.java new file mode 100644 index 0000000000..52dad9aa4d --- /dev/null +++ b/qpid/java/perftests/src/main/java/org/apache/qpid/disttest/Visitor.java @@ -0,0 +1,76 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you 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.apache.qpid.disttest; + +import java.lang.reflect.InvocationTargetException; +import java.lang.reflect.Method; + +/** + * A variation of the visitor pattern that uses reflection to call the correct + * visit method. By convention, subclasses should provide public + * <pre>visit(SpecificClass)</pre> methods. + */ +public abstract class Visitor +{ + + private static final String VISITOR_METHOD_NAME = "visit"; + + public void visit(Object targetObject) + { + Class<? extends Object> targetObjectClass = targetObject.getClass(); + final Method method = findVisitMethodForTargetObjectClass(targetObjectClass); + invokeVisitMethod(targetObject, method); + } + + private Method findVisitMethodForTargetObjectClass( + Class<? extends Object> targetObjectClass) + { + final Method method; + try + { + method = getClass().getDeclaredMethod(VISITOR_METHOD_NAME, targetObjectClass); + } + catch (Exception e) + { + throw new DistributedTestException("Failed to find method " + VISITOR_METHOD_NAME + " on object of class " + targetObjectClass, e); + } + return method; + } + + private void invokeVisitMethod(Object targetObject, final Method method) + { + try + { + method.invoke(this, targetObject); + } + catch (IllegalArgumentException e) + { + throw new DistributedTestException(e); + } + catch (IllegalAccessException e) + { + throw new DistributedTestException(e); + } + catch (InvocationTargetException e) + { + throw new DistributedTestException(e.getCause()); + } + } +} |