Add test cases and re-org packages

src/main/java/org/springframework/retry/RetryCallback.java

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+/*
+ * Copyright 2006-2007 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.springframework.retry;
+
+/**
+ * Callback interface for an operation that can be retried using a
+ * {@link RetryOperations}.
+ * 
+ * @author Rob Harrop
+ * @author Dave Syer
+ */
+public interface RetryCallback<T> {
+
+	/**
+	 * Execute an operation with retry semantics. Operations should generally be
+	 * idempotent, but implementations may choose to implement compensation
+	 * semantics when an operation is retried.
+	 * @param context the current retry context.
+	 * @return the result of the successful operation.
+	 * @throws Exception if processing fails
+	 */
+	T doWithRetry(RetryContext context) throws Exception;
+}