RESOLVED - issue BATCH-45: Create a POJO adapter for batch Tasklet

http://jira.springframework.org/browse/BATCH-45

Use the existing method invoking delegator to provide a crude adapter (not trying to pass result back in).

spring-batch-execution/src/main/java/org/springframework/batch/execution/tasklet/TaskletAdapter.java

@@ -0,0 +1,65 @@
+/*
+ * 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.batch.execution.tasklet;
+
+import org.springframework.batch.core.tasklet.Tasklet;
+import org.springframework.batch.repeat.ExitStatus;
+import org.springframework.batch.support.AbstractMethodInvokingDelegator;
+
+/**
+ * A {@link Tasklet} that wraps a method in a POJO. By default the
+ * {@link ExitStatus} is determined by comparing the return value from the POJO
+ * with null. The POJO method is usually going to have no arguments, but a
+ * static argument or array of arguments can be used by setting the arguments
+ * property.
+ * 
+ * @see AbstractMethodInvokingDelegator
+ * 
+ * @author Dave Syer
+ * 
+ */
+public class TaskletAdapter extends AbstractMethodInvokingDelegator implements Tasklet {
+
+	/**
+	 * Delegate execution to the target object and translate the return value to
+	 * an {@link ExitStatus} by invoking a method in the delegate POJO. N.B. the
+	 * delegate method should not be void, otherwise there is no way to
+	 * determine when the result indicates a finished job.
+	 * 
+	 * @see org.springframework.batch.core.tasklet.Tasklet#execute()
+	 */
+	public ExitStatus execute() throws Exception {
+		return mapResult(invokeDelegateMethod());
+	}
+
+	/**
+	 * If the result is an {@link ExitStatus} already just return that,
+	 * otherwise return {@link ExitStatus#FINISHED} if the result is null and
+	 * {@link ExitStatus#CONTINUABLE} if not.
+	 * @param result the value returned by the delegate method
+	 * @return an {@link ExitStatus} consistent with the result
+	 */
+	protected ExitStatus mapResult(Object result) {
+		if (result instanceof ExitStatus) {
+			return (ExitStatus) result;
+		}
+		if (result == null) {
+			return ExitStatus.FINISHED;
+		}
+		return ExitStatus.CONTINUABLE;
+	}
+
+}

spring-batch-execution/src/test/java/org/springframework/batch/execution/tasklet/TaskletAdapterTests.java

@@ -0,0 +1,72 @@
+/*
+ * 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.batch.execution.tasklet;
+
+import org.springframework.batch.repeat.ExitStatus;
+
+import junit.framework.TestCase;
+
+/**
+ * @author Dave Syer
+ *
+ */
+public class TaskletAdapterTests extends TestCase {
+	
+	private TaskletAdapter tasklet = new TaskletAdapter();
+	private Object result = null;
+	
+	public ExitStatus execute() {
+		return ExitStatus.NOOP;
+	}
+
+	public Object process() {
+		return result ;
+	}
+
+	/* (non-Javadoc) 
+	 * @see junit.framework.TestCase#setUp()
+	 */
+	protected void setUp() throws Exception {
+		tasklet.setTargetObject(this);
+		tasklet.setTargetMethod("execute");
+	}
+
+	/**
+	 * Test method for {@link org.springframework.batch.execution.tasklet.TaskletAdapter#execute()}.
+	 * @throws Exception 
+	 */
+	public void testExecuteWithExitStatus() throws Exception {
+		assertEquals(ExitStatus.NOOP, tasklet.execute());
+	}
+
+	/**
+	 * Test method for {@link org.springframework.batch.execution.tasklet.TaskletAdapter#mapResult(java.lang.Object)}.
+	 */
+	public void testMapResultWithNull() throws Exception {
+		tasklet.setTargetMethod("process");
+		assertEquals(ExitStatus.FINISHED, tasklet.execute());
+	}
+
+	/**
+	 * Test method for {@link org.springframework.batch.execution.tasklet.TaskletAdapter#mapResult(java.lang.Object)}.
+	 */
+	public void testMapResultWithNonNull() throws Exception {
+		tasklet.setTargetMethod("process");
+		this.result = "foo";
+		assertEquals(ExitStatus.CONTINUABLE, tasklet.execute());
+	}
+
+}