XD-1027: Create script-based batch ItemProcessor

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/support/ScriptItemProcessor.java

@@ -0,0 +1,138 @@
+/*
+ * Copyright 2014 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.item.support;
+
+import org.springframework.scripting.support.StaticScriptSource;
+import org.springframework.util.StringUtils;
+import org.springframework.batch.item.ItemProcessor;
+import org.springframework.beans.factory.InitializingBean;
+import org.springframework.core.io.Resource;
+import org.springframework.scripting.ScriptEvaluator;
+import org.springframework.scripting.ScriptSource;
+import org.springframework.scripting.support.ResourceScriptSource;
+import org.springframework.scripting.support.StandardScriptEvaluator;
+import org.springframework.util.Assert;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * <p>
+ * {@link org.springframework.batch.item.ItemProcessor} implementation that passes the current
+ * item to process to the provided script. Exposes the current item for processing via the
+ * {@link org.springframework.batch.item.support.ScriptItemProcessor#ITEM_BINDING_VARIABLE_NAME}
+ * key name ("item"). A custom key name can be set by invoking:
+ * {@link org.springframework.batch.item.support.ScriptItemProcessor#setItemBindingVariableName}
+ * with the desired key name. The thread safety of this {@link org.springframework.batch.item.ItemProcessor}
+ * depends on the implementation of the {@link org.springframework.scripting.ScriptEvaluator} used.
+ * </p>
+ *
+ *
+ * @author Chris Schaefer
+ * @since 3.0
+ */
+public class ScriptItemProcessor<I, O> implements ItemProcessor<I, O>, InitializingBean {
+	private static final String ITEM_BINDING_VARIABLE_NAME = "item";
+
+	private String language;
+	private ScriptSource script;
+	private ScriptSource scriptSource;
+	private ScriptEvaluator scriptEvaluator;
+	private String itemBindingVariableName = ITEM_BINDING_VARIABLE_NAME;
+
+	@Override
+	@SuppressWarnings("unchecked")
+	public O process(I item) throws Exception {
+		Map<String, Object> arguments = new HashMap<String, Object>();
+		arguments.put(itemBindingVariableName, item);
+
+		return (O) scriptEvaluator.evaluate(getScriptSource(), arguments);
+	}
+
+	/**
+	 * <p>
+	 * Sets the {@link org.springframework.core.io.Resource} location of the script to use.
+	 * The script language will be deduced from the filename extension.
+	 * </p>
+	 *
+	 * @param resource the {@link org.springframework.core.io.Resource} location of the script to use.
+	 */
+	public void setScript(Resource resource) {
+		Assert.notNull(resource, "The script resource cannot be null");
+
+		this.script = new ResourceScriptSource(resource);
+	}
+
+	/**
+	 * <p>
+	 * Sets the provided {@link String} as the script source code to use.
+	 * </p>
+	 *
+	 * @param scriptSource the {@link String} form of the script source code to use.
+	 * @param language the language of the script as returned by the {@link javax.script.ScriptEngineFactory}
+	 */
+	public void setScriptSource(String scriptSource, String language) {
+		Assert.hasText(language, "Language must contain the script language");
+		Assert.hasText(scriptSource, "Script source must contain the script source to evaluate");
+
+		this.language = language;
+		this.scriptSource = new StaticScriptSource(scriptSource);
+	}
+
+	/**
+	 * <p>
+	 * Provides the ability to change the key name that scripts use to obtain the current
+	 * item to process if the variable represented by:
+	 * {@link org.springframework.batch.item.support.ScriptItemProcessor#ITEM_BINDING_VARIABLE_NAME}
+	 * is not suitable ("item").
+	 * </p>
+	 *
+	 * @param itemBindingVariableName the desired binding variable name
+	 */
+	public void setItemBindingVariableName(String itemBindingVariableName) {
+		this.itemBindingVariableName = itemBindingVariableName;
+	}
+
+	@Override
+	public void afterPropertiesSet() throws Exception {
+		scriptEvaluator = new StandardScriptEvaluator();
+
+		Assert.state(scriptSource != null || script != null,
+				"Either the script source or script file must be provided");
+
+		Assert.state(scriptSource == null || script == null,
+				"Either a script source or script file must be provided, not both");
+
+		if (scriptSource != null) {
+			Assert.isTrue(!StringUtils.isEmpty(language),
+					"Language must be provided when using script source");
+
+			((StandardScriptEvaluator) scriptEvaluator).setLanguage(language);
+		}
+	}
+
+	private ScriptSource getScriptSource() {
+		if (script != null) {
+			return script;
+		}
+
+		if (scriptSource != null) {
+			return scriptSource;
+		}
+
+		throw new IllegalStateException("Either a script source or script needs to be provided.");
+	}
+}