BATCH-2270: Allow ScriptEvaluator to be injectable in the ScriptItemProcessor

Author: chrisjs

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

@@ -108,19 +108,34 @@ public void setItemBindingVariableName(String itemBindingVariableName) {
 		this.itemBindingVariableName = itemBindingVariableName;
 	}
 
+	/**
+	 * <p>
+	 * Provides the ability to set a custom {@link org.springframework.scripting.ScriptEvaluator}
+	 * implementation. If not set, a {@link org.springframework.scripting.support.StandardScriptEvaluator}
+	 * will be used by default.
+	 * </p>
+	 *
+	 * @param scriptEvaluator the {@link org.springframework.scripting.ScriptEvaluator} to use
+	 */
+	public void setScriptEvaluator(ScriptEvaluator scriptEvaluator) {
+		this.scriptEvaluator = scriptEvaluator;
+	}
+
 	@Override
 	public void afterPropertiesSet() throws Exception {
-		scriptEvaluator = new StandardScriptEvaluator();
+		if(scriptEvaluator == null) {
+			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) {
+		if (scriptSource != null && scriptEvaluator instanceof StandardScriptEvaluator) {
 			Assert.isTrue(!StringUtils.isEmpty(language),
-					"Language must be provided when using script source");
+					"Language must be provided when using the default ScriptEvaluator and raw source code");
 
 			((StandardScriptEvaluator) scriptEvaluator).setLanguage(language);
 		}

spring-batch-infrastructure/src/test/java/org/springframework/batch/item/support/ScriptItemProcessorTests.java

@@ -19,6 +19,8 @@
 import org.junit.Test;
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.Resource;
+import org.springframework.scripting.bsh.BshScriptEvaluator;
+import org.springframework.scripting.groovy.GroovyScriptEvaluator;
 
 import javax.script.ScriptEngineFactory;
 import javax.script.ScriptEngineManager;
@@ -200,6 +202,30 @@ public void testItemBindingNameChange() throws Exception {
 		assertEquals("Incorrect transformed value", "SS", scriptItemProcessor.process("ss"));
 	}
 
+	@Test
+	public void testBshScriptEvaluator() throws Exception {
+		assumeTrue(languageExists("bsh"));
+
+		ScriptItemProcessor<String, Object> scriptItemProcessor = new ScriptItemProcessor<String, Object>();
+		scriptItemProcessor.setScriptEvaluator(new BshScriptEvaluator());
+		scriptItemProcessor.setScriptSource("String process(String item) { return item.toUpperCase(); } process(item);", "bsh");
+		scriptItemProcessor.afterPropertiesSet();
+
+		assertEquals("Incorrect transformed value", "SS", scriptItemProcessor.process("ss"));
+	}
+
+	@Test
+	public void testGroovyScriptEvaluator() throws Exception {
+		assumeTrue(languageExists("groovy"));
+
+		ScriptItemProcessor<String, Object> scriptItemProcessor = new ScriptItemProcessor<String, Object>();
+		scriptItemProcessor.setScriptEvaluator(new GroovyScriptEvaluator());
+		scriptItemProcessor.setScriptSource("def process(item) { return item.toUpperCase() } \n process(item)", "groovy");
+		scriptItemProcessor.afterPropertiesSet();
+
+		assertEquals("Incorrect transformed value", "SS", scriptItemProcessor.process("ss"));
+	}
+
 	private boolean languageExists(String engineName) {
 		return availableLanguages.contains(engineName);
 	}