Add early support for JTA 2.1 read-only attribute

Closes gh-35633

spring-tx/src/main/java/org/springframework/transaction/annotation/JtaTransactionAnnotationParser.java

@@ -78,6 +78,10 @@ public class JtaTransactionAnnotationParser implements TransactionAnnotationPars
 		}
 		rbta.setRollbackRules(rollbackRules);
 
+		if (attributes.containsKey("readOnly")) {  // JTA 2.1
+			rbta.setReadOnly(attributes.getBoolean("readOnly"));
+		}
+
 		return rbta;
 	}
 

spring-tx/src/main/java/org/springframework/transaction/jta/JtaTransactionManager.java

@@ -19,6 +19,8 @@ package org.springframework.transaction.jta;
 import java.io.IOException;
 import java.io.ObjectInputStream;
 import java.io.Serializable;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
 import java.util.List;
 import java.util.Properties;
 
@@ -52,6 +54,8 @@ import org.springframework.transaction.support.AbstractPlatformTransactionManage
 import org.springframework.transaction.support.DefaultTransactionStatus;
 import org.springframework.transaction.support.TransactionSynchronization;
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
+import org.springframework.util.ReflectionUtils;
 import org.springframework.util.StringUtils;
 
 /**
@@ -139,6 +143,10 @@ public class JtaTransactionManager extends AbstractPlatformTransactionManager
 			"java:comp/TransactionSynchronizationRegistry";
 
 
+	// JTA 2.1 UserTransaction#setReadOnly(boolean) method available?
+	private static final @Nullable Method setReadOnlyMethod =
+			ClassUtils.getMethodIfAvailable(UserTransaction.class, "setReadOnly", boolean.class);
+
 	private transient JndiTemplate jndiTemplate = new JndiTemplate();
 
 	private transient @Nullable UserTransaction userTransaction;
@@ -858,6 +866,12 @@ public class JtaTransactionManager extends AbstractPlatformTransactionManager
 		applyIsolationLevel(txObject, definition.getIsolationLevel());
 		int timeout = determineTimeout(definition);
 		applyTimeout(txObject, timeout);
+
+		if (definition.isReadOnly()) {
+			setReadOnlyIfPossible(txObject.getUserTransaction(), true);
+			txObject.resetReadOnly = true;
+		}
+
 		txObject.getUserTransaction().begin();
 	}
 
@@ -904,6 +918,21 @@ public class JtaTransactionManager extends AbstractPlatformTransactionManager
 		}
 	}
 
+	private void setReadOnlyIfPossible(UserTransaction ut, boolean readOnly) throws SystemException {
+		if (setReadOnlyMethod != null) {
+			try {
+				setReadOnlyMethod.invoke(ut, readOnly);
+			}
+			catch (Exception ex) {
+				if (ex instanceof InvocationTargetException ute &&
+						ute.getTargetException() instanceof SystemException se) {
+					throw se;
+				}
+				ReflectionUtils.handleReflectionException(ex);
+			}
+		}
+	}
+
 
 	@Override
 	protected Object doSuspend(Object transaction) {
@@ -1161,6 +1190,14 @@ public class JtaTransactionManager extends AbstractPlatformTransactionManager
 	@Override
 	protected void doCleanupAfterCompletion(Object transaction) {
 		JtaTransactionObject txObject = (JtaTransactionObject) transaction;
+		if (txObject.resetReadOnly) {
+			try {
+				setReadOnlyIfPossible(txObject.getUserTransaction(), false);
+			}
+			catch (SystemException ex) {
+				logger.debug("Failed to reset read-only flag after after JTA completion", ex);
+			}
+		}
 		if (txObject.resetTransactionTimeout) {
 			try {
 				txObject.getUserTransaction().setTransactionTimeout(0);

spring-tx/src/main/java/org/springframework/transaction/jta/JtaTransactionObject.java

@@ -41,6 +41,8 @@ public class JtaTransactionObject implements SmartTransactionObject {
 
 	boolean resetTransactionTimeout = false;
 
+	boolean resetReadOnly = false;
+
 
 	/**
 	 * Create a new JtaTransactionObject for the given JTA UserTransaction.