GH-9988: Add FileExistsMode expression support

spring-integration-file/src/main/java/org/springframework/integration/file/remote/RemoteFileTemplate.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2024 the original author or authors.
+ * Copyright 2013-2025 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.
@@ -63,6 +63,7 @@
  * @author Gary Russell
  * @author Artem Bilan
  * @author Alen Turkovic
+ * @author Jooyoung Pyoung
  *
  * @since 3.0
  *
@@ -303,8 +304,6 @@ public String send(Message<?> message, String subDirectory, FileExistsMode... mo
 
 	private String send(Message<?> message, String subDirectory, FileExistsMode mode) {
 		Assert.notNull(this.directoryExpressionProcessor, "'remoteDirectoryExpression' is required");
-		Assert.isTrue(!FileExistsMode.APPEND.equals(mode) || !this.useTemporaryFileName,
-				"Cannot append when using a temporary file name");
 		Assert.isTrue(!FileExistsMode.REPLACE_IF_MODIFIED.equals(mode),
 				"FilExistsMode.REPLACE_IF_MODIFIED can only be used for local files");
 		final StreamHolder inputStreamHolder = payloadToInputStream(message);
@@ -565,7 +564,10 @@ private void sendFileToRemoteDirectory(InputStream inputStream, String temporary
 		String tempRemoteFilePath = temporaryRemoteDirectory + fileName;
 		// write remote file first with temporary file extension if enabled
 
-		String tempFilePath = tempRemoteFilePath + (this.useTemporaryFileName ? this.temporaryFileSuffix : "");
+		String tempFilePath = tempRemoteFilePath;
+		if (!FileExistsMode.APPEND.equals(mode)) {
+			tempFilePath += this.useTemporaryFileName ? this.temporaryFileSuffix : "";
+		}
 
 		if (this.autoCreateDirectory) {
 			try {

spring-integration-file/src/main/java/org/springframework/integration/file/remote/gateway/AbstractRemoteFileOutboundGateway.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -75,6 +75,7 @@
  * @author Gary Russell
  * @author Artem Bilan
  * @author Mauro Molinari
+ * @author Jooyoung Pyoung
  *
  * @since 2.1
  */
@@ -114,6 +115,8 @@ public abstract class AbstractRemoteFileOutboundGateway<F> extends AbstractReply
 
 	private Expression localFilenameGeneratorExpression;
 
+	private Expression fileExistsModeExpression;
+
 	private FileExistsMode fileExistsMode;
 
 	private Integer chmod;
@@ -486,6 +489,32 @@ public void setLocalFilenameGeneratorExpressionString(String localFilenameGenera
 		this.localFilenameGeneratorExpression = EXPRESSION_PARSER.parseExpression(localFilenameGeneratorExpression);
 	}
 
+	/**
+	 * Specify a SpEL expression to determine the action to take when files already exist.
+	 * Expression evaluation should return a {@link FileExistsMode} object.
+	 * Used for GET and MGET operations when the file already exists locally,
+	 * or PUT and MPUT when the file exists on the remote system.
+	 * @param fileExistsModeExpression the expression to use.
+	 * @since 6.5
+	 */
+	public void setFileExistsModeExpression(Expression fileExistsModeExpression) {
+		Assert.notNull(fileExistsModeExpression, "'fileExistsModeExpression' must not be null");
+		this.fileExistsModeExpression = fileExistsModeExpression;
+	}
+
+	/**
+	 * Specify a SpEL expression to determine the action to take when files already exist.
+	 * Expression evaluation should return a {@link FileExistsMode} object.
+	 * Used for GET and MGET operations when the file already exists locally,
+	 * or PUT and MPUT when the file exists on the remote system.
+	 * @param fileExistsModeExpression the String in SpEL syntax.
+	 * @since 6.5
+	 */
+	public void setFileExistsModeExpression(String fileExistsModeExpression) {
+		Assert.hasText(fileExistsModeExpression, "'fileExistsModeExpression' must not be empty");
+		this.fileExistsModeExpression = EXPRESSION_PARSER.parseExpression(fileExistsModeExpression);
+	}
+
 	/**
 	 * Determine the action to take when using GET and MGET operations when the file
 	 * already exists locally, or PUT and MPUT when the file exists on the remote
@@ -495,9 +524,6 @@ public void setLocalFilenameGeneratorExpressionString(String localFilenameGenera
 	 */
 	public void setFileExistsMode(FileExistsMode fileExistsMode) {
 		this.fileExistsMode = fileExistsMode;
-		if (FileExistsMode.APPEND.equals(fileExistsMode)) {
-			this.remoteFileTemplate.setUseTemporaryFileName(false);
-		}
 	}
 
 	/**
@@ -845,7 +871,8 @@ private String doPut(Message<?> requestMessage, String subDirectory) {
 	 * @since 5.0
 	 */
 	protected String put(Message<?> message, Session<F> session, String subDirectory) {
-		String path = this.remoteFileTemplate.send(message, subDirectory, this.fileExistsMode);
+		FileExistsMode existsMode = resolveFileExistsMode(message);
+		String path = this.remoteFileTemplate.send(message, subDirectory, existsMode);
 		if (path == null) {
 			throw new MessagingException(message, "No local file found for " + message);
 		}
@@ -1130,7 +1157,7 @@ protected File get(Message<?> message, Session<F> session, String remoteDir, //
 		}
 		final File localFile =
 				new File(generateLocalDirectory(message, remoteDir), generateLocalFileName(message, remoteFilename));
-		FileExistsMode existsMode = this.fileExistsMode;
+		FileExistsMode existsMode = resolveFileExistsMode(message);
 		boolean appending = FileExistsMode.APPEND.equals(existsMode);
 		boolean exists = localFile.exists();
 		boolean replacing = exists && (FileExistsMode.REPLACE.equals(existsMode)
@@ -1351,6 +1378,15 @@ protected String getRemoteFilename(String remoteFilePath) {
 		}
 	}
 
+	private FileExistsMode resolveFileExistsMode(Message<?> message) {
+		if (this.fileExistsModeExpression != null) {
+			EvaluationContext evaluationContext = ExpressionUtils.createStandardEvaluationContext(getBeanFactory());
+			evaluationContext.setVariable("fileExistsMode", this.fileExistsMode);
+			return this.fileExistsModeExpression.getValue(evaluationContext, message, FileExistsMode.class);
+		}
+		return this.fileExistsMode;
+	}
+
 	private File generateLocalDirectory(Message<?> message, String remoteDirectory) {
 		EvaluationContext evaluationContext = ExpressionUtils.createStandardEvaluationContext(getBeanFactory());
 		if (remoteDirectory != null) {

spring-integration-file/src/test/java/org/springframework/integration/file/remote/gateway/RemoteFileOutboundGatewayTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -29,6 +29,7 @@
 import java.util.Collection;
 import java.util.Date;
 import java.util.List;
+import java.util.Map;
 import java.util.concurrent.atomic.AtomicReference;
 
 import org.junit.jupiter.api.Test;
@@ -70,6 +71,7 @@
  * @author Gary Russell
  * @author Liu Jiong
  * @author Artem Bilan
+ * @author Jooyoung Pyoung
  *
  * @since 2.1
  */
@@ -640,6 +642,65 @@ public void read(String source, OutputStream outputStream)
 		outFile.delete();
 	}
 
+	@Test
+	@SuppressWarnings("unchecked")
+	public void testGetExistsExpression() throws Exception {
+		SessionFactory sessionFactory = mock(SessionFactory.class);
+		TestRemoteFileOutboundGateway gw = new TestRemoteFileOutboundGateway(sessionFactory, "get", "payload");
+		gw.setFileExistsModeExpression("headers[\"file.exists.mode\"]");
+		gw.setLocalDirectory(new File(this.tmpDir));
+		gw.afterPropertiesSet();
+		File outFile = new File(this.tmpDir + "/f1");
+		FileOutputStream fos = new FileOutputStream(outFile);
+		fos.write("foo".getBytes());
+		fos.close();
+		when(sessionFactory.getSession()).thenReturn(new TestSession() {
+
+			@Override
+			public TestLsEntry[] list(String path) {
+				return new TestLsEntry[] {
+						new TestLsEntry("f1", 1234, false, false, 12345, "-rw-r--r--")
+				};
+			}
+
+			@Override
+			public void read(String source, OutputStream outputStream)
+					throws IOException {
+				outputStream.write("testfile".getBytes());
+			}
+
+		});
+
+		// default (null)
+		MessageBuilder<File> out;
+
+		assertThatExceptionOfType(MessageHandlingException.class)
+				.isThrownBy(() -> gw.handleRequestMessage(new GenericMessage<>("f1")))
+				.withMessageContaining("already exists");
+
+		assertThatExceptionOfType(MessageHandlingException.class)
+				.isThrownBy(() -> gw.handleRequestMessage(
+						new GenericMessage<>("f1", Map.of("file.exists.mode", FileExistsMode.FAIL))))
+				.withMessageContaining("already exists");
+
+		out = (MessageBuilder<File>) gw.handleRequestMessage(
+				new GenericMessage<>("f1", Map.of("file.exists.mode", FileExistsMode.IGNORE)));
+		assertThat(out.getPayload()).isEqualTo(outFile);
+		assertContents("foo", outFile);
+
+		out = (MessageBuilder<File>) gw.handleRequestMessage(
+				new GenericMessage<>("f1", Map.of("file.exists.mode", FileExistsMode.APPEND)));
+		assertThat(out.getPayload()).isEqualTo(outFile);
+		assertContents("footestfile", outFile);
+
+		out = (MessageBuilder<File>) gw.handleRequestMessage(
+				new GenericMessage<>("f1", Map.of("file.exists.mode", FileExistsMode.REPLACE)));
+		assertThat(out.getPayload()).isEqualTo(outFile);
+		assertContents("testfile", outFile);
+
+		outFile.delete();
+	}
+
 	private void assertContents(String expected, File outFile) throws Exception {
 		BufferedReader reader = new BufferedReader(new FileReader(outFile));
 		assertThat(reader.readLine()).isEqualTo(expected);
@@ -860,6 +921,69 @@ public void testPutExists() throws Exception {
 		verify(session, times(1)).append(any(InputStream.class), anyString());
 	}
 
+	@Test
+	@SuppressWarnings("unchecked")
+	public void testPutExistsExpression() throws Exception {
+		SessionFactory<TestLsEntry> sessionFactory = mock(SessionFactory.class);
+		Session<TestLsEntry> session = mock(Session.class);
+		willReturn(Boolean.TRUE)
+				.given(session)
+				.exists(anyString());
+		RemoteFileTemplate<TestLsEntry> template = new RemoteFileTemplate<>(sessionFactory);
+		template.setRemoteDirectoryExpression(new LiteralExpression("foo/"));
+		template.setBeanFactory(mock(BeanFactory.class));
+		template.afterPropertiesSet();
+		TestRemoteFileOutboundGateway gw = new TestRemoteFileOutboundGateway(template, "put", "payload");
+		FileTransferringMessageHandler<TestLsEntry> handler = new FileTransferringMessageHandler<>(sessionFactory);
+		handler.setRemoteDirectoryExpression(new LiteralExpression("foo/"));
+		handler.setBeanFactory(mock(BeanFactory.class));
+		handler.afterPropertiesSet();
+		gw.afterPropertiesSet();
+		gw.setFileExistsModeExpression("headers[\"file.exists.mode\"]");
+		when(sessionFactory.getSession()).thenReturn(session);
+		MessageBuilder<String> requestMessageBuilder = MessageBuilder.withPayload("hello")
+				.setHeader(FileHeaders.FILENAME, "bar.txt");
+
+		Message<String> defaultMessage = requestMessageBuilder.build();
+		String path = (String) gw.handleRequestMessage(defaultMessage);
+		assertThat(path).isEqualTo("foo/bar.txt");
+		ArgumentCaptor<String> captor = ArgumentCaptor.forClass(String.class);
+		verify(session).write(any(InputStream.class), captor.capture());
+		assertThat(captor.getValue()).isEqualTo("foo/bar.txt.writing");
+		verify(session).rename("foo/bar.txt.writing", "foo/bar.txt");
+
+		Message<String> failMessage = requestMessageBuilder.setHeader("file.exists.mode", FileExistsMode.FAIL)
+				.build();
+		assertThatExceptionOfType(MessageDeliveryException.class)
+				.isThrownBy(() -> gw.handleRequestMessage(failMessage))
+				.withStackTraceContaining("The destination file already exists");
+
+		Message<String> replaceMessage = requestMessageBuilder.setHeader("file.exists.mode", FileExistsMode.REPLACE)
+				.build();
+		path = (String) gw.handleRequestMessage(replaceMessage);
+		assertThat(path).isEqualTo("foo/bar.txt");
+		captor = ArgumentCaptor.forClass(String.class);
+		verify(session, times(2)).write(any(InputStream.class), captor.capture());
+		assertThat(captor.getValue()).isEqualTo("foo/bar.txt.writing");
+		verify(session, times(2)).rename("foo/bar.txt.writing", "foo/bar.txt");
+
+		Message<String> appendMessage = requestMessageBuilder.setHeader("file.exists.mode", FileExistsMode.APPEND)
+				.build();
+		path = (String) gw.handleRequestMessage(appendMessage);
+		assertThat(path).isEqualTo("foo/bar.txt");
+		captor = ArgumentCaptor.forClass(String.class);
+		verify(session).append(any(InputStream.class), captor.capture());
+		assertThat(captor.getValue()).isEqualTo("foo/bar.txt");
+
+		Message<String> ignoreMessage = requestMessageBuilder.setHeader("file.exists.mode", FileExistsMode.IGNORE)
+				.build();
+		path = (String) gw.handleRequestMessage(ignoreMessage);
+		assertThat(path).isEqualTo("foo/bar.txt");
+		// no more writes/appends
+		verify(session, times(2)).write(any(InputStream.class), anyString());
+		verify(session, times(1)).append(any(InputStream.class), anyString());
+	}
+
 	@Test
 	@SuppressWarnings("unchecked")
 	public void testMput() throws Exception {