INT-4356: FileTransferMH: Add string SpEL setters

JIRA: https://jira.spring.io/browse/INT-4356

**Cherry-pick to 4.3.x**

Address PR comments:
* Remove unused variable in the test case
* Add string-based SpEL setters to the `AbstractInboundFileSynchronizer`
* Fix `@since` in the `FileTransferringMessageHandler` to the proper version

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -35,6 +35,7 @@ import org.springframework.util.Assert;
  * @author Oleg Zhurakousky
  * @author David Turanski
  * @author Gary Russell
+ *
  * @since 2.0
  */
 public class FileTransferringMessageHandler<F> extends AbstractMessageHandler {
@@ -89,6 +90,16 @@ public class FileTransferringMessageHandler<F> extends AbstractMessageHandler {
 		this.remoteFileTemplate.setRemoteDirectoryExpression(remoteDirectoryExpression);
 	}
 
+	/**
+	 * Specify a remote directory path SpEL expression.
+	 * @param remoteDirectoryExpression the remote directory expression
+	 * @since 4.3.13
+	 * @see #setRemoteDirectoryExpression(Expression)
+	 */
+	public void setRemoteDirectoryExpressionString(String remoteDirectoryExpression) {
+		setRemoteDirectoryExpression(EXPRESSION_PARSER.parseExpression(remoteDirectoryExpression));
+	}
+
 	/**
 	 * Specify a remote directory path SpEL expression.
 	 * @param temporaryRemoteDirectoryExpression the temporary remote directory expression
@@ -98,6 +109,16 @@ public class FileTransferringMessageHandler<F> extends AbstractMessageHandler {
 		this.remoteFileTemplate.setTemporaryRemoteDirectoryExpression(temporaryRemoteDirectoryExpression);
 	}
 
+	/**
+	 * Specify a remote directory path SpEL expression.
+	 * @param temporaryRemoteDirectoryExpression the temporary remote directory expression
+	 * @since 4.3.13
+	 * @see #setTemporaryRemoteDirectoryExpression(Expression)
+	 */
+	public void setTemporaryRemoteDirectoryExpressionString(String temporaryRemoteDirectoryExpression) {
+		setTemporaryRemoteDirectoryExpression(EXPRESSION_PARSER.parseExpression(temporaryRemoteDirectoryExpression));
+	}
+
 	protected String getTemporaryFileSuffix() {
 		return this.remoteFileTemplate.getTemporaryFileSuffix();
 	}

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

@@ -36,7 +36,9 @@ import org.springframework.beans.factory.BeanFactoryAware;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.expression.EvaluationContext;
 import org.springframework.expression.Expression;
+import org.springframework.expression.ExpressionParser;
 import org.springframework.expression.common.LiteralExpression;
+import org.springframework.expression.spel.standard.SpelExpressionParser;
 import org.springframework.integration.expression.ExpressionUtils;
 import org.springframework.integration.file.filters.FileListFilter;
 import org.springframework.integration.file.filters.ResettableFileListFilter;
@@ -67,6 +69,8 @@ import org.springframework.util.ObjectUtils;
 public abstract class AbstractInboundFileSynchronizer<F>
 		implements InboundFileSynchronizer, BeanFactoryAware, InitializingBean, Closeable {
 
+	protected static final ExpressionParser EXPRESSION_PARSER = new SpelExpressionParser();
+
 	protected final Log logger = LogFactory.getLog(this.getClass());
 
 	private final RemoteFileTemplate<F> remoteFileTemplate;
@@ -135,6 +139,16 @@ public abstract class AbstractInboundFileSynchronizer<F>
 		this.localFilenameGeneratorExpression = localFilenameGeneratorExpression;
 	}
 
+	/**
+	 * Set an expression used to determine the local file name.
+	 * @param localFilenameGeneratorExpression the expression.
+	 * @since 4.3.13
+	 * @see #setRemoteDirectoryExpression(Expression)
+	 */
+	public void setLocalFilenameGeneratorExpressionString(String localFilenameGeneratorExpression) {
+		setLocalFilenameGeneratorExpression(EXPRESSION_PARSER.parseExpression(localFilenameGeneratorExpression));
+	}
+
 	/**
 	 * Set a temporary file suffix to be used while transferring files. Default ".writing".
 	 * @param temporaryFileSuffix the file suffix.
@@ -161,6 +175,17 @@ public abstract class AbstractInboundFileSynchronizer<F>
 		doSetRemoteDirectoryExpression(remoteDirectoryExpression);
 	}
 
+	/**
+	 * Specify an expression that evaluates to the full path to the remote directory.
+	 * @param remoteDirectoryExpression The remote directory expression.
+	 * @since 4.3.13
+	 * @see #setRemoteDirectoryExpression(Expression)
+	 */
+	public void setRemoteDirectoryExpressionString(String remoteDirectoryExpression) {
+		setRemoteDirectoryExpression(EXPRESSION_PARSER.parseExpression(remoteDirectoryExpression));
+	}
+
+
 	protected final void doSetRemoteDirectoryExpression(Expression remoteDirectoryExpression) {
 		Assert.notNull(remoteDirectoryExpression, "'remoteDirectoryExpression' must not be null");
 		this.remoteDirectoryExpression = remoteDirectoryExpression;

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

@@ -811,7 +811,7 @@ public class RemoteFileOutboundGatewayTests {
 		template.afterPropertiesSet();
 		TestRemoteFileOutboundGateway gw = new TestRemoteFileOutboundGateway(template, "put", null);
 		FileTransferringMessageHandler<TestLsEntry> handler = new FileTransferringMessageHandler<TestLsEntry>(sessionFactory);
-		handler.setRemoteDirectoryExpression(new LiteralExpression("foo/"));
+		handler.setRemoteDirectoryExpressionString("'foo/'");
 		handler.setBeanFactory(mock(BeanFactory.class));
 		handler.afterPropertiesSet();
 		gw.afterPropertiesSet();

spring-integration-file/src/test/java/org/springframework/integration/file/remote/handler/FileTransferringMessageHandlerTests.java

@@ -53,6 +53,7 @@ import org.springframework.messaging.support.GenericMessage;
  * @author Oleg Zhurakousky
  * @author Gary Russell
  * @author Gunnar Hillert
+ * @author Artem Bilan
  */
 public class FileTransferringMessageHandlerTests {
 
@@ -130,10 +131,9 @@ public class FileTransferringMessageHandlerTests {
 		SessionFactory<F> sf = mock(SessionFactory.class);
 		Session<F> session = mock(Session.class);
 		when(sf.getSession()).thenReturn(session);
-		ExpressionParser parser = new SpelExpressionParser();
 		FileTransferringMessageHandler<F> handler = new FileTransferringMessageHandler<F>(sf);
 		handler.setBeanFactory(mock(BeanFactory.class));
-		handler.setRemoteDirectoryExpression(parser.parseExpression("headers['path']"));
+		handler.setRemoteDirectoryExpressionString("headers['path']");
 		handler.setTemporaryFileSuffix(null);
 		handler.onInit();
 	}
@@ -169,7 +169,7 @@ public class FileTransferringMessageHandlerTests {
 		Session<F> session2 = newSession();
 		Session<F> session3 = newSession();
 		when(sf.getSession()).thenReturn(session1, session2, session3);
-		handler.setRemoteDirectoryExpression(new LiteralExpression("foo"));
+		handler.setRemoteDirectoryExpressionString("'foo'");
 		handler.afterPropertiesSet();
 		for (int i = 0; i < 3; i++) {
 			try {

src/reference/asciidoc/ftp.adoc

@@ -720,7 +720,7 @@ public class FtpJavaApplication {
     @ServiceActivator(inputChannel = "ftpChannel")
     public MessageHandler handler() {
         FtpMessageHandler handler = new FtpMessageHandler(ftpSessionFactory());
-        handler.setRemoteDirectoryExpression(new LiteralExpression("remote-target-dir"));
+        handler.setRemoteDirectoryExpressionString("headers['remote-target-dir']");
         handler.setFileNameGenerator(new FileNameGenerator() {
 
             @Override

src/reference/asciidoc/sftp.adoc

@@ -773,7 +773,7 @@ public class SftpJavaApplication {
     @ServiceActivator(inputChannel = "toSftpChannel")
     public MessageHandler handler() {
         SftpMessageHandler handler = new SftpMessageHandler(sftpSessionFactory());
-        handler.setRemoteDirectoryExpression(new LiteralExpression("remote-target-dir"));
+        handler.setRemoteDirectoryExpressionString("headers['remote-target-dir']");
         handler.setFileNameGenerator(new FileNameGenerator() {
 
             @Override