在我们将spring引导升级到2.4.2版本之前，这个配置对我来说非常有效。

DefaultFtpsSessionFactory sessionFactory = new DefaultFtpsSessionFactory();
    sessionFactory.setHost("host");
    sessionFactory.setUsername("username");
    sessionFactory.setPassword("password");
    sessionFactory.setPort(21);
    sessionFactory.setClientMode(FTPClient.PASSIVE_LOCAL_DATA_CONNECTION_MODE);
    sessionFactory.setControlEncoding("UTF-8");

目前我面临以下例外情况： javax.net.ssl.SSLException: Unsupported or unrecognized SSL message 我在文件里找不到任何东西。
谢谢你的回答。
编辑1#：
@这里是堆栈跟踪：

Caused by: javax.net.ssl.SSLException: Unsupported or unrecognized SSL message
    at sun.security.ssl.SSLSocketInputRecord.handleUnknownRecord(SSLSocketInputRecord.java:439) ~[?:?]
    at sun.security.ssl.SSLSocketInputRecord.decode(SSLSocketInputRecord.java:184) ~[?:?]
    at sun.security.ssl.SSLTransport.decode(SSLTransport.java:108) ~[?:?]
    at sun.security.ssl.SSLSocketImpl.decode(SSLSocketImpl.java:1152) ~[?:?]
    at sun.security.ssl.SSLSocketImpl.readHandshakeRecord(SSLSocketImpl.java:1063) ~[?:?]
    at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:402) ~[?:?]
    at org.apache.commons.net.ftp.FTPSClient._openDataConnection_(FTPSClient.java:642) ~[commons-net-3.7.jar:3.7]
    at org.apache.commons.net.ftp.FTPClient._openDataConnection_(FTPClient.java:790) ~[commons-net-3.7.jar:3.7]
    at org.apache.commons.net.ftp.FTPClient.initiateListParsing(FTPClient.java:3456) ~[commons-net-3.7.jar:3.7]
    at org.apache.commons.net.ftp.FTPClient.initiateListParsing(FTPClient.java:3386) ~[commons-net-3.7.jar:3.7]
    at org.apache.commons.net.ftp.FTPClient.listFiles(FTPClient.java:3063) ~[commons-net-3.7.jar:3.7]
    at org.springframework.integration.ftp.session.FtpSession.list(FtpSession.java:74) ~[spring-integration-ftp-5.4.3.jar:5.4.3]
    at org.springframework.integration.ftp.session.FtpSession.list(FtpSession.java:45) ~[spring-integration-ftp-5.4.3.jar:5.4.3]
    at org.springframework.integration.file.remote.session.CachingSessionFactory$CachedSession.list(CachingSessionFactory.java:225) ~[spring-integration-file-5.4.3.jar:5.4.3]
    at org.springframework.integration.file.remote.gateway.AbstractRemoteFileOutboundGateway.listFilesInRemoteDir(AbstractRemoteFileOutboundGateway.java:948) ~[spring-integration-file-5.4.3.jar:5.4.3]
    at org.springframework.integration.file.remote.gateway.AbstractRemoteFileOutboundGateway.ls(AbstractRemoteFileOutboundGateway.java:913) ~[spring-integration-file-5.4.3.jar:5.4.3]
    at org.springframework.integration.ftp.gateway.FtpOutboundGateway.lambda$ls$0(FtpOutboundGateway.java:209) ~[spring-integration-ftp-5.4.3.jar:5.4.3]
    at org.springframework.integration.ftp.gateway.FtpOutboundGateway.doInWorkingDirectory(FtpOutboundGateway.java:285) ~[spring-integration-ftp-5.4.3.jar:5.4.3]
    at org.springframework.integration.ftp.gateway.FtpOutboundGateway.ls(FtpOutboundGateway.java:209) ~[spring-integration-ftp-5.4.3.jar:5.4.3]
    at org.springframework.integration.file.remote.gateway.AbstractRemoteFileOutboundGateway.lsRemoteFilesForMget(AbstractRemoteFileOutboundGateway.java:1202) ~[spring-integration-file-5.4.3.jar:5.4.3]
    at org.springframework.integration.file.remote.gateway.AbstractRemoteFileOutboundGateway.mGetWithRecursion(AbstractRemoteFileOutboundGateway.java:1182) ~[spring-integration-file-5.4.3.jar:5.4.3]
    at org.springframework.integration.file.remote.gateway.AbstractRemoteFileOutboundGateway.mGet(AbstractRemoteFileOutboundGateway.java:1127) ~[spring-integration-file-5.4.3.jar:5.4.3]
    at org.springframework.integration.ftp.gateway.FtpOutboundGateway.lambda$mGet$3(FtpOutboundGateway.java:230) ~[spring-integration-ftp-5.4.3.jar:5.4.3]
    at org.springframework.integration.ftp.gateway.FtpOutboundGateway.doInWorkingDirectory(FtpOutboundGateway.java:285) ~[spring-integration-ftp-5.4.3.jar:5.4.3]
    at org.springframework.integration.ftp.gateway.FtpOutboundGateway.mGet(FtpOutboundGateway.java:229) ~[spring-integration-ftp-5.4.3.jar:5.4.3]
    at org.springframework.integration.file.remote.gateway.AbstractRemoteFileOutboundGateway.lambda$doMget$9(AbstractRemoteFileOutboundGateway.java:683) ~[spring-integration-file-5.4.3.jar:5.4.3]
    at org.springframework.integration.file.remote.RemoteFileTemplate.execute(RemoteFileTemplate.java:439) ~[spring-integration-file-5.4.3.jar:5.4.3]
    at org.springframework.integration.file.remote.gateway.AbstractRemoteFileOutboundGateway.doMget(AbstractRemoteFileOutboundGateway.java:682) ~[spring-integration-file-5.4.3.jar:5.4.3]
    at org.springframework.integration.file.remote.gateway.AbstractRemoteFileOutboundGateway.handleRequestMessage(AbstractRemoteFileOutboundGateway.java:573) ~[spring-integration-file-5.4.3.jar:5.4.3]
    at org.springframework.integration.handler.AbstractReplyProducingMessageHandler.handleMessageInternal(AbstractReplyProducingMessageHandler.java:134) ~[spring-integration-core-5.4.3.jar:5.4.3]
    at org.springframework.integration.handler.AbstractMessageHandler.handleMessage(AbstractMessageHandler.java:56) ~[spring-integration-core-5.4.3.jar:5.4.3]
    ... 43 more

编辑#2

[INFO] +- commons-net:commons-net:jar:3.7.2:compile
[INFO] +- org.springframework.integration:spring-integration-ftp:jar:5.4.3:compile

编辑#3-堆栈中更高的一些异常只是为了完整性

Caused by: org.springframework.messaging.MessagingException: Failed to execute on session; nested exception is javax.net.ssl.SSLException: Unsupported or unrecognized SSL message
    at org.springframework.integration.file.remote.RemoteFileTemplate.execute(RemoteFileTemplate.java:448) ~[spring-integration-file-5.4.3.jar:5.4.3]
    at org.springframework.integration.file.remote.gateway.AbstractRemoteFileOutboundGateway.doMget(AbstractRemoteFileOutboundGateway.java:682) ~[spring-integration-file-5.4.3.jar:5.4.3]
    at org.springframework.integration.file.remote.gateway.AbstractRemoteFileOutboundGateway.handleRequestMessage(AbstractRemoteFileOutboundGateway.java:573) ~[spring-integration-file-5.4.3.jar:5.4.3]
    at org.springframework.integration.handler.AbstractReplyProducingMessageHandler.handleMessageInternal(AbstractReplyProducingMessageHandler.java:134) ~[spring-integration-core-5.4.3.jar:5.4.3]
    at org.springframework.integration.handler.AbstractMessageHandler.handleMessage(AbstractMessageHandler.java:56) ~[spring-integration-core-5.4.3.jar:5.4.3]
    ... 43 more

编辑4#使用commons进行实验-net:jar:3.7.2
以下设置工作正常

[INFO] +- commons-net:commons-net:jar:3.7.2:compile
[INFO] +- org.springframework.integration:spring-integration-ftp:jar:5.3.2.RELEASE:compile
[INFO] |  \- org.springframework.integration:spring-integration-file:jar:5.4.3:compile
[INFO] |     \- org.springframework.integration:spring-integration-core:jar:5.4.3:compile
[INFO] |        \- org.springframework.retry:spring-retry:jar:1.3.1:compile