自动装配sftpChannel

Question

我使用以下spring配置将文件从本地文件夹传输到远程SFTP服务器。

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:int="http://www.springframework.org/schema/integration"
xmlns:sftp="http://www.springframework.org/schema/integration/sftp"
xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/integration
    http://www.springframework.org/schema/integration/spring-integration.xsd
    http://www.springframework.org/schema/integration/sftp
    http://www.springframework.org/schema/integration/sftp/spring-integration-sftp-2.2.xsd">

<bean id="sftpSessionFactory"
    class="org.springframework.integration.sftp.session.DefaultSftpSessionFactory">
    <property name="host" value="xxxxxxx" />
    <property name="knownHosts" value = "C:\knownhosts"/>
    <property name="user" value="wildfly" />
    <property name="password" value="w!ldfly" />
    <property name="port" value="22" />
</bean>

<int:channel id="sftpChannel" />

<sftp:outbound-channel-adapter id="triggerFtpOutBound" channel="sftpChannel"
    session-factory="sftpSessionFactory" remote-directory="/home/wildfly">
</sftp:outbound-channel-adapter>

我使用以下代码发送文件。

@Autowired
private MessageChannel sftpChannel;

Function()
{
   File f = new File("c:/test.txt");
   Message<File> message = MessageBuilder.withPayload(f).build();
   sftpChannel.send(message);
}

我在sftpChannel.send（消息）处获得空指针异常。如何在我的代码中自动装配sftpChannel通道？