how to read file line by line using spring integration - spring-integration

Question

I am new to Spring Integration. I need to read a txt file line by line and print each line using spring integration. Can anyone have an example or any thoughts?

Answer 1

The framework doesn't currently have an out-of-the box component for this, except the file tailing channel adapter but that would need to be stopped at the end of the file.
You can write a simple POJO to read a line at-a-time and invoke it using an <inbound-channel-adapter/>.
Or, the POJO could return an Iterator that iterates over the lines and a <splitter/> will invoke the iterator until all the lines are consumed.
EDIT:
<int-file:inbound-channel-adapter directory="/tmp/test"
id="filesIn" channel="toSplitter">
<int:poller fixed-delay="5000" />
</int-file:inbound-channel-adapter>
<int:splitter input-channel="toSplitter" output-channel="logger"
ref="fileSplitter" method="split" />
<int:logging-channel-adapter id="logger" level="WARN"/>
<bean id="fileSplitter" class="foo.FileSplitter" />
I put the code for the FileSplitter in this gist.

Answer 2

You can use this code
xml code=fileCopyApplicationContext.xml
<?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:file="http://www.springframework.org/schema/integration/file"
xmlns:context="http://www.springframework.org/schema/context" xmlns:p="http://www.springframework.org/schema/p"
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/file
http://www.springframework.org/schema/integration/file/spring-integration-file.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd">
<context:property-placeholder />
<file:inbound-channel-adapter id="filesIn"
directory="E:/usmandata/logs/input/" filter="onlyPropertyFiles"
auto-startup="true">
<int:poller id="poller" fixed-delay="500" />
</file:inbound-channel-adapter>
<file:inbound-channel-adapter id="filesIn1"
directory="E:/usmandata/logs/input/" filter="onlyPropertyFiles"
auto-startup="true">
<int:poller id="poller" fixed-delay="500" />
</file:inbound-channel-adapter>
<int:service-activator input-channel="filesIn"
ref="handler" />
<bean id="handler" class="com.javarticles.spring.integration.file.FileHandler" />
<bean id="onlyPropertyFiles"
class="org.springframework.integration.file.config.FileListFilterFactoryBean"
p:filenamePattern="*.log" />
</beans>
FileHandler.java=
package com.javarticles.spring.integration.file;
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
public class FileHandler {
public void handleFile(File input) throws IOException {
// System.out.println("Copying file: " + input.getAbsolutePath());
RandomAccessFile file = new RandomAccessFile(input,"r");
FileChannel channel = file.getChannel();
//System.out.println("File size is: " + channel.size());
ByteBuffer buffer = ByteBuffer.allocate((int) channel.size());
channel.read(buffer);
buffer.flip();//Restore buffer to position 0 to read it
System.out.println("Reading content and printing ... ");
for (int i = 0; i < channel.size(); i++) {
System.out.print((char) buffer.get());
}
channel.close();
file.close();
}
}
SpringIntegrationFileCopyExample.java
package com.javarticles.spring.integration.file;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Properties;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class SpringIntegrationFileCopyExample {
public static void main(String[] args) throws InterruptedException, IOException {
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(
"fileCopyApplicationContext.xml");
}
}