File Montoring | Not updating in jsp while listening

Question

I am monitoring the file creation and modification in directory using commons-io jar.I am able to get the results in Eclipse console.

final long pollingInterval = 5 * 1000;
     String FOLDER = "C:/test";
    File folder = new File(FOLDER);
    folder.setReadable(true);
    if (!folder.exists()) {
        // Test to see if monitored folder exists
        throw new RuntimeException("Directory not found: " + FOLDER);
    }

    FileAlterationObserver observer = new FileAlterationObserver(folder);
    FileAlterationMonitor monitor =
            new FileAlterationMonitor(pollingInterval);


    FileAlterationListener listener = new FileAlterationListenerAdaptor() {
        // Is triggered when a file is created in the monitored folder

        @Override
        public void onFileCreate(File file) {
            try {
                // "file" is the reference to the newly created file
                System.out.println("File created: "
                        + file.getCanonicalPath());
                getNewMethod(file);// here in this method i am not able to return since its void.

            } catch (IOException e) {
                e.printStackTrace(System.err);
            }

        }
        @Override
        public void onFileChange(File file) {
            try {

                System.out.println("File modified: "
                        + file.getCanonicalPath());
                getNewMethod(file); // here in this method i am not able to return since its void.
            } catch (IOException e) {
                e.printStackTrace(System.err);
            }

        }

    };
    observer.addListener(listener);
    monitor.addObserver(observer);
    monitor.start();

The problem is that i cannot able to return the file name when it is calling onFileCreate and onFileChange methods.How to achieve this? And also i am trying to call one method inside onFileCreate and onFileChange which returns a list.How to return the list? Because in this listener i dont see return parameter except void.

//Calling a newMethod

public String getNewMethod(File newfile) throws IOException{

    System.out.println("getList method called : "+newfile.getCanonicalPath());
     return "redirect:finalPage"; // here the redirection is not happening

}

When i see file change/create event is triggered, i need the changes to be update in jsp.How to achieve this?

Answer 1

You can create File object before you create listener and set file in onFileCreate() method. You can also call the methods within anonymous class methods by using OuterClass.this.OuterClassMethod().

File file;
FileAlterationListener listener = new FileAlterationListenerAdaptor() {
        // Is triggered when a file is created in the monitored folder

        @Override
        public void onFileCreate(File file) {
            try {
                // "file" is the reference to the newly created file
this.file = file;                
System.out.println("File created: "
                        + file.getCanonicalPath());
OuterClassName.this.newMethod();

            } catch (IOException e) {
                e.printStackTrace(System.err);
            }

        }
        @Override
        public void onFileChange(File file) {
            try {

                System.out.println("File modified: "
                        + file.getCanonicalPath());
            } catch (IOException e) {
                e.printStackTrace(System.err);
            }

        }

    };
public list newMethod(){
// returns list here
List list = new ArrayList();
return list;
}

Note: Replace OuterClassName with actual outer class name.

Answer 2

import java.io.File;


public class Test {

    public void testMonitoring {

        final long pollingInterval = 5 * 1000;
        String FOLDER = "C:/test";
       File folder = new File(FOLDER);
       folder.setReadable(true);

       if (!folder.exists()) {
           // Test to see if monitored folder exists
           throw new RuntimeException("Directory not found: " + FOLDER);
       }

       FileAlterationObserver observer = new FileAlterationObserver(folder);
       FileAlterationMonitor monitor = new FileAlterationMonitor(pollingInterval);
       FileAlterationListener listener = new FileAlterationListenerAdaptor() 
       {
           // Is triggered when a file is created in the monitored folder

           private String filePath;

           @Override
           public void onFileCreate(File file) {
               try {
                   // "file" is the reference to the newly created file
                   System.out.println("File created: "
                           + file.getCanonicalPath());

                   setFilePath(file.getCanonicalPath());


               } catch (IOException e) {
                   e.printStackTrace(System.err);
               }

           }
           @Override
           public void onFileChange(File file) {
               try {

                   System.out.println("File modified: "
                           + file.getCanonicalPath());
               } catch (IOException e) {
                   e.printStackTrace(System.err);
               }

           }
        /**
         * @return the filePath
         */
        public String getFilePath() {
            return filePath;
        }
        /**
         * @param filePath the filePath to set
         */
        public void setFilePath(String filePath) {
            this.filePath = filePath;
        }

       };
       observer.addListener(listener);

       //getting the file path
       System.out.println(listener.getFilePath());

       monitor.addObserver(observer);
       monitor.start();
    }

}