Read file from disk through URL - java/mule

Question

I have a mule program that I want to read a file from my PC and display the content in the browser on localhost.

I have it working for one file hard coded as seen below.

public class ReadFile extends AbstractMessageTransformer {

/**
 * loads the content of the file specified in the parameter
 * 
 * @param filename
 *            the name of the file
 * @return the content of the file
 */
public String readFile(String filename) {


    File file;
    file = new File("O:\\test.txt");

    StringBuilder builder = new StringBuilder();
    BufferedReader reader = null;
    try {
        reader = new BufferedReader(new FileReader(file));
        String line = null;
        while ((line = reader.readLine()) != null)
            builder.append(line);
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        closeQuietly(reader);
    }
    return builder.toString();
}

public String getFileName(MuleMessage message) {

    Path p = Paths.get("O:\\test.txt");
    String file = p.getFileName().toString();




    return file;

}

public String setPayload(MuleMessage message, String outputEncoding) {


     message.setPayload(outputEncoding);
    return null;

}

private void closeQuietly(Closeable c) {
    if (c != null) {
        try {
            c.close();
        } catch (IOException ignored) {
        }
    }
}

@Override
public Object transformMessage(MuleMessage message, String outputEncoding)
        throws TransformerException {
    String filename = getFileName(message);
    String content = readFile(filename);
    setPayload(message, content);
    return message;
}

}

How can i specify it to read any file I input through the URL and not just my hard coded file?

Answer 1

You could use the HttpServer class for this. You application will listen HTTP requests. Therefore, you can put the following URL in your browser:

"localhost/file_to_be_loaded"

Your HttpServer will receive a GET request for URL (localhost/file_to_be_loaded)

Parse the request, load the file and respond to the browser.

It may seem complex, but is very simple. The first answer in the post below does almost all the job:

simple HTTP server in Java using only Java SE API

Good luck!

Answer 2

To achieve this you need to use Mule expression language. Follow below steps

1) use below session component after HTTP. This will store the filePath coming from your HTTP url in a session variable.

 <set-session-variable variableName="Filepath" value="#[message.inboundProperties.'http.query.params'.Filepath]" doc:name="Session Variable"/>

2) In your java code, read the session variable using below line of code. Then pass the filepath to your method insted of hardcoding

 String filePath = eventContext.getMessage().getProperty("Filepath", PropertyScope.SESSION);

3) Finally trigger the service some thing like below HTTP url with query param

http://localhost:8083/?Filepath=C:\\test.txt

I suggest, go through the mule documentation for Mule expression language. That will give more clarity on how to work this type of scenarios.

Answer 3

My Xml code

 <flow name="filetestFlow1">
    <http:listener config-ref="HTTP_Listener_Configuration" path="/" doc:name="HTTP"/>
    <logger message="--- Service triggred --" level="INFO" doc:name="Logger"/>
    <set-session-variable variableName="Filepath" value="#[message.inboundProperties.'http.query.params'.Filepath]" doc:name="Session Variable"/>
    <component class="filetest.ReadFile" doc:name="Java"/>
</flow>

Java code, Here you can observe that I implemented Callable interface

public class ReadFile implements Callable {

@Override
public Object onCall(MuleEventContext eventContext) throws Exception {
    // TODO Auto-generated method stub
    System.out.println("Service triggred in java");
    String filePath = eventContext.getMessage().getProperty("Filepath", PropertyScope.SESSION);
    MuleMessage msg = eventContext.getMessage();
    String filename = getFileName(msg,filePath);
    String content = readFile(filename,filePath);
    setPayload(msg, content);
    return msg;

}

/**
 * loads the content of the file specified in the parameter
 * 
 * @param filename
 *            the name of the file
 * @return the content of the file
 */
public String readFile(String filename,String filePath) {
    File file;
    file = new File(filePath);
    StringBuilder builder = new StringBuilder();
    BufferedReader reader = null;
    try {
        reader = new BufferedReader(new FileReader(file));
        String line = null;
        while ((line = reader.readLine()) != null)
            builder.append(line);
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        closeQuietly(reader);
    }
    return builder.toString();
}

public String getFileName(MuleMessage message,String filePath) {

    Path p = Paths.get(filePath);
    String file = p.getFileName().toString();
    return file;

}

public String setPayload(MuleMessage message, String outputEncoding) {

    message.setPayload(outputEncoding);
    //String payload1 = "#[ReadFile]";
    return null;

}

private void closeQuietly(Closeable c) {
    if (c != null) {
        try {
            c.close();
        } catch (IOException ignored) {
        }
    }
}

}