如何在liferay中读取文本文件？

Question

I have tried to read a file from controller class with this code

    ReadFile readFile = new ReadFile();
    String text = readFile.readFile("\resources\testing.txt");
    renderRequest.setAttribute("text", text);

I have fetched it from view.jsp as

    <%
    String content = (String)request.getAttribute("text");
    %>

But I am getting file not found exception. What is the way to get file content.

Answer 1

In a Java string, \\ starts an escape sequence and "\\r" and "\\t" are escaped characters. For example "\\t" is a string with the tab character. If you literally need \\t in a string, you'll have to escape the backslash

doSomething("\\resources\\testing.txt");

or just eliminate the hassle: Java operates well when you use the forward slash as directory separator

doSomething("/resources/testing.txt");

Note that this refers to a file in the root directory of whatever drive the current path is on, it might be C:\\resources\\testing.txt or D:\\resources\\testing.txt - unless your ReadFile implementation manipulates the path somehow (which I leave up to your judgement). You can test this independent of Liferay, just in a command line application. The exception gets thrown way before your jsp gets displayed (I've changed the tags to flag the relevance)

This is pure Java, completely independent of Liferay.

Answer 2

The problem is with your relative path of resources file ( testing.txt ), that needs to be absolute. And to create absolute path, first you would require, portletContext which you can get from request , as following:

PortletContext portletContext = request.getPortletSession().getPortletContext();

Where request is either renderRequest / actionRequest object. While in JSF, you can get request from externalContext , as following:

ExternalContext externalContext = FacesContext.getCurrentInstance().getExternalContext();
PortletRequest request = (PortletRequest) externalContext.getRequest();
PortletContext portletContext = request.getPortletSession().getPortletContext();

Also, as suggested by Olaf Kock , if you use \\ , you would require to escape it, otherwise use / . I prefer to use File.separator , as it returns slash as per OS (I think!).

String relativeFilePath = File.separator + "resources" + File.separator + "testing.txt";

Now, you can get absolute path using portletContext as,

String absoluteFilePath = portletContext.getRealPath(relativeFilePath);

And then, rest of your code goes, as:

ReadFile readFile = new ReadFile();
String text = readFile.readFile(absoluteFilePath);
renderRequest.setAttribute("text", text);

Answer 3

Since you're getting a FileNotFoundException, Are you sure you're pointing to the proper file route? Have you tried with the absolute path? What SO are you using? Because maybe the file separators ("\\") are the cause of your problem.

HIH.

Regards.