how to read a text file from server and display the text in index.jsp

I am woking on web service.Now I have session folders for each user, and each user has it's log file there. Now I want to read log files from java and pass it to index.jsp for show. As I have already used javax.servlet.http.HttpServletRequest req - the req.setAttribute(REQUEST_IS_LOG, log); and req.getRequestDispatch开发者_运维技巧er("index.jsp").forward(req, res); do not work for me. Can someone help me to find another way? How can I take the text from file in display it in index? Are they any way to do this with ajax? Thank you in advance!

If it's in public webcontent, just use <jsp:include>.

<pre>
    <jsp:include page="logs/user123.txt" />
</pre>

Otherwise bring a HttpServlet in between which gets an InputStream of the desired resource and writes it to the OutputStream of the response.

<pre>
    <jsp:include page="logservlet/user123.txt" />
</pre>

Or if it is located at a different public domain, use JSTL <c:import>.

<pre>
    <c:import url="http://other.com/logs/user123.txt" />
</pre>

As to the Ajax part, just do something like

document.getElementById("log").innerHTML = xhr.responseText;

See also my answer on this question for more extensive examples.

JSP:

<% BufferedReader reader = new BufferedReader(new FileReader("log.txt")); %>
<% String line; %>
<% while ((line = reader.readLine()) != null) { %>
   <%=line %>
<% } %>

This will work because jsp's can do anything Java can do. However, for larger projects you should look into using a Model-View-Controller implementation. There are several frameworks that can assist with this, such as Spring or Struts.

Finally I did like:

res.setContentType("text/plain");
            request.setAttribute(REQUEST_IS_LOG, logs);     
            request.getRequestDispatcher("index.jsp").forward(req, res);
            return;

Before I write like:

java.io.OutputStream result=res.getOutputStream();

that was why I couldn't use the method, which I wrote above. I just change to file like:

java.io.OutputStream result = new java.io.FileOutputStream((destinationDir+System.getProperty("file.separator")+"result"+n+"."+targetFormat.toLowerCase()));

and it works!