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JSPSourceServlet.javaAPI DocExample5064Tue Jun 08 11:26:42 BST 2004None

JSPSourceServlet

public class JSPSourceServlet extends HttpServlet
This servlet is intended only for learning about JSP. It returns the JSP file corresponding to the path passed as pathInfo in a form that shows the unprocessed JSP and HTML elements. If it wasn't for Internet Explorer, all this servlet would have to do would be to set the Content-Type to "text/plain" and send the file. But Internet Explorer believes it knows better than the application developer, so it bluntantly ignores this header and treats any response that contains HTML elements as "text/html", and therefore renders all HTML elements and ignores the JSP elements. To work around this, the servlet sends the response as "text/html", with all special HTML characters converted to the corresponding HTML character entities.

Note! Do not install this servlet on a production server. Doing so may be a security risk, since the source of any file can be delivered to the client, revealing things like database account names and passwords.

version
2.0
author
Hans Bergsten, Gefion software

Fields Summary
Constructors Summary
Methods Summary
private voidcopyFile(java.io.BufferedReader in, java.io.PrintWriter out)
Copies the "in" reader to the "out" writer.

param
in a BufferedReader
param
out a PrintWriter

        int chars;
        char[] buf = new char[4096];
        while ((chars = in.read(buf, 0, buf.length)) != -1) {
            out.write(buf, 0, chars);
            out.flush();
        }
public voiddoGet(javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse res)
Handles a GET request by sending the contents of the resource specified by the servlet path to the client.

param
req an HttpServletRequest
param
res an HttpServletResponse
exception
IOException

        // Get the pathInfo
        String path = req.getPathInfo(); 
        
        // Check for invalid characters in the path. For files under
	// WEB-INF, only accept tag files
        if (path.indexOf("..") != -1 || 
	    (path.toUpperCase().indexOf("WEB-INF") != -1) && 
	    !path.endsWith(".tag")){
            res.sendError(HttpServletResponse.SC_FORBIDDEN,
                "Illegal characters found in path " + path);
            return;
        }

        sendFile(path, res);
private voidsendFile(java.lang.String path, javax.servlet.http.HttpServletResponse res)
Sends the contents of a file to the client.

param
pathInfo the file URI
param
res an HttpServletResponse
exception
IOException

        URL file = getServletContext().getResource(path);
        if (file == null) { 
            res.sendError(HttpServletResponse.SC_NOT_FOUND,
                path + " not found.");
            return;
        }
        
        res.setStatus(HttpServletResponse.SC_OK);
        /* 
	 * Use "text/html" and convert HTML characters to
         * character entities, to fool IE as explained above
	 */
        res.setContentType("text/html");
        PrintWriter out = res.getWriter();
        // Add HTML header
        out.println("<html><head><title>" + path + "</title></head>");
        out.println("<body><pre>");
        
        // Read the file and convert it
        BufferedReader in = 
	    new BufferedReader(new InputStreamReader(file.openStream()));
        StringWriter rawText = new StringWriter();
        copyFile(in, new PrintWriter(rawText));
        in.close();
        out.write(toHTMLString(rawText.toString()));
        
        // Add HTML footer
        out.println("</pre></body></html>");
        out.close();
public java.lang.StringtoHTMLString(java.lang.String in)
Returns the specified string converted to a format suitable for HTML. All signle-quote, double-quote, greater-than, less-than and ampersand characters are replaces with their corresponding HTML Character Entity code.

param
in the String to convert
return
the converted String

        StringBuffer out = new StringBuffer();
        for (int i = 0; in != null && i < in.length(); i++) {
            char c = in.charAt(i);
            if (c == '\'") {
                out.append("'");
            }
            else if (c == '\"") {
                out.append(""");
            }
            else if (c == '<") {
                out.append("<");
            }
            else if (c == '>") {
                out.append(">");
            }
            else if (c == '&") {
                out.append("&");
            }
            else {
                out.append(c);
            }
        }
        return out.toString();