prod/net/jaekl/frank/ErrorHandler.java

   1 package net.jaekl.frank;
   2
   3 import java.io.ByteArrayOutputStream;
   4 import java.io.PrintStream;
   5 import java.io.PrintWriter;
   6 import java.net.SocketTimeoutException;
   7 import java.text.MessageFormat;
   8 import java.util.Locale;
   9
  10 import net.jaekl.qd.http.InvalidResponseException;
  11
  12 public class ErrorHandler {
  13         static final String JAVASCRIPT_PART1 =
  14                         "<SCRIPT>\n" +
  15                         "  var show_hide = function() {\n" +
  16                         "  var theDiv = document.getElementById('details');\n" +
  17                         "  var theButton = document.getElementById('details_btn');\n" +
  18                         "  if (theDiv.style.display === 'block' || theDiv.style.display === '') {\n" +
  19                         "    theDiv.style.display = 'none';\n" +
  20                         "  theButton.value = '";
  21         // insert "show details" text here
  22         static final String JAVASCRIPT_PART2 = "';\n" +
  23                         "  }\n" +
  24                         "  else {\n" +
  25                         "    theDiv.style.display = 'block';\n" +
  26                         "    theButton.value = '";
  27         // insert "hide details" text here
  28         static final String JAVASCRIPT_PART3 = "';\n" +
  29                         "  }\n" +
  30                         "}\n" +
  31                         "</SCRIPT>";
  32
  33         void writeScript(PrintWriter pw, FrankBundle bundle) {
  34                 String javaScript = JAVASCRIPT_PART1 +
  35                                         bundle.get(FrankBundle.SHOW_DETAILS) +
  36                                         JAVASCRIPT_PART2 +
  37                                         bundle.get(FrankBundle.HIDE_DETAILS) +
  38                                         JAVASCRIPT_PART3;
  39
  40                 pw.println(javaScript);
  41         }
  42
  43         void explain(PrintWriter pw, Throwable t, FrankBundle bundle) {
  44                 Throwable cause = t;
  45                 if (t instanceof FrankException) {
  46                         if (null != t.getCause()) {
  47                                 cause = t.getCause();
  48                         }
  49                 }
  50
  51                 pw.println("<P>");
  52                 if (cause instanceof InvalidResponseException) {
  53                         InvalidResponseException ire = (InvalidResponseException)cause;
  54
  55                         pw.println(bundle.get(FrankBundle.INVALID_RESPONSE));
  56                         pw.println("<P ID=\"errtable\">");
  57                         pw.println("  <TABLE>");
  58                         pw.println("    <TR><TD CLASS=\"head\">" + bundle.get(FrankBundle.URL_CONTACTED)
  59                                         + "</TD><TD>" + ire.getUrl() + "</TD></TR>");
  60                         pw.println("    <TR CLASS=\"alt\"><TD CLASS=\"head\">" + bundle.get(FrankBundle.REQUEST_MADE)
  61                                         + "</TD><TD>" + ire.getMethod() + "</TD></TR>");
  62                         pw.println("    <TR><TD CLASS=\"head\">" + bundle.get(FrankBundle.ANSWER_RECEIVED)
  63                                         + "</TD><TD>" + ire.getResponse() + "</TD></TR>");
  64                         pw.println("  </TABLE>");
  65                         pw.println("</P>");
  66                         pw.println("<P>" + bundle.get(FrankBundle.MAYBE_SERVER_PROBLEM) + "</P>");
  67                 }
  68                 else if (cause instanceof SocketTimeoutException) {
  69                         pw.println(bundle.get(FrankBundle.SERVER_TIMEOUT));
  70                 }
  71                 else {
  72                         pw.println(bundle.get(FrankBundle.UNEXPECTED_EXCEPTION));
  73                 }
  74                 pw.println("</P>");
  75         }
  76
  77         void writeErrorPage(PrintWriter pw, Throwable t, Locale locale) {
  78                 Style style = new Style();
  79                 ByteArrayOutputStream baos = new ByteArrayOutputStream();
  80                 PrintStream ps = new PrintStream(baos);
  81                 FrankBundle bundle = FrankBundle.getInst(locale);
  82
  83                 pw.println("<HTML><HEAD>");
  84                 pw.println("<TITLE>" +
  85                                 bundle.get(FrankBundle.FRANK) + ": " +
  86                                 bundle.get(FrankBundle.ERROR_PAGE) +
  87                                 "</TITLE>");
  88                 style.writeStyle(pw);
  89                 writeScript(pw, bundle);
  90                 pw.println("</HEAD>");
  91
  92                 pw.println("<BODY>");
  93                 pw.println("<TABLE ID=\"errhead\" WIDTH=\"100%\"><TR><TD>" +
  94                                 bundle.get(FrankBundle.FRANK) + ": " +
  95                                 bundle.get(FrankBundle.UNEXPECTED_ERROR) +
  96                                 "</TD></TR></TABLE>");
  97
  98                 explain(pw, t, bundle);
  99
 100                 // Note that, if we cared about security, we would log this stack trace to a
 101                 // server log, and only report a cross-reference to the log file back to the
 102                 // end user's browser, to avoid potentially exposing internal info that we
 103                 // don't want to share.
 104                 // At least at this point, we don't care (that much), and trade off a
 105                 // potential information leak in favour of reducing our code complexity
 106                 // and the administrator's workload.
 107
 108                 pw.println("<P><INPUT TYPE=\"button\" ID=\"details_btn\" VALUE=\"" +
 109                                 bundle.get(FrankBundle.SHOW_DETAILS) +
 110                                 "\" ONCLICK=\"show_hide();\"/></P>");
 111                 pw.println("<P>");
 112                 pw.println("<DIV ID=\"details\" STYLE=\"display: none;\"><PRE>");
 113
 114                 t.printStackTrace(ps);
 115                 String stackTrace = baos.toString();
 116                 pw.println(stackTrace);
 117
 118                 pw.println("</PRE>\n</P>\n</DIV>");
 119
 120                 String returnToMainFormat = bundle.get(FrankBundle.RETURN_TO_MAIN_PAGE);
 121                 String returnToMain = MessageFormat.format(returnToMainFormat, "/");
 122                 pw.println("<P>" + returnToMain + "</P>");
 123                 pw.println("</BODY></HTML>");
 124         }
 125 }