Problem with Servlet 1

MarkShark · Aug 22, 2001

I'm very new to Java and was thrown into it by default. I have a servlet that will not compile due to miss placed throws and catches. Any help here in telling me what goes where would be greatly appreciated.

import cmi.xml.AU;
import cmi.xml.Block;
import cmi.xml.CourseReader;
import cmi.xml.CSFElement;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.i

bjectInputStream;
import java.i

bjectOutputStream;
import java.io.PrintWriter;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;

import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Vector;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpServlet;

import org.jdom.JDOMException;

public class LessonServlet extends HttpServlet
{
public void init (ServletConfig config) throws ServletException
{
super.init (config);
/*try {
Class.forName (GlobalData.DatabaseDriverName).newInstance();
_jdbcConnection = DriverManager.getConnection (GlobalData.DatabaseName);

//load serialized course data
loadCourseData();
}
catch (Exception xcp) {
xcp.printStackTrace();
}*/
}

public void doGet( HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException
{
boolean normalMode = true;

try {
HttpSession session = request.getSession (true);
ObjectInputStream in =new ObjectInputStream(request.getInputStream());
//can I load the session given the id??
//System.out.println ("Lesson.valid session " + session.getId() + ": " + request.isRequestedSessionIdValid());

Class.forName (GlobalData.DatabaseDriverName).newInstance();
_jdbcConnection = DriverManager.getConnection (GlobalData.DatabaseName, "tesco", "scorm&quot

;

//load serialized course data
loadCourseData();

JDBCHelper dbHelper = new JDBCHelper (_jdbcConnection);

//get student ID
Integer studentID = (Integer) session.getValue ("studentID&quot

;
//get course ID
Integer courseID = (Integer) session.getValue ("courseID&quot

;
//get lesson ID
String lessonID = request.getParameter ("lessonID&quot

;
if (lessonID == null) {
lessonID = (String) session.getValue ("lessonID&quot

;
}

if (studentID == null || courseID == null || lessonID == null) {
//reset session data by re-logging the user
sendProfileError (response.getOutputStream());
return;
}

//store lesson ID in session
session.putValue ("lessonID", lessonID);

String auID = request.getParameter ("auID&quot

;
String mode = request.getParameter ("mode&quot

;
if (mode != null) {
session.putValue ("mode", mode);
}
else {
mode = (String) session.getValue ("mode&quot

;
}
if (mode.equalsIgnoreCase ("review&quot

) {
normalMode = false;
}
else {
normalMode = true;
}

//synchronize access to course hash table
synchronized (_courseHash)
{
//make sure _courseHash is in tact
if (_courseHash == null) {
//try reloading it....
loadCourseData();
if (_courseHash == null) {
//error
response.getOutputStream().close();
throw new IOException ("Corrupt course data&quot

;
}
}
if (! _courseHash.containsKey (courseID.toString())) {
//try reloading it....
loadCourseData();
if (! _courseHash.containsKey (courseID.toString())) {
//error
response.getOutputStream().close();
throw new IOException ("Corrupt course data (course not found)&quot

;
}
}
}

if (auID == null) {
//show course menu
Hashtable hash = (Hashtable) _courseHash.get (courseID.toString());
sendAvailableAUs (hash, studentID.intValue(), courseID.intValue(), lessonID, response.getOutputStream(), response, dbHelper);
return;
}

//if AU has not been attempted, initialize it
Integer auDataID = new Integer (getAUDataID (studentID.intValue(), courseID.intValue(), lessonID, auID, dbHelper));
//if (getAUDataID (studentID.intValue(), courseID.intValue(), lessonID, auID, dbHelper) == -1) {
if (auDataID.intValue() == -1) {
int newID = initializeAUData (studentID.intValue(), courseID.intValue(), lessonID, auID, dbHelper);
dbHelper.addAUToPath (studentID.intValue(), courseID.intValue(), lessonID, auID);
auDataID = new Integer (newID);
}

session.putValue ("AUID", auID);
session.putValue ("AUDataID", auDataID);

sendAU (studentID.intValue(), courseID.intValue(), lessonID, auID, auDataID.intValue(), normalMode, response.getOutputStream(), dbHelper);
}
//to do: detailed messages should be sent to the client depending on which
// exception was thrown. Don't have one try/catch....have one for each situation
catch (Exception e) {
e.printStackTrace();
handleException(response, e);
ObjectOutputStream out =new
ObjectOutputStream(response.getOutputStream());
out.writeObject(e.getMessage());
out.flush();
out.close();
}
}

public void destroy()
{
try {
if (_jdbcConnection != null) {
_jdbcConnection.close();
}
}
catch (Exception ignored) {}
}

private int initializeAUData (int studentID, int courseID, String lessonID, String auID, JDBCHelper dbHelper)
{
String sqlQuery = null;
ResultSet results = null;
try {
//get student's name
sqlQuery = "SELECT Full_Name" +
" FROM " + GlobalData.StudentTable +
" WHERE Student_ID = " + studentID;
results = dbHelper.doQuery (sqlQuery);
if (! results.next()) {
//error
return -1;
}
String studentName = results.getString (1);
results.close();

sqlQuery = "Insert Into " + GlobalData.AUDataTable +
"(Course_ID, Lesson_ID, AU_ID, student_id, student_name, lesson_location, credit," +
" lesson_status, entry, exit, score_raw, score_max, score_min, total_time," +
" session_time, lesson_mode, suspend_data, launch_data, Evaluation_ID, Objective_ID)" +
" Values (" + courseID + ", '" + lessonID + "', '" + auID + "', " + studentID + ", '" + studentName + "'," +
" 'NA', 'credit'," + " 'not attempted', 'ab-initio', " + "'NA', " + 0 + ", " + 0 + ", " + 0 +
", '00:00:00.0', '00:00:00.0', " + " 'normal'" + ", 'NA', " + "'NA', " + 0 + ", " + 0 + &quot

;";
dbHelper.executeUpdate (sqlQuery);

return getAUDataID (studentID, courseID, lessonID,auID, dbHelper);
}
catch (Exception e) {
handleException(response, e);
e.printStackTrace();
}
return -1;
}

private int getAUDataID (int studentID, int courseID, String lessonID, String auID, JDBCHelper dbHelper)
throws SQLException
{
String sqlQuery = "SELECT AUData_ID, lesson_status, lesson_mode, exit" +
" FROM " + GlobalData.AUDataTable +
" WHERE student_id = " + studentID +
" AND Course_ID = " + courseID +
" AND Lesson_ID = " + "'" + lessonID + "'" +
" AND AU_ID = '" + auID + "';";
ResultSet results = dbHelper.doQuery (sqlQuery);
if (results.next()) {
return results.getInt ("AUData_ID&quot

;
}
return -1;
}

private void sendAU (int studentID, int courseID, String lessonID, String auID, int auDataID, boolean normalMode, ServletOutputStream htmlOut, JDBCHelper dbHelper)
throws IOException, ClassNotFoundException
{
Hashtable hash = null;
synchronized (_courseHash)
{
hash = (Hashtable) _courseHash.get (String.valueOf (courseID));
if (hash == null) {
loadCourseData();
hash = (Hashtable) _courseHash.get (String.valueOf (courseID));
if (hash == null) {
throw new IOException ("Corrupt course data (course not found)&quot

;
}
}
}
AU au = (AU) hash.get (auID);

try {
if (! normalMode) {
dbHelper.setReviewMode (auDataID);
}
String courseFileName = getFileName (String.valueOf (courseID), dbHelper);
File file = new File (courseFileName);
//create absolute path to file so we can resolve relative URLs
//String newFileName = file.getParent() + "\\" + au.getLaunchParams();
//for Unix: use '/' instead of '\'
String newFileName = file.getParent() + "/" + au.getLaunchParams();
BufferedReader buf = new BufferedReader (new FileReader (newFileName));
PrintWriter htmlWriter = new PrintWriter (htmlOut);
String temp;
htmlWriter.write (getAUHtml (au.getLaunchParams()));
htmlWriter.flush();
htmlWriter.close();
}
catch (Exception e) {
handleException(response, e);
e.printStackTrace();
ObjectOutputStream out =new ObjectOutputStream(response.getOutputStream());
out.writeObject (e.getMessage());
out.flush();
pw.close();
}
}

private String getAUHtml (String path){
path = path.replace ('\\', '/');
String response;
response = "<html>\n" +
"<head>\n" +
"</head>\n" +
"<body>\n" +
"<script language=\"JavaScript\">\n" +
"document.location = \"/cmi/courses/" + path + "\"\n" +
"</script>\n" +
"</body>\n" +
"</html>\n";
return response;
}

private void sendAvailableAUs (Hashtable hash, int studentID, int courseID, String lessonID, ServletOutputStream out, HttpServletResponse response, JDBCHelper dbHelper)
{
StringBuffer buf = new StringBuffer (200);
Block block = (Block) hash.get (lessonID);
AU au = null;

try {
Vector completedAUs = dbHelper.getCompletedAUs (studentID, courseID, lessonID);
buf.append ("<html>\n" +
"<head>\n" +
"<title>" + block.getTitle() + " units</title>\n" +
"<script language=\"JavaScript\">\n" +
"function go() {\n" +
" var form = document.goForm;\n" +
" var index = form.gotoSelect.selectedIndex;\n" +
" if (index == 0) {\n" +
" document.location = \"/servlet/CourseServlet?courseID=" + courseID + "\";\n" +
" }\n" +
" else if (index == 1) {\n" +
" top.restart();\n" +
" }\n" +
"}\n" +
"</script>\n" +
"</head>\n" +
"<body background=\"/cmi/images/marble.jpg\">\n" +
"<center><h1><b><u>" + block.getTitle() + "</u></b></h1></center>\n" +
"<p></p>\n<p></p>\n" +
"<b>" + block.getTitle() + " contains the following units: </b>\n" +
"<dl>\n&quot

;

Enumeration enum = block.getChildren();
while (enum.hasMoreElements()) {
String temp = (String) enum.nextElement();
CSFElement element = (CSFElement) hash.get (temp);
if (element.getType().equals ("au&quot

) {
au = (AU) element;
if (completedAUs.contains (au.getID())) {
buf.append ("<dt><p><img src=\"/cmi/images/node2.gif\"><a href=\"/servlet/LessonServlet?lessonID=" + block.getID() + "&auID=" + au.getID() + "&mode=review\">" + au.getTitle() + " (<i>review</i>) </a></p></dt>\n&quot

;
}
else {
buf.append ("<dt><p><img src=\"/cmi/images/node.gif\"><a href=\"" + response.encodeURL ("/servlet/LessonServlet?lessonID=" + block.getID() + "&auID=" + au.getID() + "&mode=normal&quot

+ "\">" + au.getTitle() + "</a></p></dt>\n&quot

;
}
}
else if (element.getType().equals ("block&quot

) {
buf.append ("<dt><p><img src=\"/cmi/images/folder.gif\"><a href=\"" + response.encodeURL ("/servlet/LessonServlet?lessonID=" + element.getID() + "&mode=normal&quot

+ "\">" + element.getTitle() + "</a></p></dt>\n&quot

;
}
}
buf.append ("</dl>\n" +
"<br><br>\n" +
"<form name=\"goForm\">\n" +
"<select name=\"gotoSelect\">\n" +
" <option value=\"lesson\">Lesson Menu</option>\n" +
" <option value=\"exit\">Exit LMS</option>\n" +
"</select>\n" +
"<input type=\"button\" value=\"Go\" onClick=\"go()\">\n" +
"</form>\n" +
"</body>\n" +
"</html>&quot

;
catch (Exception e) {
e.printStackTrace();
}

{
e.printStackTrace();
ObjectOutputStream out =new ObjectOutputStream(response.getOutputStream());
out.writeObject(e.getMessage());
out.flush();
out.close();
}

}
private String getFileName (String courseID, JDBCHelper dbHelper)
throws ClassNotFoundException, SQLException
{
ResultSet results = null;
String fileName = null;
String sqlQuery = "SELECT CourseFile" +
" FROM Course" +
" WHERE Course_ID = " + Integer.parseInt (courseID) + ";";
results = dbHelper.doQuery (sqlQuery);
if (results.next()) {
fileName = results.getString (1);
}
else {
//need to do more than this

System.out.println ("crap!&quot

;
}
results.close();

return fileName;
}

private void loadCourseData()
throws IOException, ClassNotFoundException
{
//load serialized course data
File file = new File (GlobalData.DataFileName);
if (! file.exists()) {
//error
throw new FileNotFoundException (GlobalData.DataFileName + " not found.&quot

;
}
FileInputStream fis = new FileInputStream (GlobalData.DataFileName);
ObjectInputStream ois = new ObjectInputStream (fis);
_courseHash = (Hashtable) ois.readObject();
ois.close();
}

private void sendProfileError (ServletOutputStream out)
{
String html = "<html>\n" +
"<body>\n" +
"<p>An error has occurred with your profile. Please " +
"<a href=\"\" onClick=\"top.restart(); return true\">login again</a>" +
"</body>\n" +
"</html>\n";

ObjectOutputStream out =new ObjectOutputStream(response.getOutputStream());
out.writeObject(e.getMessage());
out.flush();
out.close();
}

private Connection _jdbcConnection;
private Hashtable _courseHash;
}

wushutwist · Aug 22, 2001

What is the exact compilation error? Wushutwist

MarkShark · Aug 22, 2001

The errors I'm getting are as follows:

C:\My Documents\Mark's\SpinWeb\htdocs\WEB-INF\classes\LessonServlet.java:342: 'catch' without 'try'.
catch (Exception e) {
^
C:\My Documents\Mark's\SpinWeb\htdocs\WEB-INF\classes\LessonServlet.java:354: '}' expected.
}
^
C:\My Documents\Mark's\SpinWeb\htdocs\WEB-INF\classes\LessonServlet.java:355: 'try' without 'catch' or 'finally'.
private String getFileName (String courseID, JDBCHelper dbHelper)
^
C:\My Documents\Mark's\SpinWeb\htdocs\WEB-INF\classes\LessonServlet.java:355: Statement expected.
private String getFileName (String courseID, JDBCHelper dbHelper)
^

wushutwist · Aug 22, 2001

Right above the getFileName method (line 355 ?) you have a piece of code that looks like this:

Code:

            catch (Exception e) {
            e.printStackTrace();
        }
           
         { 
            e.printStackTrace();
            ObjectOutputStream out =new ObjectOutputStream(response.getOutputStream());
            out.writeObject(e.getMessage());
            out.flush();
            out.close();            
        }
   }

I am guessing but I think it should look like this:

Code:

        } /* END OF TRY BLOCK */

        catch (Exception e) { 
            e.printStackTrace();
            ObjectOutputStream out =new ObjectOutputStream(response.getOutputStream());
            out.writeObject(e.getMessage());
            out.flush();
            out.close();            
        } /* END OF CATCH BLOCK */

   } /* END OF sendAvailableAUs METHOD

I am not saying that this is all that is wrong but it definitely doesn't help

Wushutwist

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Problem with Servlet 1

MarkShark

Programmer

wushutwist

Programmer

MarkShark

Programmer

wushutwist

Programmer

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