I am new to this forum. I have a doubt about JSP/servlet in my application
I have developed an application in which user may search some data based on some criteria and he will get data from database(through Hibernate to servlet and to JSP). When some data is displayed on screen based on search he/she may try to copy the URL and forward to anyone or If he try to open in different browser it is showing an empty page.
eg: if i try to paste the link given bellow it is showing blank page
example link
but i need to display the data how this can be achieved.
Edited: After clicking on job search in menu bar as mentioned in comments the page will redirect to a servlet
if(action.equals("searchjob")){
String requireskills=request.getParameter("txt_requireSkills");
String location=request.getParameter("txt_locationName");
session.setAttribute("location",location);
String minexp1=request.getParameter("dd_minimum");
String maxexp1=request.getParameter("dd_maximum");
jobsearchDAO = new JobSearchDAOImpl();
List<JobPostInfo> data=jobsearchDAO.jobsearchlist(requireskills,location,minexp1,maxexp1);
if(data!=null && data.size()!=0){
//save data
if(!(session.getAttribute("LoginObject")==null)){
JobSeeker jobSeeker=(JobSeeker)session.getAttribute("LoginObject");
JobSearchCriteria jobsearchcriteria= new JobSearchCriteria();
jobsearchDAO=new JobSearchDAOImpl();
jobsearchcriteria.setKeyWords(requireskills);
jobsearchcriteria.setLocation(location);
JobSeeker jobseeker=(JobSeeker)session.getAttribute("jobseeker");
//
// jobsearchcriteria.setJobSeeker(jobseeker.getJobSeekerSn());
jobsearchcriteria.setJscTs(new Date());
int value=jobsearchDAO.savesearch(jobsearchcriteria);
System.out.println("savesearch value------>"+value);
}
session.setAttribute("jobsearchlist", data);
// session.setAttribute("success","Search Criteria is saved to database.");
response.sendRedirect("jobsearchresult.jsp");
}else
{
session.setAttribute("error","No Records found");
response.sendRedirect("jobsearch.jsp");
}
}
This is the code in DAOIMPL
public List<JobPostInfo> jobsearchlist(String requireskills,String location,String minexp1,String maxexp1) throws Exception{
long minexp;
long maxexp;
try{
session =getSession();
//Criteria Query
Criteria query=session.createCriteria(JobPostInfo.class,"jpost");
// if(minexp1.equals("0") && (maxexp1.equals("") || maxexp1==null)){
if((minexp1.equals("-1") || minexp1=="-1") && maxexp1==null){
}
else if(minexp1.equals("0")){
minexp=Long.parseLong(minexp1);
long min=1;
query.add(Restrictions.lt("jpost.experienceMin",min));
}else if(!(minexp1.equals("") || minexp1==null) && maxexp1.equals("-1")) {
minexp=Long.parseLong(minexp1);
query.add(Restrictions.ge("jpost.experienceMin",minexp));
}else if(!(minexp1==null && maxexp1==null)){
minexp=Long.parseLong(minexp1);
maxexp=Long.parseLong(maxexp1);
query.add(Restrictions.and(Restrictions.ge("jpost.experienceMin",minexp),Restrictions.le("jpost.experienceMax",maxexp)));
}
//For Location
if(!(location==null|| location.equals(""))){
query.createAlias("jpost.location","location");
query.add(Restrictions.like("location.locationName",location).ignoreCase());
}
//For Keyword
if(!(requireskills==null || requireskills.equals(""))){
query.add(Restrictions.like("jpost.requiredSkills","%"+requireskills+"%").ignoreCase());
}//requireskills
List<JobPostInfo> list = query.setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY).list();
if(list.size()==0){
return null;
}else{
return list;
}
}catch(HibernateException e){
e.printStackTrace();
}finally {
close(session);
}
return null;
}
I solved my problem. It's a very basic mistake and I hope this will help others:
response.sendRedirect("jobsearchresult.jsp") is replaced by request.getRequestDispatcher("studentinformation.jsp").forward(request, response)
or include-method. The second thing is, the session is created and initialized with the servlet. When I copy the link in a different browser, a certain block of the servlet will be executed. Example:
action.equals("searchjob")
So at the time the session is not available yet, I initialize it in every block like separating declaration and initialization.
Related
I have a login servlet that processes post request with username and password parameters, and does something like this:
Instant pageGenStart = Instant.now();
String username = req.getParameter("username");
String password = req.getParameter("password");
resp.setContentType("text/html;charset=utf-8");
User user = null;
try {
user = userService.getByUsername(username);
} catch (SQLException e) {
e.printStackTrace();
}
if (user == null && !password.equals("")) {
try {
user = new User(username, password);
user.setId(userService.addNewUser(username, password));
charactersService.addNewCharacter(user);
sessionsService.add(req.getSession().getId(), user.getId());
} catch (SQLException e) {
e.printStackTrace();
}
resp.setContentType("text/html;charset=utf-8");
resp.setStatus(HttpServletResponse.SC_OK);
Duration time = Duration.between(pageGenStart, Instant.now());
resp.sendRedirect("/main");
}
If user is not found in db, create new user and redirect him to main page. Normally i would just put this "time" variable into page, but i redirect my response to other servlet where doGet method is called. How do i let other servlet know how long login servlet took to proccess post request?
You can pass value from one servlet to another in many ways like :
Storing values in session ( You have to take care of session management)
Creating class having static ConcurrentHashMap and storing time gap per user session and fetching it using session ID. (same problem need to take care when to clear cache).
Use already defined lib ( best option as you need not to worry about session management and cache clear).
I perfer EH-cache for these kind of perposes you can see a good example from the Link.
I'm trying to make a application in which put some data in database and from the html page i want to search the data in database. I'm using the servlet api, i successfully retrieve the data from the database, but for the data which is not present in the database i required to get the "data not found" message on the same html page. I write the condition for checking the data for database, but for the data not present in the database i get the error message of "null pointer exception" and the while loop doesn't break by itself after checking whole data in database.
// this while loop doesn't terminate by itself if the data is not found in the database.
int flag=0;
while(rs.next()){
if (rs.getString(1).equals(fname)&&(rs.getString(2).equals(lname)))
{
String message=rs.getString(4);
out.print("<h2 align='center'>"+message+"</h2>");
RequestDispatcher disp = req.getRequestDispatcher("/index.html");
disp.include(req,res);
flag=1;
}
}
if(flag==0)
{
out.print("<h1>"+"data not found"+"</h1>");
RequestDispatcher disp = req.getRequestDispatcher("/index.html");
disp.include(req,res);
System.out.println(flag);
}
}
You should assign the value to a variable then check if is not null first:
String tmp = rs.getString(1);
if (tmp != null && tmp.equals(fname) && tmp.equals(lname)) {...}
I am using Couchbase Lite SDK for android and saving an object instance of MyClass as a document in the database. MyClass has an attribute that stores the date in the java.util.Date. During run time, I fetch all the instances of MyClass saved in the database and store them in the ArrayList<MyClass>. When I insert a new document into the database and read the values from the database to show all the entered instances, the date field saved in the database is retrieved as a Long when I next try to fetch the details from the database. The code I use to load the details from the database is:
Code snippet 1:
for (Field field: fields) {
field.setAccessible(true);
if (properties.containsKey(field.getName())) {
if ("date".equals(field.getName())) {
Log.d("DebugTag", properties.get(field.getName()) + "");
long dateLong = (Long) properties.get(field.getName());
details.setDate(new Date(dateLong));
} else {
field.set(details, properties.get(field.getName()));
}
} else if("_id".equals(field.getName())) {
details.set_id(document.getId());
} else {
final String msg = "Field " + field.getName() + " not present in document ";
Log.e(TAG, msg);
}
}
You can see that I have added an additional check in case the field is date. This works perfectly fine. So, I save a new entry to database and come back to the page where I see all the entries made into the database.
Now, I have implemented a new functionality to update the details of a record in the database. For updating the record I have the following implementation:
Code snippet 2:
public static boolean updateDocument(Database database, String docID, Map<String, Object> map) {
if (null == database || null == map || null == docID) {
return false;
}
boolean success = true;
Document document = database.getDocument(docID);
try {
// Have to put in the last revision id as well to update the document.
// If we do not do this, this will throw exception.
map.put("_rev", document.getProperty("_rev"));
// Putting new properties in the document ...
document.putProperties(map);
} catch (CouchbaseLiteException e) {
Log.e(TAG, "Error putting property", e);
success = false;
}
return success;
}
After doing this when I try to reload the items, it gives me exception while reading the date field in my Code snippet 1 saying that the Date object cannot be typecasted as Long and the application crashes. Now, when I again open the application, it works perfectly fine with all the changes to the edited entry reflecting correctly. Can anyone let me know the reason for this? I suspect, until we close the database connection, the changes are not committed to the actual database location and the date field in the updated entry is kept in the cache as the Date object in my case.
PS: Although, I have found a workaround for this by setting the date as a Long object in the payload (map in function updateDocument() in Code snippet 2), it would still be interesting to understand the problem I faced.
Looking at this further, this could be reasons related to auto-boxing where long to Long conversion of primitive types to the object wrapper class is crashing the application when trying to save.
Have you tried:
long value = Long.parseLong((String)...);
More specifically in Code snippet 1:
long dateLong = Long.parseLong((String)properties.get(field.getName()));
EDIT: Alex Martelli Gave me a great answer which I changed only slightly in order to get working properly for me
The answer to this problem for me was
public boolean Login2(String usernamein, String passwordin) {
DatastoreService datastore = DatastoreServiceFactory
.getDatastoreService();
Filter usernamefilter = new FilterPredicate("username",
FilterOperator.EQUAL, usernamein);
Query validuserquery = new Query("Users").setFilter(usernamefilter)
.setKeysOnly();
Entity theUser = datastore.prepare(validuserquery).asSingleEntity();
if (theUser == null) {
System.out.println("Username not found");
return false;
}
return true;
}
End of EDIT
Original Post
Okay so I have spent the entire day trying to do this and have tried my best to research it but I can't do it! :(
I feel like there is probably and easy answer but I can't work it out, I feel like I have tried Everything! please please please help D:
I have a Login section of code on its own .jsp page called Index.jsp
String username = "";
String password = "";
try {
if (request.getParameter("usernamein") != null && request.getParameter("passwordin") != null) {
username = (request.getParameter("usernamein"));
password = request.getParameter("passwordin");
if(login.Login2(username, password)){
response.sendRedirect("Race.jsp");
System.out.println("go to next page");
} else {//need username/password
out.println("your username or password is incorrect");
}
}
} catch (Exception e) {
out.println("problem in getting u an p error =" + e);
}
Part way through that code is the line (login.Login2(username, password))
that code calls a method in a class using java use bean thingy
the method it calls is this:
public boolean Login2(String usernamein, String passwordin) {
DatastoreService datastore = DatastoreServiceFactory.getDatastoreService();
Filter usernamefilter = new FilterPredicate("username", FilterOperator.EQUAL, usernamein);
Query validuserquery = new Query("Users");
validuserquery.addProjection(new PropertyProjection("username", null));
System.out.println(validuserquery);
List<Entity> list = datastore.prepare(validuserquery).asList(FetchOptions.Builder.withLimit(100));
System.out.println(list);
for (Entity username : list){
System.out.println("username is equal to '"+username+"'");
if(username.equals(usernamein)){
return true;
}else
System.out.println("was not equal");
return false;
}
return false;
}
I'm trying to only go to the next page in the top code if the if statement is true, meaning that the username does exist, eventually I want it to only go to then next page if the username and password are both in the same entity i.e. the combination exists.
I hope you guys understand what i am trying to do and can help me
oh the System.out.println() for the username value outputs this:
username is equal to '<Entity [user("id")/Users(5910974510923776)]:
username = RawValue [value=[B#187c4d7]
>
'
If you need any more info just ask and i'll add it to the post :D ty
You would be best advised to query the datastore for just the username of interest...:
Query validuserquery = new Query("Users").
setFilter(new Query.FilterPredicate("username",
Query.FilterOperator.EQUAL,
usernamein)
).setKeysOnly();
Entity anyentity = datastore.prepare(validuserquery).asSingleEntity();
if(anyentity == null) {
System.out.println("was not equal");
return false;
}
return true;
This assumes there are no entities with duplicated username in your store (though you could deal with that by catching exception PreparedQuery.TooManyResultsException -- if that gets raised, it means you have more than one entity with that username, so that would be a return true case too:-).
The core idea is: getting every user entity and checking their usernames in your application code is really wasteful of resources (quite apart from the bugs in your code in this case) -- use queries to get only the relevant entity or entities, if any!-)
Try searching a bit more next time. It's not that hard, your issue was pretty easy. In any case :
Your query returns a full object, not just properties of your object. You need to do
entity.getProperty("username")
So that you see your property, not the full object.
More info here.
what I'm trying to do is relative simple
In my webapp there are these two servlets:
(I will write some pseudocode)
servlet A code: :
HttpSession sess = req.getSession();
String str = (String) sess.getAttribute("log");
if(str == null)
{
// send html page with a form
// to enter password and name
// data will be proceessed by servlet B
}
else
{
// send html page with a form
// to enter only a name
//data will be proceessed by servlet B
}
servlet B code: :
HttpSession sess = req.getSession();
String logged = (String) sess.getAttribute("log");
if(logged == null)
{
//check if password correct
if(correct)
{
sess.setAttribute("log","ok");
// print name
// and tell the user
// that next time password
// will not be requested
}
else
{
// print error message
}
}
else
{
// print name
}
for some reason the second time the servlet A is called after that the user filled in password and name correctly
str is null so the if part gets printed.
EDIT:
I discovered that if the user after inserting the password and
being redirected to servletB writes the url of servletA by himself
all goes right , but it odesn't work when the user gets back to the previous
page using a link created by servletA:
A HREF=\"http://localhost:8080/Blog/ServletA\" back
again , any suggestions why this happens?
I believe its not entering in your if(correct) block i.e. correct condition is not getting satisfied. Correct the condition there and make sure, it sets the log attribute in the session. Once a attribute is set into the session, its there until session expires or your remove it.