Avoid out.println inside servlet
Is there a nice way to avoid hardcoding of HTML tag inside the servlet?
I know it can be done by XML and XSL, but it is hard !!
Is there any example i can look at to start?
Is there any other way to do that? I want to separate the logic from the style with static and dynamic content, dynamic stand for "based on the logged on user profile"..
Thank you.
Yes, but i have lot of servlet, part of our framework, already implemented (all abstract class), move to JSP mean re-write all this servlet as normal class, i would like to write just a few classes to render html for the specified application.
I know somebody did using XSL but it is hard to find some good example or tutorial.
Thank you anyway.
Similar Messages
-
Tomcat Servlet: System.out.println in servlet not printing to catalina.out
Hello friends ,
When i m using System.out.println() in servlet its o/p should come in catalina.out but its not coming plz help me....one thing more can we replace exixting catalina.out file with new one...
please Help me soon.
Thanksgo to[u] TOMCAT_DIR/config/server.xml.
Open this xml file and find something like <Logger className="org.apache.catalina.logger.FileLogger"
prefix="catalina_log." suffix=".txt"
timestamp="true"/>and
<Logger className="org.apache.catalina.logger.FileLogger"
directory="logs" prefix="localhost_log." suffix=".txt"
timestamp="true"/>You can change the log file name to another one.
It's much better to use a logger tool like log4j (http://logging.apache.org/log4j/docs/download.html) then using a System.out.println()...
hope that helps -
Error on out.println inside declaration block
I am trying to generate a html page from a method iside the jsp page. When I use out.println inside the declaration block (<%! ---- %>) I am getting following error : "Undefined variable or class name: out".
I have tried using System.out.println, but that sends the output to the consol, and not the html page.
What is the workaround for this ??
Following is the test jsp page to illustrate the problem:
<%@page language="java" %>
<%@page import="wt.doc.*" %>
<%@page import="wt.fc.*" %>
<%@page import="wt.query.*" %>
<jsp:useBean id="wtcontext" class="wt.httpgw.WTContextBean" scope="request"/>
<jsp:setProperty name="wtcontext" property="request" value="<%=request%>"/>
<html>
<body>
<%!
public void prntest(){
System.out.println("This will print the message only to console");
out.println("This does not work");
%>
<h1>This is to test out.println function</h1>
<%
out.println("<br>This out.println statement works as expected<br>");
%>
<br>Now try this<br>
<%prntest();%>
</body>
</html>Hai ,
Here you are trying to access implict object "out" outside the Scriplets ie in function outside the init/service method .
To get output from prntest() , you have pass a reference of JspWriter out to it .ie Your function should be
<%!
public void prntest(JspWriter out2){
System.out.println("This will print the message only to console");
out2.println("This does not work");
%>
<%prntest(out);%>
This should now work .
rakesh -
System.out.println in Servlets/JSPs
Hi,
Which file and directory in JDeveloper 10g (10.1.3.0) on windows does the output of System.out.println get logged to? THanks in advance.
regards,Goes to standard out, not a file. So if you're running the embedded server you will see it in your Embedded Server Console window. However, you should never be using system.out.println in a servlet/jsp. Instead use commons logging or log4j to get log messages.
-
Hi I have given System.out.println in my EJB object. But I am not able to see the output in my console. But when I give printStackTrace in my JSP(from where I can EJB)....it is displaying the exception....
So my question is Can we give System.out... in EJB?. Should we set any property to see the output of System.out...in the console?.Here is my code
From UserManager I call the EJB
public boolean validateSignOn(String strUserName,String strPassword) throws ProdSchedException{
try{
UserMgrHome home = (UserMgrHome)getEJBHome("UserMgr",UserMgrHome.class);
UserMgr userMgr = home.create();
return userMgr.validateSignOn(strUserName,strPassword);
catch(RemoteException rex){
ServerLog.log(rex.getMessage(),ServerLog.ERROR);
throw new ProdSchedException(rex,"Server Failed");
catch(CreateException cex){
ServerLog.log(cex.getMessage(),ServerLog.ERROR);
throw new ProdSchedException(cex,"Create Exception");
This is my EJB code
import javax.ejb.*;
import java.rmi.RemoteException;
import java.util.*;
import javax.xml.parsers.*;
import org.xml.sax.*;
import org.w3c.dom.*;
import java.io.*;
* User Manager Session Bean
public class UserMgrEJB implements SessionBean {
SessionContext cntx;
public boolean validateSignOn(String strUserName,String strPassword) throws ProdSchedException{
UserDAO dao = new UserDAO();
System.out.println("Inside EJB");
boolean bValidUser = dao.validateUser(strUserName,strPassword);
if(!bValidUser){
throw new ProdSchedException("Invalid User");
return bValidUser;
//Bean methods
public void ejbCreate(){
System.out.println("Inside EJB Create");
public void ejbRemove(){
public void ejbActivate(){
System.out.println("Inside EJB Activate");
public void ejbPassivate(){
public void setSessionContext(SessionContext cntx){
this.cntx = cntx;
This is mu UserDAO code
public class UserDAO extends DAO{
public boolean validateUser(String userName,String password) throws ProdSchedException{
Connection conn = null;
PreparedStatement stmt = null;
ResultSet result = null;
System.out.println("Inside validateUser in DAO");
try{
boolean bIsValidUser = true;
String selectStatement = "SELECT SYSDATE from DUAL";
conn = getConnection();
stmt = conn.prepareStatement(selectStatement);
result = stmt.executeQuery();
while(result.next()){
bIsValidUser = true;
return bIsValidUser;
catch(SQLException sqex){
ServerLog.log(sqex.getMessage(),ServerLog.ERROR);
throw new ProdSchedException(sqex,sqex.getMessage());
finally{
try{
close(conn,stmt,result);
catch(ProdSchedException slex){
ServerLog.log(slex.getMessage(),ServerLog.ERROR);
throw slex;
} // end class
And the error I get in the console is this(since I have given printStackTrace in my JSP)
ProdSchedException: SQL Error
at UserDAO.validateUser(UserDAO.java:
44)
at UserMgrEJB.validateSignOn(
UserMgrEJB.java:26)
at UserMgrEJB_p3hctp_EOImpl.v
alidateSignOn(UserMgrEJB_p3hctp_EOImpl.java:46)
at UserManager.validateSignOn(User
Manager.java:20)
at jsp_servlet._public.__login._jspService(__login.java:123)
at weblogic.servlet.jsp.JspBase.service(JspBase.java:27)
at weblogic.servlet.internal.ServletStubImpl$ServletInvocationAction.run
(ServletStubImpl.java:1094)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubIm
pl.java:437)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubIm
pl.java:319)
at weblogic.servlet.internal.WebAppServletContext$ServletInvocationActio
n.run(WebAppServletContext.java:5626)
at weblogic.security.service.SecurityServiceManager.runAs(SecurityServic
eManager.java:685)
at weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppSe
rvletContext.java:3213)
at weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestIm
pl.java:2555)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:251)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:219) -
I want to select a value from my databases and to print it on the screen, but it doesn't recognize my out. println and I don't understand why.
I have a class that extend another class which extends HttpServlet.
The code is the following:
@WebServlet(name = "vizualizare_denumire", urlPatterns = {"/vizualizare_denumire"})
public class vizualizare_denumire extends vizualizare_statiuni {
String den_s,criteriu;
protected void actualizare_db(String criteriu,String sql_statement){
try{
String dbURL="jdbc:odbc:statiuni";
String user="";
String pass="";
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Connection c=DriverManager.getConnection(dbURL,user,pass);
Statement s=c.createStatement();
ResultSet r=s.executeQuery(sql_statement);
criteriu=r.getString(1);
out.println(criteriu);
s.close();
catch(ClassNotFoundException a){}
catch(SQLException a){}
@Override
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
try {
out.println("<html>");
out.println("<head>");
out.println("<title>Servlet vizualizare_denumire</title>");
out.println("</head>");
out.println("<body>");
den_s=request.getParameter("den_s");
sql_statement="select caracter from statiune where den_s="+den_s;
actualizare_db("caracter",sql_statement);
out.println("</body>");
out.println("</html>");
} finally {
out.close();
Can someone help me??
Edited by: 900482 on Dec 3, 2011 8:24 AM900482 wrote:
it doesn't recognize my out. println and I don't understand why.Because there is no variable with the name in scope, i.e. your method doesn't have an out variable and you don't have a class level variable either.
You do have the out variable in your other method, processRequest. What you can do is pass it as a parameter to your actualizare_db method. -
How to dynamically generate HTML in Servlet without all the out.println?
Since I am not sure whether this is a Java Servlet or JSP problem, so I will describe my situation. And hopefully someone can propose a good solution. I came from a PHP, so Java Servlet and JSP are still a little bit foreign for me.
My problem
My front end is a JSP page that essentially contains a form (lets call it form1). The reason it is a JSP not a HTML is because I will need to load form data from the backend and display them in the form. Once the user submits the form, it will go to a backend Java Servlet (lets call it servlet 1), which loads data from files according to user input. Then, I will need to dynamically create a new form (lets call it form2) based on the data loaded from files. Once the user inputs and submits form2, another Java Servlet (servlet 2) will do more processing. That is the end of line. Both form1 and form2 require Javascript.
My question is that since servlet 1 will need to dynamically create form2. I naturally will want a presentation control. Instead of doing out.println(html code), I want to use JSP and write direct HTML code. On the other hand, can JSP be used as a form action? So basically, in form 1, can I do <form action= /xxx.jsp> I think I saw something like this, but I lack the comprehensive JSP knowledge to know for sure. More importantly, if hypothetically JSP can be used, how do I handle functions such as doGet(HttpServletRequest request, HttpServletResponse response), which is used in servlet1.
Thank you,
Mno, servlets should not be used to generate a view, that is what a JSP is for. So let your backend servlet fetch the data, put it for example as attributes of the request scope (request.setAttribute()) and then forward control to a JSP that will generate the view, based on the information you stored in the request scope. That is the proper way of using servlets & JSPs; use servlets to invoke business logic classes, use JSPs combined with JSTL to generate the view. If you do it properly, you don't need ANY java code in your JSP.
-
Hi,
I've been developing servlets for a year now and have found it ridiculous to output the whole HTML page using numerous out.println() lines. I think for a problem so vastly faced, there should have been a solution long time back (other than JSP)
Atleast something like a htmlOut() method which would be a variant of the println() method which did the following:
1. Take the whole HTML page output syntax as argument in one go.
2. Smart way to use escape characters by parsing the argument for non-end of line double quotes (")
3. Even another method so that the HTML page could be written in a seperate file and the file could be the argument to the out method.
I think these steps would enhance the usability of Servlets many folds!
Tell me what you think!
Ashish TengsheYou can write your own output stream with all that functionality and set it as the default output stream for System class
see --
http://java.sun.com/j2se/1.3/docs/api/java/lang/System.html#setOut(java.io.PrintStream) -
How can I see whatever I print through System.out.println in my servlets when I use iplanet 4.1
how can I see whatever I print through System.out.println in my servlets when I use iplanet 4.1
Hi Nitin,
Look out the below link, Hope this helps you.
http://knowledgebase.iplanet.com/ikb/kb/articles/4235.html
http://knowledgebase.iplanet.com/ikb/kb/articles/4790.html
http://knowledgebase.iplanet.com/ikb/kb/articles/4699.html
Regards,
Dakshin.
Developer Technical Support
Sun Microsystems
http://www.sun.com/developers/support. -
System.out.println()'s inside implementation
Hello,
We all know the System.out.prinltn() API. But I want to know the inside implementation of System.out.println() API. Where can I get this implementation?
Furthermore, can anyone explain concretely about how to implement System.out.println()? Can you tell me in a great detail?
JohnWen604
21-June-2005I just cannot understand what is the magic behind
d that one API can control the hardware(i.e. control
the screen to print one "simple" sentance). Do youIt's called "native OS methods". And you're not controlling anything, the graphics driver does. You're just asking the OS to ask the driver to ask the graphics card to send the appropriate signals.
think that is just just the magic of our grand new
computer? So If I can fully understand how the
hardware is controlled by the Application Program, I
will be more sensible in writing software. Just likeI doubt that. The more sensible way would be to stick to a useful level of abstraction and good design.
you know the IC's inner structure if you want to be
an qualified Electronic Engineer. Do
you think so?No.
Besides, from some OS books I know that
w that Application program written in Java will
become some OS commands that is ready for going
through the OS's command processor. I just do not
understand how that primitive Java code is written
which is OS command and can tell hardware(screen) to
print something. Do you know what that primitive Java
code is?-- The primitive Java code that is a OS
command to tell screen to print something. The
primitive java code 's examples are "+", "for",
"while", "private". The primitive java code does not
mean API.No. It's called "instructions".
What you said about setOut0(), I think
setOut0() is simply an API. Do you know the
implementation of this setout0() API? There must be
implementation and there must be the primitive Java
code. Do you agree with me?No. It's N-A-T-I-V-E. No Java code. Nowhere. Just C++ or whatever. -
Control Statement inside System.out.println
I am printing something like this:
System.out.println(parts1[0] + "|" + parts1[1]); Now, I want to keep a check i.e. if parts1[1] is say 3 I want to printout Hi and if parts1[1] is any other digit I printout Hello. [parts is obtained by using split method from data]
Can I do it inside the print statement?Be judicious about this though. Unless the ternary expression and the overall argument to println are both very simple, you'll end up with an unreadable, unmaintainable mess. The only advantage to doing it all inside the println argument is compactness. If it gets unwieldy, break it up into separate statements, assign the end result to a variable, and print that.
-
System.out.println statements inside my session beans
I have some System.out.println statements inside my session beans to track some error conditions. I would like to know where this output will be printed. Is there any text file I should look for or start up any console to see the output.
I am running iPlanet SP3 test drive edition iPlanet Web Server 4.1 on WIndows NT machine.Hi,
These statements will be printed on the kjs logs file. To view them, go to control panel-> services-> select the iPlanet Application server and click "start up" tab. Check " allow this sevice to interact with the desk top" in the service window that has been popped up. Restart the iPlanet Application server.
View the kjs window. All your System.out.println statements will be printed out there.
If you have any further queries please get back to the forum.
Thanks for visiting our web forum,
Rakesh. -
How does System.out.println(). Work inside src.zip file !
Hello guyz,
I was just wondering how System.out.println() worked so i opened up the src.zip file and checked the source code. But could not understand it. As written i remember
"out is an object encapsulated in the System class."
Thats ok. But i could not understand the code.
public final static PrintStream out = nullPrintStream();
private static PrintStream nullPrintStream() throws NullPointerException {
if (currentTimeMillis() > 0) {
return null;
throw new NullPointerException();
}Also when i ran the DJ Decompiler it decompiled it to this:
public class One
public static void main(String args[])
System.out.println("hello world");
import java.io.PrintStream;
public class One
public One()
public static void main(String args[])
System.out.println("hello world");
}Also, why does it need to import PrintStream ?Peter__Lawrey wrote:
I was just wondering how System.out.println() worked so i opened up the src.zip file and checked the source code.This value is a place holder. This value is changed as soon as enough of the JVM is initialised for printing to work.
Also, why does it need to import PrintStream ? It doesn't, but it is used in the code so DJ is including it just in case.Sorry,
But i don't understand at all. -
Problem in printing the data from database when i print inside servlet
hi to all!
the objective of the code below is getting the data from database table and has to send that data to the web browser using out.println .note: out - PrintWriter object
In a getQuestion method, i am getting the data from database table and store it in String q and when i print the q within this method it is getting printed, but i got the null value when i printed the String q inside service method doPost. why..? its puzzling me.
package servlet;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;
public class test extends HttpServlet {
Connection con;
ResultSet rs;
Statement s;
StringBuffer q;
StringBuffer o1;
StringBuffer o2;
StringBuffer o3;
public void getQuestion() throws Exception
if(rs.next())
q=new StringBuffer(rs.getString("question"));
o1=new StringBuffer(rs.getString("option1"));
o2=new StringBuffer(rs.getString("option2"));
o3=new StringBuffer(rs.getString("option3"));
System.out.println(q);
System.out.println(o1);
System.out.println(o2);
System.out.println(o3);
public void connect(){
try
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
con=DriverManager.getConnection("jdbc:odbc:ds","sa","server");
s=con.createStatement();
rs=s.executeQuery("select * from qa order by newid()");
getQuestion();
catch(Exception e)
System.out.println("erroe");
public void doPost(HttpServletRequest request,HttpServletResponse response)
throws IOException,ServletException
response.setContentType("text/html");
new test().connect();
PrintWriter out=response.getWriter();
request.setAttribute("question", q);
request.setAttribute("option1", o1);
request.setAttribute("option2", o2);
request.setAttribute("option3", o3);
//RequestDispatcher rd=getServletContext().getRequestDispatcher("/show.jsp");
//rd.forward(request, response);
out.println("<html>");
out.println("<head>");
out.println("<title>" + "shock!!!" + "</title>");
out.println("</head>");
out.println("<body>");
out.println("<h2>"+"Read twice before u answer"+"<h2>");
out.println("<p></p>");
//why the value of q is not getting printed, instead i get null
out.println("<h2>"+ q +"<h2>");
out.println("how is it");
out.println("</body>");
out.println("</html>");
Edited by: Mahesh_yeswecan on Nov 29, 2008 10:42 AMAs u said , i have done a silly mistake earlier. though i have corrected the code still i am getting the same null value
package servlet;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;
public class test extends HttpServlet {
Connection con;
ResultSet rs;
Statement s;
StringBuffer q;
StringBuffer o1;
StringBuffer o2;
StringBuffer o3;
public void getQuestion() throws Exception
if(rs.next())
q=new StringBuffer(rs.getString("question"));
o1=new StringBuffer(rs.getString("option1"));
o2=new StringBuffer(rs.getString("option2"));
o3=new StringBuffer(rs.getString("option3"));
System.out.println(q);
System.out.println(o1);
System.out.println(o2);
System.out.println(o3);
public void connect(){
try
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
con=DriverManager.getConnection("jdbc:odbc:ds","sa","server");
s=con.createStatement();
rs=s.executeQuery("select * from qa order by newid()");
getQuestion();
catch(Exception e)
System.out.println("erroe");
public void doPost(HttpServletRequest request,HttpServletResponse response)
throws IOException,ServletException
response.setContentType("text/html");
connect();
PrintWriter out=response.getWriter();
request.setAttribute("question", q);
request.setAttribute("option1", o1);
request.setAttribute("option2", o2);
request.setAttribute("option3", o3);
//RequestDispatcher rd=getServletContext().getRequestDispatcher("/show.jsp");
//rd.forward(request, response);
out.println("<html>");
out.println("<head>");
out.println("<title>" + "shock!!!" + "</title>");
out.println("</head>");
out.println("<body>");
out.println("<h2>"+"Read twice before u answer"+"<h2>");
out.println("<p></p>");
//why the value of q is not getting printed, instead i get null
out.println("<h2>"+ q +"<h2>");
out.println("how is it");
out.println("</body>");
out.println("</html>");
} -
System.out.println not showing up in the console
Hi,
I've some System.out.println statements in a static block in a Stateless
Session Bean. I could not see these outputs in the Weblogic console. I'm
using Weblogic 5.1 Any one faced this problem before? any help is
appreciated.
Thanks & Regards,
Nithi.Take a look in the weblogic log files they might be redirecting std out.
"Ryan LeCompte" <[email protected]> wrote:
>
Hello Nithi,
I'm all out of ideas, unfortunately! However, check out the following
links for
some possible insight into the problem:
http://groups.google.com/groups?q=System.out.println+5.1+WebLogic&start=60&hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=3d3df18e%40newsgroups.bea.com&rnum=69
http://groups.google.com/groups?q=System.out.println+5.1+WebLogic&start=70&hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=3977417b%40newsgroups.bea.com&rnum=71
http://groups.google.com/groups?q=System.out.println+5.1+WebLogic&start=200&hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=3bc20346%241%40newsgroups.bea.com&rnum=209
Best regards,
Ryan LeCompte
[email protected]
http://www.louisiana.edu/~rml7669
"Nithi Rajan" <[email protected]> wrote:
Hi Ryan,
Thanks for your reply and sorry for the long silence. I was on vocation.
Thre problem still remains.I'm very sure that the EJB
is deployed by WebLogic as I'm able to call some methods.
and I'm also calling EJB methods from Servlet. But my
System.out.println statments work fine in the Servlet and
not inside EJB (or anyother classes used by EJB).
Any one has faced similar problems? BTW am using WebLogic 5.1
Thanks in advance,
Regards,
Nithi.
"Ryan LeCompte" <[email protected]> wrote in message
news:[email protected]...
Hello Nithi,
I find it strange that your System.out.println statements are beingexecuted from
within your servlets, but not in your stateless session bean. Are
you
positive
that your EJB is being located and deployed by WebLogic? The statementsin
your
static { } block should be executed as soon as the WebLogic class
loader
finds
the class and loads it into the JVM. I would suggest examining theconsole
and
try to determine if your EJB is in fact being deployed. Are you invokingmethods
on the EJB inside of your servlets? Are you using any logging frameworkfrom within
the EJBs which would redirect output to a file?
Best regards,
Ryan LeCompte
[email protected]
http://www.louisiana.edu/~rml7669
"Nithi Rajan" <[email protected]> wrote:
Hi Ryan,
Thanks for your reply. The setting in the weblogic.properties is
as
follows.
weblogic.system.enableConsole=true
So, that tells me that I should see all the System.out.printlns right?
(Pleasecorrect me if I'm wrong). I can see all the System.out.println
from
my
servletand not from the Session Bean (even if the System.out.println
is
outside
static block).
Please let me know your thoughts.
Thanks & Regards,
Nithi.
"Ryan LeCompte" <[email protected]> wrote in message
news:[email protected]...
Hello Nithi,
Are you sure that you don't have WebLogic configured to redirect
all
messages
to a file instead of the console? Are you able to see yourSystem.out.println
statements when placed within other methods of your stateless sessionbean? Please
be a bit more specific.
Thank you,
Ryan LeCompte
[email protected]
http://www.louisiana.edu/~rml7669
"Nithi Rajan" <[email protected]> wrote:
Hi,
I've some System.out.println statements in a static block in a
Stateless
Session Bean. I could not see these outputs in the Weblogic console.
I'm
using Weblogic 5.1 Any one faced this problem before? any helpis
appreciated.
Thanks & Regards,
Nithi.
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