Html templates and servlets

this is probably one of the best site...

www.servletcentral.com

these article.. will interest u...
http://www.servletcentral.com/1998-12/designprocess.dchtml

http://www.servletcentral.com/1999-01/design.dchtml

check www.javasoft.com for some Java Server Pages (JSP) info

erm... so far the one of the better sites is the ibm tutorial.

could u guys show me  some working examples on how to insert specific file templates...

it's a long story ...
what's the exact problem ?

load template file - convert it to String, replace all the '%user%' strings with curent user name and write the result String to the Socket output stream.

well ok... long story.

Lets say i have a file containing a tags for an imagemap and the <img src> for the image... i'll call the file imagemap01.template.

so, how do i say insert this template into my document.

<%insert=imagemap01.template%>

or if i'm doing some formatting would it be

<table>
<tr>
<td> <%insert=imagemap01.template%> </td>
</tr>
<table>

you can load the whole file into a String, parse is yourself and replace all the tags. or you want some existing server application to handle it ?

loading the whole file into a string is a cool way to do it... atleast for a start...

some sample coding would be nice
i'll increase the points to 200 if its a working model!!! :)

mine for some reason didn't.. i got a blank file when it should have displayed
the text from the file...

ok I'm posting some old code .... I'll post some comments after it.


import java.io.*;
import java.util.*;
import testutor.backend.ServerConfig;


public class HTMLTemplateManager1
{
    private static String htmlTemplateFile = "template.html";
    public static final String TEMPLATE_MAINPAGE = "mainpage";
    public static final String TEMPLATE_LOGINPAGE = "loginpage";
    public static final String TEMPLATE_MAINERRORPAGE =  "mainerrorpage";

    public static String[] standardTemplates =
       {TEMPLATE_MAINPAGE, TEMPLATE_LOGINPAGE, TEMPLATE_MAINERRORPAGE};    

    public static Hashtable templates = new Hashtable();
    public static Hashtable lines = new Hashtable();
    public static Hashtable substs = new Hashtable();
               
    public static String getTemplate(String templateName)
    {
        String st = (String)templates.get(templateName);
        if (st != null)
            return st;
        else
            return "";
    }
   
    public static void init()
    {
        try {
           
            htmlTemplateFile = ServerConfig.getHtmlTemplateFile();
            loadTemplates();
//            printTemplates ();
            expandTemplates();
//            printTemplates ();
            checkForStandardTemplates();
            getStandardDefines();
        } catch (Exception e)
        {
            log("HTMLTemplateManager can't initialize. ", e);
            if (e instanceof RuntimeException)
                throw(RuntimeException)e;
            else
                throw new RuntimeException ("HTMLTemplateManager can't initialize: " + e.getMessage());
        }
       
    }
   
  public static void getStandardDefines() throws IOException
  {
    String defines = (String)templates.get("standarddefines");
    substs.put("%appleturltag:)%", ServerConfig.getAppletArchiveTag());
    substs.put("%redirecturl%", ServerConfig.getRedirectURL());    
   
    if (defines == null)
    {
      log("Warning:standarddefines section does on exist in templates file." );
      return;
    }
   
    BufferedReader br = new BufferedReader(new StringReader(defines));
    String st, st1;
    int n;
    while ((st = br.readLine()) != null)
    {
      st = st.trim();
      if (st.startsWith("<!--") && (n = st.indexOf("%define%")) != -1)
      {
        StringTokenizer tokens = new StringTokenizer (st.substring(n));
        tokens.nextToken(); // the %define%
        String key = tokens.nextToken();
        n = st.indexOf(key);
       
        st1 = st.substring(n + key.length());
        n = st1.indexOf("-->");
        st1 = st1.substring(0, n);
        substs.put(key, st1.trim());
      }
    }
  }
   
/*
    public static void initStandardSubstitutions()
    {
//        substs.put("%totalwidth%", "780");
        substs.put("%totalwidthright%", "650");
        substs.put("%totalwidthleft%", "130");
//        substs.put("%servleturl%", "/servlet/TestServlet15");
        substs.put("%bgcolor%", "#C0C0C0");
        substs.put("%bgcolorleft%", "#b0b0d0");
//        substs.put("%bgcolorleft%", "#a080d0");
        substs.put("%appleturltag:)%", ServerConfig.getAppletArchiveTag());
        substs.put("%redirecturl%", ServerConfig.getRedirectURL());
    }
*/    
    public static void setStandardSubstitution(String name, String val)
    {
        substs.put(name, val);
    }

    public static void setServletURL(String val)
    {
        substs.put("%servleturl%", val);
    }
/*
    public static void setAppletURL(String val)
    {
        substs.put("%servleturl%", val);
    }
  */  

    public static void printTemplates ()
    {
        log("printTemplates");
        String key, value;
        Enumeration e = templates.keys();
        while (e.hasMoreElements())
        {
            key = (String) e.nextElement();
            value = getTemplate(key);
            log("key = " + key + ", value = " + value);
         }
    }
    public static String reformatWithStandartSubstitutions(String orig)
    {
        String st = orig;
        String key, value;
        Enumeration e = substs.keys();
        while (e.hasMoreElements())
        {
            key = (String) e.nextElement();
            value = (String)substs.get(key);
            st = replaceAllStrings(st, key, value);
        }
        return st;
    }
   
    public static String replaceAllStrings(String orig, String from, String to)
    {
        int n;
        while ( (n = orig.indexOf(from)) != -1)
        {
            String t = "" + orig.substring(0, n) + to + orig.substring(n + from.length());
            orig = t;
        }
        return orig;
    }

/*
  exapnds all the include directives. throws Exception if it detects include cycle.
*/    
  private static void expandTemplates() throws IOException
  {
    String st;
    String key;
    boolean hasFound;
    do
    {
      hasFound = false;
      Enumeration e = templates.keys();
      while (e.hasMoreElements())
      {
        hasFound = false;
        key = (String) e.nextElement();
//        log("key = " + key);
        if (expandTemplate(key))
          hasFound = true;
      }
    } while (hasFound != false);
  }
 
  private static Hashtable expandHash = new Hashtable();
  private static void log(String s)
  {
    log(s, null);
  }
  private static void log(String s, Exception e)
  {
    System.out.println(" " + s);
    if (e != null) e.printStackTrace();
  }
  private static boolean expandTemplate(String templateName) throws IOException
  {
    String st;
    int n;
//    log("expanding " + templateName);
    String value = (String)templates.get(templateName);
   
    if (value == null || value.indexOf("%include%") == -1) return false;
    if (expandHash.get(templateName) != null)
      throw new RuntimeException("Cyclic include detected while expanding template " + templateName);
    expandHash.put(templateName, "hi");
   
    StringBuffer buf = new StringBuffer();  
    BufferedReader br = new BufferedReader(new StringReader(value));
//    log("reading lines ...");
    while ((st = br.readLine()) != null)
    {
      String st1 = st.trim();
      if (st1.length() == 0) continue;
      if (st1.startsWith("<!--"))
      {
        if ((n = st1.indexOf("%include%")) != -1)
        {
//          log("%include% detected");
          StringTokenizer tokens = new StringTokenizer (st1.substring(n));
          tokens.nextToken(); // the %include%
          String subTemplate = tokens.nextToken();
          if (!"-->".equals(tokens.nextToken()))
              throw(new RuntimeException ("Bad include directive in template " + templateName));
         
          expandTemplate(subTemplate);
          st = (String)templates.get(subTemplate);
          if (st == null)
              throw(new RuntimeException ("Can't expand include directive in template " + templateName + " - subTemplate " + subTemplate + " does not exists."));
        }
        else if ((n = st1.indexOf("%define%")) != -1)
        {
         
        }
        else
          continue; // clear all the comments
      }
      if (buf.length() != 0) buf.append("\r\n");
      buf.append(st);
    }
    templates.put(templateName, buf.toString());
    expandHash.remove(templateName);
    return true;
  }
/*
  loads a bunch of tempalte definitions from a file
*/    
    private static void loadTemplates() throws IOException
    {
        String curSectionName = null;        
        StringBuffer curTemplate = new StringBuffer();
   
        BufferedReader br = new BufferedReader (new FileReader(htmlTemplateFile));
        String st;
        int n;
        int line = 0;
                   
        while ((st = br.readLine()) != null)
        {
           line++;
           String st1 = st.trim();
           if (st1.startsWith("<!--") && ((n = st1.indexOf("%section%")) != -1))
           {
  //           log(" " + line + ": " + st1);
                // section tag found !!
                if (curSectionName != null)
                {
                  if (templates.get(curSectionName) != null)
                    log("loadTemplates Warning: section already exists: " + curSectionName);
                  else
                    templates.put(curSectionName, curTemplate.toString());
                }
                curTemplate = new StringBuffer();
               
                StringTokenizer tokens = new StringTokenizer (st1.substring(n));
                tokens.nextToken();
                if (!tokens.hasMoreTokens())
                    throw(new RuntimeException ("Invalid template file format at line " + line));
                curSectionName = tokens.nextToken();
                lines.put(curSectionName, new Integer(line));
           }
           else
           {
               curTemplate.append("\r\n");
               curTemplate.append(st);
           }
        }
       
        if (curSectionName != null)
        {
          if (templates.get(curSectionName) != null)
            log("loadTemplates Warning: section already exists: " + curSectionName);
          else
            templates.put(curSectionName, curTemplate.toString());
        }
       
        br.close();
    }
 
 /*
   checks if several standard tempaltes are loaded.
   throws Exception if some standard template is not loaded
 */
     public static void checkForStandardTemplates()
    {
        int n = standardTemplates.length;
        for (int i = 0; i < n; i++)
        {
            if (templates.get(standardTemplates[i]) == null)
            {
                throw new RuntimeException ("HTMLTemplateManager can't fine template [" + i +
                    "]: " + standardTemplates[i]);
                   
            }
        }
    }
       
    public static String getMainPage()
    {
        return getTemplate(TEMPLATE_MAINPAGE);
    }    
    public static String getLoginPage()
    {
        return getTemplate(TEMPLATE_LOGINPAGE);
    }    
    public static String getMainErrorPage()
    {
        return getTemplate(TEMPLATE_MAINERRORPAGE);
    }
   

}

you won't be able to compile the class directly, because you don't have the ServerConfig file
(this is a simple configuration object)
 
Hashtable templates is the hashtable with the template names + tamplate bodies
Hashtable lines is helper Hashtable - template name + start line (so that you can print nice erro messages)
Hashtable substs contains the substitutions the substitution

loadTemplates() loads the template definitons from a file
expandTemplates() expands the %include% directives
checkForStandardTemplates() checks if some standard templates are loaded
getStandardDefines() loads some substitutions from a template named standarddefines
 
setStandardSubstitution() adds another substitution
reformatWithStandartSubstitutions(String orig)replaces all the substitutions inside some string (template)
replaceAllStrings(...) replaces some substitution (ugly implementation - you can use String.replace() instead)

 
a sample template file
 
<!--- %section% standarddefines -->
    <!--- %define% %totalwidthleft% 130 -->
    <!--- %define% %totalwidthright% 650 -->
    <!--- %define% %bgcolor% #C0C0C0 -->
    <!--- %define% %bgcolorleft% #b0b0d0 -->    
    <!--- %define% %bgcolor2% #eeeeff -->

    <!--- %define % %bgcolor% #a0a0a0 -->
    <!--- %define % %bgcolorleft% #d0b0c0 -->    
<!--- defines end -->

<!--- %section% mainpage -->
    <!--- %include% commonheader -->
    <!--- %include% mainleftmenu -->
    <!--- %include% mainsubpage -->
    <!--- %include% commonfooter -->
<!--- mainpage end -->
 
<!--- %section% commonheader -->
    <html>
    <head>
        <title>Testutor - %title% </title>
    </head>
   
    <!--- start of header --->
    <body bgcolor="%bgcolor%" text="#000000" topmargin=0 leftmargin=0>
        <table  cellpadding=16 cellspacing=1 border=0>
            <tr valign=top>
                <td width=%totalwidthleft% height=30 valign=bottom align=center> <font size=5 color="#ff0000">La-La</font> </td>
                <td height=30 align=center valign=bottom bgcolor="#000000"> <font size=5 color="#f0f0f0">  &nbsp; %header% </font> </td>
            </tr>
    <!--- end of header --->        
   
    <tr valign=top>
<!--- commonheader end -->
 
   
and so on ...
 
the code is ugly and uncompilable (it's part of some old project), but maybe, you'll find some interesting solutions
  (or some 'ugly' pieces of code ...), but ...
   
if you need more help, you'd better post your code (or send it directly to heyhey_iname.com)
 
best regards
  heyhey

well... i'll take it anyway, after a while
i've worked with using Beans to incorporate to actually compartmentalize
the different components... but ur ideas provided some start...

thanks anyway.

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