001// Copyright (c) 2001 Hursh Jain (http://www.mollypages.org) 002// The Molly framework is freely distributable under the terms of an 003// MIT-style license. For details, see the molly pages web site at: 004// http://www.mollypages.org/. Use, modify, have fun ! 005 006package fc.web.page; 007 008import java.io.*; 009import java.util.*; 010 011import javax.servlet.*; 012import javax.servlet.http.*; 013 014/** 015A page is a cool and sane replacement for JSP's with much better syntax. 016<p> 017Server side pages implement this interface via the concrete {@link PageImpl} 018class. This class has some additional utility methods as well that page 019authors may find useful. 020 021@author hursh jain 022*/ 023public interface Page 024{ 025//all pages result in java files with this package name; 026public static String PACKAGE_NAME = "molly.pages"; 027 028//not used: public static String DEFAULT_ERROR_PAGE = "/molly/error.mp"; 029public static int DEFAULT_BUFFER_SIZE = 8048; 030 031/** 032The default mime-type for each page. Usually, there should be no reason 033to change this. However, if need be, this can be changed via a page 034compiler directive or turned off entirely. If it's turned off, then the 035mime-type should be manually specified via the {@link 036javax.servlet.ServletResponse.setContentType} method. 037*/ 038public static String DEFAULT_MIME_TYPE = "text/html"; 039 040/** 041The default encoding of the page, specified in the header sent back to 042the client. This can be changed to utf-8, utf-16 or any other coding by 043a page directive. Alternately, this can be set to an empty string and a 044different encoding can also be specified in the <head> section of 045the html document, for example: 046<pre> 047<head><meta http-equiv=content-type content='text/html; charset=UTF-8'></head> 048</pre> 049<font color=red>Encodings can be tricky. We are first compiling 050a page into a java source file, then running the source file and 051sending it's output to the browser. <b>Read the page 052<a href="http://www.mollypages.org/page/charset.mp">encoding 053and charsets</a> if you are using any non-us-ascii or non- 054ISO-8859-1</b> characters in your molly source page.</font> 055*/ 056public static String DEFAULT_ENCODING = "ISO-8859-1"; 057 058public void render(HttpServletRequest req, HttpServletResponse res) throws Exception; 059 060/** 061This method is invoked whenever a page is created and before it 062is run. 063<p> 064Pages should override this method to instantiate/set-up page 065variables as needed. (pages have no-arg constructors so like 066most of the servlet API, setup and initialization of variables 067is done in a init method instead). 068<p> 069When overriding this class, you must remember to 070call: <tt>super.init</tt> 071<p> 072The page class is reloaded if the page is modified. Variables 073should therefore be cleaned up in the {@link destory} method 074as needed. 075*/ 076public void init(PageServlet servlet, String contextRelativePagePath) throws ServletException; 077 078/** 079This method is invoked whenever a page is destoryed/unloaded 080*/ 081public void destroy(); 082 083/** 084Returns the path to this page from the web servers <i>document root</i>. 085<p>So for example, if the page is at <code>foo/bar.mp</code> and is running 086under the webapp context of <code>context1</code>, then the page path 087will be: <code>/context1/foo/bar.mp</code>. If there is no specific 088web app (i.e., the most common case of a default "" webapp), then the page 089path will be <code>/foo/bar.mp</code> 090<p> 091This page path is essentially what needs to be typed in the browsers 092URL window to invoke the page. It's also useful as form action parameters. 093For example, in a molly page: 094<blockquote> 095<pre> 096.. 097<form action="[=getPagePath(req)]" method="post"> 098.. 099</form> 100</pre> 101</blockquote> 102This will submit the form to the same page where the form is defined. This 103can be hard coded of course but by using <code>getPagePath</code>, the html 104does not have to be changed if the name of the page changes on disk. 105*/ 106public String getPagePath(HttpServletRequest req); 107 108/** 109Returns the real absolute directory path for the {@link #getPagePath PagePath}. 110<p> 111So, for example, for a webserver document root at 112<code>/web/sites/default/</code> and a page located in 113<code>foo/bar.mp</code>, the real path will be: 114<code>/web/sites/default/foo/bar.mp</code> 115*/ 116public String getRealPath(HttpServletRequest req); 117 118/** 119Redirects the client to the new page location. This is a thin (possibly 120easier to remember) wrapper around the {@link HttpServletResponse.sendRedirect} method. 121<p> 122The location parameter can be relative to the specified request's URI or 123relative to the context root if it contains a leading '/'. The webapp name 124(if any) does <b>not</b> have to be specified, the redirect will creates a 125full URL <u>(including the webapp context path)</u> suitable for this 126purpose. 127<p> 128For example: 129<style> 130#redirects {background: #cccccc; } 131#redirects tr {background: white; } 132#redirects .head {font-weight: bold; } 133</style> 134<table id=redirects border=0 cellspacing=1 cellpadding=7> 135<tr class=head> 136 <td width="25%">webapp context</td> 137 <td width="25%">current page</td> 138 <td width="25%">location parameter</td> 139 <td width="25%">resulting page</td> 140</tr> 141<tr> 142 <td>default web app ("/")</td> 143 <td>foo/bar.mp</td> 144 <td>baz.mp</td> 145 <td>foo/baz.mp</td> 146</tr> 147<tr> 148 <td>default web app ("/")</td> 149 <td>foo/bar.mp</td> 150 <td>/baz.mp</td> 151 <td>baz.mp</td> 152</tr> 153<tr> 154 <td>/myapp</td> 155 <td>foo/bar.mp</td> 156 <td>baz.mp</td> 157 <td>/myapp/foo/baz.mp</td> 158</tr> 159<tr> 160 <td>/myapp</td> 161 <td>foo/bar.mp</td> 162 <td>/baz.mp</td> 163 <td>/myapp/baz.mp</td> 164</tr> 165</table> 166 167@param req the current request 168@param res the current response 169@param location location to redirect to. 170*/ 171public void clientRedirect(HttpServletRequest req, HttpServletResponse res, String newLocation) throws IOException; 172 173/** 174Returns a thread specific CharArrayWriter that can be passed to this method 175as various points in the page. The contents of this writer can then be 176printed on the page when desired. 177<p> 178Note: The writer is <b>not</b> reset or flushed when it is retrieved. It 179must be <font color=blue>reset manually</font> via calling the {@link 180java.io.CharArrayWriter#reset} method. This design-decision allows request 181threads to collect debugging data across multiple pages. 182<p> 183The suggested usage idiom is: 184<blockquote> 185<pre> 186 dbg(true); 187 CharArrayWriter <font color=blue>cw</font> = getThreadLocalWriter(): 188 bug(<font color=blue>cw</font>, "some message"); 189 ... 190 bug(<font color=blue>cw</font>, "other message"); 191 ... 192 <font color=blue> 193 cw.writeTo(out); 194 cw.reset(); 195 </font> 196</pre> 197</blockquote> 198*/ 199public CharArrayWriter getThreadLocalWriter(); 200 201/* 202These are in PageImpl but do they need to be in the Page interface as well ? 203Subject to change so prolly not, thus commented out. hj 204 205public void startTimer(); 206public long getTime(); 207public void dbg(boolean val); 208public void dbgPrefix(String dbg_prefix); 209public void dbgSuffix(String dbg_suffix); 210public void bug(final Writer writer, final Object str1) throws IOException; 211public void bug(final Writer writer, final Object str1, final Object str2) throws IOException; 212public void bug(final Writer writer, final Object str1, final Object str2, final Object str3) throws IOException; 213public void bug(final Writer writer, final Object str1, final Object str2, final Object str3, final Object... args) throws IOException; 214*/ 215}