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From "Craig R. McClanahan" <Craig.McClana...@eng.sun.com>
Subject Re: About jsp:include
Date Wed, 29 Nov 2000 06:38:43 GMT
Kazuhiro Kazama wrote:

> I have a question about jsp:include's specification & implementation.
>
> JSP 1.1 specification says "Content is not parsed; it is included in
> place." in "2.7.5 Including Data in JSP Pages".
>
> But current Tomcat 3.2b8 implementation convert its contents from Java
> VM's native character encoding to the specified charset in the case
> that charset is specified in content-type header.
>
> Is this behavior right? I think that a character set conversion is a
> kind of parsing and it may produce errors.
>
> By my guess, a "jsp:include" action calls include method of
> RequestDispatcher class, and it probably calls StaticIntercepter class
> finally.
>
> And StaticIntercepter create Reader according to Java VM's native
> character encoding.
>
>             if( res.isUsingWriter() ) {
>                 InputStreamReader r = new InputStreamReader(in);
>                 PrintWriter out=res.getWriter();
>
> Therefore, conversion error is occured when output charset isn't the
> same as Java VM's native character encoding.
>
> In Japan, it is a general case to use many character encodings
> (ISO-8859-1, ISO-2022-JP, Shift_JIS etc.).
>
> cf.
> InputStreamReader(in)
>   = InputStreamReader(in, ByteToCharConverter.getDefault())
>
> For example, the following is a simple JSP program that switch HTML
> files according to browser's accept-language header such as apache's
> Multiviews directive. A japanese HTML file's charset is euc-jp.
>
> This program works well on Solaris 2 (Java VM's native character
> encoding is euc-jp), but don't work on Windows (Java VM's native
> character encoding is MS932) because conversion error is occured.
>
> <%@ page import="java.util.Locale" %>
> <%
>         String language = "en";
>         String file = "index.html";
>         Locale locale = request.getLocale();
>         if (locale != null) {
>             language = locale.getLanguage();
>         }
>         if (language.equalsIgnoreCase("ja")) {
>             response.setContentType("text/html; charset=euc-jp");
>             file += ".ja";
>         } else {
>             response.setContentType("text/html");
>         }
> %>
> <jsp:include page="<%= file %>" flush="true"/>
>

Kazuhiro,

The specification also says that you should be setting the character encoding of
the response (in the including page) with the <%@ page %> directive.  Could you
try using the following approach, instead of what you tried above:

    <%@ page contentType="text;html" %>
    <jsp:include page="index.html" flush="true" />

or

    <%@ page contentType="text;html; charset=euc-jp" %>
    <jsp:include page="index.html.ja" flush="true" />

and see if you still have the problem.

I understand that you would prefer the flexibility to set the character encoding
of the response dynamically.  However, such behavior is not currently supported
in the JSP specification, and changing the content type at runtime (as you are
doing in your example above) is not going to work, because the JSP page compiler
is going to assume you always want the platform default character encoding
(since there was no declared character encoding at compile time).

>
> Kazuhiro Kazama (kazama@ingrid.org)     NTT Network Innovation Laboratories

Craig McClanahan



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