Why does POST not honor charset, but an AJAX request does? tomcat 6

Question

I have a tomcat based application that needs to submit a form capable of handling utf-8 characters. When submitted via ajax, the data is returned correctly from getParameter

Answer 1

form post (outputs chars in iso)

You don't need to specify the charset there. The browser will use the charset which is specified in HTTP response header.

Just

is enough.

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xml declaration:

Irrelevant. It's only relevant for XML parsers. Webbrowsers doesn't parse text/html as XML. This is only relevant for the server side (if you're using a XML based view technology like Facelets or JSPX, on plain JSP this is superfluous).

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Doctype:

Irrelevant. It's only relevant for HTML parsers. Besides, it doesn't specify any charset. Instead, the one in the HTTP response header will be used. If you aren't using a XML based view technology like Facelets or JSPX, this can be as good .

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meta tag:

Irrelevant. It's only relevant when the HTML page is been viewed from local disk or is to be parsed locally. Instead, the one in the HTTP response header will be used.

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jvm parameters:

-Dfile.encoding=UTF-8

Irrelevant. It's only relevant to Sun/Oracle(!) JVM to parse the source files.

---

I have also tried using request.setCharacterEncoding("UTF-8"); but it seems as if tomcat simply ignores it. I am not using the RequestDumper valve.

This will only work when the request body is not been parsed yet (i.e. you haven't called getParameter() and so on beforehand). You need to call this as early as possible. A Filter is a perfect place for this. Otherwise it will be ignored.

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From what I've read, POST data encoding is mostly dependent on the page encoding where the form is. As far as I can tell, my page is correctly encoded in utf-8.

It's dependent on the HTTP response header.

All you need to do are the following three things:

1. Add the following to top of your JSP:

   <%@page pageEncoding="UTF-8" %>
   

   This will set the response encoding to UTF-8 and set the response header to UTF-8.

2. Create a Filter which does the following in doFilter() method:

   if (request.getCharacterEncoding() == null) {
       request.setCharacterEncoding("UTF-8");
   }
   chain.doFilter(request, response);
   

   This will make that the POST request body will be processed as UTF-8.

3. Change the entry in Tomcat/conf/server.xml as follows:

   This will make that the GET query strings will be processed as UTF-8.

See also:

• Unicode - How to get characters right? - contains practical background information and detailed solutions for Java EE web developers.