Question

It feels like I’m stuck.
I’m trying to write the simplest servlet Filter (and deploy it to tomcat). It’s a groovy code, but actually I’m heavily using java approaches here, so it is almost copy-paste, that’s the reason I’ve added java tag as well.

My question is – how can I insert UTF-8 string to filter?
Here is the code:

public class SimpleFilter implements javax.servlet.Filter

{
    ...
    public void doFilter(ServletRequest request, ServletResponse response,
           FilterChain chain) 
           throws java.io.IOException, javax.servlet.ServletException
    {   
            PrintWriter out = response.getWriter()
            chain.doFilter(request, wrapResponse((HttpServletResponse) response))

            response.setCharacterEncoding('UTF-8')
            response.setContentType('text/plain')

            def saw = 'АБВГДЕЙКА ЭТО НЕПРОСТАЯ ПЕРЕДАЧА ABCDEFGHIJKLMNOP!!!'
            def bytes = saw.getBytes('UTF-8')
            def content = new String(bytes, 'UTF-8')

            response.setContentLength(content.length())
            out.write(content);
            out.close();
    }   

    private static HttpServletResponse  wrapResponse(HttpServletResponse response) {
        return new HttpServletResponseWrapper(response) {
            @Override
            public PrintWriter getWriter() {
                 def writer  = new OutputStreamWriter(new ByteArrayOutputStream(), 'UTF-8')
                 return new PrintWriter(writer)
            }   
        }   
    }   
}

Content-Type of the filtered page is text/plain;charset=ISO-8859-1.
So, content type have changed, but charset is ignored.

As you can see, I’ve take some measures (I guess quite naive) to make sure content is UTF-8, but none of these steps actually was helpful.

I’ve also tried to add URIEncoding="UTF-8" or useBodyEncodingForUri="true" attributes to
Connector in tomcat conf/server.xml

It would be nice if somebody explained me what I’m doing wrong.

UPD: just a bit of explanation – I’m writing XSLT-applying filter, that is the real reason I’m trying to discard whole request.

Answer 1

def saw = 'АБВГДЕЙКА ЭТО НЕПРОСТАЯ ПЕРЕДАЧА ABCDEFGHIJKLMNOP!!!'
def bytes = saw.getBytes('UTF-8')
def content = new String(bytes, 'UTF-8')

Does not change a thing between saw and content. What you want is to do (using the outputstream and not the writer, this is why the charset is reset to ISO-8859-1 See tomcat doc):

out.write(saw.getBytes("UTF-8);

Your code looks okay to set the charset as UTF-8.

I don’t understand what you are doing with HttpResponseWrapper.

To make it clear, this will work:

public void doFilter(ServletRequest request, ServletResponse response,
   FilterChain chain) 
   throws java.io.IOException, javax.servlet.ServletException
{   
    OutputStream out = response.getOutputStream()

    response.setCharacterEncoding('UTF-8')
    response.setContentType('text/plain')

    def saw = 'АБВГДЕЙКА ЭТО НЕПРОСТАЯ ПЕРЕДАЧА ABCDEFGHIJKLMNOP!!!'

    response.setContentLength(saw.length())
    out.write(content.getBytes("UTF-8"));

}