setcharacterencodingfilter.java

Java Web开发详解.书中例子的源代码(JSPlesson)

package org.sunxin.lesson.jsp.ch21;

import java.io.IOException;
import javax.servlet.*;

public class SetCharacterEncodingFilter implements Filter
{
    protected String encoding = null;
    protected FilterConfig filterConfig = null;
    protected boolean ignore = true;
    
    public void init(FilterConfig filterConfig) throws ServletException
    {
        this.filterConfig = filterConfig;
        this.encoding = filterConfig.getInitParameter("encoding");
        String value = filterConfig.getInitParameter("ignore");
        
        if (value == null)
            this.ignore = true;
        else if (value.equalsIgnoreCase("true"))
            this.ignore = true;
        else if (value.equalsIgnoreCase("yes"))
            this.ignore = true;
        else
            this.ignore = false;
    }
    
    public void doFilter(ServletRequest request,
                         ServletResponse response,
                         FilterChain chain)
                  throws IOException, ServletException
    {
        if (ignore || (request.getCharacterEncoding() == null))
        {
            String encoding = selectEncoding(request);
            if (encoding != null)
                request.setCharacterEncoding(encoding);
        }
        response.setContentType("text/html; charset="+encoding);
        chain.doFilter(request, response);
    }
    
    protected String selectEncoding(ServletRequest request)
    {
        return (this.encoding);
    }
    
    public void destroy()
    {
        this.encoding = null;
        this.filterConfig = null;
    }
}