setcharacterencodingfilter.java

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/*
 * SetCharacterEncoding.java
 *
 * Created on February 5, 2002, 5:44 PM
 */

package com.sun.j2ee.workflow.control.filters;




import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

import javax.servlet.UnavailableException;


/** Example filter that unconditionally sets the character encoding to be used
 * in parsing the incoming request to a value specified by the
 * <strong>encoding</string> filter initialization parameter in the web app
 * deployment descriptor (</code>/WEB-INF/web.xml</code>).  This filter could
 * easily be extended to be more intelligent about what character encoding to
 * set, based on characteristics of the incoming request (such as the values
 * of the <code>Accept-Language</code> and <code>User-Agent</code> headers,
 * or a value stashed in the current user's session).
 *
 * @author Craig McClanahan, Jian Cai
 * @version $Revision: 1.2 $ $Date: 2002/10/03 23:29:45 $
 */
//modified by James Cai

public class SetCharacterEncodingFilter implements Filter {
    
    // ----------------------------------------------------- Instance Variables
    
    
    /**
     * The default character encoding to set for requests that pass through
     * this filter.
     */
    protected String encoding = null;
    
    
    /**
     * The filter configuration object we are associated with.  If this value
     * is null, this filter instance is not currently configured.
     */
    protected FilterConfig filterConfig = null;
    
    
    // --------------------------------------------------------- Public Methods
    
    
    /**
     * Take this filter out of service.
     */
    public void destroy() {
        
        this.encoding = null;
        this.filterConfig = null;
        
    }
    
    
    /**
     * Select and set (if specified) the character encoding to be used to
     * interpret request parameters for this request.
     *
     * @param request The servlet request we are processing
     * @param result The servlet response we are creating
     * @param chain The filter chain we are processing
     *
     * @exception IOException if an input/output error occurs
     * @exception ServletException if a servlet error occurs
     */
    public void doFilter(ServletRequest request, ServletResponse response,
    FilterChain chain)
    throws IOException, ServletException {
        
        // Select and set (if needed) the character encoding to be used
        HttpServletRequest httprequest = (HttpServletRequest)request;
        String encoding = null;
        HttpSession session = httprequest.getSession();
        String language = (String)session.getAttribute("tplanguage");
        System.out.println("SetCharacterEncoding: language=" + language);
        
        if ((language==null)&&(request.getParameter("language")!=null)) {
            session.setAttribute("tplanguage", request.getParameter("language"));
        }
        
        if ((language!=null)&&(language.equals("Chinese"))) {
            encoding = "gb2312";
        }
        
        if (encoding != null)
            request.setCharacterEncoding(encoding);
        // Pass control on to the next filter locale
        chain.doFilter(request, response);
        if ((language!=null)&&(language.equals("Chinese"))) {
            response.setContentType("text/html;charset=gb2312");
        }
        
        
    }
    
    
    /**
     * Place this filter into service.
     *
     * @param filterConfig The filter configuration object
     */
    public void init(FilterConfig filterConfig) throws ServletException {
        
        this.filterConfig = filterConfig;
        this.encoding = filterConfig.getInitParameter("encoding");
        
    }
    
    
    // ------------------------------------------------------ Protected Methods
    
    
    /**
     * Select an appropriate character encoding to be used, based on the
     * characteristics of the current request and/or filter initialization
     * parameters.  If no character encoding should be set, return
     * <code>null</code>.
     * <p>
     * The default implementation unconditionally returns the value configured
     * by the <strong>encoding</strong> initialization parameter for this
     * filter.
     *
     * @param request The servlet request we are processing
     */
    protected String selectEncoding(ServletRequest request) {
        
        return (this.encoding);
        
    }
    
    
}