setcharacterencodingfilter.java

用struts,ajax实现的聊天室

package filter;

import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;


public class SetCharacterEncodingFilter
    implements Filter {


  protected String encoding = null;

  protected FilterConfig filterConfig = null;

  protected boolean ignore = true;

  public void destroy() {

    this.encoding = null;
    this.filterConfig = null;

  }

  public void doFilter(ServletRequest request, ServletResponse response,
                       FilterChain chain) throws IOException, ServletException {

    // Conditionally select and set the character encoding to be used
    if (ignore || (request.getCharacterEncoding() == null)) {
      String encoding = selectEncoding(request);
      if (encoding != null) {
        request.setCharacterEncoding(encoding);  
      }
    }

    // Pass control on to the next filter
    chain.doFilter(request, response);

  }

  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;
    }

  }

  protected String selectEncoding(ServletRequest request) {

    return (this.encoding);

  }

}