Encoding Filter实现

核心提示：public class CharacterEncodingFilter implements Filter { // - Instance Variables /** * The default character encoding to set for requests that pass through *

public class CharacterEncodingFilter 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;

　  /**
　　 * Should a character encoding specified by the client be ignored?
　　 */
　  protected boolean ignore = true;

　  // --------------------------------------------------------- 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 {

　  // 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);
　　　　　  }
　　　  }