过滤器

来源：互联网发布：寻侠猎空神龙突破数据编辑：程序博客网时间：2024/06/09 20:14

以下是servlet中的内容

package com.hzu.web;

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 {

// ----------------------------------------------------- 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);
  }

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

}

/**
* 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");
  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 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);

}
}

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以下是web.xml中的配置