package com.pdsu.filter;

import java.io.IOException;
import java.io.UnsupportedEncodingException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;

/**
 * 類說明：字元過濾器
 * 
 * @author 作者: LiuJunGuang
 * @version 建立時間：2011-11-18 下午07:05:51
 */
public class CharacterEncodingFilter implements Filter {
	private String encode = "UTF-8";// 預設UTF-8編碼

	public void init(FilterConfig filterConfig) throws ServletException {
		String encoding = filterConfig.getInitParameter("encode");
		if (encoding != null) {
			encode = encoding;
		}
	}

	public void doFilter(ServletRequest req, ServletResponse resp,
			FilterChain chain) throws IOException, ServletException {
		HttpServletRequest request = (HttpServletRequest) req;
		HttpServletResponse response = (HttpServletResponse) resp;
		// 設定request編碼
		request.setCharacterEncoding(encode);
		// 設定相應資訊
		response.setContentType("text/html;charset=" + encode);
		response.setCharacterEncoding(encode);
		chain.doFilter(new CharacterEncodingRequest(request), response);
	}

	public void destroy() {

	}

}

/**
 * 對Get方式傳遞的請求引數進行編碼
 */
class CharacterEncodingRequest extends HttpServletRequestWrapper {
	private HttpServletRequest request = null;

	public CharacterEncodingRequest(HttpServletRequest request) {
		super(request);
		this.request = request;
	}

	/**
	 * 對引數重新編碼
	 */
	@Override
	public String getParameter(String name) {
		String value = super.getParameter(name);
         if(value == null)
               return null;
         String method = request.getMethod();
		if ("get".equalsIgnoreCase(method)) {
			try {
				value = new String(value.getBytes("ISO8859-1"),
						request.getCharacterEncoding());
			} catch (UnsupportedEncodingException e) {
				e.printStackTrace();
			}
		}
		return value;
	}

}
 

在web.xml中新增如下內容：

<filter>
  	<filter-name>characterEncodingFilter</filter-name>
  	<filter-class>com.pdsu.filter.CharacterEncodingFilter</filter-class>
  	<init-param>
  		<param-name>encode</param-name>
  		<param-value>UTF-8</param-value>
  	</init-param>
  </filter>
  <filter-mapping>
  	<filter-name>characterEncodingFilter</filter-name>
  	<url-pattern>/*</url-pattern>
  </filter-mapping>