Struts2 get 传值乱码过滤器配置

package cn.org.du.Encode;

import java.io.IOException;
import java.util.Map;
import java.util.Set;

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.HttpServletResponse;

public class EncodeFilter implements Filter {

private FilterConfig filterConfig = null;

public void destroy() {
this.filterConfig = null;
}

@SuppressWarnings("unchecked")
public void doFilter(ServletRequest req, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
String encoding = this.filterConfig.getInitParameter("encoding");

HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse resp = (HttpServletResponse) response;
request.setCharacterEncoding(encoding);
resp.setContentType("text/html;charset="+encoding);
// System.out.println(request.getQueryString());
// 处理GET参数
if (request.getMethod().equalsIgnoreCase("get")) {
Map paramMap = req.getParameterMap();
String[] queryStringArray = { "" };
if (request.getQueryString() != null) {
queryStringArray = request.getQueryString().split("&");
}
for (int i = 0; i < queryStringArray.length; i++) {
queryStringArray[i] = queryStringArray[i].replaceAll("(.*)=(.*)", "$1");
}
Set<String> keySet = paramMap.keySet();
for (String key : keySet) {
// check where param from
boolean isFromGet = false;
for (String paramFromGet : queryStringArray) {
if (key.equals(paramFromGet)) {
isFromGet = true;
}
}
if (!isFromGet) {
continue;
}
String[] paramArray = (String[]) paramMap.get(key);
for (int i = 0; i < paramArray.length; i++) {
paramArray[i] = new String(paramArray[i].getBytes("iso-8859-1"), encoding);
}
}
}
chain.doFilter(req, resp);
}

public void init(FilterConfig filterConfig) throws ServletException {
this.filterConfig = filterConfig;
}
}

-----------------web.xml配置---------------------

<filter>
<filter-name>encodeFilter</filter-name>
<filter-class>cn.org.du.Encode.EncodeFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>utf-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>encodeFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>