實現了全站的編碼過濾，並且實現了，get請求編碼過濾

public class EncodeFilter implements Filter {

    public void init(FilterConfig filterConfig) throws ServletException {
    }

    public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {
        //處理post方式的亂碼
 

        //request.setCharacterEncoding("utf-8");

        HttpServletRequest req = (HttpServletRequest) request;
        MyRequest myReq = new MyRequest(req);

        chain.doFilter(myReq, response);
    }

    public void destroy() {
    }

}
//裝飾者模式 實現自定義getParameter函式 實現當返回String的時候進行編碼
class MyRequest extends  HttpServletRequestWrapper
{
    ServletRequest r;
    private
 
 HttpServletRequest req;
     MyRequest(HttpServletRequest req)
    {
         super(req);    
         this.req = req;
    }

//  @Override
//  public String getParameter(String name) {
//      String value = req.getParameter(name);
//      try {
//          return new String(value.getBytes("ISO8859-1"),"utf-8");
 

//      } catch (UnsupportedEncodingException e) {
//          e.printStackTrace();
//      }
//      return null;
//  }

    @Override
    public String getParameter(String name) {
        Map<String,String[]> map = getParameterMap();
        return map.get(name)[0];

    }

    @Override
    public String[] getParameterValues(String name) {
        Map<String,String[]> map = getParameterMap();
        return map.get(name);
    }
//因為getParameterMap函式如果使用過一次，再使用的時候就又進行一次編碼，就是亂碼了。所以就定義flag令該函式只能使用一次
    boolean flag = true;
    @Override
    public Map<String,String[]> getParameterMap() {
        Map<String,String[]> map = req.getParameterMap();
        if(flag){
            for(Map.Entry<String, String[]> en:map.entrySet()){
                 String[] arr = en.getValue();
                 for(int i=0;i<arr.length;i++){
                     //陣列中的每個值都要再編碼再解碼處理
                     try {
                        arr[i] = new String(arr[i].getBytes("ISO8859-1"),"utf-8");
                    } catch (UnsupportedEncodingException e) {
                        e.printStackTrace();
                    }
                 }
            }
            flag = false;
        }
        return map;
    }