public class GenericalEncodingFilter extends HttpServletRequestWrapper{
//定義改變後的請求
private HttpServletRequest request;
public GenericalEncodingFilter(HttpServletRequest request) {
super(request);//呼叫父類的構造方法
this.request = request;

}

//增強request的getParamter方法；
@Override
public String getParameter(String name){
    //根據請求方法的不同去處理
    //獲得請求方式
    String method = request.getMethod();
    String value=null;
    if("post".equalsIgnoreCase(method)){
        try {
            request.setCharacterEncoding("UTF-8");
        } catch (UnsupportedEncodingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return super.getParameter(name);
    }else if ("get".equalsIgnoreCase(method)) {

        try {
             value= new String(request.getParameter(name).getBytes("utf-8"),"utf-8");
        } catch (UnsupportedEncodingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    return value;
}
 

}
使用裝飾者模式增強request的getParamter()方法

注意：使用裝飾者模式的前提：【1、被增強的類和增強的類實現相同的介面，2、在增強的類中獲得被增強的類的引用】