javaWeb 字体替换过滤器

字体替换过滤器继承HttpServletRequestWrapper,重定义了: getParameter(),getParameterValues(),getParameterMap(),增强字节替换功能,满足更多的请求情况.

一: 字节替换过滤器:

 package cc.openhome.controler;

 import javax.servlet.*;
 import javax.servlet.annotation.WebFilter;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import java.io.IOException;

 @WebFilter("/*")
 public class HtmlFilter implements Filter {
     @Override
     public void init(FilterConfig filterConfig) throws ServletException {

     }

     @Override
     public void doFilter(ServletRequest sreq, ServletResponse sresp, FilterChain chain) throws IOException, ServletException {
         HttpServletRequest req = (HttpServletRequest) sreq;
         HttpServletResponse resp = (HttpServletResponse) sresp;
         MyHtmlRequest mreq = new MyHtmlRequest(req);
         chain.doFilter(mreq,resp);
     }
     @Override
     public void destroy() {

     }
 }

字节替换处理部分:

 package cc.openhome.controler;

 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletRequestWrapper;
 import java.util.*;

 public class MyHtmlRequest extends HttpServletRequestWrapper {

     private HttpServletRequest req;
     public MyHtmlRequest(HttpServletRequest req){

         super(req);
         this.req = req;
     }

     public String getParameter(String name){
         String value = getRequest().getParameter(name);
         if(value == null){
             return null;
         }
         return filter(value);
     }

     public String [] getParameterValues(String name){
         String [] values = getRequest().getParameterValues(name);
         String [] res = new String[values.length];
         if(values == null){
             return null;
         }
         for(int i = 0;i < values.length;i++){
             res[i] = filter(values[i]);
         }
         return res;

     }

     public Map<String,String[]> getParameterMap(){
         Map<String,String[]> values = getRequest().getParameterMap();
         Map<String,String[]> res = new HashMap<String, String[]>();
         List <String> listv= new ArrayList<String>();
         String [] arrv;
         for(Iterator<String> it = values.keySet().iterator();it.hasNext();){
             String k = it.next();
             String [] v = values.get(k);
             if(v == null || v.length == 0){
                 continue;
             }
             else {
                 for (int i = 0;i < v.length;i++){
                     listv.add(filter(v[i]));
                 }
                 arrv = new String[listv.size()];
                 arrv = listv.toArray(arrv);
             }
             res.put(k,arrv);
         }
         if(res == null){
             return null;
         }
         return res;
     }

     public String filter(String message){
         if(message == null){
             return null;
         }
         char content[] = new char[message.length()];
         message.getChars(0,message.length(),content,0);
         StringBuilder result = new StringBuilder(content.length + 50);
         for(int i = 0;i < content.length;i++){
             switch (content[i]){
                 case '<':
                     result.append("&lt;");
                     break;
                 case '>':
                     result.append("&gt;");
                     break;
                 case '&':
                     result.append("&amp;");
                     break;
                 case '"':
                     result.append("&quot");
                     break;
                 default:
                     result.append(content[i]);
             }
         }
         return result.toString();
     }
 }

对请求参数进行扩充,Filter方法处理请求到值.Filter方法可以扩充为功能更强大的方法.

二,总结:

(1).对getParameter(),getParameterValues(),getParameterMap(),方法有了更深入的理解.对于前端传入的复杂数据类型如checkbox数据,密码用户名等复杂数据类型处理

有了概念.

(2),首次使用List容器.