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:

 1 package cc.openhome.controler;
 2 
 3 import javax.servlet.*;
 4 import javax.servlet.annotation.WebFilter;
 5 import javax.servlet.http.HttpServletRequest;
 6 import javax.servlet.http.HttpServletResponse;
 7 import java.io.IOException;
 8 
 9 @WebFilter("/*")
10 public class HtmlFilter implements Filter {
11     @Override
12     public void init(FilterConfig filterConfig) throws ServletException {
13 
14     }
15 
16     @Override
17     public void doFilter(ServletRequest sreq, ServletResponse sresp, FilterChain chain) throws IOException, ServletException {
18         HttpServletRequest req = (HttpServletRequest) sreq;
19         HttpServletResponse resp = (HttpServletResponse) sresp;
20         MyHtmlRequest mreq = new MyHtmlRequest(req);
21         chain.doFilter(mreq,resp);
22     }
23     @Override
24     public void destroy() {
25 
26     }
27 }

字节替换处理部分:

 1 package cc.openhome.controler;
 2 
 3 import javax.servlet.http.HttpServletRequest;
 4 import javax.servlet.http.HttpServletRequestWrapper;
 5 import java.util.*;
 6 
 7 public class MyHtmlRequest extends HttpServletRequestWrapper {
 8 
 9     private HttpServletRequest req;
10     public MyHtmlRequest(HttpServletRequest req){
11 
12         super(req);
13         this.req = req;
14     }
15 
16     public String getParameter(String name){
17         String value = getRequest().getParameter(name);
18         if(value == null){
19             return null;
20         }
21         return filter(value);
22     }
23 
24     public String [] getParameterValues(String name){
25         String [] values = getRequest().getParameterValues(name);
26         String [] res = new String[values.length];
27         if(values == null){
28             return null;
29         }
30         for(int i = 0;i < values.length;i++){
31             res[i] = filter(values[i]);
32         }
33         return res;
34 
35     }
36 
37     public Map<String,String[]> getParameterMap(){
38         Map<String,String[]> values = getRequest().getParameterMap();
39         Map<String,String[]> res = new HashMap<String, String[]>();
40         List <String> listv= new ArrayList<String>();
41         String [] arrv;
42         for(Iterator<String> it = values.keySet().iterator();it.hasNext();){
43             String k = it.next();
44             String [] v = values.get(k);
45             if(v == null || v.length == 0){
46                 continue;
47             }
48             else {
49                 for (int i = 0;i < v.length;i++){
50                     listv.add(filter(v[i]));
51                 }
52                 arrv = new String[listv.size()];
53                 arrv = listv.toArray(arrv);
54             }
55             res.put(k,arrv);
56         }
57         if(res == null){
58             return null;
59         }
60         return res;
61     }
62 
63     public String filter(String message){
64         if(message == null){
65             return null;
66         }
67         char content[] = new char[message.length()];
68         message.getChars(0,message.length(),content,0);
69         StringBuilder result = new StringBuilder(content.length + 50);
70         for(int i = 0;i < content.length;i++){
71             switch (content[i]){
72                 case '<':
73                     result.append("&lt;");
74                     break;
75                 case '>':
76                     result.append("&gt;");
77                     break;
78                 case '&':
79                     result.append("&amp;");
80                     break;
81                 case '"':
82                     result.append("&quot");
83                     break;
84                 default:
85                     result.append(content[i]);
86             }
87         }
88         return result.toString();
89     }
90 }

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.