EL和函数库

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <taglib xmlns="http://java.sun.com/xml/ns/j2ee"
 3   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4   xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
 5   version="2.0">
 6   <tlib-version>1.0</tlib-version>
 7   <short-name>jnb</short-name>
 8   <function>
 9     <name>filter</name>
10     <function-class>cn.itcast.utils.HTMLFilter</function-class>
11     <function-signature>java.lang.String filter(java.lang.String)</function-signature>
12   </function>
13 </taglib>  

 1 public final class HTMLFilter {
 2     public static String filter(String message) {
 3         if (message == null)
 4             return (null);
 5         char content[] = new char[message.length()];
 6         message.getChars(0, message.length(), content, 0);
 7         StringBuffer result = new StringBuffer(content.length + 50);
 8         for (int i = 0; i < content.length; i++) {
 9             switch (content[i]) {
10             case ‘<‘:
11                 result.append("&lt;");
12                 break;
13             case ‘>‘:
14                 result.append("&gt;");
15                 break;
16             case ‘&‘:
17                 result.append("&amp;");
18                 break;
19             case ‘"‘:
20                 result.append("&quot;");
21                 break;
22             default:
23                 result.append(content[i]);
24             }
25         }
26         return (result.toString());
27 
28     }
29 }