JSTL 标签库

• out 标签

    value:输出值，default:默认输出值，escape:特殊字符是否转义
    
    HtmlUtils.htmlUnescape(help); -> 富文本不转义(Spring)

• redirect 标签

• set 标签

     -> 方式一
     -> 方式二
     -> 赋值

• remove 标签

     -> 请求域移除参数

• if 标签

    结果为True，执行标签体
    
         
                new
         
    

• case 标签

    <%--大写转换小写--%>
    ${fn:toLowerCase("ITCAST")}

    <%--小写转换大写--%>
    ${fn:toUpperCase("wjx")}

• fn:contains 标签

    <%--区别大小写--%>
    ${fn:contains("wjx","w")};

    ${fn:contains("wjx","W")};

    <%--不区别大小写--%>
    ${fn:containsIgnoreCase("wjx","w" )};

    ${fn:containsIgnoreCase("wjx","W" )};

• fn:escapeXml 标签

    ${fn:escapeXml("
")}

    

    ${"我"}

• fn:indexOf 标签

    ${fn:indexOf("wjx","w" )}

    ${fn:indexOf("wjx","j" )}

    ${fn:indexOf("wjx","x" )}

• fn:join 标签

    <%  String strs[]={"www","itcast","com"};  %>
    
    ${fn:join(strs,".")}

• fn:length 标签

    <%
    int[] array={1,2,3,4};
    List list = new ArrayList();
    list.add("one");
    list.add("two");
    list.add("three");
    %>

    
    
    数组长度:${fn:length(array)}

    集合长度:${fn:length(list)}

    字符串长度:${fn:length("Tomcat")}

• fn:replace 标签

    <%--字符串替换--%>
    ${fn:replace("w.j.x","." ,"" )}

• fn:split 标签

• fn:substring 标签

    <%--字符串抽取--%>
    ${fn:substring("wjx",0 ,2 )}

    ${fn:substringBefore("wjx", "j")}

    ${fn:substringAfter("wjx","j" )}

• fn:trim 标签

    <%--清除字符串前后的空格--%>
    ${fn:trim("wjx")}

• fn:startsWith 标签 、fn:endsWith 标签

    <%--开头--%>
    ${fn:startsWith("wjx","w")}

    ${fn:startsWith("wjx","j")}

    <%--结束--%>
    ${fn:endsWith("wjx","x" )}

    ${fn:endsWith("wjx","j" )}

• catch 标签

    
        <%
        int j=10;
        int i=0;
        System.out.println(j/i);
        %>
    

• choose 标签

    
        
            param没有参数
        
        
        
            wjx
        

        
            else
        
    

• forEach 标签

<%--数组--%>
<%
    String[] fruits = {"apple", "orange", "grape", "banana"};
%>

    ${wjx}



<%--Map集合--%>
<%
    Map map = new HashMap();
    map.put("Tom", "123");
    map.put("Mike", "123");
    map.put("Lina", "123");
%>

    ${map.key}  ${map.value}



<%--List集合--%>
<%
    List list = new ArrayList();
    list.add("red");
    list.add("yellow");
    list.add("blue");
    list.add("green");
%>

    ${!status.first} -> 第一个Item
    ${!status.last} -> 最后一个Item
    ${color} 

• forTokens 标签

    ${token}
 

• formatDate 标签

<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>

• EL表达式的判断符号

                     等于  ==    eq 
                   不等于  !=    ne、neq
                     大于  >     gt 
                     小于  <     lt 
                 大于等于  >=    ge、gte
                 小于等于  <=    le、lte
                       与  &&    and 
                       或  ||    or 
                       非  !     not 
                       加  + 
                       减  - 
                       乘  * 
                     除以  /     div 
                     求莫  %     mod