Java in Java util. Map. Contains() method call

Is there any way to call java. in JSP? util. Map. Contains () method, where map is the attribute of the bean

Solution

${fooBean.fooMap.containsValue("baz")}

${fooBean.fooMap.containsValue("baz")}

The above applies to JSP 2.2 or later If you are using a pre JSP 2.2 container (such as Java EE 5), the El function may be a better solution

Static Java methods:

package contains;
import java.util.Map;
public class Maps {
    public static boolean containsValue(Map<?,?> map,Object value) {
        return map.containsValue(value);
    }
}

Document WEB-INF / TLDs / maps tld：

<?xml version="1.0" encoding="UTF-8"?>
<taglib version="2.1"
  xmlns="http://java.sun.com/xml/ns/javaee"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd">
  <tlib-version>1.0</tlib-version>
  <short-name>maps</short-name>
  <uri>/WEB-INF/tlds/maps</uri>
   <function>
    <description>Returns true if the value is contained</description>
    <name>containsValue</name>
    <function-class>contains.Maps</function-class>
    <function-signature>
      boolean containsValue(java.util.Map,java.lang.Object)
    </function-signature>
  </function>
</taglib>

Usage:

<%@taglib prefix="maps" uri="/WEB-INF/tlds/maps" %>
...
${maps:containsValue(fooBean.fooMap,"baz")}