Vérification de la demande de valeur de paramètre dans Struts2 tag

Modifier:
Il y a une différence entre "" (guillemets doubles) et '' (simple quotes) dans OGNL.

Guillemets évaluer les caractères uniques à cordes pendant que les guillemets simples évaluer les caractères uniques de types de Caractères. Vous pouvez mettre plusieurs caractères entre guillemets simples et elle sera évaluée comme une chaîne de caractères.

Demande ultérieure de la portée n'est pas

Map<String, String> 

mais

Map<String, String[]> 

comme on peut le voir ci-dessous au cours des 5 dernières lignes de la page jsp.

JSP

<%@taglib prefix="s" uri="/struts-tags"%>
<!-- values from action where letters = "abcd" -->
<s:property value="letters"/><br/> <!-- Displays: abcd -->
<s:property value="letters.equals('abcd')"/><br/> <!-- Displays: true -->
<s:property value="'abcd'.compareTo('abcd')"/><br/> <!-- Displays: 0 -->
<s:property value="'abcd'.compareTo('abcd') == 0"/><br/> <!-- Displays: true -->
<s:property value="'abcd'.equals('abcd')"/><br/> <!-- Displays: true -->
<s:property value="'abcd'.equals(letters)"/><br/> <!-- Displays: true -->
<br/>
<!-- RUN with ?test=a&test2=abc appended to the url -->
<!-- Time for the numbers from action where number = 1-->
<s:property value="number"/><br/><!-- Displays: 1 -->
<s:property value="number.toString()"/><br/><!-- Displays: 1 -->
<!-- OGNL strings in certain cases must be double quoted -->
<s:property value='"1".equals(number.toString())'/><br/><!-- Displays: true -->
<!-- As we can see single quotes does automatic type conversion to Character which is then evaluates false-->
<s:property value="'1'.equals(number.toString())"/><br/><!-- Displays: false -->
<!-- here a string is compared to an integer which is false-->
<s:property value='"1".equals(number)'/><br/><!-- Displays: false -->
<br/><!-- Request Variables -->
<s:property value="#parameters['test']"/><br/><!-- Displays: a -->
<!-- a is single quoted so automatic type conversion probably converted it to a Character, which is not equal to string "a" -->
<s:property value="'a'.equals(#parameters['test'])"/><br/><!-- Displays: false -->
<!-- both are strings so equality works as expected -->
<s:property value='#parameters["test"]'/><br/><!-- Displays: a -->
<s:property value='"a".equals(#parameters["test"])'/><br/><!-- Displays: false because #parameters["test"] is a string[] and calling toString on string[] does not work -->
<!-- #parameters['test2'] now is 'abc' automatic type conversion of OGNL swill convert 'abc' to a string and so both are equal -->
<s:property value='#parameters["test2"]'/><br/>
<!-- Double quotes must be a string -->
<s:property value='"abc".compareTo(#parameters["test2"]) == 0'/><br/><!-- Displays: true -->
<!-- Single quote so automatic type conversion... string of chars is converted to String -->
<s:property value="'abc'.compareTo(#parameters['test2']) == 0"/><br/><!-- Displays: true -->
<!-- Out of curiosity I'd like to know if '1' is an Integer or a Byte -->
<s:property value="'1'.toString()"/><br/><!-- Answer: Neither it prints "class java.lang.Character" -->
<!-- 'a' is a Character however equals calls toString() -->
<!-- But the request object (and session too) is not <string, string> but <string, string[]> -->
1: <s:property value='"1".class'/><br/> <!-- class java.lang.String -->
2: <s:property value='#parameters["test"].class'/><br/> <!-- Array of string: class [Ljava.lang.String; -->
3: <s:property value='#parameters["test"][0].class'/><br/> <!-- This is what we need: class java.lang.String -->
<s:property value='#parameters["test"][0].equals("a")'/><br/> <!-- Now this works -->
<s:property value="#parameters['test'][0].equals('a'.toString())"/><br/> <!-- this is another way, leaving off the .toString results in false -->

Test.jsp (Action)

paquet struts2;
import com.opensymphony.xwork2.ActionSupport;

public class test extends ActionSupport{
public String letters = "abcd";
public int number = 1;
}

OriginalL'auteur Quaternion