Notice
I wrote this article and was originally published on Qiita on 3 September 2019.
Package used
- spring-webmvc-5.1.9.RELEASE
- thymeleaf-3.0.11.RELEASE
- thymeleaf-spring5-3.0.11.RELEASE
- thymeleaf-extras-springsecurity5-3.0.4.RELEASE
How?
First look into following code which extract from guide from thymeleaf.
<div sec:authorize="isAuthenticated()">
This content is only shown to authenticated users.
</div>
<div sec:authorize="hasRole('ROLE_ADMIN')">
This content is only shown to administrators.
</div>
<div sec:authorize="hasRole('ROLE_USER')">
This content is only shown to users.
</div>
Attribute value of "sec:authorize" is handle by class org.thymeleaf.extras.springsecurity5.dialect.processor.AuthorizeAttrProcessor
public final class AuthorizeAttrProcessor extends AbstractStandardConditionalVisibilityTagProcessor {
@Override
protected boolean isVisible(
final ITemplateContext context, final IProcessableElementTag tag,
final AttributeName attributeName, final String attributeValue) {
final String attrValue = (attributeValue == null? null : attributeValue.trim());
if (attrValue == null || attrValue.length() == 0) {
return false;
}
final Authentication authentication = AuthUtils.getAuthenticationObject(context);
if (authentication == null) {
return false;
}
return AuthUtils.authorizeUsingAccessExpression(context, attrValue, authentication);
}
// ...
}
Attribute value of "sec:authorize" will be processed by SpEL
This code
<div sec:authorize="isAuthenticated()">
This content is only shown to authenticated users.
</div>
have the same meaning of
<div sec:authorize="${isAuthenticated()}">
This content is only shown to authenticated users.
</div>
due to text between brackets will be extract by org.thymeleaf.extras.springsecurity5.auth.AuthUtils.MvcAuthUtils.authorizeUsingAccessExpressionMvc(IExpressionContext, String, Authentication) before pass to SpEL.
private static final class MvcAuthUtils {
private static boolean authorizeUsingAccessExpressionMvc(
final IExpressionContext context,
final String accessExpression, final Authentication authentication) {
/*
* In case this expression is specified as a standard variable expression (${...}), clean it.
*/
final String expr =
((accessExpression != null && accessExpression.startsWith("${") && accessExpression.endsWith("}"))?
accessExpression.substring(2, accessExpression.length() - 1) :
accessExpression);
// ...
// pass to SpEL
return (ExpressionUtils.evaluateAsBoolean(expressionObject, wrappedEvaluationContext));
}
// ...
}
isAuthenticated() and hasRole() is function of class org.springframework.security.web.access.expression.WebSecurityExpressionRoot
EvaluationContext used by SpEL is build from org.springframework.security.access.expression.AbstractSecurityExpressionHandler.createEvaluationContext(Authentication, T).
public abstract class AbstractSecurityExpressionHandler<T> implements
SecurityExpressionHandler<T>, ApplicationContextAware {
public final EvaluationContext createEvaluationContext(Authentication authentication,
T invocation) {
SecurityExpressionOperations root = createSecurityExpressionRoot(authentication,
invocation);
StandardEvaluationContext ctx = createEvaluationContextInternal(authentication,
invocation);
ctx.setBeanResolver(br);
ctx.setRootObject(root);
return ctx;
}
// ...
}
Variable "root" is instance of class org.springframework.security.web.access.expression.WebSecurityExpressionRoot.
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