Spring boot +Spring Security + Thymeleaf 认证失败返回错误信息

[Please make sure to select the branch corresponding to the version of Thymeleaf you are using]

Status

This is a thymeleaf extras module, not a part of the Thymeleaf core (and as such following its own versioning schema), but fully supported by the Thymeleaf team.

This repository contains two projects:

• thymeleaf-extras-springsecurity3 for integration with Spring Security 3.x
• thymeleaf-extras-springsecurity4 for integration with Spring Security 4.x

Current versions:

• Version 3.0.2.RELEASE - for Thymeleaf 3.0 (requires Thymeleaf 3.0.3+)
• Version 2.1.3.RELEASE - for Thymeleaf 2.1 (requires Thymeleaf 2.1.2+)

License

This software is licensed under the [Apache License 2.0] (http://www.apache.org/licenses/LICENSE-2.0.html).

Requirements (3.0.x)

• Thymeleaf 3.0.0+
• Spring Framework version 3.0.x to 4.3.x
• Spring Security version 3.0.x to 4.2.x
• Web environment (Spring Security integration cannot work offline)

Maven info

• groupId: org.thymeleaf.extras
• artifactId:
• Spring Security 3 integration package: thymeleaf-extras-springsecurity3
• Spring Security 4 integration package: thymeleaf-extras-springsecurity4

Distribution packages

Distribution packages (binaries + sources + javadoc) can be downloaded from SourceForge.

Features

This module provides a new dialect called org.thymeleaf.extras.springsecurity3.dialect.SpringSecurityDialect or org.thymeleaf.extras.springsecurity4.dialect.SpringSecurityDialect (depending on the Spring Security version), with default prefix sec. It includes:

• New expression utility objects:
• #authentication representing the Spring Security authentication object (an object implementing the org.springframework.security.core.Authentication interface).
• #authorization: a expression utility object with methods for checking authorization based on expressions, URLs and Access Control Lists.
• New attributes:
• sec:authentication="prop" outputs a prop property of the authentication object, similar to the Spring Security <sec:authentication/> JSP tag.
• sec:authorize="expr" or sec:authorize-expr="expr" renders the element children (tag content) if the authenticated user is authorized to see it according to the specified Spring Security expression.
• sec:authorize-url="url" renders the element children (tag content) if the authenticated user is authorized to see the specified URL.
• sec:authorize-acl="object :: permissions" renders the element children (tag content) if the authenticated user has the specified permissions on the specified domain object, according to Spring Source's Access Control List system.

---

Configuration

In order to use the thymeleaf-extras-springsecurity3 or thymeleaf-extras-springsecurity4 modules in our Spring MVC application, we will first need to configure our application in the usual way for Spring + Thymeleaf applications (TemplateEngine bean, template resolvers, etc.), and add the SpringSecurity dialect to our Template Engine so that we can use the sec:* attributes and special expression utility objects:

    <bean id="templateEngine" class="org.thymeleaf.spring4.SpringTemplateEngine">
      ...
      <property name="additionalDialects">
        <set>
          <!-- Note the package would change to 'springsecurity3' if you are using that version -->
          <bean class="org.thymeleaf.extras.springsecurity4.dialect.SpringSecurityDialect"/>
        </set>
      </property>
	  ...
    </bean>

And that's all!

Using the expression utility objects

The #authentication object can be easily used, like this:

    <div th:text="${#authentication.name}">
        The value of the "name" property of the authentication object should appear here.
    </div>

The #authorization object can be used in a similar way, normally in th:if or th:unlesstags:

    <div th:if="${#authorization.expression('hasRole(''ROLE_ADMIN'')')}">
        This will only be displayed if authenticated user has role ROLE_ADMIN.
    </div>

The #authorization object is an instance of org.thymeleaf.extras.springsecurity[3|4].auth.Authorization, see this class and its documentation to understand all the methods offered.

Using the attributes

Using the sec:authentication attribute is equivalent to using the #authentication object, but using its own attribute:

    <div sec:authentication="name">
        The value of the "name" property of the authentication object should appear here.
    </div>

The sec:authorize and sec:authorize-expr attributes are exactly the same. They work equivalently to a th:if that evaluated an #authorization.expression(...) expression, by evaluating a Spring Security Expression:

    <div sec:authorize="hasRole('ROLE_ADMIN')">
        This will only be displayed if authenticated user has role ROLE_ADMIN.
    </div>

These Spring Security Expressions in sec:authorize attributes are in fact Spring EL expressions evaluated on a SpringSecurity-specific root object containing methods such as hasRole(...), getPrincipal(), etc.

As with normal Spring EL expressions, Thymeleaf allows you to access a series of objects from them including the context variables map (the #vars object). In fact, you are allowed to surround your access expression with ${...} if it makes you feel more comfortable:

    <div sec:authorize="${hasRole(#vars.expectedRole)}">
        This will only be displayed if authenticated user has a role computed by the controller.
    </div>

Remember that Spring Security sets a special security-oriented object as expression root, which is why you would not be able to access the expectedRole variable directly in the above expression.

Another way of checking authorization is sec:authorize-url, which allows you to check whether a user is authorized to visit a specific URL or not:

    <div sec:authorize-url="/admin">
        This will only be displayed if authenticated user can call the "/admin" URL.
    </div>

For specifying a specific HTTP method, do:

    <div sec:authorize-url="POST /admin">
        This will only be displayed if authenticated user can call the "/admin" URL
        using the POST HTTP method.
    </div>

Finally, there is an attribute for checking authorization using Spring Security's Access Control Lists, which needs the specification of a domain object and the permissions defined on it that we are asking for.

    <div sec:authorize-acl="${obj} :: '1,3'">
        This will only be displayed if authenticated user has permissions "1" and "3"
        on domain object referenced by context variable "obj".
    </div>

In this attribute, both domain object and permission specifications are considered to be thymeleaf Standard Expressions.

Namespace

The namespace for both Spring 3 and 4 versions of this dialect is http://www.thymeleaf.org/extras/spring-security.

	<html xmlns:sec="http://www.thymeleaf.org/extras/spring-security">

Getting the namespace incorrect won't impact processing of your template. It might however impact your IDE when it comes to things like suggestions/auto-completion in your templates.

https://github.com/thymeleaf/thymeleaf-extras-springsecurity

spring boot以其众多友谊的特性，如零配置、微服务等，吸引了很多的粉丝。而其与Spring Security安全框架的无缝结合，使其具备的安全的特性。在此基础上使用Thymeleaf模板引擎进行渲染，静动态结合，让页面开发更加简单、直观。

通过表单提交登录的用户名和密码是登录接口比较常见的一种设计。在初学的过程中，我也不例外的采用个这种方式。表单设计见下图。

登录成功，完成正常的主页面跳转，这个不存在问题。存在问题的是，登录失败了该咋办呢？我就在考虑，由于thymeleaf的局部刷新操作，登录失败了将登录失败的异常信息显示在登录页面，也就是表单上。于是，我的登录设计又变成了如下图所示的表单。

        

         通过这种方法，当登录表单验证失败时，会该用户显示”用户名或密码错误，请重试”，这当然是比较好的，但是验证失败的情况不仅仅是用户名或密码错误吧，应该还有其它的情形，比较常见的就有，该用户已被锁定，该用户不存在，请先注册等。

那么该如何区分这么情形呢，怎么把登录表单验证失败的比较详细的状况显示给用户呢。经过一段时间的调研，发现Spring boot提供了比较完美的解决方案，而其秘密就在Spring Security的配置中。我项目中的Spring Security配置如下图所示。

而我在阅读Spring Security源码时，当认证失败时，找寻到以下处理的代码

而重点就在saveException函数，而此函数的具体代码如下：

从这段代码中，我们可以清晰的看到，认证失败的异常信息被保存在Session中，如果我们可以读取Session中的信息那么，之前所遇到的问题就迎刃而解了吧。

事实上，事物的发展从来不是一帆风顺的，解决问题也是类似。我了解到Thymeleaf提供了读取缓存Session的方案，就迫不及待的进行尝试，于是乎，我的登录表单又变成了如下模样，红线指出的是Thymleaf缓存的读取方式。

这样就可以显示验证失败的具体信息了吗？经过我的测试，我发现，此信息是未定义。也就是说，模样读取到缓存中的信息。

通过在网上查找资料，我在浩瀚的百度的犄角旮旯里，查找到以下的代码片段。

         我如获至宝，仿佛见到了光明。在配置文件配置的时代，可以设置登录失败的跳转页面为”/login.html?error=true”,而我设置的是“/login?error”，那么是否可以设置为类似的true呢？我迫不及待的进行尝试。于是乎，我Spring Security的Java Config又变成了如下的样子。

经过验证，通过这样设置，完美的解决了我遇到的问题，到现在，我仍没有明白设置true的含义，望知道的读者可以告诉小编。

小编来总结哈，在Spring boot +Spring Security + Thymeleaf框架下，通过用户名/密码表单提交，在登录界面获取异常信息的步骤，主要有以下两点：

其一：将登录失败的url设置为”/login?error=true”(即后缀带?error=true),使前端的thymleaf可以读取Session；

其二：Thymeleaf提供的读取缓存中信息的方法${session.SPRING_SECURITY_LAST_EXCEPTION.message}，两者缺一不可。

http://blog.csdn.net/sun1021873926/article/details/60332059