spring-security基礎使用

###spring-security框架的使用
spring-security是Spring 項目組中用來提供安全認證服務的框架。
####1.引入依賴

<dependencies>
	<dependency>
	   <groupId>org.springframework.security</groupId>
	   <artifactId>spring-security-web</artifactId>
	   <version>5.0.1.RELEASE</version>
	</dependency>
	<dependency>
	   <groupId>org.springframework.security</groupId>
	   <artifactId>spring-security-config</artifactId>
	   <version>5.0.1.RELEASE</version>
	</dependency>
</dependencies>

####2.在web.xml文件中進行配置

 <context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>classpath:spring-security.xml</param-value>
</context-param>
<listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<filter>
    <filter-name>springSecurityFilterChain</filter-name>
    <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
</filter>
<filter-mapping>
    <filter-name>springSecurityFilterChain</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

####3.spring-security配置文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:security="http://www.springframework.org/schema/security"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/security
    http://www.springframework.org/schema/security/spring-security.xsd">

    <!--開啓jsr250權限控制註解-->
    <security:global-method-security jsr250-annotations="enabled"/>
    
    <!--開啓spring-security自帶的權限註解-->
    <security:global-method-security secured-annotations="enabled" />
    <!-- 配置不攔截的資源 -->
    <security:http pattern="/login.jsp" security="none"/>
    <security:http pattern="/failer.jsp" security="none"/>
    <security:http pattern="/css/**" security="none"/>
    <security:http pattern="/img/**" security="none"/>
    <security:http pattern="/plugins/**" security="none"/>
    <!--
    	配置具體的規則
    	auto-config="true"	不用自己編寫登錄的頁面，框架提供默認登錄頁面
    	use-expressions="false"	是否使用SPEL表達式（沒學習過）
    -->
    <security:http auto-config="true" use-expressions="true">
        <!-- 配置具體的攔截的規則 pattern="請求路徑的規則" access="訪問系統的人，必須有ROLE_USER的角色" -->
        <security:intercept-url pattern="/**" access="hasAnyRole('ROLE_USER','ROLE_ADMIN')"/>

        <!-- 定義跳轉的具體的頁面 -->
        <security:form-login
                login-page="/login.jsp"
                login-processing-url="/login"
                authentication-failure-url="/failer.jsp"
                authentication-success-forward-url="/pages/main.jsp"
        />
        <!--default-target-url="/index.jsp"
        該配置表示有權限的用戶登錄跳轉指定路徑，無權限的用戶登錄直接報403權限不足的錯誤
         authentication-success-forward-url="/pages/main.jsp"
         該配置不論用戶是否有權限，只要賬號密碼正確登錄後都會跳轉到指定路徑
         當以上兩個配置同時存在，優先按後者跳轉路徑
         -->

        <!-- 關閉跨域請求 -->
        <security:csrf disabled="true"/>
        <!-- 退出 -->
        <security:logout invalidate-session="true" logout-url="/logout" logout-success-url="/login.jsp"/>

    </security:http>

    <!-- 切換成數據庫中的用戶名和密碼 -->
    <security:authentication-manager>
        <security:authentication-provider user-service-ref="userService">
            <!-- 配置加密的方式-->
            <security:password-encoder ref="passwordEncoder"/>
        </security:authentication-provider>
    </security:authentication-manager>

    <!-- 配置加密類 -->
    <bean id="passwordEncoder" class="org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder"/>

    <!-- 提供了入門的方式，在內存中存入用戶名和密碼
    <security:authentication-manager>
    	<security:authentication-provider>
    		<security:user-service>
    			<security:user name="admin" password="{noop}admin" authorities="ROLE_USER"/>
    		</security:user-service>
    	</security:authentication-provider>
    </security:authentication-manager>
    -->

</beans>

####4.Spring Security使用數據庫認證

將sping-security當做controller層，點擊登錄去調用service層，具體代碼實現見練習代碼（UserServiceimpl）

####5.服務器端方法級權限控制
在服務器端我們可以通過Spring security提供的註解對方法來進行權限控制。Spring Security在
方法的權限控制上支持三種類型的註解，JSR-250註解、@Secured註解和支持表達式的註解，這三種註解默認都是沒有啓用的，需要單獨通過global-method-security元素的對應屬性進行啓用

• JSR-250註解
  
• Security註解
  
• SPEL表達式註解
  

####6.頁面端標籤控制權限