初始spring security（一）

第一次接触spring security，第一个例子是最简单，实现的功能也仅仅是权限控制一些最基本的功能；

首先是web.xml文件：

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
    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-app_2_5.xsd">
  <display-name></display-name>    
   <!-- 获取application-security.xml的位置 -->
  <context-param>
   <param-name>contextConfigLocation</param-name>
   <param-value>
   classpath:application*.xml
   </param-value>
  </context-param>
   <!-- 对spring容器进行实例化(监听) -->
   <listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
   <listener>
    <listener-class>org.springframework.security.web.session.HttpSessionEventPublisher</listener-class>
   </listener>
   <!-- SpringSecurity必须的filter -->
   <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>
   <!-- 设置session时间 -->
   <session-config>
   <session-timeout>30</session-timeout>
   </session-config>
</web-app>

web.xml的配置比较熟悉，所有没有什么太难的。

接下来是核心applicationContext-security.xml

<?xml version="1.0" encoding="UTF-8"?>  
<beans xmlns="http://www.springframework.org/schema/beans"  
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"   
    xmlns:security="http://www.springframework.org/schema/security"  
    xsi:schemaLocation="http://www.springframework.org/schema/beans   
            http://www.springframework.org/schema/beans/spring-beans-3.0.xsd  
            http://www.springframework.org/schema/security   
            http://www.springframework.org/schema/security/spring-security-3.0.xsd"> 
<!-- 配置保护资源 -->
<security:http auto-config="true" access-denied-page="/deniedpage.jsp">
<!-- 设置同步会话控制 -->
<security:session-management  invalid-session-url="/login.jsp" session-fixation-protection="none">
<security:concurrency-control max-sessions="1" error-if-maximum-exceeded="false" expired-url="/sessionTimeout.jsp"/>
</security:session-management>
<!-- http表达验证 -->
<security:form-login login-page="/login.jsp" authentication-failure-url="/login.jsp?login_error=1" default-target-url="/success.jsp"/>
<security:logout/>
<security:intercept-url pattern="/login.jsp" access="IS_AUTHENTICATED_ANONYMOUSLY"/>
<security:intercept-url pattern="/index.jsp" access="ROLE_USER,ROLE_ADMIN"/>
<security:intercept-url pattern="/**" access="ROLE_USER"/>

</security:http>
<!-- 配置用户 -->
<security:authentication-manager>
<security:authentication-provider>
<security:jdbc-user-service data-source-ref="dataSource"/>
</security:authentication-provider>
</security:authentication-manager>
<!-- 配置数据库信息 -->
<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
<property name="driverClass" value="${db.driverClass}"/>
<property name="jdbcUrl" value="${db.jdbcUrl}"/>
<property name="user" value="${db.user}"/>
<property name="password" value="${db.password}"/>
</bean>
<!-- 读取资源文件 -->
<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<list>
<value>classpath:constants.properties</value>
</list>
</property>
</bean>
</beans>

注解：

1、从session缓存中获取当前session信息，如果发现过期了，就跳转到expired-url配置的url或者响应session失效提示信息。当前session有哪些情况会导致session失效呢？这里的失效并不是指在web容器中session的失效，而是spring security把登录成功的session封装为SessionInformation并放到注册类缓存中，如果SessionInformation的expired变量为true，则表示session已失效。所以，ConcurrentSessionFilter过滤器主要检查SessionInformation的expired变量的值。

2、如果concurrency-control标签配置了error-if-maximum-exceeded="true"，max-sessions="1"，那么第二次登录时，是登录不了的。如果error-if-maximum-exceeded="false"，那么第二次是能够登录到系统的，但是第一个登录的账号再次发起请求时，会跳转到expired-url配置的url中（如果没有配置，则显示This session has been expired (possibly due to multiple concurrent logins being attempted as the same user).提示信息）

然后是连接数据库的constants.properties:

db.driverClass=com.mysql,jdbc.Driver
db.jdbcUrl=jdbc:mysql://localhost:3306/springsecurity
db.user=root
db.password=luwenhu

最后就是jsp文件，这个没有什么特别的，比如login.jsp：

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    <title>登录界面</title>
  </head>
  <body onload="document.f.j_username.focus();">
  <c:if test="${not empty param.login_error }">
  <font color="red">
  登录失败，请重试！<br/>
  原因：<c:out value="${SPRING_SECURITY_LAST_EXCEPTION.message }"></c:out>
  </font>
  </c:if>
   <form action="/acegi1/j_spring_security_check" method="post">
   username:<input type="text" name="j_username"/><br/>
   password:<input type="password" name="j_password"/></br>
   <input type="checkbox" name="_spring_security_remember_me">两周内自动登录
   <input type="submit" value="用户登录">
   </form>
  </body>
</html>

今天就学了这些，明天继续深入spring security，加入自己的filter。