Spring security获取当前用户

1、如果在jsp页面中获取可以使用spring security的标签

页面引入标签

<%@ taglib prefix="sec" uri="http://www.springframework.org/security/tags" %>

使用：

 username : 

即可显示当前用户。

2.java代码中使用

 UserDetails userDetails = (UserDetails) SecurityContextHolder.getContext().getAuthentication() .getPrincipal();

 但我在实际运用中发现获得的Authentication为null。仔细看了下源代码发现，如果想用上面的代码获得当前用户，必须在spring    

     security过滤器执行中执行，否则在过滤链执行完时org.springframework.security.web.context.SecurityContextPersistenceFilter类会

     调用SecurityContextHolder.clearContext();而把SecurityContextHolder清空，所以会得到null。    经过spring security认证后，     

     security会把一个SecurityContextImpl对象存储到session中，此对象中有当前用户的各种资料

SecurityContextImpl securityContextImpl = (SecurityContextImpl) request
 .getSession().getAttribute("SPRING_SECURITY_CONTEXT");
// 登录名
System.out.println("Username:"
 + securityContextImpl.getAuthentication().getName());
// 登录密码，未加密的
System.out.println("Credentials:"
 + securityContextImpl.getAuthentication().getCredentials());
WebAuthenticationDetails details = (WebAuthenticationDetails) securityContextImpl
 .getAuthentication().getDetails();
// 获得访问地址
System.out.println("RemoteAddress" + details.getRemoteAddress());
// 获得sessionid
System.out.println("SessionId" + details.getSessionId());
// 获得当前用户所拥有的权限
List authorities = (List) securityContextImpl
 .getAuthentication().getAuthorities();
for (GrantedAuthority grantedAuthority : authorities) {
 System.out.println("Authority" + grantedAuthority.getAuthority());
}