User user=getPassWordByUserName(userName); if(user==null){ return null; } SimpleAuthenticationInfo authenticationInfo=new SimpleAuthenticationInfo(user.getUsername(),user.getPassword(),"customRealm");

SimpleAuthenticationInfo authenticationInfo=new SimpleAuthenticationInfo(user.getUsername(),user.getPassword(),"customRealm");

方法里面的userName和password以及自定义customRealm都分别是用来干嘛的啊？  有点不是很理解