新增AuthenticationUtil,获取当前登录用户名
diff --git a/samples/security/src/main/java/com/supwisdom/leaveschool/app/controller/web/admin/WebAdminUserController.java b/samples/security/src/main/java/com/supwisdom/leaveschool/app/controller/web/admin/WebAdminUserController.java
index 0dedae4..3e88ead 100644
--- a/samples/security/src/main/java/com/supwisdom/leaveschool/app/controller/web/admin/WebAdminUserController.java
+++ b/samples/security/src/main/java/com/supwisdom/leaveschool/app/controller/web/admin/WebAdminUserController.java
@@ -3,12 +3,17 @@
 import org.springframework.stereotype.Controller;
 import org.springframework.web.bind.annotation.RequestMapping;
 
+import com.supwisdom.leaveschool.app.util.AuthenticationUtil;
+
 @Controller
 @RequestMapping("/web/admin/user")
 public class WebAdminUserController {
 
   @RequestMapping("/index")
   public String userIndex() {
+    
+    AuthenticationUtil.currentUsername();
+    
     return "web/admin/user/index";
   }
 
diff --git a/samples/security/src/main/java/com/supwisdom/leaveschool/app/util/AuthenticationUtil.java b/samples/security/src/main/java/com/supwisdom/leaveschool/app/util/AuthenticationUtil.java
new file mode 100644
index 0000000..adc1cfd
--- /dev/null
+++ b/samples/security/src/main/java/com/supwisdom/leaveschool/app/util/AuthenticationUtil.java
@@ -0,0 +1,44 @@
+package com.supwisdom.leaveschool.app.util;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.security.core.Authentication;
+import org.springframework.security.core.context.SecurityContextHolder;
+
+import com.supwisdom.leaveschool.app.security.core.userdetails.MyUser;
+
+public class AuthenticationUtil {
+
+  private static final Logger logger = LoggerFactory.getLogger(AuthenticationUtil.class);
+
+  public static String currentUsername() {
+
+    Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
+
+    if (authentication == null) {
+      logger.error("authentication is null");
+      return null;
+    }
+
+    logger.debug("authentication is {}", authentication.getPrincipal());
+
+    if (!authentication.isAuthenticated()) {
+      logger.error("authentication is not authenticated");
+      return null;
+    }
+
+    if (authentication.getPrincipal() == null) {
+      logger.error("authentication's principal is null");
+      return null;
+    }
+
+    logger.debug("authentication's principal is {}", authentication.getPrincipal());
+
+    if (authentication.getPrincipal() instanceof MyUser) {
+      return ((MyUser) authentication.getPrincipal()).getUsername();
+    }
+
+    return null;
+  }
+
+}