只允许一个用户同时登陆

src/main/java/com/keymobile/proxy/conf/SecurityConfig.java

@@ -55,6 +55,7 @@ public class SecurityConfig extends WebSecurityConfigurerAdapter {
         http.formLogin().loginProcessingUrl("/signin");
         http.logout().logoutUrl("/signout");
         http.logout().logoutSuccessHandler(logoutSuccessHandler);
+        http.sessionManagement().maximumSessions(1).expiredUrl("/login");
     }
 
 }