diff --git a/design-pattern/gof/src/adapter/after/Account.java b/design-pattern/gof/src/adapter/after/Account.java
new file mode 100644
index 00000000..e5bf464c
--- /dev/null
+++ b/design-pattern/gof/src/adapter/after/Account.java
@@ -0,0 +1,42 @@
+package adapter.after;
+
+import adapter.after.security.UserDetails;
+
+public class Account implements UserDetails {
+
+    private String name;
+
+    private String password;
+
+    private String email;
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    @Override
+    public String getUsername() {
+        return this.name;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public void setPassword(String password) {
+        this.password = password;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+}
diff --git a/design-pattern/gof/src/adapter/after/AccountService.java b/design-pattern/gof/src/adapter/after/AccountService.java
new file mode 100644
index 00000000..e09e5e48
--- /dev/null
+++ b/design-pattern/gof/src/adapter/after/AccountService.java
@@ -0,0 +1,28 @@
+package adapter.after;
+
+import adapter.after.security.UserDetails;
+import adapter.after.security.UserDetailsService;
+
+public class AccountService implements UserDetailsService {
+
+    public Account findAccountByUsername(String username) {
+        Account account = new Account();
+        account.setName(username);
+        account.setPassword(username);
+        account.setEmail(username);
+        return account;
+    }
+
+    public void createNewAccount(Account account) {
+
+    }
+
+    public void updateAccount(Account account) {
+
+    }
+
+    @Override
+    public UserDetails loadUser(String username) {
+        return findAccountByUsername(username);
+    }
+}
diff --git a/design-pattern/gof/src/adapter/after/AccountUserDetails.java b/design-pattern/gof/src/adapter/after/AccountUserDetails.java
new file mode 100644
index 00000000..00c675b0
--- /dev/null
+++ b/design-pattern/gof/src/adapter/after/AccountUserDetails.java
@@ -0,0 +1,22 @@
+package adapter.after;
+
+import adapter.after.security.UserDetails;
+
+public class AccountUserDetails implements UserDetails {
+
+    private Account account;
+
+    public AccountUserDetails(Account account) {
+        this.account = account;
+    }
+
+    @Override
+    public String getUsername() {
+        return this.account.getName();
+    }
+
+    @Override
+    public String getPassword() {
+        return this.account.getPassword();
+    }
+}
diff --git a/design-pattern/gof/src/adapter/after/AccountUserDetailsService.java b/design-pattern/gof/src/adapter/after/AccountUserDetailsService.java
new file mode 100644
index 00000000..ec3c3666
--- /dev/null
+++ b/design-pattern/gof/src/adapter/after/AccountUserDetailsService.java
@@ -0,0 +1,19 @@
+package adapter.after;
+
+import adapter.after.security.UserDetails;
+import adapter.after.security.UserDetailsService;
+
+public class AccountUserDetailsService implements UserDetailsService {
+
+    AccountService accountService;
+
+    public AccountUserDetailsService(AccountService accountService) {
+        this.accountService = accountService;
+    }
+
+    @Override
+    public UserDetails loadUser(String username) {
+        Account account = accountService.findAccountByUsername(username);
+        return new AccountUserDetails(account);
+    }
+}
diff --git a/design-pattern/gof/src/adapter/after/App.java b/design-pattern/gof/src/adapter/after/App.java
new file mode 100644
index 00000000..4f2dad96
--- /dev/null
+++ b/design-pattern/gof/src/adapter/after/App.java
@@ -0,0 +1,21 @@
+package adapter.after;
+
+import adapter.after.security.LoginHandler;
+import adapter.after.security.UserDetailsService;
+
+public class App {
+
+    public static void main(String[] args) {
+        // 클래스 따로 생성
+//        AccountService accountService = new AccountService();
+//        UserDetailsService userDetailsService = new AccountUserDetailsService(accountService);
+//        LoginHandler loginHandler = new LoginHandler(userDetailsService);
+//        String login = loginHandler.login("kim", "kim");
+//        System.out.println("login = " + login);
+
+        UserDetailsService userDetailsService = new AccountService();
+        LoginHandler loginHandler = new LoginHandler(userDetailsService);
+        String login = loginHandler.login("kim", "kim");
+        System.out.println("login = " + login);
+    }
+}
diff --git a/design-pattern/gof/src/adapter/after/security/LoginHandler.java b/design-pattern/gof/src/adapter/after/security/LoginHandler.java
new file mode 100644
index 00000000..1c8f127d
--- /dev/null
+++ b/design-pattern/gof/src/adapter/after/security/LoginHandler.java
@@ -0,0 +1,19 @@
+package adapter.after.security;
+
+public class LoginHandler {
+
+    UserDetailsService userDetailsService;
+
+    public LoginHandler(UserDetailsService userDetailsService) {
+        this.userDetailsService = userDetailsService;
+    }
+
+    public String login(String username, String password) {
+        UserDetails userDetails = userDetailsService.loadUser(username);
+        if (userDetails.getPassword().equals(password)) {
+            return userDetails.getUsername();
+        } else {
+            throw new IllegalArgumentException();
+        }
+    }
+}
diff --git a/design-pattern/gof/src/adapter/after/security/UserDetails.java b/design-pattern/gof/src/adapter/after/security/UserDetails.java
new file mode 100644
index 00000000..06f0b416
--- /dev/null
+++ b/design-pattern/gof/src/adapter/after/security/UserDetails.java
@@ -0,0 +1,9 @@
+package adapter.after.security;
+
+public interface UserDetails {
+
+    String getUsername();
+
+    String getPassword();
+
+}
diff --git a/design-pattern/gof/src/adapter/after/security/UserDetailsService.java b/design-pattern/gof/src/adapter/after/security/UserDetailsService.java
new file mode 100644
index 00000000..b200919b
--- /dev/null
+++ b/design-pattern/gof/src/adapter/after/security/UserDetailsService.java
@@ -0,0 +1,7 @@
+package adapter.after.security;
+
+public interface UserDetailsService {
+
+    UserDetails loadUser(String username);
+
+}
diff --git a/design-pattern/gof/src/adapter/before/Account.java b/design-pattern/gof/src/adapter/before/Account.java
new file mode 100644
index 00000000..d8d451c4
--- /dev/null
+++ b/design-pattern/gof/src/adapter/before/Account.java
@@ -0,0 +1,35 @@
+package adapter.before;
+
+public class Account {
+
+    private String name;
+
+    private String password;
+
+    private String email;
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public void setPassword(String password) {
+        this.password = password;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+}
diff --git a/design-pattern/gof/src/adapter/before/AccountService.java b/design-pattern/gof/src/adapter/before/AccountService.java
new file mode 100644
index 00000000..173f94c0
--- /dev/null
+++ b/design-pattern/gof/src/adapter/before/AccountService.java
@@ -0,0 +1,21 @@
+package adapter.before;
+
+public class AccountService {
+
+    public Account findAccountByUsername(String username) {
+        Account account = new Account();
+        account.setName(username);
+        account.setPassword(username);
+        account.setEmail(username);
+        return account;
+    }
+
+    public void createNewAccount(Account account) {
+
+    }
+
+    public void updateAccount(Account account) {
+
+    }
+
+}
diff --git a/design-pattern/gof/src/adapter/before/security/LoginHandler.java b/design-pattern/gof/src/adapter/before/security/LoginHandler.java
new file mode 100644
index 00000000..5ee771c2
--- /dev/null
+++ b/design-pattern/gof/src/adapter/before/security/LoginHandler.java
@@ -0,0 +1,19 @@
+package adapter.before.security;
+
+public class LoginHandler {
+
+    UserDetailsService userDetailsService;
+
+    public LoginHandler(UserDetailsService userDetailsService) {
+        this.userDetailsService = userDetailsService;
+    }
+
+    public String login(String username, String password) {
+        UserDetails userDetails = userDetailsService.loadUser(username);
+        if (userDetails.getPassword().equals(password)) {
+            return userDetails.getUsername();
+        } else {
+            throw new IllegalArgumentException();
+        }
+    }
+}
diff --git a/design-pattern/gof/src/adapter/before/security/UserDetails.java b/design-pattern/gof/src/adapter/before/security/UserDetails.java
new file mode 100644
index 00000000..0d99e9ee
--- /dev/null
+++ b/design-pattern/gof/src/adapter/before/security/UserDetails.java
@@ -0,0 +1,9 @@
+package adapter.before.security;
+
+public interface UserDetails {
+
+    String getUsername();
+
+    String getPassword();
+
+}
diff --git a/design-pattern/gof/src/adapter/before/security/UserDetailsService.java b/design-pattern/gof/src/adapter/before/security/UserDetailsService.java
new file mode 100644
index 00000000..c13feb90
--- /dev/null
+++ b/design-pattern/gof/src/adapter/before/security/UserDetailsService.java
@@ -0,0 +1,7 @@
+package adapter.before.security;
+
+public interface UserDetailsService {
+
+    UserDetails loadUser(String username);
+
+}