How do I secure a Java web application with authentication and authorization?

By I Wayan Saryada in Spring Security 0 Comment

Securing a Java web application typically means adding:

  1. Authentication — verifying who the user is.
  2. Authorization — deciding what the authenticated user can access.
  3. Session/token protection — keeping the login state secure.
  4. Transport and application hardening — HTTPS, CSRF protection, password hashing, etc.

Since your stack includes Spring MVC / Spring Data JPA / Jakarta EE, the most common approach is Spring Security.

1. Add Spring Security

If you use Maven:

<dependency>
    <groupId>org.springframework.security</groupId>
    <artifactId>spring-security-web</artifactId>
</dependency>

<dependency>
    <groupId>org.springframework.security</groupId>
    <artifactId>spring-security-config</artifactId>
</dependency>

If this is a Spring Boot app, use:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-security</artifactId>
</dependency>

2. Create a Security Configuration

For modern Spring Security, define a SecurityFilterChain.

package com.example.security;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.web.SecurityFilterChain;

@Configuration
public class SecurityConfig {

    @Bean
    public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
        return http
                .authorizeHttpRequests(auth -> auth
                        .requestMatchers("/", "/login", "/css/**", "/js/**").permitAll()
                        .requestMatchers("/admin/**").hasRole("ADMIN")
                        .requestMatchers("/user/**").hasAnyRole("USER", "ADMIN")
                        .anyRequest().authenticated()
                )
                .formLogin(form -> form
                        .loginPage("/login")
                        .defaultSuccessUrl("/dashboard", true)
                        .permitAll()
                )
                .logout(logout -> logout
                        .logoutUrl("/logout")
                        .logoutSuccessUrl("/")
                        .invalidateHttpSession(true)
                        .deleteCookies("JSESSIONID")
                )
                .build();
    }
}

This configuration means:

URL Access
/, /login, static files Public
/user/** USER or ADMIN
/admin/** ADMIN only
Everything else Must be logged in

3. Store Users in the Database

A simple JPA entity could look like this:

package com.example.user;

import jakarta.persistence.CollectionTable;
import jakarta.persistence.ElementCollection;
import jakarta.persistence.Entity;
import jakarta.persistence.FetchType;
import jakarta.persistence.Id;
import jakarta.persistence.JoinColumn;
import jakarta.persistence.Table;
import lombok.Getter;
import lombok.Setter;

import java.util.Set;

@Entity
@Table(name = "app_users")
@Getter
@Setter
public class User {

    @Id
    private Long id;

    private String username;

    private String password;

    private boolean enabled = true;

    @ElementCollection(fetch = FetchType.EAGER)
    @CollectionTable(
            name = "app_user_roles",
            joinColumns = @JoinColumn(name = "user_id")
    )
    private Set<String> roles;
}

Example roles:

ROLE_USER
ROLE_ADMIN

Spring Security’s hasRole("ADMIN") checks for ROLE_ADMIN internally.

4. Create a Repository

package com.example.user;

import org.springframework.data.jpa.repository.JpaRepository;

import java.util.Optional;

public interface UserRepository extends JpaRepository<User, Long> {

    Optional<User> findByUsername(String username);
}

5. Implement UserDetailsService

Spring Security uses UserDetailsService to load users during login.

package com.example.security;

import com.example.user.User;
import com.example.user.UserRepository;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.core.userdetails.UsernameNotFoundException;

public class DatabaseUserDetailsService implements UserDetailsService {

    private final UserRepository userRepository;

    public DatabaseUserDetailsService(UserRepository userRepository) {
        this.userRepository = userRepository;
    }

    @Override
    public UserDetails loadUserByUsername(String username) {
        User user = userRepository.findByUsername(username)
                .orElseThrow(() -> new UsernameNotFoundException(username));

        return org.springframework.security.core.userdetails.User
                .withUsername(user.getUsername())
                .password(user.getPassword())
                .authorities(user.getRoles().toArray(String[]::new))
                .disabled(!user.isEnabled())
                .build();
    }
}

Register it as a bean:

@Bean
public UserDetailsService userDetailsService(UserRepository userRepository) {
    return new DatabaseUserDetailsService(userRepository);
}

6. Hash Passwords with BCrypt

Never store plain-text passwords.

import org.springframework.context.annotation.Bean;
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
import org.springframework.security.crypto.password.PasswordEncoder;

@Bean
public PasswordEncoder passwordEncoder() {
    return new BCryptPasswordEncoder();
}

When registering a user:

user.setPassword(passwordEncoder.encode(rawPassword));

A stored password should look similar to:

$2a$10$...

7. Add Method-Level Authorization

You can also secure service methods.

Enable method security:

import org.springframework.context.annotation.Configuration;
import org.springframework.security.config.annotation.method.configuration.EnableMethodSecurity;

@Configuration
@EnableMethodSecurity
public class MethodSecurityConfig {
}

Then protect methods:

import org.springframework.security.access.prepost.PreAuthorize;
import org.springframework.stereotype.Service;

@Service
public class ReportService {

    @PreAuthorize("hasRole('ADMIN')")
    public void deleteReport(Long reportId) {
        // admin-only logic
    }

    @PreAuthorize("hasAnyRole('USER', 'ADMIN')")
    public Object viewReport(Long reportId) {
        // user/admin logic
        return new Object();
    }
}

8. Protect Against CSRF

For browser-based apps using sessions and forms, keep CSRF enabled.

Spring Security enables CSRF by default.

In a Thymeleaf form, include the CSRF token:

<form method="post" action="/profile">
    <input type="hidden"
           name="${_csrf.parameterName}"
           value="${_csrf.token}" />

    <button type="submit">Save</button>
</form>

For JSP:

<input type="hidden"
       name="${_csrf.parameterName}"
       value="${_csrf.token}" />

For stateless REST APIs using JWT, CSRF is often disabled because the API does not rely on cookies for authentication.

9. Use HTTPS

Always run authentication over HTTPS.

For production:

server.ssl.enabled=true
server.ssl.key-store=classpath:keystore.p12
server.ssl.key-store-password=changeit
server.ssl.key-store-type=PKCS12
server.ssl.key-alias=myapp

If your app is behind a reverse proxy, configure forwarded headers correctly so Spring knows the original request was HTTPS.

server.forward-headers-strategy=framework

10. Use Secure Session Cookies

Configure cookies as secure and HTTP-only.

server.servlet.session.cookie.http-only=true
server.servlet.session.cookie.secure=true
server.servlet.session.cookie.same-site=lax

Use same-site=strict if your app does not require cross-site navigation flows.

11. Example REST API Authorization

For controller endpoints:

import org.springframework.security.access.prepost.PreAuthorize;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class AdminController {

    @GetMapping("/admin/stats")
    @PreAuthorize("hasRole('ADMIN')")
    public String stats() {
        return "admin stats";
    }
}

Or configure URL-based access:

.requestMatchers("/api/admin/**").hasRole("ADMIN")
.requestMatchers("/api/user/**").hasAnyRole("USER", "ADMIN")

12. JWT Option for Stateless APIs

If your frontend is separate, such as React, Angular, mobile, or another client, you may use JWT or OAuth2.

Typical setup:

.oauth2ResourceServer(oauth2 -> oauth2.jwt())

Then secure routes:

.authorizeHttpRequests(auth -> auth
        .requestMatchers("/api/public/**").permitAll()
        .requestMatchers("/api/admin/**").hasRole("ADMIN")
        .anyRequest().authenticated()
)

For production, prefer a standards-based identity provider such as:

  • Keycloak
  • Auth0
  • Okta
  • Microsoft Entra ID
  • AWS Cognito

13. Important Security Checklist

Use this checklist before production:

  • Hash passwords with BCrypt, Argon2, or PBKDF2
  • Never store plain-text passwords
  • Use HTTPS only
  • Keep CSRF enabled for session-based browser apps
  • Use secure HTTP-only cookies
  • Validate all user inputs
  • Apply authorization in the service layer for sensitive business operations
  • Avoid exposing stack traces or internal errors
  • Lock down admin endpoints
  • Use least-privilege roles
  • Add audit logging for sensitive actions
  • Rate-limit login attempts
  • Use MFA for admin users
  • Keep dependencies updated
  • Add security headers
  • Do not put secrets in source code

Minimal Spring Security Setup

A compact working configuration could look like this:

package com.example.security;

import com.example.user.UserRepository;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.config.annotation.method.configuration.EnableMethodSecurity;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
import org.springframework.security.crypto.password.PasswordEncoder;
import org.springframework.security.web.SecurityFilterChain;

@Configuration
@EnableMethodSecurity
public class SecurityConfig {

    @Bean
    public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
        return http
                .authorizeHttpRequests(auth -> auth
                        .requestMatchers("/", "/login", "/css/**", "/js/**").permitAll()
                        .requestMatchers("/admin/**").hasRole("ADMIN")
                        .requestMatchers("/user/**").hasAnyRole("USER", "ADMIN")
                        .anyRequest().authenticated()
                )
                .formLogin(form -> form
                        .loginPage("/login")
                        .defaultSuccessUrl("/dashboard", true)
                        .permitAll()
                )
                .logout(logout -> logout
                        .logoutSuccessUrl("/")
                        .invalidateHttpSession(true)
                        .deleteCookies("JSESSIONID")
                )
                .build();
    }

    @Bean
    public UserDetailsService userDetailsService(UserRepository userRepository) {
        return new DatabaseUserDetailsService(userRepository);
    }

    @Bean
    public PasswordEncoder passwordEncoder() {
        return new BCryptPasswordEncoder();
    }
}

For most Java web applications, the recommended path is:

Spring Security + database-backed users + BCrypt password hashing + role-based authorization + HTTPS + CSRF protection.

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