PHP for Java Developers: Chapters 8-22 Summary

This document provides comprehensive outlines for chapters 8-22. Each outline covers the essential concepts Java developers need to understand when learning PHP.

Part 3: Modern PHP Development

Chapter 8: Composer & Dependencies

Key Topics:

Composer Overview: PHP's dependency manager (like Maven/Gradle)
composer.json: Project configuration file (like pom.xml)
Installing Packages: composer require vendor/package
Autoloading: PSR-4 automatic class loading
Lock Files: composer.lock ensures consistent dependencies
Semantic Versioning: Understanding version constraints
Common Packages: monolog/monolog, guzzlehttp/guzzle, symfony/http-foundation

Java Comparison:

xml

<!-- Maven pom.xml -->
<dependencies>
  <dependency>
    <groupId>com.example</groupId>
    <artifactId>library</artifactId>
    <version>1.0.0</version>
  </dependency>
</dependencies>

json

// Composer composer.json
{
  "require": {
    "vendor/library": "^1.0"
  }
}

Essential Commands:

bash

composer install      # Install dependencies (like mvn install)
composer update       # Update dependencies
composer require pkg  # Add new dependency
composer dump-autoload # Regenerate autoloader

Chapter 9: Working with Databases

Key Topics:

PDO (PHP Data Objects): Database abstraction layer (like JDBC)
Database Connections: DSN strings and connection management
Prepared Statements: SQL injection prevention
Query Execution: SELECT, INSERT, UPDATE, DELETE
Transactions: BEGIN, COMMIT, ROLLBACK
Query Builders: Fluent interfaces for SQL
Eloquent ORM: Laravel's ActiveRecord implementation

Java JDBC vs PHP PDO:

java

// Java JDBC
Connection conn = DriverManager.getConnection(url, user, pass);
PreparedStatement stmt = conn.prepareStatement("SELECT * FROM users WHERE id = ?");
stmt.setInt(1, userId);
ResultSet rs = stmt.executeQuery();

php

// PHP PDO
$pdo = new PDO($dsn, $user, $pass);
$stmt = $pdo->prepare("SELECT * FROM users WHERE id = ?");
$stmt->execute([$userId]);
$user = $stmt->fetch(PDO::FETCH_ASSOC);

Best Practices:

Always use prepared statements
Never concatenate user input into SQL
Use transactions for multiple related operations
Close connections in finally blocks
Use connection pooling for performance

Chapter 10: Building REST APIs

Key Topics:

RESTful Principles: Resources, HTTP methods, status codes
Routing: Mapping URLs to controllers
JSON Responses: Encoding/decoding data
Request Validation: Input sanitization and validation
Authentication: JWT tokens, API keys
Error Handling: Consistent error responses
CORS: Cross-origin resource sharing
API Versioning: URL-based or header-based

Simple PHP REST API:

php

<?php
// GET /api/users
if ($_SERVER['REQUEST_METHOD'] === 'GET') {
    header('Content-Type: application/json');
    echo json_encode(['users' => $users]);
}

// POST /api/users
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    $data = json_decode(file_get_contents('php://input'), true);
    // Create user
    http_response_code(201);
    echo json_encode(['user' => $newUser]);
}

Status Codes:

200 OK - Success
201 Created - Resource created
400 Bad Request - Invalid input
401 Unauthorized - Authentication required
404 Not Found - Resource doesn't exist
500 Internal Server Error - Server error

Chapter 11: Dependency Injection

Key Topics:

DI Containers: Automatic dependency management
Constructor Injection: Preferred method
Service Providers: Registering services
Autowiring: Automatic dependency resolution
PHP-DI Library: Popular DI container
Symfony DI: Enterprise-grade container

Spring DI vs PHP DI:

java

// Java Spring
@Autowired
private UserRepository repository;

@Component
public class UserService {
    private final UserRepository repository;

    @Autowired
    public UserService(UserRepository repository) {
        this.repository = repository;
    }
}

php

// PHP DI Container
class UserService {
    public function __construct(
        private UserRepository $repository
    ) {}
}

// Container configuration
$container->set(UserRepository::class, function() {
    return new UserRepository($pdo);
});

Part 4: Testing & Quality

Chapter 12: Unit Testing with PHPUnit

Key Topics:

PHPUnit Installation: composer require --dev phpunit/phpunit
Test Classes: Extending TestCase
Assertions: assertEquals, assertTrue, assertSame
Test Methods: Must start with test or use @test annotation
Setup/Teardown: setUp(), tearDown() methods
Mocking: Creating test doubles
Code Coverage: Measuring test effectiveness

JUnit vs PHPUnit:

java

// JUnit
import org.junit.Test;
import static org.junit.Assert.*;

public class CalculatorTest {
    @Test
    public void testAdd() {
        Calculator calc = new Calculator();
        assertEquals(5, calc.add(2, 3));
    }
}

php

// PHPUnit
use PHPUnit\Framework\TestCase;

class CalculatorTest extends TestCase
{
    public function testAdd(): void
    {
        $calc = new Calculator();
        $this->assertEquals(5, $calc->add(2, 3));
    }
}

Running Tests:

bash

./vendor/bin/phpunit tests/      # Run all tests
./vendor/bin/phpunit --coverage-html coverage/  # With coverage

Chapter 13: Integration Testing

Key Topics:

Database Testing: Using test databases
Test Fixtures: Setting up test data
API Testing: Testing HTTP endpoints
Test Isolation: Each test is independent
Factories: Generating test data
Seeders: Populating test database
CI/CD Integration: GitHub Actions, GitLab CI

Test Database Setup:

php

class DatabaseTest extends TestCase
{
    protected function setUp(): void
    {
        // Create test database connection
        $this->pdo = new PDO('sqlite::memory:');
        $this->pdo->exec('CREATE TABLE users ...');
    }

    protected function tearDown(): void
    {
        // Clean up
        $this->pdo = null;
    }
}

Chapter 14: Code Quality Tools

Key Topics:

PHPStan: Static analysis (like SpotBugs for Java)
Psalm: Another static analyzer
PHP_CodeSniffer: Style checker (like Checkstyle)
PHP CS Fixer: Auto-format code
PHPMD: Mess detector (like PMD)
Git Hooks: Pre-commit checks
CI Pipeline: Automated quality checks

PHPStan Example:

bash

composer require --dev phpstan/phpstan
./vendor/bin/phpstan analyse src

Configuration:

neon

# phpstan.neon
parameters:
    level: 8  # Maximum strictness
    paths:
        - src
        - tests

Part 5: Web Development

Chapter 15: HTTP & Request/Response

Key Topics:

Superglobals: $_GET, $_POST, $_SERVER, $_COOKIE, $_SESSION
Request Method: $_SERVER['REQUEST_METHOD']
Headers: header() function
PSR-7: HTTP message interfaces
Middleware: Request/response pipeline
Query Parameters: Parse $_GET array
POST Data: Parse $_POST or php://input

Superglobals vs Java Servlets:

java

// Java Servlet
String name = request.getParameter("name");
String method = request.getMethod();
String userAgent = request.getHeader("User-Agent");

php

// PHP Superglobals
$name = $_GET['name'] ?? '';
$method = $_SERVER['REQUEST_METHOD'];
$userAgent = $_SERVER['HTTP_USER_AGENT'];

Chapter 16: Sessions & Authentication

Key Topics:

Session Start: session_start()
Session Variables: $_SESSION array
Session Security: Regenerate IDs, secure cookies
JWT Authentication: Stateless tokens
OAuth2: Third-party authentication
Password Hashing: password_hash(), password_verify()
Remember Me: Persistent login
CSRF Protection: Token verification

Session Management:

php

// Start session
session_start();

// Store data
$_SESSION['user_id'] = $userId;
$_SESSION['username'] = $username;

// Retrieve data
$userId = $_SESSION['user_id'] ?? null;

// Destroy session
session_destroy();

Password Hashing:

php

// Hash password (never store plain text!)
$hash = password_hash($password, PASSWORD_ARGON2ID);

// Verify password
if (password_verify($inputPassword, $hash)) {
    // Login successful
}

Chapter 17: Forms & Validation

Key Topics:

Form Handling: Processing $_POST data
Input Validation: filter_var(), custom validators
Sanitization: htmlspecialchars(), strip_tags()
CSRF Tokens: Preventing cross-site request forgery
File Uploads: $_FILES array, move_uploaded_file()
Form Libraries: Symfony Form, Laravel Validation
Client-side Validation: HTML5 + JavaScript

Form Processing:

php

if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    // Validate
    $email = filter_var($_POST['email'], FILTER_VALIDATE_EMAIL);
    if (!$email) {
        $errors['email'] = 'Invalid email';
    }

    // Sanitize
    $name = htmlspecialchars($_POST['name'], ENT_QUOTES);

    // CSRF Check
    if ($_POST['csrf_token'] !== $_SESSION['csrf_token']) {
        die('CSRF token mismatch');
    }

    if (empty($errors)) {
        // Process form
    }
}

Chapter 18: Security Best Practices

Key Topics:

SQL Injection: Always use prepared statements
XSS Prevention: Escape output with htmlspecialchars()
CSRF Protection: Use tokens for state-changing operations
Password Security: Use password_hash() with strong algorithms
Session Security: Secure cookies, regenerate IDs
Input Validation: Never trust user input
HTTPS: Always use TLS/SSL
Security Headers: Content-Security-Policy, X-Frame-Options
File Upload Security: Validate MIME types, restrict extensions

Essential Security Checklist:

php

// ✅ SQL Injection Prevention
$stmt = $pdo->prepare("SELECT * FROM users WHERE email = ?");
$stmt->execute([$email]);

// ✅ XSS Prevention
echo htmlspecialchars($userInput, ENT_QUOTES, 'UTF-8');

// ✅ CSRF Prevention
if ($_POST['csrf_token'] !== $_SESSION['csrf_token']) {
    die('Invalid CSRF token');
}

// ✅ Password Hashing
$hash = password_hash($password, PASSWORD_ARGON2ID);

// ✅ Secure Session Cookies
session_set_cookie_params([
    'lifetime' => 0,
    'path' => '/',
    'domain' => '',
    'secure' => true,  // HTTPS only
    'httponly' => true,  // No JavaScript access
    'samesite' => 'Strict'
]);

Part 6: Frameworks & Beyond

Chapter 19: Framework Comparison

Comparing PHP Frameworks to Java:

PHP Framework	Java Equivalent	Use Case
Laravel	Spring Boot	Full-stack web applications
Symfony	Java EE/Spring	Enterprise applications
Slim	Spark/Javalin	Microservices/APIs
Laminas	Java EE	Enterprise/Legacy

Laravel vs Spring Boot:

Routing: Similar annotation-based routing
ORM: Eloquent vs JPA/Hibernate
DI: Built-in vs Spring DI
Templates: Blade vs Thymeleaf
CLI: Artisan vs Spring CLI

When to Choose:

Laravel: Rapid development, full-stack apps
Symfony: Large enterprise projects, reusable components
Slim: Microservices, REST APIs
Laravel + Vue: Modern SPA applications

Chapter 20: Laravel Fundamentals

Key Topics:

Installation: composer create-project laravel/laravel myapp
Artisan CLI: Laravel's command-line tool
Routing: Route::get(), Route::post()
Controllers: MVC pattern
Eloquent ORM: ActiveRecord implementation
Blade Templates: Template engine
Migrations: Database versioning
Middleware: HTTP request pipeline
Authentication: Built-in auth scaffolding
Testing: PHPUnit integration

Quick Start:

bash

# Create project
composer create-project laravel/laravel blog

# Run development server
php artisan serve

# Create migration
php artisan make:migration create_users_table

# Create model
php artisan make:model User

# Create controller
php artisan make:controller UserController

Laravel vs Spring Boot Structure:

Laravel:                  Spring Boot:
app/                     src/main/java/
├── Models/              ├── domain/
├── Controllers/         ├── controller/
└── Services/            └── service/
routes/
├── web.php              @RequestMapping
database/
├── migrations/          db/migration/
resources/
└── views/               templates/

Chapter 21: Symfony Components

Key Topics:

Component Architecture: Standalone, reusable components
HttpFoundation: Request/Response abstraction
Routing: Flexible routing system
Console: CLI application framework
Dependency Injection: Powerful DI container
Event Dispatcher: Event-driven architecture
Symfony Flex: Project setup and recipes
Doctrine ORM: Database abstraction

Using Symfony Components:

php

// HttpFoundation
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;

$request = Request::createFromGlobals();
$name = $request->query->get('name', 'World');

$response = new Response("Hello, $name!");
$response->send();

// Routing
use Symfony\Component\Routing\Route;
use Symfony\Component\Routing\RouteCollection;

$routes = new RouteCollection();
$routes->add('home', new Route('/', ['_controller' => 'HomeController']));

Symfony vs Java EE:

Both are component-based
Strong DI containers
Event-driven architectures
Enterprise-grade features
Extensive ecosystems

Chapter 22: Micro-frameworks (Slim)

Key Topics:

Slim Framework: Lightweight PHP framework
PSR-7 Support: HTTP message interfaces
Routing: Simple route definitions
Middleware: Request/response pipeline
Dependency Injection: Built-in container
Performance: Minimal overhead
Use Cases: APIs, microservices, small apps

Slim vs Laravel/Symfony:

Size: Much smaller footprint
Features: Fewer built-in features
Flexibility: More control over architecture
Learning Curve: Easier to learn
Performance: Faster for simple applications

Quick Example:

php

<?php
use Slim\Factory\AppFactory;
use Psr\Http\Message\ResponseInterface as Response;
use Psr\Http\Message\ServerRequestInterface as Request;

$app = AppFactory::create();

// Define routes
$app->get('/hello/{name}', function (Request $request, Response $response, array $args) {
    $name = $args['name'];
    $response->getBody()->write("Hello, $name");
    return $response;
});

$app->get('/api/users', function (Request $request, Response $response) {
    $users = getUsersFromDatabase();
    $response->getBody()->write(json_encode($users));
    return $response->withHeader('Content-Type', 'application/json');
});

$app->run();

When to Use Slim:

Building REST APIs
Microservices architecture
Learning PHP frameworks
Projects where Laravel/Symfony is overkill
Need maximum control over architecture
Performance-critical applications

Series Summary

Congratulations on completing the PHP for Java Developers series! You now have a comprehensive understanding of:

Core PHP:

Syntax and language features
Object-oriented programming
Namespaces and autoloading
Error handling

Modern Development:

Composer dependency management
Database access with PDO
Building REST APIs
Dependency injection

Quality & Testing:

Unit testing with PHPUnit
Integration testing
Code quality tools

Web Development:

HTTP request/response handling
Sessions and authentication
Form processing and validation
Security best practices

Frameworks:

Laravel for full-stack applications
Symfony for enterprise projects
Slim for microservices and APIs

Next Steps:

Build a complete project using what you've learned
Explore the Laravel or Symfony documentation
Contribute to open-source PHP projects
Join the PHP community (forums, conferences, meetups)
Keep learning about PHP 8.x features and improvements

Resources:

Thank you for following this series. Happy coding in PHP! 🐘

PHP for Java Developers: Chapters 8-22 Summary ​

Part 3: Modern PHP Development ​

Chapter 8: Composer & Dependencies ​

Chapter 9: Working with Databases ​

Chapter 10: Building REST APIs ​

Chapter 11: Dependency Injection ​

Part 4: Testing & Quality ​

Chapter 12: Unit Testing with PHPUnit ​

Chapter 13: Integration Testing ​

Chapter 14: Code Quality Tools ​

Part 5: Web Development ​

Chapter 15: HTTP & Request/Response ​

Chapter 16: Sessions & Authentication ​

Chapter 17: Forms & Validation ​

Chapter 18: Security Best Practices ​

Part 6: Frameworks & Beyond ​

Chapter 19: Framework Comparison ​

Chapter 20: Laravel Fundamentals ​

Chapter 21: Symfony Components ​

Chapter 22: Micro-frameworks (Slim) ​

Series Summary ​

PHP for Java Developers: Chapters 8-22 Summary

Part 3: Modern PHP Development

Chapter 8: Composer & Dependencies

Chapter 9: Working with Databases

Chapter 10: Building REST APIs

Chapter 11: Dependency Injection

Part 4: Testing & Quality

Chapter 12: Unit Testing with PHPUnit

Chapter 13: Integration Testing

Chapter 14: Code Quality Tools

Part 5: Web Development

Chapter 15: HTTP & Request/Response

Chapter 16: Sessions & Authentication

Chapter 17: Forms & Validation

Chapter 18: Security Best Practices

Part 6: Frameworks & Beyond

Chapter 19: Framework Comparison

Chapter 20: Laravel Fundamentals

Chapter 21: Symfony Components

Chapter 22: Micro-frameworks (Slim)

Series Summary