Chapter 7: Libraries & Tools

1 Composer in Depth

Composer is the dependency management tool for PHP and the cornerstone of the entire modern PHP ecosystem. It handles downloading and installing third-party packages and automatically generates autoload files.

Common Commands

# 初始化项目（交互式生成 composer.json）
composer init

# 安装一个包（自动写入 composer.json 并下载）
composer require guzzlehttp/guzzle

# 安装开发依赖（仅开发环境使用）
composer require --dev phpunit/phpunit

# 根据 composer.lock 安装所有依赖（部署时使用）
composer install

# 更新依赖到最新兼容版本
composer update

# 更新 autoload 映射（添加新类后）
composer dump-autoload

composer.json Structure

{
    "name": "myvendor/myproject",
    "description": "我的 PHP 项目",
    "type": "project",
    "require": {
        "php": ">=8.4",
        "guzzlehttp/guzzle": "^7.8",
        "monolog/monolog": "^3.0",
        "nesbot/carbon": "~3.0"
    },
    "require-dev": {
        "phpunit/phpunit": "^11.0"
    },
    "autoload": {
        "psr-4": {
            "App\\": "src/"
        }
    },
    "autoload-dev": {
        "psr-4": {
            "Tests\\": "tests/"
        }
    }
}

Version Constraints

PSR-4 Autoloading

After configuring autoload.psr-4, you only need to include vendor/autoload.php and all classes will be autoloaded:

<?php
// 项目入口文件
require __DIR__ . '/vendor/autoload.php';

// 直接使用，无需手动 require 每个文件
use App\Services\UserService;
use App\Models\User;

$service = new UserService();
$user = $service->findById(1);

Directory mapping: namespace App\Services\UserService maps to file src/Services/UserService.php.

2 Guzzle — HTTP Client

Guzzle is the most popular HTTP client library for PHP, providing a clean API for sending HTTP requests, handling responses, and supporting async concurrency.

composer require guzzlehttp/guzzle

Basic Usage

<?php
require 'vendor/autoload.php';

use GuzzleHttp\Client;
use GuzzleHttp\Exception\RequestException;

$client = new Client([
    'base_uri' => 'https://api.example.com',
    'timeout'  => 5.0,
]);

// GET 请求
$response = $client->get('/users', [
    'query' => ['page' => 1, 'limit' => 10],
    'headers' => [
        'Authorization' => 'Bearer ' . $token,
        'Accept' => 'application/json',
    ],
]);

$statusCode = $response->getStatusCode();        // 200
$body = json_decode($response->getBody(), true);  // 解析 JSON

// POST 请求（发送 JSON）
$response = $client->post('/users', [
    'json' => [
        'name'  => '张三',
        'email' => 'zhangsan@example.com',
    ],
]);

// POST 表单数据
$response = $client->post('/login', [
    'form_params' => [
        'username' => 'admin',
        'password' => 'secret',
    ],
]);

Exception Handling

<?php
try {
    $response = $client->get('/users/999');
} catch (RequestException $e) {
    if ($e->hasResponse()) {
        $error = json_decode($e->getResponse()->getBody(), true);
        echo "错误: " . $error['message'];
    } else {
        echo "请求失败: " . $e->getMessage();
    }
}

Async Requests

<?php
use GuzzleHttp\Promise\Utils;

$promises = [
    'users'    => $client->getAsync('/users'),
    'products' => $client->getAsync('/products'),
    'orders'   => $client->getAsync('/orders'),
];

// 并发执行所有请求
$results = Utils::unwrap($promises);

$users    = json_decode($results['users']->getBody(), true);
$products = json_decode($results['products']->getBody(), true);
$orders   = json_decode($results['orders']->getBody(), true);

3 Monolog — Logging Library

Monolog is the standard logging library for PHP (following the PSR-3 interface), supporting output to files, databases, Slack, email, and many other targets. Frameworks like Laravel and Symfony include Monolog by default.

composer require monolog/monolog

Basic Usage

<?php
require 'vendor/autoload.php';

use Monolog\Logger;
use Monolog\Handler\StreamHandler;
use Monolog\Handler\RotatingFileHandler;
use Monolog\Formatter\LineFormatter;

// 创建日志通道
$log = new Logger('app');

// Handler 1：所有日志写入文件
$log->pushHandler(new StreamHandler(__DIR__ . '/logs/app.log', Logger::DEBUG));

// Handler 2：错误日志单独归档，按天轮转，保留 30 天
$errorHandler = new RotatingFileHandler(
    __DIR__ . '/logs/error.log',
    30,              // 保留天数
    Logger::ERROR    // 最低记录级别
);
$log->pushHandler($errorHandler);

// 写入日志
$log->debug('调试信息', ['module' => 'auth']);
$log->info('用户登录成功', ['user_id' => 42]);
$log->warning('缓存命中率低', ['rate' => 0.35]);
$log->error('数据库连接失败', ['host' => 'db.example.com']);
$log->critical('支付网关无响应');

Log Levels (Low to High)

Custom Formatting

<?php
$formatter = new LineFormatter(
    "[%datetime%] %channel%.%level_name%: %message% %context%\n",
    'Y-m-d H:i:s'
);

$handler = new StreamHandler(__DIR__ . '/logs/app.log', Logger::DEBUG);
$handler->setFormatter($formatter);

$log = new Logger('app');
$log->pushHandler($handler);
// 输出: [2026-03-31 10:30:00] app.INFO: 用户登录成功 {"user_id":42}

4 Carbon — Date & Time

Carbon is an enhanced wrapper around PHP's DateTime, providing an extremely fluent API for date and time handling. It comes integrated by default in Laravel.

composer require nesbot/carbon

Creating & Formatting

<?php
require 'vendor/autoload.php';

use Carbon\Carbon;

// 创建实例
$now = Carbon::now();                         // 当前时间
$today = Carbon::today();                     // 今天 00:00:00
$date = Carbon::create(2026, 3, 31, 10, 30);  // 指定时间
$parsed = Carbon::parse('2026-03-31 10:30:00');

// 格式化输出
echo $now->format('Y-m-d H:i:s');   // 2026-03-31 10:30:00
echo $now->toDateString();           // 2026-03-31
echo $now->toDateTimeString();       // 2026-03-31 10:30:00
echo $now->isoFormat('YYYY年MM月DD日'); // 2026年03月31日

Date Arithmetic

<?php
$now = Carbon::now();

// 加减运算
$tomorrow = $now->copy()->addDay();
$nextWeek = $now->copy()->addWeek();
$lastMonth = $now->copy()->subMonth();
$future = $now->copy()->addDays(45)->addHours(3);

// 链式操作
$deadline = Carbon::parse('2026-12-31')
    ->subDays(7)
    ->startOfDay();   // 2026-12-24 00:00:00

Comparison & Differences

<?php
$start = Carbon::parse('2026-01-01');
$end = Carbon::parse('2026-03-31');

echo $start->diffInDays($end);        // 89
echo $start->diffInMonths($end);      // 2
echo $start->diffForHumans($end);     // "2个月前"

// 布尔判断
$date = Carbon::parse('2026-03-31');
$date->isWeekday();     // true
$date->isToday();       // true (假设今天是 3/31)
$date->isFuture();      // false
$date->isPast();        // false
$date->isLeapYear();    // false

// 比较
$a = Carbon::parse('2026-01-01');
$b = Carbon::parse('2026-06-01');
$a->lt($b);   // true (less than)
$a->gte($b);  // false (greater than or equal)

Timezone Handling

<?php
$beijing = Carbon::now('Asia/Shanghai');
$newYork = $beijing->copy()->setTimezone('America/New_York');

echo $beijing->format('Y-m-d H:i');   // 2026-03-31 22:30
echo $newYork->format('Y-m-d H:i');   // 2026-03-31 10:30

5 PHPUnit — Unit Testing

PHPUnit is the de facto standard testing framework for PHP, supporting unit testing, mocking, code coverage, and more.

# 安装为开发依赖
composer require --dev phpunit/phpunit

# 运行测试
./vendor/bin/phpunit

phpunit.xml Configuration

<?xml version="1.0" encoding="UTF-8"?>
<phpunit bootstrap="vendor/autoload.php"
         colors="true"
         stopOnFailure="false">
    <testsuites>
        <testsuite name="Unit">
            <directory>tests</directory>
        </testsuite>
    </testsuites>
    <source>
        <include>
            <directory>src</directory>
        </include>
    </source>
</phpunit>

Writing Test Classes

<?php
// tests/CalculatorTest.php
namespace Tests;

use PHPUnit\Framework\TestCase;
use App\Calculator;

class CalculatorTest extends TestCase
{
    private Calculator $calc;

    // 每个测试方法执行前调用
    protected function setUp(): void
    {
        $this->calc = new Calculator();
    }

    // 每个测试方法执行后调用
    protected function tearDown(): void
    {
        // 清理资源（如果需要）
    }

    public function testAdd(): void
    {
        $this->assertEquals(5, $this->calc->add(2, 3));
        $this->assertEquals(0, $this->calc->add(-1, 1));
    }

    public function testDivide(): void
    {
        $this->assertEquals(2.5, $this->calc->divide(5, 2));
    }

    public function testDivideByZeroThrowsException(): void
    {
        $this->expectException(\InvalidArgumentException::class);
        $this->expectExceptionMessage('除数不能为零');
        $this->calc->divide(10, 0);
    }
}

Common Assertions

<?php
// 相等性
$this->assertEquals('hello', $result);     // 值相等（== 宽松比较）
$this->assertSame('hello', $result);       // 类型+值完全相同（===）

// 布尔
$this->assertTrue($user->isActive());
$this->assertFalse($user->isBanned());
$this->assertNull($user->deletedAt());

// 数组
$this->assertCount(3, $items);
$this->assertContains('admin', $roles);
$this->assertArrayHasKey('email', $data);
$this->assertEmpty($errors);

// 类型与实例
$this->assertInstanceOf(User::class, $result);
$this->assertIsString($name);
$this->assertIsArray($list);

// 字符串
$this->assertStringContainsString('error', $message);
$this->assertMatchesRegularExpression('/^\d{4}-\d{2}/', $date);

Data Providers

<?php
use PHPUnit\Framework\Attributes\DataProvider;

class MathTest extends TestCase
{
    public static function additionProvider(): array
    {
        return [
            '正数相加'   => [3, 4, 7],
            '负数相加'   => [-1, -2, -3],
            '零加任意数' => [0, 5, 5],
            '大数相加'   => [PHP_INT_MAX, 0, PHP_INT_MAX],
        ];
    }

    #[DataProvider('additionProvider')]
    public function testAdd(int $a, int $b, int $expected): void
    {
        $this->assertSame($expected, $a + $b);
    }
}

# 运行特定测试文件
./vendor/bin/phpunit tests/CalculatorTest.php

# 运行特定方法
./vendor/bin/phpunit --filter testAdd

# 显示详细输出
./vendor/bin/phpunit --testdox

6 vlucas/phpdotenv — Environment Variables

phpdotenv loads environment variables from a .env file, separating sensitive configuration (database passwords, API keys) from code.

composer require vlucas/phpdotenv

.env File Example

# .env（不要提交到 Git！加入 .gitignore）
APP_NAME=MyApp
APP_ENV=production
APP_DEBUG=false

DB_HOST=127.0.0.1
DB_PORT=3306
DB_DATABASE=myapp
DB_USERNAME=root
DB_PASSWORD=secret

REDIS_HOST=127.0.0.1
API_KEY=sk-xxxxxxxxxxxx

Loading & Usage

<?php
require 'vendor/autoload.php';

// 加载 .env 文件（通常在应用入口处执行一次）
$dotenv = Dotenv\Dotenv::createImmutable(__DIR__);
$dotenv->load();

// 必须存在的变量（缺少则抛异常）
$dotenv->required(['DB_HOST', 'DB_DATABASE', 'DB_USERNAME']);

// 读取环境变量（三种方式）
$dbHost = $_ENV['DB_HOST'];               // 推荐
$dbHost = $_SERVER['DB_HOST'];            // 也可以
$dbHost = getenv('DB_HOST');              // 传统方式

// 实际使用
$dsn = sprintf(
    'mysql:host=%s;port=%s;dbname=%s;charset=utf8mb4',
    $_ENV['DB_HOST'],
    $_ENV['DB_PORT'],
    $_ENV['DB_DATABASE']
);

$pdo = new PDO($dsn, $_ENV['DB_USERNAME'], $_ENV['DB_PASSWORD']);

Best Practices

7 Other Recommended Libraries

The PHP ecosystem has many high-quality libraries. Here are some frequently used in real projects:

Quick Examples

<?php
// ramsey/uuid - 生成 UUID
use Ramsey\Uuid\Uuid;

$uuid = Uuid::uuid4()->toString();  // "550e8400-e29b-41d4-a716-446655440000"
$uuid7 = Uuid::uuid7()->toString(); // 时间排序的 UUID v7

// respect/validation - 数据验证
use Respect\Validation\Validator as v;

$valid = v::email()->validate('user@example.com');          // true
$valid = v::stringType()->length(2, 50)->validate('张三');   // true
$valid = v::numericVal()->between(1, 100)->validate(42);    // true

// predis/predis - Redis 操作
$redis = new Predis\Client(['host' => '127.0.0.1']);
$redis->set('user:1:name', '张三');
$redis->expire('user:1:name', 3600);
$name = $redis->get('user:1:name'); // "张三"

8 PHP Framework Overview

After mastering PHP fundamentals, choosing a framework can dramatically boost development efficiency. Here are the three most popular frameworks today:

Quick Project Creation

# Laravel
composer create-project laravel/laravel my-app
cd my-app && php artisan serve   # 启动开发服务器 http://localhost:8000

# Symfony
composer create-project symfony/skeleton my-app
cd my-app && symfony server:start

# Slim
composer require slim/slim slim/psr7

Slim Micro-Framework Example

<?php
// public/index.php
require __DIR__ . '/../vendor/autoload.php';

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

$app = AppFactory::create();
$app->addErrorMiddleware(true, true, true);

$app->get('/', function (Request $request, Response $response) {
    $response->getBody()->write(json_encode(['message' => '你好，PHP！']));
    return $response->withHeader('Content-Type', 'application/json');
});

$app->get('/users/{id}', function (Request $request, Response $response, array $args) {
    $userId = $args['id'];
    $response->getBody()->write(json_encode(['id' => $userId]));
    return $response->withHeader('Content-Type', 'application/json');
});

$app->run();

9 Chapter Summary