使用 psr-4 自动加载

创建项目

1. 创建一个项目test,目录结构为：

引入 Composer

使用 composer init 命令创建 composer.json 文件

**

$ composer init
  Welcome to the Composer config generator
This command will guide you through creating your composer.json config.
Package name (<vendor>/<name>) [asus/test]: king/testproject
Description []: This is a test project
Author [yangyi <2497471389@qq.com>, n to skip]:
Minimum Stability []:
Package Type (e.g. library, project, metapackage, composer-plugin) []: project
License []: MIT
Define your dependencies.
Would you like to define your dependencies (require) interactively [yes]? n
Would you like to define your dev dependencies (require-dev) interactively [yes]? n
{
    "name": "king/testproject",
    "description": "This is a test project",
    "type": "project",
    "license": "MIT",
    "authors": [
        {
            "name": "yangyi",
            "email": "2497471389@qq.com"
        }
    ],
    "require": {}
}
Do you confirm generation [yes]? yes

在 composer.json 文件中加入 psr-4

**

{
    "name": "yangyi/laravel-teach",
    "description": "This is a yangyi project",
    "type": "library",
    "license": "MIT",
    "authors": [
        {
            "name": "yangyi",
            "email": "2497471389@qq.com"
        }
    ],
    "autoload":{
        "psr-4":{
            "yangyi\\app\\":"./src/"
        }
    },
    "require": {}
}

注意：yangyi\app 代表命名空间，./src/ 代表对应的目录

运行composer更新命令，它会把我们需要的文件都自动下载到 vendor 目录下

composer update

现在的目录结构

在 src 下建立一个文件 ./src/database/Mysql.php

<?php

namespace yangyi\app\database;

class Mysql{
    public function index(){
        return 'This is a mysql';
    }
}

在index.php 中 引入 ./vendor/autoload.php 就可以了

**

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

use yangyi\app\database\Mysql;

$mysql = new Mysql();

echo $mysql->index();

测试输出

This is a mysql