<?php
/**
 * 数据操作类
 */
class Request {
    //允许的请求方式
    private static $method_type = array('get', 'post', 'put', 'patch', 'delete');
    //测试数据
    private static $test_class = array(
        1 => array('name' => '托福班', 'count' => 18),
        2 => array('name' => '雅思班', 'count' => 20),
    );


    public static function getRequest() {
        //请求方式
        $method = strtolower($_SERVER['REQUEST_METHOD']);
        if (in_array($method, self::$method_type)) {
            //调用请求方式对应的方法
            $data_name = $method . 'Data';
            return self::$data_name($_REQUEST);
        }
        return false;
    }


    //GET 获取信息
    private static function getData($request_data) {
        $class_id = (int)$request_data['class'];
        //GET /class/ID：获取某个指定班的信息
        if ($class_id > 0) {
            return self::$test_class[$class_id];
        } else {//GET /class：列出所有班级
            return self::$test_class;
        }
    }


    //POST /class：新建一个班
    private static function postData($request_data) {
        if (!empty($request_data['name'])) {
            $data['name'] = $request_data['name'];
            $data['count'] = (int)$request_data['count'];
            self::$test_class[] = $data;
            return self::$test_class;//返回新生成的资源对象
        } else {
            return false;
        }
    }


    //PUT /class/ID：更新某个指定班的信息（全部信息）
    private static function putData($request_data) {
        $class_id = (int)$request_data['class'];
        if ($class_id == 0) {
            return false;
        }
        $data = array();
        if (!empty($request_data['name']) && isset($request_data['count'])) {
            $data['name'] = $request_data['name'];
            $data['count'] = (int)$request_data['count'];
            self::$test_class[$class_id] = $data;
            return self::$test_class;
        } else {
            return false;
        }
    }


    //PATCH /class/ID：更新某个指定班的信息（部分信息）
    private static function patchData($request_data) {
        $class_id = (int)$request_data['class'];
        if ($class_id == 0) {
            return false;
        }
        if (!empty($request_data['name'])) {
            self::$test_class[$class_id]['name'] = $request_data['name'];
        }
        if (isset($request_data['count'])) {
            self::$test_class[$class_id]['count'] = (int)$request_data['count'];
        }
        return self::$test_class;
    }


    //DELETE /class/ID：删除某个班
    private static function deleteData($request_data) {
        $class_id = (int)$request_data['class'];
        if ($class_id == 0) {
            return false;
        }
        unset(self::$test_class[$class_id]);
        return self::$test_class;
    }
}

<?php
class Response {
    const HTTP_VERSION = "HTTP/1.1";
    //返回结果
    public static function sendResponse($data) {
        //获取数据
        if ($data) {
            $code = 200;
            $message = 'OK';
        } else {
            $code = 404;
            $data = array('error' => 'Not Found');
            $message = 'Not Found';
        }


        //输出结果
        header(self::HTTP_VERSION . " " . $code . " " . $message);
        $content_type = isset($_SERVER['CONTENT_TYPE']) ? $_SERVER['CONTENT_TYPE'] : $_SERVER['HTTP_ACCEPT'];
        if (strpos($content_type, 'application/json') !== false) {
            header("Content-Type: application/json");
            echo self::encodeJson($data);
        } else if (strpos($content_type, 'application/xml') !== false) {
            header("Content-Type: application/xml");
            echo self::encodeXml($data);
        } else {
            header("Content-Type: text/html");
            echo self::encodeHtml($data);
        }
    }


    //json格式
    private static function encodeJson($responseData) {
        return json_encode($responseData);
    }


    //xml格式
    private static function encodeXml($responseData) {
        $xml = new SimpleXMLElement('<?xml version="1.0"?><rest></rest>');
        foreach ($responseData as $key => $value) {
            if (is_array($value)) {
                foreach ($value as $k => $v) {
                    $xml->addChild($k, $v);
                }
            } else {
                $xml->addChild($key, $value);
            }
        }
        return $xml->asXML();
    }


    //html格式
    private static function encodeHtml($responseData) {
        $html = "<table border='1'>";
        foreach ($responseData as $key => $value) {
            $html .= "<tr>";
            if (is_array($value)) {
                foreach ($value as $k => $v) {
                    $html .= "<td>" . $k . "</td><td>" . $v . "</td>";
                }
            } else {
                $html .= "<td>" . $key . "</td><td>" . $value . "</td>";
            }
            $html .= "</tr>";
        }
        $html .= "</table>";
        return $html;
    }
}

<?php
//数据操作类
require('Request.php');
//输出类
require('Response.php');
//获取数据
$data = Request::getRequest();
//输出结果
Response::sendResponse($data);