like.php

<?php
/* MySQL 数据库名称 */
define('DB_NAME', 'wordpress');

/* MySQL 数据库用户名 */
define('DB_USER', 'root');

/* MySQL 数据库密码 */
define('DB_PASSWD', 'root');

/* MySQL 主机 */
define('DB_HOST', 'localhost');

/**
 * @Author: prpr
 * @Date:   2016-01-22 21:28:52
 * @Last Modified by:   prpr
 * @Last Modified time: 2016-01-22 23:23:09
 */

$conn = new mysqli(DB_HOST, DB_USER, DB_PASSWD, DB_NAME);
$conn->query("SET names UTF8");

if ($conn->connect_error) {
	die("Unable to connect to database. ".$conn->connect_error."<br />
		Check if database config correct in the file header.");
}

header('Access-Control-Allow-Origin: *');
header("Content-Type: application/json; charset=utf-8");

if (!isset($_GET['action']) || $_GET['action'] == "get") {
	echo getCount();
} else {
	echo like();
}

function like() {
	global $conn;
	$ip = getClientIp();
	$ip_result = $conn->query("SELECT * FROM votes WHERE ip='$ip'");
	if ($ip_result->num_rows == 0) {
		$conn->query("INSERT INTO votes (ip) values ('$ip')");
		$json['success'] = 1;
		$json['msg'] = 'Successfully liked.';
		return json_encode($json);
	} else { // repeated ip
		$json['success'] = 0;
		$json['msg'] = 'Repeated IP address.';
		return json_encode($json);
	}
}

function getCount() {
	global $conn;
	if ($result = $conn->query("SELECT COUNT(*) FROM votes")) {
		$json['success'] = 1;
		$json['like'] = $result->fetch_array()[0];
		return json_encode($json);
	}
	die($conn->connect_error);
}

function getClientIp() {
	if (!empty($_SERVER['HTTP_CLIENT_IP'])) {
	    $ip = $_SERVER['HTTP_CLIENT_IP'];
	} elseif (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {
	    $ip = $_SERVER['HTTP_X_FORWARDED_FOR'];
	} else {
	    $ip = $_SERVER['REMOTE_ADDR'];
	}
	return $ip;
}

/**
 * Create tables automatically
 * This function cant be access by default
 *
 * @return void
 */
function createTables() {
	global $conn;
	$sql = "CREATE TABLE IF NOT EXISTS `votes` (
			  `id` int(10) NOT NULL AUTO_INCREMENT,
			  `ip` varchar(40) NOT NULL,
			  PRIMARY KEY (`id`),
			  UNIQUE KEY `id` (`id`)
			) ENGINE=MyISAM AUTO_INCREMENT=121 DEFAULT CHARSET=utf8;";
	if ($conn->query($sql)) {
		echo "Tables successfully created.";
	}

}