利用百度api实现文字转语音（ThinkPHP5 版）

<?php
namespace app\common\service;

use think\Cache;
use think\Log;

/**
 * 百度语音合成（ThinkPHP5 版）
 * 密钥通过后台配置读取
 */
class BaiduTts
{


    const TOKEN_CACHE_KEY = 'baidu_tts_token';
    const TOKEN_TTL       = 7000;

    private static $instance = null;

    private $appId;
    private $apiKey;
    private $secretKey;

    public static function instance()
    {
        if (is_null(self::$instance)) {
            self::$instance = new self();
        }
        return self::$instance;
    }

    private function __construct($appId, $apiKey, $secretKey)
    {
        // 从后台读取
     $this->appId=$appId;
     $this->apiKey= $apiKey;
     $this->secretKey=$secretKey;
        if (!$this->appId || !$this->apiKey || !$this->secretKey) {
            throw new \Exception('请在后台配置百度语音合成密钥');
        }
    }

    /**
     * 通过密钥生成单例
     */
    public static function create($appId, $apiKey, $secretKey): self
    {
        // 支持多租户：用密钥 md5 做区分
        $key = 'baidu_tts_' . md5($appId . $apiKey);
        if (!isset(self::$instance[$key])) {
            self::$instance[$key] = new self($appId, $apiKey, $secretKey);
        }
        return self::$instance[$key];
    }

    /* 主入口 */
    public function synthesis(string $text, string $saveDir = ''): string
    {
        $text = $this->plainText($text);   // 先净化
        if ($text === '') {
            throw new \Exception('合成文本不能为空');
        }

        $saveDir = $saveDir ?: RUNTIME_PATH . 'tts' . DS;
        if (!is_dir($saveDir)) {
            mkdir($saveDir, 0755, true);
        }
        $mp3File = $saveDir . md5($text) . '.mp3';
        if (is_file($mp3File)) {
            return $mp3File;
        }
        $token = $this->getAccessToken();
        $this->doSynthesis($text, $token, $mp3File);
        return $mp3File;
    }

    /* 获取/刷新 token */
    private function getAccessToken(): string
    {
        $token = Cache::get(self::TOKEN_CACHE_KEY);
        if ($token) return $token;

        $url = 'https://aip.baidubce.com/oauth/2.0/token?' . http_build_query([
                'grant_type'    => 'client_credentials',
                'client_id'     => $this->apiKey,
                'client_secret' => $this->secretKey,
            ]);
        $resp = json_decode(file_get_contents($url), true);
        if (empty($resp['access_token'])) {
            Log::error('BaiduTts getAccessToken failed: ' . json_encode($resp));
            throw new \Exception('获取百度 access_token 失败');
        }
        $token = $resp['access_token'];
        Cache::set(self::TOKEN_CACHE_KEY, $token, self::TOKEN_TTL);
        return $token;
    }

    /* 真正合成 */
    private function doSynthesis(string $text, string $token, string $saveFile): void
    {
        $api = 'https://tsn.baidu.com/text2audio';
        $param = [
            'tok' => $token,
            'tex' => $text,
            'cuid' => md5(uniqid()),
            'ctp' => 1,
            'lan' => 'zh',
            'aue' => 3,
            'per' => 0,
            'spd' => 5,
            'pit' => 5,
            'vol' => 5,
        ];
        $audio = $this->httpPost($api, http_build_query($param));
        if (strpos($audio, '{') === 0) {
            $err = json_decode($audio, true);
            Log::error('BaiduTts synthesis failed: ' . $audio);
            throw new \Exception('合成失败：' . ($err['err_msg'] ?? '未知'));
        }
        file_put_contents($saveFile, $audio);
    }

    private function httpPost(string $url, string $body): string
    {
        $ch = curl_init();
        curl_setopt_array($ch, [
            CURLOPT_URL            => $url,
            CURLOPT_POST           => true,
            CURLOPT_POSTFIELDS     => $body,
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_SSL_VERIFYPEER => false,
            CURLOPT_TIMEOUT        => 30,
            CURLOPT_HTTPHEADER     => ['Content-Type: application/x-www-form-urlencoded'],
        ]);
        $resp = curl_exec($ch);
        if ($resp === false) {
            throw new \Exception('Curl Error: ' . curl_error($ch));
        }
        curl_close($ch);
        return $resp;
    }
    /**
     * 把文字处理成适合 TTS 朗读的内容
     * 1. 去 HTML 标签 & 实体  2. 去多余空白  3. 去不可见符号
     * 4. 把常见符号转成口语
     */
    private function plainText(string $raw): string
    {
        // 先统一编码
        $raw = mb_convert_encoding($raw, 'UTF-8', 'UTF-8');

        /* --- 1. 剥掉所有 HTML 标签 & 实体 --- */
        $raw = strip_tags($raw);
        $raw = html_entity_decode($raw, ENT_QUOTES | ENT_HTML5, 'UTF-8');

        /* --- 2. 删掉非打印字符（除了空格、换行） --- */
        $raw = preg_replace('/[\x{00}-\x{08}\x{0B}-\x{0C}\x{0E}-\x{1F}\x{7F}]+/u', '', $raw);

        /* --- 3. 把常见符号口语化 --- */
        $map = [
            '&' => '和',
            '@' => '在',
            '#' => '号',
            '©' => '版权',
            '®' => '注册商标',
            '℃' => '摄氏度',
            '￥' => '元',
            '$' => '美元',
            '%' => '百分之',
            '°' => '度',
            '+' => '加',
            '=' => '等于',
            '×' => '乘',
            '÷' => '除以',
            '>' => '大于',
            '<' => '小于',
            '/' => '每',
            '\\' => '、',
            '|' => '或',
            '【' => '（',
            '】' => '）',
            '[' => '（',
            ']' => '）',
            '{' => '（',
            '}' => '）',
            '（' => '（', // 全角括号保留
            '）' => '）',
            '——' => '，', // 破折号
            '—'  => '，',
            '…'  => '，',
            '·'  => '点',
            '•'  => '点',
            '※'  => '星',
            '①' => '1',
            '②' => '2',
            '③' => '3',
            '④' => '4',
            '⑤' => '5',
            '⑥' => '6',
            '⑦' => '7',
            '⑧' => '8',
            '⑨' => '9',
            '⑩' => '10',
        ];
        $raw = strtr($raw, $map);

        /* --- 4. 连续空格、制表、换行 合并成单个空格 --- */
        $raw = preg_replace('/\s+/u', ' ', $raw);

        /* --- 5. 去掉首尾空格 --- */
        return trim($raw);
    }
}