package com.xxx.xxx.Util;

import android.content.Context;

import android.media.MediaPlayer;

import android.speech.tts.TextToSpeech;

import android.util.Log;

import java.io.File;

import java.util.HashMap;

import java.util.Locale;

import java.util.concurrent.ConcurrentLinkedQueue;

public class TTSUtil implements TextToSpeech.OnInitListener {

    private MediaPlayer mediaPlayer = new MediaPlayer();

    private final TextToSpeech mTextToSpeech;//TTS对象

    private final ConcurrentLinkedQueue mBufferedMessages;//消息队列

    private Context mContext;

    private boolean mIsReady;//标识符

    public TTSUtil(Context context){

        this.mContext=context;//获取上下文

        this.mBufferedMessages=new ConcurrentLinkedQueue();//实例化队列

        this.mTextToSpeech=new TextToSpeech(this.mContext,this);//实例化TTS

    }

    //初始化TTS引擎

    @Override

    public void onInit(int status) {

        Log.i("TextToSpeechDemo",String.valueOf(status));

        if(status==TextToSpeech.SUCCESS){

            int result = this.mTextToSpeech.setLanguage(Locale.CHINA);//设置识别语音为英文或者中文

            synchronized (this){

                this.mIsReady=true;//设置标识符为true

                for(Object bufferedMessage : this.mBufferedMessages){

                    String s = String.valueOf(bufferedMessage);

                    speakText(s);//读语音

                }

                this.mBufferedMessages.clear();//读完后清空队列

            }

        }

    }

    //释放资源

    public void release(){

        synchronized (this){

            this.mTextToSpeech.shutdown();

            this.mIsReady=false;

        }

    }

    //更新消息队列，或者读语音

    public void notifyNewMessage(String text){

        //如果已经有音频文件，使用MediaPlayer播放

        try {

            File file = new File(mContext.getCacheDir().getAbsolutePath()+"//", text+".wav");

            if(file.exists()) {
                mediaPlayer.reset();

　　　　　　　　   mediaPlayer.setDataSource(file.getPath()); // 指定音频文件的路径

                mediaPlayer.prepare(); // 让MediaPlayer进入到准备状态

                mediaPlayer.start();

                return;

            }

        } catch (Exception e) {

            e.printStackTrace();

        }

        String message=text;

        synchronized (this){

            if(this.mIsReady){

                speakText(message);

            }else{

                this.mBufferedMessages.add(message);

            }

        }

    }

    //把TTS朗读结果保存

    public void sayTofile(String text)

    {

        HashMap<String,

                String> ttsRender = new HashMap<String,

                String>();

        String destFileName =  mContext.getCacheDir().getAbsolutePath()+"//"+text+".wav";

            ttsRender.put(TextToSpeech.Engine.KEY_PARAM_UTTERANCE_ID,

                    text);

            this.mTextToSpeech.synthesizeToFile(text,

                    ttsRender, destFileName);

    }

    //自定义文字播放

    public void sayFromFile(String text)

    {

        String destFileName = mContext.getCacheDir().getAbsolutePath()+"//"+text+".wav";

        this.mTextToSpeech.addSpeech(text,destFileName);

        this.mTextToSpeech.speak(text,TextToSpeech.QUEUE_FLUSH, null);

    }

    //读语音处理

    private void speakText(String message){

        HashMap params=new HashMap();

        params.put(TextToSpeech.Engine.KEY_PARAM_STREAM,"STREAM_NOTIFICATION");//设置播放类型（音频流类型）

        this.mTextToSpeech.speak(message, TextToSpeech.QUEUE_ADD, params);//将这个发音任务添加当前任务之后

        this.mTextToSpeech.playSilence(100,TextToSpeech.QUEUE_ADD,params);//间隔多长时间

    }

}

ttsUtil.sayTofile("测试语音");

ttsUtil.notifyNewMessage("测试语音");

比如上面第一句话执行后，第二句话直接调用wav文件。
注：程序中代码片段来自网友分享。

有的时候播放tts还是会无声情况，直接把wav文件放入程序资源中调用方法：https://www.cnblogs.com/zhaogaojian/p/10128827.html