利用百度语音识别技术实现语音转成文字的应用（Java版附源码）

一、基本介绍

语音交互的需求场景越来越多，很多开发者都想做一款把语音转换成文字的游戏或者应用，这需要用到语音识别技术，这里会对如何使用完全免费的百度语音开放平台来快速开发，拥有高大上的语音识别技术的应用。

二、引入jar包

下载jacob-1.18.zip
并导入jacob.jar、json-20160810.jar、log4j-1.2.17.jar
将解压后的文件中jacob-1.18-x64.dll复制到对应的JDK中（我的是C:Program FilesJavajdk1.8.0_152jrein）

三、代码实例

1、工具类，ConnUtil

package baidu.restapi.common;
 
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.URLEncoder;
 
/**
 * 与连接相关的Util类
 */
public class ConnUtil {
 
    /**
     * UrlEncode， UTF-8 编码
     *
     * @param str 原始字符串
     * @return
     */
    public static String urlEncode(String str) {
        String result = null;
        try {
            result = URLEncoder.encode(str, "UTF-8");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        return result;
    }
 
    /**
     * 从HttpURLConnection 获取返回的字符串
     *
     * @param conn
     * @return
     * @throws IOException
     * @throws DemoException
     */
    public static String getResponseString(HttpURLConnection conn) throws IOException, DemoException {
        return new String(getResponseBytes(conn));
    }
 
    /**
     * 从HttpURLConnection 获取返回的bytes
     * 注意 HttpURLConnection自身问题， 400类错误，会直接抛出异常。不能获取conn.getInputStream();
     *
     * @param conn
     * @return
     * @throws IOException   http请求错误
     * @throws DemoException http 的状态码不是 200
     */
    public static byte[] getResponseBytes(HttpURLConnection conn) throws IOException, DemoException {
        int responseCode = conn.getResponseCode();
        if (responseCode != 200) {
            System.err.println("http 请求返回的状态码错误，期望200， 当前是 " + responseCode);
            if (responseCode == 401) {
                System.err.println("可能是appkey appSecret 填错");
            }
            throw new DemoException("http response code is" + responseCode);
        }
 
        InputStream inputStream = conn.getInputStream();
        byte[] result = getInputStreamContent(inputStream);
        return result;
    }
 
    /**
     * 将InputStream内的内容全部读取，作为bytes返回
     *
     * @param is
     * @return
     * @throws IOException @see InputStream.read()
     */
    public static byte[] getInputStreamContent(InputStream is) throws IOException {
        byte[] b = new byte[1024];
        // 定义一个输出流存储接收到的数据
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        // 开始接收数据
        int len = 0;
        while (true) {
            len = is.read(b);
            if (len == -1) {
                // 数据读完
                break;
            }
            byteArrayOutputStream.write(b, 0, len);
        }
        return byteArrayOutputStream.toByteArray();
    }
}

2、token的获取类，TokenHolder  

package baidu.restapi.common;
 
import org.json.JSONObject;
 
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.URL;
 
/**
 * token的获取类
 * 将apiKey和secretKey换取token，注意有效期保存在expiresAt
 */
public class TokenHolder {
 
    public static final String ASR_SCOPE = "audio_voice_assistant_get";
 
    public static final String TTS_SCOPE = "audio_tts_post";
 
    /**
     * url , Token的url，http可以改为https
     */
    private static final String url = "http://openapi.baidu.com/oauth/2.0/token";
 
    /**
     * asr的权限 scope 是  "audio_voice_assistant_get"
     * tts 的权限 scope 是 "audio_tts_post"
     */
    private String scope;
 
    /**
     * 网页上申请语音识别应用获取的apiKey
     */
    private String apiKey;
 
    /**
     * 网页上申请语音识别应用获取的secretKey
     */
    private String secretKey;
 
    /**
     * 保存访问接口获取的token
     */
    private String token;
 
    /**
     * 当前的时间戳，毫秒
     */
    private long expiresAt;
 
    /**
     * @param apiKey    网页上申请语音识别应用获取的apiKey
     * @param secretKey 网页上申请语音识别应用获取的secretKey
     */
    public TokenHolder(String apiKey, String secretKey, String scope) {
        this.apiKey = apiKey;
        this.secretKey = secretKey;
        this.scope = scope;
    }
 
    /**
     * 获取token，refresh 方法后调用有效
     *
     * @return
     */
    public String getToken() {
        return token;
    }
 
    /**
     * 获取过期时间，refresh 方法后调用有效
     *
     * @return
     */
    public long getExpiresAt() {
        return expiresAt;
    }
 
    /**
     * 获取token
     *
     * @return
     * @throws IOException   http请求错误
     * @throws DemoException http接口返回不是 200, access_token未获取
     */
    public void resfresh() throws Exception {
        String getTokenURL = url + "?grant_type=client_credentials"
                + "&client_id=" + ConnUtil.urlEncode(apiKey) + "&client_secret=" + ConnUtil.urlEncode(secretKey);
 
        // 打印的url出来放到浏览器内可以复现
        System.out.println("token url:" + getTokenURL);
 
        URL url = new URL(getTokenURL);
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setConnectTimeout(5000);
        String result = ConnUtil.getResponseString(conn);
        System.out.println("Token result json:" + result);
        parseJson(result);
    }
 
    /**
     * @param result token接口获得的result
     * @throws DemoException
     */
    private void parseJson(String result) throws Exception {
        JSONObject json = new JSONObject(result);
        if (!json.has("access_token")) {
            // 返回没有access_token字段
            throw new DemoException("access_token not obtained, " + result);
        }
        if (!json.has("scope")) {
            // 返回没有scope字段
            throw new DemoException("scopenot obtained, " + result);
        }
        if (!json.getString("scope").contains(scope)) {
            throw new DemoException("scope not exist, " + scope + "," + result);
        }
        token = json.getString("access_token");
        expiresAt = System.currentTimeMillis() + json.getLong("expires_in") * 1000;
    }
}

3、异常类，DemoException 

package baidu.restapi.common;
 
public class DemoException extends Exception {
    public DemoException(String message) {
        super(message);
    }
}

4、测试类，TtsMain 

package baidu.restapi.ttsdemo;
 
import baidu.restapi.common.ConnUtil;
import baidu.restapi.common.TokenHolder;
import java.io.File;
import java.io.FileOutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
 
public class TtsMain {
 
    public static void main(String[] args) throws Exception {
        (new TtsMain()).run();
    }
 
    //  填写网页上申请的appkey 如 $apiKey="g8eBUMSokVB1BHGmgxxxxxx"
    private final String appKey = "4E1BG9lTnlSeIf1NQFlrSq6h";
 
    // 填写网页上申请的APP SECRET 如 $secretKey="94dc99566550d87f8fa8ece112xxxxx"
    private final String secretKey = "544ca4657ba8002e3dea3ac2f5fdd241";
 
    // text 的内容为"欢迎使用百度语音合成"的urlencode,utf-8 编码
    // 可以百度搜索"urlencode"
    private final String text = "欢迎使用百度语音";
 
    // 发音人选择, 0为普通女声，1为普通男生，3为情感合成-度逍遥，4为情感合成-度丫丫，默认为普通女声
    private final int per = 0;
    // 语速，取值0-9，默认为5中语速
    private final int spd = 5;
    // 音调，取值0-9，默认为5中语调
    private final int pit = 5;
    // 音量，取值0-9，默认为5中音量
    private final int vol = 5;
 
    public final String url = "http://tsn.baidu.com/text2audio"; // 可以使用https
 
    private String cuid = "1234567JAVA";
 
    private void run() throws Exception {
        TokenHolder holder = new TokenHolder(appKey, secretKey, TokenHolder.ASR_SCOPE);
        holder.resfresh();
        String token = holder.getToken();
 
        String url2 = url + "?tex=" + ConnUtil.urlEncode(text);
        url2 += "&per=" + per;
        url2 += "&spd=" + spd;
        url2 += "&pit=" + pit;
        url2 += "&vol=" + vol;
        url2 += "&cuid=" + cuid;
        url2 += "&tok=" + token;
        url2 += "&lan=zh&ctp=1";
        // System.out.println(url2); // 反馈请带上此url，浏览器上可以测试
        HttpURLConnection conn = (HttpURLConnection) new URL(url2).openConnection();
        conn.setConnectTimeout(5000);
        String contentType = conn.getContentType();
        if (contentType.contains("mp3")) {
            byte[] bytes = ConnUtil.getResponseBytes(conn);
            File file = new File("result.mp3"); // 打开mp3文件即可播放
            // System.out.println( file.getAbsolutePath());
            FileOutputStream os = new FileOutputStream(file);
            os.write(bytes);
            os.close();
            System.out.println("mp3 file write to " + file.getAbsolutePath());
        } else {
            System.err.println("ERROR: content-type= " + contentType);
            String res  = ConnUtil.getResponseString(conn);
            System.err.println(res);
        }
    }
}

 5、实现效果