百度语音识别REST API使用方法（含JAVA代码）——不需要集成SDK的方法

上一篇文章http://blog.csdn.net/zpf8861/article/details/32322089已经介绍了百度语音识别REST API的使用步骤和功能介绍，这篇文章主要通过一个实例代码来展示如何使用该API。

本文代码为JAVA版，可以用于Android应用开发中，下面介绍其中重要的代码。

获得Token

其中apiKey和secretKey是从百度开放平台获得的，获得方法参看上一篇文章。

private static void getToken() throws Exception {
      String getTokenURL = "https://openapi.baidu.com/oauth/2.0/token?grant_type=client_credentials" +
          "&client_id=" + apiKey + "&client_secret=" + secretKey;
      HttpURLConnection conn = (HttpURLConnection) new URL(getTokenURL).openConnection();
      token = new JSONObject(printResponse(conn)).getString("access_token");
  }

现在假设语音文件为testFileName =test.pcm，保存在一个文件中，该文件可以有很多方法获得，比如在Android中调用录音相关的API，下面代码展示了如何通过Http网络请求获得识别结果。

Http连接采用Post方式，首先需要设定参数，然后上传本地的语音数据。

private static void method1() throws Exception {
       File pcmFile = new File(testFileName);
       HttpURLConnection conn = (HttpURLConnection) new URL(serverURL).openConnection();

       // construct params
       JSONObject params = new JSONObject();
       params.put("format", "pcm");
       params.put("rate", 8000);
       params.put("channel", "1");
       params.put("token", token);
       params.put("cuid", cuid);
       params.put("len", pcmFile.length());
       params.put("speech", DatatypeConverter.printBase64Binary(loadFile(pcmFile)));

       // add request header
       conn.setRequestMethod("POST");
       conn.setRequestProperty("Content-Type", "application/json; charset=utf-8");

       conn.setDoInput(true);
       conn.setDoOutput(true);

       // send request
       DataOutputStream wr = new DataOutputStream(conn.getOutputStream());
       wr.writeBytes(params.toString());
       wr.flush();
       wr.close();

       printResponse(conn);
   }

然后是获得响应的方法，具体处理识别结果

private static void method2() throws Exception {
      File pcmFile = new File(testFileName);
      HttpURLConnection conn = (HttpURLConnection) new URL(serverURL
              + "?cuid=" + cuid + "&token=" + token).openConnection();

      // add request header
      conn.setRequestMethod("POST");
      conn.setRequestProperty("Content-Type", "audio/pcm; rate=8000");

      conn.setDoInput(true);
      conn.setDoOutput(true);

      // send request
      DataOutputStream wr = new DataOutputStream(conn.getOutputStream());
      wr.write(loadFile(pcmFile));
      wr.flush();
      wr.close();

      printResponse(conn);
  }

下面展示了该demo的全部代码，开发者可以填入自己的KEY尝试使用。

public class Sample {

    private static final String serverURL = "http://vop.baidu.com/server_api";
    private static String token = "";
    private static final String testFileName = "test.pcm";
    //put your own params here
    private static final String apiKey = "";
    private static final String secretKey = "";
    private static final String cuid = "";

    public static void main(String[] args) throws Exception {
        getToken();
        method1();
        method2();
    }

    private static void getToken() throws Exception {
        String getTokenURL = "https://openapi.baidu.com/oauth/2.0/token?grant_type=client_credentials" +
            "&client_id=" + apiKey + "&client_secret=" + secretKey;
        HttpURLConnection conn = (HttpURLConnection) new URL(getTokenURL).openConnection();
        token = new JSONObject(printResponse(conn)).getString("access_token");
    }

    private static void method1() throws Exception {
        File pcmFile = new File(testFileName);
        HttpURLConnection conn = (HttpURLConnection) new URL(serverURL).openConnection();

        // construct params
        JSONObject params = new JSONObject();
        params.put("format", "pcm");
        params.put("rate", 8000);
        params.put("channel", "1");
        params.put("token", token);
        params.put("cuid", cuid);
        params.put("len", pcmFile.length());
        params.put("speech", DatatypeConverter.printBase64Binary(loadFile(pcmFile)));

        // add request header
        conn.setRequestMethod("POST");
        conn.setRequestProperty("Content-Type", "application/json; charset=utf-8");

        conn.setDoInput(true);
        conn.setDoOutput(true);

        // send request
        DataOutputStream wr = new DataOutputStream(conn.getOutputStream());
        wr.writeBytes(params.toString());
        wr.flush();
        wr.close();

        printResponse(conn);
    }

    private static void method2() throws Exception {
        File pcmFile = new File(testFileName);
        HttpURLConnection conn = (HttpURLConnection) new URL(serverURL
                + "?cuid=" + cuid + "&token=" + token).openConnection();

        // add request header
        conn.setRequestMethod("POST");
        conn.setRequestProperty("Content-Type", "audio/pcm; rate=8000");

        conn.setDoInput(true);
        conn.setDoOutput(true);

        // send request
        DataOutputStream wr = new DataOutputStream(conn.getOutputStream());
        wr.write(loadFile(pcmFile));
        wr.flush();
        wr.close();

        printResponse(conn);
    }

    private static void printResponse(HttpURLConnection conn) throws Exception {
        if (conn.getResponseCode() != 200) {
            // request error
        }
        InputStream is = conn.getInputStream();
        BufferedReader rd = new BufferedReader(new InputStreamReader(is));
        String line;
        StringBuffer response = new StringBuffer();
        while ((line = rd.readLine()) != null) {
            response.append(line);
            response.append('\r');
        }
        rd.close();
        System.out.println(new JSONObject(response.toString()).toString(4));
    }

    private static byte[] loadFile(File file) throws IOException {
        InputStream is = new FileInputStream(file);

        long length = file.length();r
        byte[] bytes = new byte[(int) length];

        int offset = 0;
        int numRead = 0;
        while (offset < bytes.length
                && (numRead = is.read(bytes, offset, bytes.length - offset)) >= 0) {
            offset += numRead;
        }

        if (offset < bytes.length) {
            is.close();
            throw new IOException("Could not completely read file " + file.getName());
        }

        is.close();
        return bytes;
    }
}