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;
}
}