Android ApiDemos示例解析(46)：App->Voice Recognition

这个例子需要Android系统中安装了支持RecognizerIntent.ACTION_RECOGNIZE_SPEECH的应用，比如Google的 Voice Search应用。

模拟器上缺省没有安装，可以参见如何在Android emulator上安装 APK 在模拟器上安装一个Voice Search。

本例VoiceRecognition首先通过PackageManager检测本机是否安装了支持RecognizerIntent.ACTION_RECOGNIZE_SPEECH，如果有，则Enable Speak按钮，否则显示“Recognizer not present”

[java]
// Check to see if a recognition activity is present
PackageManager pm = getPackageManager();
List<ResolveInfo> activities = pm.queryIntentActivities(
new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH), 0);
if (activities.size() != 0) {
speakButton.setOnClickListener(this);
} else {
speakButton.setEnabled(false);
speakButton.setText("Recognizer not present");
}
// Check to see if a recognition activity is present
PackageManager pm = getPackageManager();
List<ResolveInfo> activities = pm.queryIntentActivities(
new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH), 0);
if (activities.size() != 0) {
speakButton.setOnClickListener(this);
} else {
speakButton.setEnabled(false);
speakButton.setText("Recognizer not present");
}

如果本机上安装了Google的Voice Search，点击“Speak!”则会启动语音输入对话框：

Speak按钮对应的代码如下：

[java]
Intent intent = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);
intent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL,
RecognizerIntent.LANGUAGE_MODEL_FREE_FORM);
intent.putExtra(RecognizerIntent.EXTRA_PROMPT, "Speech recognition demo");
startActivityForResult(intent, VOICE_RECOGNITION_REQUEST_CODE);
Intent intent = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);
intent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL,
RecognizerIntent.LANGUAGE_MODEL_FREE_FORM);
intent.putExtra(RecognizerIntent.EXTRA_PROMPT, "Speech recognition demo");
startActivityForResult(intent, VOICE_RECOGNITION_REQUEST_CODE);

采用的是startActivityForResult这是因为我们需要从语音输入对话框获取用户输入。RecognizerIntent.EXTRA_PROMPT定义对应框提示。 RecognizerIntent.LANGUAGE_MODEL_FREE_FORM 为语音输入类型，这里使用自由格式，另外一种为WEB_SEARCH主要用于Web搜索。

下面代码响应从语音输入对话框返回值：

[java]
if (requestCode == VOICE_RECOGNITION_REQUEST_CODE
    && resultCode == RESULT_OK) {
// Fill the list view with the strings the recognizer
// thought it could have heard
ArrayList<String> matches = data.getStringArrayListExtra(
RecognizerIntent.EXTRA_RESULTS);
mList.setAdapter(new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1,
matches));
}
if (requestCode == VOICE_RECOGNITION_REQUEST_CODE
    && resultCode == RESULT_OK) {
// Fill the list view with the strings the recognizer
// thought it could have heard
ArrayList<String> matches = data.getStringArrayListExtra(
RecognizerIntent.EXTRA_RESULTS);
mList.setAdapter(new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1,
matches));
}

在列表中显示由语音识别返回的文字：

作者：mapdigit

补充：移动开发 , Android ,