Android 听筒模式的具体实现实例

一、利用距离感应器监听听筒靠近耳朵事件
准确的说距离感应器并不能监听到你是否把手机靠近耳朵，也许是你用手挡在了距离感应器前面，但这不是我们关心的，我们关心的是当你的耳朵靠近听筒时，我们要捕获到这个事件

step 1，新建实现SensorEventListener接口的类并实现onSensorChanged(SensorEvent event)方法

public class MainActivity extends Activity implements SensorEventListener

step 2，得到距离感应器的实例

audioManager = (AudioManager) this
    .getSystemService(Context.AUDIO_SERVICE);
  mSensorManager = (SensorManager) getSystemService

(Context.SENSOR_SERVICE);
  mSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_PROXIMITY);

step 3，在onSensorChanged方法中判断是否靠近听筒

public void onSensorChanged(SensorEvent event) {
 // TODO Auto-generated method stub
 float range = event.values[0];

 if (range == mSensor.getMaximumRange()) {
  Toast.makeText(this, "正常模式", Toast.LENGTH_LONG).show();
 } else {
  Toast.makeText(this, "听筒模式", Toast.LENGTH_LONG).show();
 }

step 4, 向SensorManager注册监听距离感应器

 @Override
 protected void onResume() {
  mSensorManager.registerListener(this, mSensor,
    SensorManager.SENSOR_DELAY_NORMAL);
  super.onResume();
 }
 @Override
 protected void onPause() {
  mSensorManager.unregisterListener(this);
  super.onPause();
 }

二、根据距离感应器改变AudioManager播放模式
默认情况下，播放语音都是用外置喇叭或者耳机，我们需要编码实现播放的切换。

step 1，在AndroidManifest文件中添加权限声明

<uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />

step 2，切换播放模式

 public void onSensorChanged(SensorEvent event) {
  // TODO Auto-generated method stub
  float range = event.values[0];

  if (range == mSensor.getMaximumRange()) {
   Toast.makeText(this, "正常模式", Toast.LENGTH_LONG).show();
    audioManager.setMode(AudioManager.MODE_NORMAL);
  } else {
   Toast.makeText(this, "听筒模式", Toast.LENGTH_LONG).show();
    audioManager.setMode(AudioManager.MODE_IN_CALL);
  }

完整代码：

package com.markjoker.sensortest;

import java.io.FileInputStream;
import java.io.IOException;

import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.util.Log;
import android.view.Menu;
import android.widget.Toast;

public class MainActivity extends Activity implements SensorEventListener {
 private AudioManager audioManager;
 private SensorManager mSensorManager;
 private Sensor mSensor;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  init();
 }

 private void init() {
  audioManager = (AudioManager) this
    .getSystemService(Context.AUDIO_SERVICE);
  mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
  mSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_PROXIMITY);

  MediaPlayer mPlayer = new MediaPlayer();
  try {
   mPlayer.reset();
   mPlayer.setDataSource(new FileInputStream("/sdcard/snow.mp3").getFD());
   mPlayer.prepare();
   mPlayer.start();
  } catch (IllegalArgumentException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (SecurityException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (IllegalStateException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
 }

 @Override
 protected void onResume() {
  mSensorManager.registerListener(this, mSensor,
    SensorManager.SENSOR_DELAY_NORMAL);
  super.onResume();
 }

 @Override
 protected void onPause() {
  // TODO Auto-generated method stub
  mSensorManager.unregisterListener(this);
  super.onPause();
 }

 @Override
 public void onSensorChanged(SensorEvent event) {
  // TODO Auto-generated method stub
  float range = event.values[0];

  if (range == mSensor.getMaximumRange()) {
   Toast.makeText(this, "正常模式", Toast.LENGTH_LONG).show();
    audioManager.setMode(AudioManager.MODE_NORMAL);
  } else {
   Toast.makeText(this, "听筒模式", Toast.LENGTH_LONG).show();
    audioManager.setMode(AudioManager.MODE_IN_CALL);
  }
 }

 @Override
 public void onAccuracyChanged(Sensor sensor, int accuracy) {
  // TODO Auto-generated method stub

 }

}