[Android開發常見問題-5] 如何檢測耳機的插入狀態

近期在研究如何通過耳機進行一些控制操作，自然涉及到如何檢測耳機是否插入的狀態，經過一番查詢和實驗，總結如下

1.原理：

其實android系統在耳機插入和拔出的時候都會發送廣播，所以我們要想檢測耳機的狀態只需要注冊響應的BroadCastReceiver，對狀態進行響應的判斷就ok了。

這個廣播的名字叫做：android.intent.action.HEADSET_PLUG

注意，在manifest.xml裡面要添加響應的權限：

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

注意，廣播要在java文件中動態注冊。

2.代碼

[java]

/**
 * Created By:alex
 */ 
 
package com.alex.erji; 
 
import android.app.Activity; 
import android.content.BroadcastReceiver; 
import android.content.Context; 
import android.content.Intent; 
import android.content.IntentFilter; 
import android.os.Bundle; 
import android.widget.Toast; 
 
public class MainActivity extends Activity { 
 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState); 
        setContentView(R.layout.activity_main); 
 
        //給廣播綁定響應的過濾器  
        IntentFilter intentFilter = new IntentFilter(); 
        intentFilter.addAction("android.intent.action.HEADSET_PLUG"); 
        HeadsetReceiver headsetReceiver = new HeadsetReceiver(); 
        registerReceiver(headsetReceiver, intentFilter); 
 
    } 
 
    //自己定義的廣播接收器  
    public class HeadsetReceiver extends BroadcastReceiver { 
 
        @Override 
        public void onReceive(Context context, Intent intent) { 
            if (intent.hasExtra("state")) { 
                if (0 == intent.getIntExtra("state", 0)) { 
                    Toast.makeText(context, "耳機未插入", Toast.LENGTH_SHORT).show(); 
                } else if (1 == intent.getIntExtra("state", 0)) { 
                    Toast.makeText(context, "耳機已插入", Toast.LENGTH_SHORT).show(); 
                } 
            } 
 
        } 
    } 
} 

/**
 * Created By:alex
 */

package com.alex.erji;

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.widget.Toast;

public class MainActivity extends Activity {

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

  //給廣播綁定響應的過濾器
  IntentFilter intentFilter = new IntentFilter();
  intentFilter.addAction("android.intent.action.HEADSET_PLUG");
  HeadsetReceiver headsetReceiver = new HeadsetReceiver();
  registerReceiver(headsetReceiver, intentFilter);

 }

 //自己定義的廣播接收器
 public class HeadsetReceiver extends BroadcastReceiver {

  @Override
  public void onReceive(Context context, Intent intent) {
   if (intent.hasExtra("state")) {
    if (0 == intent.getIntExtra("state", 0)) {
     Toast.makeText(context, "耳機未插入", Toast.LENGTH_SHORT).show();
    } else if (1 == intent.getIntExtra("state", 0)) {
     Toast.makeText(context, "耳機已插入", Toast.LENGTH_SHORT).show();
    }
   }

  }
 }
}

正常運行後，插入耳機時會提醒“耳機已插入”，拔出耳機時提醒“耳機未插入”。