这是一款可以在多个Android设备上同时播放音乐的应用程序
有2个部分，一个是dj播放器模式（播放音乐的设备），另一个是扬声器模式
dj播放模式活动在android jelly bean（4.1,4.2,4.3）上运行良好但在较新版本（4.4,5）强制关闭发生
问题是什么？
dj玩家活动
package com.example.musicsaround.dj;
import java.io.File;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.Uri;
import android.net.wifi.WifiManager;
import android.net.wifi.p2p.WifiP2pConfig;
import android.net.wifi.p2p.WifiP2pDevice;
import android.net.wifi.p2p.WifiP2pInfo;
import android.net.wifi.p2p.WifiP2pManager;
import android.net.wifi.p2p.WifiP2pManager.ActionListener;
import android.net.wifi.p2p.WifiP2pManager.Channel;
import android.net.wifi.p2p.WifiP2pManager.ChannelListener;
import android.os.Bundle;
import android.os.CountDownTimer;
import android.util.Log;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.TextView;
import android.widget.Toast;
import com.example.musicsaround.R;
import com.example.musicsaround.Timer;
import com.example.musicsaround.Utilities;
import com.example.musicsaround.dj.ServerDeviceListFragment.DJFragmentListener;
public class DJActivity extends Activity implements ChannelListener,
DJFragmentListener
{
public final static int DJ_MODE = 15;
public static final String TAG = "DJ Mode Activity";
private WifiP2pManager manager;
private boolean channelRetried = false;
private boolean isWifiP2pEnabled = false;
private BroadcastReceiver receiver = null;
ProgressDialog progressDialog = null;
private Timer timer;
private CountDownTimer keepAliveTimer;
// Keep the Wifi Alive every 5 seconds
private static final int KEEPALIVE_INTERVAL = 5000;
// critical component for Wi-fi Direct connectivity
private Channel channel;
private final IntentFilter intentFilter = new IntentFilter();
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_dj);
// need these intent filters to catch the Wi-fi direct events
intentFilter.addAction(WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION);
intentFilter.addAction(WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION);
intentFilter
.addAction(WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION);
intentFilter
.addAction(WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION);
manager = (WifiP2pManager) getSystemService(Context.WIFI_P2P_SERVICE);
channel = manager.initialize(this, getMainLooper(), null);
TextView txt_time = (TextView) this.findViewById(R.id.txt_dj_time);
// start a timer with 25 ms precision
this.timer = new Timer(Timer.DEFAULT_TIMER_PRECISION);
// asynchronous call to start a timer
this.timer.startTimer();
keepAliveTimer = new CountDownTimer(KEEPALIVE_INTERVAL,
KEEPALIVE_INTERVAL)
{
@Override
public void onTick(long millisUntilFinished)
{
}
@Override
public void onFinish()
{
enableWifi();
keepAliveTimer.start();
}
};
}
/** register the BroadcastReceiver with the intent values to be matched */
@Override
public void onResume()
{
super.onResume();
receiver = new ServerWiFiDirectBR(manager, channel, this);
registerReceiver(receiver, intentFilter);
// ***Start discovering right away!
discoverDevices();
keepAliveTimer.start();
}
public void enableWifi()
{
WifiManager wifiManager = (WifiManager) this
.getSystemService(this.WIFI_SERVICE);
wifiManager.setWifiEnabled(true);
}
/**
* UI to show the discovery process
*/
public void onInitiateDiscovery()
{
if (progressDialog != null && progressDialog.isShowing())
{
progressDialog.dismiss();
}
progressDialog = ProgressDialog.show(this, "Press back to cancel",
"finding peers", true, true,
new DialogInterface.OnCancelListener()
{
@Override
public void onCancel(DialogInterface dialog)
{
// stop discovery
manager.stopPeerDiscovery(channel,
new WifiP2pManager.ActionListener()
{
@Override
public void onFailure(int reason)
{
// Toast.makeText(DJActivity.this,
// "Stopping Discovery Failed : " +
// reason,
// Toast.LENGTH_SHORT).show();
Log.e(TAG,
"Stopping Discovery Failed. Error Code is: "
+ reason);
}
@Override
public void onSuccess()
{
Log.d(TAG, "Discovery stopped.");
}
});
}
});
}
public void discoverDevices()
{
// TODO: need a better non-blocking UI to notify users we are
// discovering
// onInitiateDiscovery();
// first turn on the wifi p2p
enableWifi();
channelRetried = false;
manager.discoverPeers(channel, new WifiP2pManager.ActionListener()
{
@Override
public void onSuccess()
{
// Toast.makeText(DJActivity.this,
// "Discovery Initiated",
// Toast.LENGTH_SHORT).show();
Log.d(TAG, "Discovery Initiated.");
}
// if we failed, then stop the discovery and start again
@Override
public void onFailure(int reasonCode)
{
Log.e(TAG, "Discovery Failed. Error Code is: " + reasonCode);
manager.stopPeerDiscovery(channel,
new WifiP2pManager.ActionListener()
{
@Override
public void onFailure(int reason)
{
// Toast.makeText(DJActivity.this,
// "Stopping Discovery Failed : " + reason,
// Toast.LENGTH_SHORT).show();
Log.e(TAG,
"Stopping Discovery Failed. Error Code is: "
+ reason);
}
@Override
public void onSuccess()
{
manager.discoverPeers(channel,
new WifiP2pManager.ActionListener()
{
@Override
public void onSuccess()
{
// Toast.makeText(DJActivity.this,
// "Discovery Initiated",
// Toast.LENGTH_SHORT)
// .show();
Log.d(TAG,
"Discovery Initiated.");
}
@Override
public void onFailure(int reasonCode)
{
Log.e(TAG,
"Discovery Failed. Error Code is: "
+ reasonCode);
}
});
}
});
}
});
}
@Override
public void onPause()
{
super.onPause();
unregisterReceiver(receiver);
keepAliveTimer.cancel();
}
@Override
public void onDestroy()
{
disconnect();
super.onDestroy();
}
@Override
public boolean onCreateOptionsMenu(Menu menu)
{
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.wifidirect_less, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item)
{
switch (item.getItemId())
{
case R.id.atn_direct_enable:
if (manager != null && channel != null)
{
// Since this is the system wireless settings activity, it's
// not going to send us a result. We will be notified by
// WiFiDeviceBroadcastReceiver instead.
Intent intent = new Intent();
// jump to wi-fi Direct settings
intent.setClassName("com.android.settings",
"com.android.settings.Settings$WifiP2pSettingsActivity");
startActivity(intent);
}
else
{
Log.e(TAG, "channel or manager is null");
}
return true;
case R.id.atn_direct_discover:
discoverDevices();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
/**
* Remove all peers and clear all fields. This is called on
* BroadcastReceiver receiving a state change event. This is merely an UI
* update.
*/
public void resetDeviceList()
{
ServerDeviceListFragment fragmentList = (ServerDeviceListFragment) getFragmentManager()
.findFragmentById(R.id.frag_djs_devices);
if (fragmentList != null)
{
fragmentList.clearPeers();
}
}
@Override
public void onChannelDisconnected()
{
// we will try once more
if (manager != null && !channelRetried)
{
Toast.makeText(this, "Wi-fi Direct Channel lost. Trying again...",
Toast.LENGTH_LONG).show();
resetDeviceList();
channelRetried = true;
manager.initialize(this, getMainLooper(), this);
}
else
{
Toast.makeText(
this,
"Wi-fi Direct Channel is still lost. Try disabling / re-enabling Wi-fi Direct in the P2P Settings.",
Toast.LENGTH_LONG).show();
}
}
@Override
public void showDetails(WifiP2pDevice device)
{
// TODO: This is for debugging, showing the device details
DJMusicFragment fragMusic = (DJMusicFragment) getFragmentManager()
.findFragmentById(R.id.frag_dj_music);
}
@Override
public void showInfo(WifiP2pInfo info)
{
DJMusicFragment fragMusic = (DJMusicFragment) getFragmentManager()
.findFragmentById(R.id.frag_dj_music);
if (info.isGroupOwner)
{
// fragMusic.setDebugText("I am the group owner.");
}
else
{
// fragMusic.setDebugText("I am not the group owner.");
}
}
/*
* Cancel an ongoing connection in progress. We won't actually use this
* method all that much
*
* (non-Javadoc)
*
* @see
* com.example.musicsaround.dj.ServerDeviceListFragment.DJFragmentListener
* #cancelDisconnect()
*/
@Override
public void cancelDisconnect()
{
/*
* A cancel abort request by user. Disconnect i.e. removeGroup if
* already connected. Else, request WifiP2pManager to abort the ongoing
* request
*/
if (manager != null)
{
Log.d(TAG, "Someone requested a cancel connect!");
final ServerDeviceListFragment fragment = (ServerDeviceListFragment) getFragmentManager()
.findFragmentById(R.id.frag_djs_devices);
if (fragment.getDevice() == null
|| fragment.getDevice().status == WifiP2pDevice.CONNECTED)
{
// we don't disconnect the whole group... it would be nice just
// to disconnect that one guy
// disconnect();
}
else if (fragment.getDevice().status == WifiP2pDevice.AVAILABLE
|| fragment.getDevice().status == WifiP2pDevice.INVITED
|| fragment.getDevice().status == WifiP2pDevice.CONNECTED)
{
manager.cancelConnect(channel, new ActionListener()
{
@Override
public void onSuccess()
{
// Toast.makeText(DJActivity.this,
// "Aborting connection",
// Toast.LENGTH_SHORT).show();
}
@Override
public void onFailure(int reasonCode)
{
// Toast.makeText(
// DJActivity.this,
// "Connect abort request failed. Reason Code: "
// + reasonCode, Toast.LENGTH_SHORT)
// .show();
Log.e(TAG,
"Could not abort connection, the reason is: "
+ reasonCode);
}
});
}
}
}
/*
* This is the main method to connect to a device through Wi-Fi Direct!
*
* (non-Javadoc)
*
* @see
* com.example.musicsaround.dj.ServerDeviceListFragment.DJFragmentListener
* #connect(android.net.wifi.p2p.WifiP2pConfig)
*/
@Override
public void connect(WifiP2pConfig config)
{
if (manager == null)
{
return;
}
// in DJ mode, we want to become the group owner
WifiP2pConfig newConfig = config;
newConfig.groupOwnerIntent = DJ_MODE;
manager.connect(channel, newConfig, new ActionListener()
{
@Override
public void onSuccess()
{
// WiFiDirectBroadcastReceiver will notify us. Ignore for now.
}
@Override
public void onFailure(int reason)
{
Toast.makeText(DJActivity.this,
"Connection failed. Retrying...", Toast.LENGTH_SHORT)
.show();
Log.e(TAG,
"Wi-fi Direct connection failed. The error code is: "
+ reason);
}
});
}
@Override
public void disconnect()
{
if (manager == null)
{
return;
}
// TODO: why do we have to remove the whole group upon disconnect?
// perhaps we only need to do so upon exiting DJ mode
manager.removeGroup(channel, new ActionListener()
{
@Override
public void onFailure(int reasonCode)
{
Log.e(TAG, "Disconnect failed. Reason is: " + reasonCode);
}
@Override
public void onSuccess()
{
Toast.makeText(DJActivity.this, "Disconnected a device.",
Toast.LENGTH_SHORT).show();
Log.d(TAG, "Disconnected from a device.");
}
});
}
/**
* @param isWifiP2pEnabled
* the isWifiP2pEnabled to set
*/
public void setIsWifiP2pEnabled(boolean isWifiP2pEnabled)
{
this.isWifiP2pEnabled = isWifiP2pEnabled;
}
public void playRemoteMusic(Uri musicFileURI, long startTime, int startPos)
{
ServerDeviceListFragment fragmentList = (ServerDeviceListFragment) getFragmentManager()
.findFragmentById(R.id.frag_djs_devices);
// convert URI to actual file path
Uri filePathFromActivity = Uri.parse(Utilities.getRealPathFromUri(
(Activity) this, musicFileURI));
File audioFile = new File(filePathFromActivity.getPath());
fragmentList.playMusicOnClients(audioFile, startTime, startPos);
}
public void playRemoteMusic(String musicFilePath, long startTime,
int startPos)
{
ServerDeviceListFragment fragmentList = (ServerDeviceListFragment) getFragmentManager()
.findFragmentById(R.id.frag_djs_devices);
File audioFile = new File(musicFilePath);
fragmentList.playMusicOnClients(audioFile, startTime, startPos);
}
public void stopRemoteMusic()
{
ServerDeviceListFragment fragmentList = (ServerDeviceListFragment) getFragmentManager()
.findFragmentById(R.id.frag_djs_devices);
fragmentList.stopMusicOnClients();
}
public Timer getTimer()
{
return timer;
}
}
songsmanager：
package com.example.musicsaround;
import java.io.File;
import java.io.FilenameFilter;
import java.util.ArrayList;
import java.util.HashMap;
public class SongsManager {
// SDCard Path
final String MEDIA_PATH = new String("/sdcard/Download");
private ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();
// Constructor
public SongsManager(){
}
/**
* Function to read all mp3 files from sdcard
* and store the details in ArrayList
* */
public ArrayList<HashMap<String, String>> getPlayList(){
File home = new File(MEDIA_PATH);
if (home.listFiles(new FileExtensionFilter()).length > 0) {
for (File file : home.listFiles(new FileExtensionFilter())) {
HashMap<String, String> song = new HashMap<String, String>();
song.put("songTitle", file.getName().substring(0, (file.getName().length() - 4)));
song.put("songPath", file.getPath());
// Adding each song to SongList
songsList.add(song);
}
}
// return songs list array
return songsList;
}
/**
* Class to filter files which are having .mp3 extension
* */
class FileExtensionFilter implements FilenameFilter {
public boolean accept(File dir, String name) {
return (name.endsWith(".mp3") || name.endsWith(".MP3"));
}
}
}
和logcat错误：
10-19 02:07:55.147: E/AndroidRuntime(1521): Process: com.example.musicsaround, PID: 1521
10-19 02:07:55.147: E/AndroidRuntime(1521): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.musicsaround/com.example.musicsaround.dj.DJActivity}: android.view.InflateException: Binary XML file line #13: Error inflating class fragment
10-19 02:07:55.147: E/AndroidRuntime(1521): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2184)
10-19 02:07:55.147: E/AndroidRuntime(1521): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
10-19 02:07:55.147: E/AndroidRuntime(1521): at android.app.ActivityThread.access$800(ActivityThread.java:135)
10-19 02:07:55.147: E/AndroidRuntime(1521): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
10-19 02:07:55.147: E/AndroidRuntime(1521): at android.os.Handler.dispatchMessage(Handler.java:102)
10-19 02:07:55.147: E/AndroidRuntime(1521): at android.os.Looper.loop(Looper.java:136)
10-19 02:07:55.147: E/AndroidRuntime(1521): at android.app.ActivityThread.main(ActivityThread.java:5001)
10-19 02:07:55.147: E/AndroidRuntime(1521): at java.lang.reflect.Method.invokeNative(Native Method)
10-19 02:07:55.147: E/AndroidRuntime(1521): at java.lang.reflect.Method.invoke(Method.java:515)
10-19 02:07:55.147: E/AndroidRuntime(1521): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
10-19 02:07:55.147: E/AndroidRuntime(1521): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
10-19 02:07:55.147: E/AndroidRuntime(1521): at dalvik.system.NativeStart.main(Native Method)
10-19 02:07:55.147: E/AndroidRuntime(1521): Caused by: android.view.InflateException: Binary XML file line #13: Error inflating class fragment
10-19 02:07:55.147: E/AndroidRuntime(1521): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:713)
10-19 02:07:55.147: E/AndroidRuntime(1521): at android.view.LayoutInflater.rInflate(LayoutInflater.java:755)
10-19 02:07:55.147: E/AndroidRuntime(1521): at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
10-19 02:07:55.147: E/AndroidRuntime(1521): at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
10-19 02:07:55.147: E/AndroidRuntime(1521): at android.view.LayoutInflater.inflate(LayoutInflater.java:353)
10-19 02:07:55.147: E/AndroidRuntime(1521): at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:290)
10-19 02:07:55.147: E/AndroidRuntime(1521): at android.app.Activity.setContentView(Activity.java:1929)
10-19 02:07:55.147: E/AndroidRuntime(1521): at com.example.musicsaround.dj.DJActivity.onCreate(DJActivity.java:62)
10-19 02:07:55.147: E/AndroidRuntime(1521): at android.app.Activity.performCreate(Activity.java:5231)
10-19 02:07:55.147: E/AndroidRuntime(1521): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
10-19 02:07:55.147: E/AndroidRuntime(1521): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2148)
10-19 02:07:55.147: E/AndroidRuntime(1521): ... 11 more
10-19 02:07:55.147: E/AndroidRuntime(1521): Caused by: java.lang.NullPointerException
10-19 02:07:55.147: E/AndroidRuntime(1521): at com.example.musicsaround.SongsManager.getPlayList(SongsManager.java:25)
10-19 02:07:55.147: E/AndroidRuntime(1521): at com.example.musicsaround.dj.DJMusicFragment.onCreateView(DJMusicFragment.java:126)
10-19 02:07:55.147: E/AndroidRuntime(1521): at android.app.Fragment.performCreateView(Fragment.java:1700)
10-19 02:07:55.147: E/AndroidRuntime(1521): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:866)
10-19 02:07:55.147: E/AndroidRuntime(1521): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1040)
10-19 02:07:55.147: E/AndroidRuntime(1521): at android.app.FragmentManagerImpl.addFragment(FragmentManager.java:1142)
10-19 02:07:55.147: E/AndroidRuntime(1521): at android.app.Activity.onCreateView(Activity.java:4786)
10-19 02:07:55.147: E/AndroidRuntime(1521): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:689)
答案 0 :(得分：2)
它在您的日志中：
9 02：07：55.147：E / AndroidRuntime（1521）：引起： java.lang.NullPointerException 10-19 02：07：55.147： E / AndroidRuntime（1521）：at com.example.musicsaround.SongsManager.getPlayList（SongsManager.java:25） 10-19 02：07：55.147：E / AndroidRuntime（1521）：at com.example.musicsaround.dj.DJMusicFragment.onCreateView（DJMusicFragment.java:126）
NullPointerException课程SongsManager课程第25行getPlayList为{{1}}。
答案 1 :(得分：0)
您可以使用FrameLayout而不是片段
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/linearLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".DJActivity" >
<FrameLayout
android:id="@+id/frag_dj_music"
android:name="com.example.musicsaround.dj.DJMusicFragment"
android:layout_width="match_parent"
android:layout_height="300dp" />
<FrameLayout
android:id="@+id/frag_djs_devices"
android:name="com.example.musicsaround.dj.ServerDeviceListFragment"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<TextView
android:id="@+id/txt_dj_time"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="DJ Time" />
</LinearLayout>