这个问题让我很沮丧很长一段时间，我希望有人可以帮助我。我正在使用Service Builder将自定义实体公开给JSON Web Service API，我想在我的portlet中使用它。我不能使用动态查询，因为稍后会有几个更复杂的查询有多个连接，我觉得自定义sql是最好的选择。但是，我甚至无法开始查询，因为对openSession（）的调用会抛出一个NPE。这是我的代码（我为长度道歉，但我真的不知道我在这里做错了什么，我只是想包括所有相关的内容）：
ServiceImpl类：
@JSONWebService
public class MBMessagesAsDiscussionPrimeServiceImpl extends MBMessagesAsDiscussionPrimeServiceBaseImpl {
@Override
public List<MBMessagesAsDiscussionPrime> getMessagesAsDiscussionPrime() throws SystemException {
MBMessagesAsDiscussionPrimeFinder finder = new MBMessagesAsDiscussionPrimeFinderImpl();
return finder.findByGroupId();
}
}
我的FinderImpl类：
public class MBMessagesAsDiscussionPrimeFinderImpl extends BasePersistenceImpl<MBMessagesAsDiscussionPrime> implements MBMessagesAsDiscussionPrimeFinder {
@Override
public List<MBMessagesAsDiscussionPrime> findByGroupId() throws SystemException {
SessionFactory sessionFactory = (SessionFactory) PortalBeanLocatorUtil.locate("liferaySessionFactory");
Session session = null;
try {
session = sessionFactory.openSession(); //exception here
//other stuff here, eventually...
} catch (Exception e) {
throw new SystemException(e);
} finally {
closeSession(session); //throws NPE here
}
}
}
自定义查询：
<?xml version="1.0" encoding="UTF-8"?>
<custom-sql>
<sql
id="com.test.portlet.service.persistence.MBMessagesAsDiscussionPrimeFinder.findByGroupId">
<![CDATA[
SELECT * FROM MBMessage, MBThread
WHERE
(MBMessage.threadId = MBThread.threadId) AND
(MBThread.groupID = ?)
ORDER BY
MBThread.rootMessageId DESC, MBMessage.messageId ASC
]]>
</sql>
</custom-sql>
和service.xml：
<?xml version="1.0"?>
<!DOCTYPE service-builder PUBLIC
"-//Liferay//DTD Service Builder 6.1.0//EN"
"http://www.liferay.com/dtd/liferay-service-builder_6_1_0.dtd">
<service-builder package-path="com.test.portlet">
<namespace>MBMessagesAsDiscussionPrime</namespace>
<entity name="MBMessagesAsDiscussionPrime" uuid="true" local-service="true" remote-service="true">
<column name="messageId" type="long" primary="true" />
<column name="threadId" type="long"/>
<column name="userId" type="long"/>
<column name="userName" type="String"/>
<column name="body" type="String"/>
<reference package-path="com.liferay.portlet.messageboards" entity="MBMessage" />
<reference package-path="com.liferay.portlet.messageboards" entity="MBThread" />
</entity>
</service-builder>
从localhost：8080 / custom-query-portlet / api / jsonws可以看到服务功能，这是我从中调用它的地方。除了在ServiceImpl类上设置@JSONWebService之外，还有什么特别需要做的事情，因为这是远程调用的吗？拜托，有人帮我解决这个问题。它让我爬上了墙！
答案 0 :(得分：0)
试试此代码
@Override
public List<MBMessagesAsDiscussionPrime> findByGroupId() throws SystemException {
Session session = null;
try {
session = openSession();
//other stuff here, eventually...
} catch (Exception e) {
throw new SystemException(e);
}
}
HTH
答案 1 :(得分：0)
使用Liferay 6.1.20和构建我使用maven和Liferay插件版本6.2.10.9。
确保您的MBMessagesAsDiscussionPrimeFinderImpl类位于service.persistence包/文件夹中。
运行服务构建器时，它会为您的WhateverFinderImpl生成接口。在你的情况下MBMessagesAsDiscussionPrimeFinderImpl。另外，它添加了代码以将其实例化到WhateverLocalServiceImpl中。在您的情况下，它似乎是MBMessagesAsDiscussionPrimeServiceImpl。
如果您的MBMessagesAsDiscussionPrimeServiceImpl类等同于WhateverLocalServiceImpl，那么它应该已经在其中实例化了您的MBMessagesAsDiscussionPrimeFinderImpl类，并且您可以将代码更改为以下内容并且它将起作用。
public class PlayerService extends Service implements MediaPlayer.OnPreparedListener,
MediaPlayer.OnErrorListener, MediaPlayer.OnCompletionListener,
MediaPlayer.OnBufferingUpdateListener{
private static final String ACTION_PLAY = "action.PLAY";
private static final String ACTION_PAUSE = "action.PAUSE";
private static final String ACTION_RESUME = "action.RESUME";
private static final String ACTION_SEEK = "action.SEEK_TO";
private static final String ACTION_NEXT = "action.NEXT";
private static final String ACTION_PREVIOUS = "action.PREVIOUS";
private static final String ACTION_REPEAT = "action.REPEAT";
private MediaPlayer mediaPlayer = null;
private String curentURL;
private boolean repeat = false;
private int currentPosition;
private final BroadcastReceiver receiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
Log.i("TEST", "Primesc comanda prin BroadcastReceiver " + intent.getAction());
String action = intent.getAction();
if(action.equals(ACTION_PLAY)){
curentURL = intent.getStringExtra("musicURL");
currentPosition = intent.getIntExtra("musicPosition", 0);
try {
if(mediaPlayer.isPlaying()) {
mediaPlayer.stop();
}
mediaPlayer.reset();
mediaPlayer.setDataSource(intent.getStringExtra("musicURL"));
mediaPlayer.prepareAsync();
} catch (IOException e) {
e.printStackTrace();
}
}
else if(action.equals(ACTION_PAUSE)){
if(mediaPlayer.isPlaying())
mediaPlayer.pause();
} else if(action.equals(ACTION_RESUME)){
if(!mediaPlayer.isPlaying())
mediaPlayer.start();
} else if(action.equals(ACTION_SEEK)){
if(mediaPlayer.isPlaying())
mediaPlayer.seekTo(intent.getIntExtra("seekProgress", 0) * 100);
Log.i("TEST","Dau seek la "+intent.getIntExtra("seekProgress", 0));
} else if(action.equals(ACTION_NEXT)){
Intent nextIntent = new Intent("action.activity.NEXT");
intent.putExtra("nextPosition", currentPosition+1);
sendBroadcast(nextIntent);
} else if(action.equals(ACTION_PREVIOUS)){
Intent previousIntent = new Intent("action.activity.PREVIOUS");
intent.putExtra("previousPosition", currentPosition-1);
sendBroadcast(previousIntent);
} else if(action.equals(ACTION_REPEAT)) {
repeat = intent.getBooleanExtra("repeatStatus", false);
}
}
};
@Override
public void onCreate() {
mediaPlayer = new MediaPlayer();
mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
mediaPlayer.setOnPreparedListener(this);
mediaPlayer.setOnCompletionListener(this);
mediaPlayer.setOnErrorListener(this);
mediaPlayer.setOnBufferingUpdateListener(this);
IntentFilter filter = new IntentFilter();
filter.addAction(ACTION_PLAY);
filter.addAction(ACTION_PAUSE);
filter.addAction(ACTION_NEXT);
filter.addAction(ACTION_RESUME);
filter.addAction(ACTION_PREVIOUS);
filter.addAction(ACTION_SEEK);
filter.addAction(ACTION_REPEAT);
registerReceiver(receiver, filter);
Notification notification = new Notification(R.drawable.playlisticon, getText(R.string.ticker_text),
System.currentTimeMillis());
Intent notificationIntent = new Intent(this, musicPlayer.class);
PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, notificationIntent, 0);
notification.setLatestEventInfo(this, getText(R.string.notification_title),
getText(R.string.notification_message), pendingIntent);
startForeground(1337, notification);
Log.i("TEST","onCreate se apeleaza");
}
@Override
public void onDestroy() {
unregisterReceiver(receiver);
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.i("TEST","A pornit service-ul");
return START_STICKY;
}
@Override
public IBinder onBind(Intent intent) {
Log.i("TEST", "Se face onBind");
return null;
}
@Override
public void onPrepared(MediaPlayer mp) {
mp.start();
Intent intent = new Intent("action.activity.UPDATE_UI");
intent.putExtra("duration", mp.getDuration());
sendBroadcast(intent);
}
@Override
public boolean onError(MediaPlayer mp, int what, int extra) {
Log.i("TEST", "Eroare incerc din nou "+what+" "+extra);
try {
if(mediaPlayer.isPlaying()) {
mediaPlayer.stop();
}
mediaPlayer.reset();
mediaPlayer.setDataSource(curentURL);
mediaPlayer.prepareAsync();
} catch (IOException e) {
e.printStackTrace();
}
return true;
}
@Override
public void onCompletion(MediaPlayer mediaPlayer) {
Log.i("TEST", "Action onComplete");
if(repeat) {
Intent intent = new Intent("action.activity.REPEAT");
intent.putExtra("currentPosition", currentPosition);
sendBroadcast(intent);
} else {
Intent intent = new Intent("action.activity.NEXT");
intent.putExtra("nextPosition", currentPosition+1);
sendBroadcast(intent);
}
}
@Override
public void onBufferingUpdate(MediaPlayer mp, int percent) {
if(mediaPlayer.isPlaying()){
Intent intent = new Intent("action.activity.UPDATE_BUFFER");
intent.putExtra("progress", percent);
intent.putExtra("seekBarProgress", mp.getCurrentPosition() / 100);
intent.putExtra("mediaCurentPosition", mp.getCurrentPosition());
sendBroadcast(intent);
Log.i("TEST","Current Position = "+mp.getCurrentPosition());
}
}
}
对于mBMessagesAsDiscussionPrimeFinder，驼峰案例可能有所不同。