Android如何在intentservice中实现TCP ip客户端
我制作了一个简单的TCP客户端,当我使用简单的活动和按钮来发送消息时,它工作得很好 现在,我在这里使用相同的GoogleGeoFence示例实现geofence应用程序Android如何在intentservice中实现TCP ip客户端,android,tcp,nullpointerexception,android-intentservice,android-geofence,Android,Tcp,Nullpointerexception,Android Intentservice,Android Geofence,我制作了一个简单的TCP客户端,当我使用简单的活动和按钮来发送消息时,它工作得很好 现在,我在这里使用相同的GoogleGeoFence示例实现geofence应用程序 public class GeofenceTransitionsIntentService extends IntentService { protected static final String TAG = "GeofenceTransitionsIS"; /** * This constructor is requi
public class GeofenceTransitionsIntentService extends IntentService {
protected static final String TAG = "GeofenceTransitionsIS";
/**
* This constructor is required, and calls the super IntentService(String)
* constructor with the name for a worker thread.
*/
public GeofenceTransitionsIntentService() {
// Use the TAG to name the worker thread.
super(TAG);
}
@Override
public void onCreate() {
super.onCreate();
}
/**
* Handles incoming intents.
* @param intent sent by Location Services. This Intent is provided to Location
* Services (inside a PendingIntent) when addGeofences() is called.
*/
@Override
protected void onHandleIntent(Intent intent) {
GeofencingEvent geofencingEvent = GeofencingEvent.fromIntent(intent);
if (geofencingEvent.hasError()) {
String errorMessage = GeofenceErrorMessages.getErrorString(this,
geofencingEvent.getErrorCode());
Log.e(TAG, errorMessage);
return;
}
// Get the transition type.
int geofenceTransition = geofencingEvent.getGeofenceTransition();
// Test that the reported transition was of interest.
if (geofenceTransition == Geofence.GEOFENCE_TRANSITION_ENTER ||
geofenceTransition == Geofence.GEOFENCE_TRANSITION_EXIT) {
// Get the geofences that were triggered. A single event can trigger multiple geofences.
List<Geofence> triggeringGeofences = geofencingEvent.getTriggeringGeofences();
// Get the transition details as a String.
String geofenceTransitionDetails = getGeofenceTransitionDetails(
this,
geofenceTransition,
triggeringGeofences
);
// Send notification and log the transition details.
sendNotification(geofenceTransitionDetails);
Log.i(TAG, geofenceTransitionDetails);
} else {
// Log the error.
Log.e(TAG, getString(R.string.geofence_transition_invalid_type, geofenceTransition));
}
}
/**
* Gets transition details and returns them as a formatted string.
*
* @param context The app context.
* @param geofenceTransition The ID of the geofence transition.
* @param triggeringGeofences The geofence(s) triggered.
* @return The transition details formatted as String.
*/
private String getGeofenceTransitionDetails(
Context context,
int geofenceTransition,
List<Geofence> triggeringGeofences) {
String geofenceTransitionString = getTransitionString(geofenceTransition);
// Get the Ids of each geofence that was triggered.
ArrayList triggeringGeofencesIdsList = new ArrayList();
for (Geofence geofence : triggeringGeofences) {
triggeringGeofencesIdsList.add(geofence.getRequestId());
}
String triggeringGeofencesIdsString = TextUtils.join(", ", triggeringGeofencesIdsList);
return geofenceTransitionString + ": " + triggeringGeofencesIdsString;
}
/**
* Posts a notification in the notification bar when a transition is detected.
* If the user clicks the notification, control goes to the MainActivity.
*/
private void sendNotification(String notificationDetails) {
// Create an explicit content Intent that starts the main Activity.
Intent notificationIntent = new Intent(getApplicationContext(), MainActivity.class);
// Construct a task stack.
TaskStackBuilder stackBuilder = TaskStackBuilder.create(this);
// Add the main Activity to the task stack as the parent.
stackBuilder.addParentStack(MainActivity.class);
// Push the content Intent onto the stack.
stackBuilder.addNextIntent(notificationIntent);
// Get a PendingIntent containing the entire back stack.
PendingIntent notificationPendingIntent =
stackBuilder.getPendingIntent(0, PendingIntent.FLAG_UPDATE_CURRENT);
// Get a notification builder that's compatible with platform versions >= 4
NotificationCompat.Builder builder = new NotificationCompat.Builder(this);
// Define the notification settings.
builder.setSmallIcon(R.drawable.ic_launcher)
// In a real app, you may want to use a library like Volley
// to decode the Bitmap.
.setLargeIcon(BitmapFactory.decodeResource(getResources(),
R.drawable.ic_launcher))
.setColor(Color.RED)
.setContentTitle(notificationDetails)
.setContentText(getString(R.string.geofence_transition_notification_text))
.setContentIntent(notificationPendingIntent);
// Dismiss notification once the user touches it.
builder.setAutoCancel(true);
// Get an instance of the Notification manager
NotificationManager mNotificationManager =
(NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
// Issue the notification
mNotificationManager.notify(0, builder.build());
}
/**
* Maps geofence transition types to their human-readable equivalents.
*
* @param transitionType A transition type constant defined in Geofence
* @return A String indicating the type of transition
*/
private String getTransitionString(int transitionType) {
switch (transitionType) {
case Geofence.GEOFENCE_TRANSITION_ENTER:
return getString(R.string.geofence_transition_entered);
case Geofence.GEOFENCE_TRANSITION_EXIT:
return getString(R.string.geofence_transition_exited);
default:
return getString(R.string.unknown_geofence_transition);
}
}
}
开始向服务器发送消息的线程
Thread thread=new Thread(){
@Override
public void run() {
try {
mTcpClient.sendMessage("halo server");
} catch (Exception e) {
e.printStackTrace();
}
}
};
thread.start();
这是第一次进入地球围栏并成功发送消息
但下一次进入/退出时将出现错误
sendmessage方法上的java.lang.NullPointerException
我想问题是我没有正确启动和关闭连接,有人能帮我吗
编辑
异步任务类
public class ConnectTask extends AsyncTask<String, String, TCPClient> {
@Override
protected TCPClient doInBackground(String... message) {
// create a TCPClient object
mTcpClient = new TCPClient(new TCPClient.OnMessageReceived() {
@Override
//here the messageReceived method is implemented
public void messageReceived(String message) {
//this method calls the onProgressUpdate
publishProgress(message);
}
});
mTcpClient.run();
return null;
}
@Override
protected void onProgressUpdate(String... values) {
super.onProgressUpdate(values);
}
}
解决办法很简单 我只是将tcp对象转换为静态对象 旧的 新的
我真的不明白为什么它是静态的,如果有人能解释这一点,我将不胜感激我假设ConnectTask是您打开服务器连接的类。。在这里发布它,这样我们就可以检查它了..是的,我编辑代码来查看它当你有NullPointerException时哪个指针是空的?哪种说法导致了它?logcat会告诉你的。然后告诉我们.mTcpClient.sendMessage(“halo服务器”);第一次发送消息,第二次将抛出空指针异常,如果我关闭服务器并重新运行,它将发送消息一次,然后返回到异常,我必须关闭服务器并重新运行每条消息,因为IntentService是无状态的。在IntentService内部处理intent后,将处理所有变量。
public class ConnectTask extends AsyncTask<String, String, TCPClient> {
@Override
protected TCPClient doInBackground(String... message) {
// create a TCPClient object
mTcpClient = new TCPClient(new TCPClient.OnMessageReceived() {
@Override
//here the messageReceived method is implemented
public void messageReceived(String message) {
//this method calls the onProgressUpdate
publishProgress(message);
}
});
mTcpClient.run();
return null;
}
@Override
protected void onProgressUpdate(String... values) {
super.onProgressUpdate(values);
}
}
public class TCPClient {
// message to send to the server
private String mServerMessage;
// sends message received notifications
private OnMessageReceived mMessageListener = null;
// while this is true, the server will continue running
private boolean mRun = false;
// used to send messages
private PrintWriter mBufferOut;
// used to read messages from the server
private BufferedReader mBufferIn;
/**
* Constructor of the class.
*/
public TCPClient(OnMessageReceived listener) {
mMessageListener = listener;
}
/**
* Sends the message entered by client to the server
*
* @param message text entered by client
*/
public void sendMessage(String message) {
if (mBufferOut != null && !mBufferOut.checkError()) {
mBufferOut.println(message);
mBufferOut.flush();
}
}
/**
* Close the connection and release the members
*/
public void stopClient() {
sendMessage("close"+"bye");
mRun = false;
if (mBufferOut != null) {
mBufferOut.flush();
mBufferOut.close();
}
mMessageListener = null;
mBufferIn = null;
mBufferOut = null;
mServerMessage = null;
}
public void run() {
mRun = true;
try {
InetAddress serverAddr = InetAddress.getByName(Constants.SERVER_IP);
Log.e("TCP Client", "C: Connecting...");
//create a socket to make the connection with the server
Socket socket = new Socket(serverAddr, Constants.SERVER_PORT);
try {
//sends the message to the server
mBufferOut = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())), true);
//receives the message which the server sends back
mBufferIn = new BufferedReader(new InputStreamReader(socket.getInputStream()));
sendMessage("name"+"hi");
while (mRun) {
mServerMessage = mBufferIn.readLine();
if (mServerMessage != null && mMessageListener != null) {
//call the method messageReceived from MyActivity class
mMessageListener.messageReceived(mServerMessage);
}
}
Log.e("RESPONSE FROM SERVER", "S: Received Message: '" + mServerMessage + "'");
} catch (Exception e) {
Log.e("TCP", "S: Error", e);
} finally {
socket.close();
}
} catch (Exception e) {
Log.e("TCP", "C: Error", e);
}
}
//Declare the interface.
public interface OnMessageReceived {
public void messageReceived(String message);
}
}
private TCPClient mTcpClient;
private static TCPClient mTcpClient;