我试图运行publish（）方法Class Listener。
但每当发生错误时。通过创建访问Listener var = new Listener (); var.publish ()。他在Listener class中要求建筑师。公开的Listener（）{}留空了。我可以在System.out.printl ("blabla")中调用Listener，但发布（）不会。
也许是因为publish () Listener中的方法Class使用了connectionDetails，我可能不得不将其传递给构造函数。
有助于从Publish()致电ActionListener/Connect()。
班级听众：
package org.eclipse.paho.android.service.sample;
import android.content.Context;
import android.content.Intent;
import android.util.Log;
import android.view.MenuItem;
import android.view.MenuItem.OnMenuItemClickListener;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.RadioGroup;
import android.widget.TextView;
import org.eclipse.paho.android.service.MqttAndroidClient;
import org.eclipse.paho.android.service.sample.ActionListener.Action;
import org.eclipse.paho.android.service.sample.Connection.ConnectionStatus;
import org.eclipse.paho.client.mqttv3.MqttException;
import org.eclipse.paho.client.mqttv3.MqttSecurityException;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Map.Entry;
import java.util.logging.LogManager;
/**
* Deals with actions performed in the {@link ClientConnections} activity
* and the {@link ConnectionDetails} activity and associated fragments
*
*/
public class Listener implements OnMenuItemClickListener {
/** The handle to a {@link Connection} object which contains the {@link MqttAndroidClient} associated with this object **/
private String clientHandle = null;
/** {@link ConnectionDetails} reference used to perform some actions**/
private ConnectionDetails connectionDetails = null;
/** {@link ClientConnections} reference used to perform some actions**/
private ClientConnections clientConnections = null;
/** {@link Context} used to load and format strings **/
private Context context = null;
/** Whether Paho is logging is enabled**/
static boolean logging = false;
/**
* Constructs a listener object for use with {@link ConnectionDetails} activity and
* associated fragments.
* @param connectionDetails The instance of {@link ConnectionDetails}
* @param clientHandle The handle to the client that the actions are to be performed on
*/
public Listener(ConnectionDetails connectionDetails, String clientHandle)
{
this.connectionDetails = connectionDetails;
this.clientHandle = clientHandle;
context = connectionDetails;
}
/**
* Constructs a listener object for use with {@link ClientConnections} activity.
* @param clientConnections
*/
public Listener(ClientConnections clientConnections) {
this.clientConnections = clientConnections;
context = this.clientConnections;
}
public Listener( ) {
}
/**
* Perform the needed action required based on the button that
* the user has clicked.
*
* @param item The menu item that was clicked
* @return If there is anymore processing to be done
*
*/
@Override
public boolean onMenuItemClick(MenuItem item) {
int id = item.getItemId();
switch (id)
{
case R.id.publish :
publish();
break;
case R.id.subscribe :
subscribe();
break;
}
return false;
}
/**
* Publish the message the user has specified
*/
public void publish()
{
String topic = ((EditText)connectionDetails.findViewById(R.id.lastWillTopic))
.getText().toString();
String message = ((EditText) connectionDetails.findViewById(R.id.lastWill)).getText()
.toString();
RadioGroup radio = (RadioGroup) connectionDetails.findViewById(R.id.qosRadio);
int checked = radio.getCheckedRadioButtonId();
int qos = ActivityConstants.defaultQos;
switch (checked) {
case R.id.qos0 :
qos = 0;
break;
case R.id.qos1 :
qos = 1;
break;
case R.id.qos2 :
qos = 2;
break;
}
boolean retained = ((CheckBox) connectionDetails.findViewById(R.id.retained))
.isChecked();
String[] args = new String[2];
args[0] = message;
args[1] = topic+";qos:"+qos+";retained:"+retained;
try {
Connections.getInstance(context).getConnection(clientHandle).getClient()
.publish(topic, message.getBytes(), qos, retained, null, new ActionListener(context, Action.PUBLISH, clientHandle, args));
}
catch (MqttSecurityException e) {
Log.e(this.getClass().getCanonicalName(), "Failed to publish a messged from the client with the handle " + clientHandle, e);
}
catch (MqttException e) {
Log.e(this.getClass().getCanonicalName(), "Failed to publish a messged from the client with the handle " + clientHandle, e);
}
}
}
类ActionListener
package org.eclipse.paho.android.service.sample;
import android.content.Context;
import android.widget.Toast;
import org.eclipse.paho.android.service.sample.Connection.ConnectionStatus;
import org.eclipse.paho.client.mqttv3.IMqttActionListener;
import org.eclipse.paho.client.mqttv3.IMqttToken;
/**
* This Class handles receiving information from the
* {@link MqttAndroidClient} and updating the {@link Connection} associated with
* the action
*/
class ActionListener implements IMqttActionListener {
/**
* Actions that can be performed Asynchronously <strong>and</strong> associated with a
* {@link ActionListener} object
*
*/
enum Action {
/** Connect Action **/
CONNECT,
/** Disconnect Action **/
DISCONNECT,
/** Subscribe Action **/
SUBSCRIBE,
/** Publish Action **/
PUBLISH
}
/**
* The {@link Action} that is associated with this instance of
* <code>ActionListener</code>
**/
private Action action;
/** The arguments passed to be used for formatting strings**/
private String[] additionalArgs;
/** Handle of the {@link Connection} this action was being executed on **/
private String clientHandle;
/** {@link Context} for performing various operations **/
private Context context;
/**
* Creates a generic action listener for actions performed form any activity
*
* @param context
* The application context
* @param action
* The action that is being performed
* @param clientHandle
* The handle for the client which the action is being performed
* on
* @param additionalArgs
* Used for as arguments for string formating
*/
public ActionListener(Context context, Action action,
String clientHandle, String... additionalArgs) {
this.context = context;
this.action = action;
this.clientHandle = clientHandle;
this.additionalArgs = additionalArgs;
}
/**
* The action associated with this listener has been successful.
*
* @param asyncActionToken
* This argument is not used
*/
@Override
public void onSuccess(IMqttToken asyncActionToken) {
switch (action) {
case CONNECT :
connect();
break;
case DISCONNECT :
disconnect();
break;
}
}
/**
* A disconnection action has been successfully completed, update the
* connection object associated with the client this action belongs to and
* then notify the user of success.
*/
private void disconnect() {
Connection c = Connections.getInstance(context).getConnection(clientHandle);
c.changeConnectionStatus(ConnectionStatus.DISCONNECTED);
String actionTaken = context.getString(R.string.toast_disconnected);
c.addAction(actionTaken);
}
/**
* A connection action has been successfully completed, update the
* connection object associated with the client this action belongs to and
* then notify the user of success.
*/
private void connect() {
Connection c = Connections.getInstance(context).getConnection(clientHandle);
c.changeConnectionStatus(Connection.ConnectionStatus.CONNECTED);
c.addAction("Client Connected");
Listener var = new Listener();
var.publish();
}
}
我的Logcat：
09-27 11:22:21.824 3324-3324/org.eclipse.paho.android.service.sample D/dalvikvm﹕ GC_FOR_ALLOC freed 232K, 9% free 3239K/3552K, paused 6ms, total 12ms
09-27 11:22:22.304 3324-3494/org.eclipse.paho.android.service.sample D/AlarmPingSender﹕ Register alarmreceiver to MqttServiceMqttService.pingSender.Quarto
09-27 11:22:22.304 3324-3494/org.eclipse.paho.android.service.sample D/AlarmPingSender﹕ Schedule next alarm at 1443367352311
09-27 11:22:22.324 3324-3324/org.eclipse.paho.android.service.sample D/AndroidRuntime﹕ Shutting down VM
09-27 11:22:22.324 3324-3324/org.eclipse.paho.android.service.sample W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0xb3ce0b20)
09-27 11:22:22.334 3324-3324/org.eclipse.paho.android.service.sample D/dalvikvm﹕ GC_FOR_ALLOC freed 353K, 12% free 3401K/3832K, paused 9ms, total 10ms
--------- beginning of /dev/log/system
09-27 11:22:22.344 3324-3324/org.eclipse.paho.android.service.sample E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: org.eclipse.paho.android.service.sample, PID: 3324
java.lang.NullPointerException
at org.eclipse.paho.android.service.sample.Listener.publish(Listener.java:245)
at org.eclipse.paho.android.service.sample.ActionListener.connect(ActionListener.java:164)
at org.eclipse.paho.android.service.sample.ActionListener.onSuccess(ActionListener.java:92)
at org.eclipse.paho.android.service.MqttTokenAndroid.notifyComplete(MqttTokenAndroid.java:124)
at org.eclipse.paho.android.service.MqttAndroidClient.simpleAction(MqttAndroidClient.java:1370)
at org.eclipse.paho.android.service.MqttAndroidClient.connectAction(MqttAndroidClient.java:1325)
at org.eclipse.paho.android.service.MqttAndroidClient.onReceive(MqttAndroidClient.java:1265)
at android.support.v4.content.LocalBroadcastManager.executePendingBroadcasts(LocalBroadcastManager.java:297)
at android.support.v4.content.LocalBroadcastManager.access$000(LocalBroadcastManager.java:46)
at android.support.v4.content.LocalBroadcastManager$1.handleMessage(LocalBroadcastManager.java:116)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)