Spring service injection with #Autowired results NullPointerException - spring

Question

I am trying to inject a service in GeofenceMonitoring class using
#Autowired
private IDeviceService deviceService;
but I am getting a NullPointerException
This is the interface of the service and below it's implementation :
IDeviceService
package com.sifast.gpstracking.service;
import java.util.List;
import org.springframework.transaction.annotation.Transactional;
import com.sifast.gpstracking.model.Device;
import com.sifast.gpstracking.service.util.IGenericService;
#Transactional
public interface IDeviceService extends IGenericService<Device, Integer> {
Device findDeviceByUniqueId(String uniqueId);
List<Device> findAllDevice();
}
DeviceService
package com.sifast.gpstracking.service.impl;
import java.io.Serializable;
import java.util.List;
import org.hibernate.Query;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import com.sifast.gpstracking.dao.impl.DeviceDao;
import com.sifast.gpstracking.model.Device;
import com.sifast.gpstracking.service.IDeviceService;
import com.sifast.gpstracking.service.util.GenericService;
#Service("deviceService")
public class DeviceService extends GenericService<Device, Integer> implements IDeviceService, Serializable {
private static final long serialVersionUID = 1L;
#Autowired
private DeviceDao deviceDao;
#Override
public Device findDeviceByUniqueId(String uniqueId) {
Query query = deviceDao.getSession().getNamedQuery("findDeviceByUniqueId").setString("uniqueId", uniqueId);
return deviceDao.findOne(query);
}
#Override
public List<Device> findAllDevice() {
return deviceDao.findAll(Device.class);
}
}
And here when I try to inject the service :
GeofenceMonitoring
package com.sifast.gpstracking.webServiceRest;
import java.util.ArrayList;
import java.util.List;
import org.primefaces.model.map.LatLng;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.ComponentScan;
import com.sifast.gpastracking.monitoring.IMonitor;
import com.sifast.gpstracking.model.Device;
import com.sifast.gpstracking.model.Geofence;
import com.sifast.gpstracking.model.GeofenceDevice;
import com.sifast.gpstracking.model.Point;
import com.sifast.gpstracking.push.DevicePositionData;
import com.sifast.gpstracking.service.IDeviceService;
import com.sifast.gpstracking.service.util.IntersectionGeofence;
#ComponentScan("com.sifast.gpstracking")
public class GeofenceMonitor implements IMonitor {
ArrayList<Geofence> geofences = new ArrayList<Geofence>();
GeofenceDevice geofenceDevice;
Boolean geofenced=false;
public static final Logger logger = LoggerFactory.getLogger(GeofenceMonitor.class);
#Autowired
private IDeviceService serviceDevice;
public GeofenceMonitor() {
}
#Override
public void updateMonitor(DevicePositionData devicePositionData) {
//logger.debug("DEVICE ID = " + devicePositionData.getUniqueId());
Device device = serviceDevice.findDeviceByUniqueId(devicePositionData.getUniqueId());
LatLng currentPosition = new LatLng(devicePositionData.getLatitude(), devicePositionData.getLongitude());
for (GeofenceDevice geofenceDevice : device.getListGeofenceDevice()) {
List<LatLng> listPoint = convertListPointToListLatLng(geofenceDevice.getGeofence().getListPoint());
logger.debug("SIZE =====> "+listPoint.size());
if (IntersectionGeofence.isPointInsidePolygon(currentPosition, listPoint))
{
geofenced = true;
logger.debug("Le device " + devicePositionData.getDeviceName() + " a dépassé la zone limitée");
break;
}
}
}
private List<LatLng> convertListPointToListLatLng(List<Point> listPoint)
{
List<LatLng> listLatLng = new ArrayList<LatLng>();
for (Point point : listPoint){
listLatLng.add(new LatLng(point.getLatitude(),point.getLongitude()));
}
return listLatLng;
}
}
And finally ApplicationContext.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.2.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.2.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.2.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd">
<mvc:annotation-driven />
<!-- Activates scanning of annotations -->
<context:component-scan base-package="com.sifast.gpstracking" />
<context:annotation-config/>
<context:spring-configured/>
<!-- Database Configuration -->
<import resource="/database/dataSource.xml" />
<import resource="/database/hibernate.xml" />
<!-- Transaction Manager is defined -->
<bean id="txManager" class="org.springframework.orm.hibernate4.HibernateTransactionManager">
<property name="sessionFactory" ref="sessionFactory" />
</bean>
<!-- Enable the configuration of transactional behavior based on annotations -->
<tx:annotation-driven transaction-manager="txManager" />
<mvc:annotation-driven></mvc:annotation-driven>
<!-- Pour avoir accès au resources comme les fichiers /js et /css lorsqu'on utilise un mapping / avec le servletDispatcher dans le web.xml -->
<mvc:resources mapping="/css/**" location="/resources/css/" />
<mvc:resources mapping="/images/**" location="/resources/images/" />
<!-- Init DataBase -->
<bean id="dbInit"
class="org.springframework.jdbc.datasource.init.ResourceDatabasePopulator">
<property name="scripts">
<list>
<value>classpath:sql/1.0.0/CreateData.sql</value>
</list>
</property>
<property name="continueOnError" value="true" />
</bean>
<bean id="startupScripts"
class="org.springframework.jdbc.datasource.init.DataSourceInitializer">
<property name="dataSource">
<ref bean="dataSource" />
</property>
<property name="databasePopulator">
<ref bean="dbInit" />
</property>
</bean>
</beans>

Answer 1

It's because that IDeviceService is an interface. Spring won't know which instance you want to autowire, since the default way to autowire is byType, if I'm not wrong.
Try this
#Autowired
#Qualifier("deviceService")
private IDeviceService deviceService;
try double stars first
<context:component-scan base-package="com.sifast.gpstracking.**" />
An simple example to get bean via applicationContext.getBean()
http://www.mkyong.com/spring/quick-start-maven-spring-example/
And you want to get it in web environment, you can inject it.
How to inject ApplicationContext itself

Answer 2

Is your GeofenceMonitor bean registered in the application context ? From your code snippets its missing streotype annotations (#Component / #Service etc) So it wont be auto detected and any specified dependencies wont be injected. Change #ComponentScan("com.sifast.gpstracking")
public class GeofenceMonitor implements IMonitor to #Component public class GeofenceMonitor implements IMonitor

Answer 3

the problem was that I am creating a new instance of GeofenceMonitor with new GeofenceMonitor() in a service class that's meant to handle the web service invokation.
So I modified it to #Scope("singleton") and added #PostConstruct private void init(). Below is my code:
PositionNotification (web service class)
#Service("positionNotification")
#Path("/positionNotification")
#Scope("singleton")
public class PositionNotification implements Serializable, IMonitorable {
private static final long serialVersionUID = 1L;
#Autowired
private GeofenceMonitor geofence;
private static ArrayList<IMonitor> monitors;
/*static {
monitors = new ArrayList<IMonitor>();
monitors.add(new SpeedMonitor());
monitors.add(geofence);
}*/
#Autowired
private IDeviceService deviceService;
#Autowired
private IPositionService positionService;
private final static String CHANNEL = "/notify";
public static final Logger logger = LoggerFactory.getLogger(PositionNotification.class);
private static final int STATUS_OK = 200;
#PostConstruct
private void init(){
monitors = new ArrayList<IMonitor>();
monitors.add(new SpeedMonitor());
monitors.add(geofence);
}
#POST
#Path("/getGeoLocFromDevice")
public Response test(#FormParam("LATITUDE") String latitude, #FormParam("LONGITUDE") String longitude, #FormParam("DEVICE_ID") String uniqueId,
#FormParam("SPEED") String speed, #FormParam("Horodateur") String date) {
logger.debug("X long: " + latitude + " __ Y lat: " + longitude + " uniqueId " + uniqueId + " " + date);
Device device = deviceService.findDeviceByUniqueId(uniqueId);
if (device != null) {
if (speed == null) {
speed = "0";
}
String address = AddressResolver.AddressReseolve(latitude, longitude);
DevicePositionData devicePositionData = new DevicePositionData();
devicePositionData.setLatitude(Double.valueOf(latitude));
devicePositionData.setLongitude(Double.valueOf(longitude));
devicePositionData.setUniqueId(uniqueId);
devicePositionData.setAddress(address);
devicePositionData.setDeviceName(device.getName());
devicePositionData.setSpeed(Double.parseDouble(speed));
devicePositionData.setIcon(device.getType().getIconActive());
Position position = new Position();
position.setAddress(address);
position.setLatitude(Double.valueOf(latitude));
position.setLongitude(Double.valueOf(longitude));
if (date != null) {
try {
position.setDatePosition(new SimpleDateFormat("dd-MM-yyyy HH:mm:ss").parse(date));
devicePositionData.setDatePosition(date);
device.setLastUpdate(new SimpleDateFormat("dd-MM-yyyy HH:mm:ss").parse(date));
} catch (ParseException e) {
e.printStackTrace();
}
} else {
position.setDatePosition(new Date());
devicePositionData.setDatePosition(new SimpleDateFormat("dd-MM-yyyy HH:mm:ss").format(new Date()));
device.setLastUpdate(new Date());
}
position.setSpeed(Double.parseDouble(speed));
position.setDevice(device);
positionService.saveOrUpdateService(position);
deviceService.saveOrUpdateService(device);
if (EventBusFactory.getDefault() != null) {
EventBus eventBus = EventBusFactory.getDefault().eventBus();
eventBus.publish(CHANNEL, devicePositionData);
}
notifyMonitors(devicePositionData);
}
return Response.status(STATUS_OK).build();
}
#Override
public void notifyMonitors(DevicePositionData devicePositionData) {
for (IMonitor monitor : monitors) {
monitor.updateMonitor(devicePositionData);
}
}
#Override
public void addMonitor(IMonitor monitor) {
monitors.add(monitor);
}
#Override
public void deleteMonitor(IMonitor monitor) {
monitors.remove(monitor);
}
#Override
public void clearMonitors() {
monitors.clear();
}
}