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POHow do I load properties with Spring when also using Camel?
 

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  1. POHow do I load properties with Spring when also using Camel?
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    <p>I have a HelloWorld Java project that uses Camel to obtain a Map, and print out its contents in JSON format. The Map currently has hardcoded values, but I really want to change my code so that it uses Spring to load a sensor.properties file of nested key,value pairs into this Map.</p> <p>I have another Java project I wrote that only uses Spring, and can load the sensor.properties file just fine into an Arraylist object.</p> <p>However, when I try to use code from that project to load the sensor.properties in my HelloWorld project I get the following Camel error with a NPE:</p> <pre><code>Returning Map 3310 [hello.world.request.timer] ERROR org.apache.camel.processor.DefaultErrorHandler - Failed delivery for exchangeId: 4e984884-df7f-4b82-a977-f5cf4c311814. Exhausted after delivery attempt: 1 caught: java.lang.NullPointerException java.lang.NullPointerException at sample.SensorGenerator.getSensors(SensorGenerator.java:17) at sample.HelloWorld.returnMap(HelloWorld.java:22) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:606) at org.apache.camel.component.bean.MethodInfo.invoke(MethodInfo.java:231) at org.apache.camel.component.bean.MethodInfo$1.proceed(MethodInfo.java:146) at org.apache.camel.component.bean.BeanProcessor.process(BeanProcessor.java:138) org.apache.camel.management.InstrumentationProcessor.process(InstrumentationProcessor.java:67) at org.apache.camel.processor.DelegateProcessor.processNext(DelegateProcessor.java:53) at org.apache.camel.processor.DelegateProcessor.proceed(DelegateProcessor.java:82) at org.apache.camel.processor.interceptor.TraceInterceptor.process(TraceInterceptor.java:97) at org.apache.camel.management.InstrumentationProcessor.process(InstrumentationProcessor.java:67) at org.apache.camel.processor.RedeliveryErrorHandler.processExchange(RedeliveryErrorHandler.java:185) at org.apache.camel.processor.RedeliveryErrorHandler.processErrorHandler(RedeliveryErrorHandler.java:151) at org.apache.camel.processor.RedeliveryErrorHandler.process(RedeliveryErrorHandler.java:89) at org.apache.camel.processor.DefaultErrorHandler.process(DefaultErrorHandler.java:49) at org.apache.camel.processor.DefaultChannel.process(DefaultChannel.java:228) at org.apache.camel.processor.Pipeline.process(Pipeline.java:75) at org.apache.camel.processor.UnitOfWorkProcessor.processNext(UnitOfWorkProcessor.java:70) at org.apache.camel.processor.DelegateProcessor.process(DelegateProcessor.java:48) at org. apache.camel.management.InstrumentationProcessor.process(InstrumentationProcessor.java:67) at org.apache.camel.component.timer.TimerConsumer.sendTimerExchange(TimerConsumer.java:102) at org.apache.camel.component.timer.TimerConsumer$1.run(TimerConsumer.java:49) at java.util.TimerThread.mainLoop(Timer.java:555) at java.util.TimerThread.run(Timer.java:505) </code></pre> <p>Is there something I need to add to my applicationContext.xml to tell Camel that Spring will load my sensor.properties? Do I need to use the Spring integration component specified at <a href="http://camel.apache.org/springintegration.html" rel="nofollow">http://camel.apache.org/springintegration.html</a> ?</p> <p>Here is my current ApplicationContext.xml:</p> <pre><code> &lt;?xml version="1.0" encoding="UTF-8"?&gt; &lt;beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:camel="http://camel.apache.org/schema/spring" xmlns:context="http://www.springframework.org/schema/context" xmlns:util="http://www.springframework.org/schema/util" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.0.xsd http://camel.apache.org/schema/spring http://camel.apache.org/schema/spring/camel-spring.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"&gt; &lt;bean class="org.springframework.context.annotation.CommonAnnotationBeanPostProcessor" /&gt; &lt;context:component-scan base-package="sample" /&gt; &lt;context:annotation-config /&gt; &lt;camel:camelContext id="HelloWorldContext"&gt; &lt;!-- Add Jackson library to render Java Map into JSON --&gt; &lt;camel:dataFormats&gt; &lt;camel:json id="jack" library="Jackson"/&gt; &lt;/camel:dataFormats&gt; &lt;camel:route&gt; &lt;!-- sends a request to the hello world JMS queue every 10 seconds --&gt; &lt;camel:from uri="timer://hello.world.request.timer?fixedRate=true&amp;amp;period=10000" /&gt; &lt;camel:to uri="log:hello.world.request?level=INFO?showAll=true" /&gt; &lt;camel:bean ref="helloWorld" /&gt; &lt;!-- now print out the map in JSON format --&gt; &lt;camel:marshal ref ="jack"/&gt; &lt;camel:convertBodyTo type="java.lang.String" /&gt; &lt;camel:log message="${body}"/&gt; &lt;!-- now log the message --&gt; &lt;camel:to uri="log:hello.world.response?level=INFO?showAll=true" /&gt; &lt;/camel:route&gt; &lt;/camel:camelContext&gt; &lt;bean id="jms" class="org.apache.activemq.camel.component.ActiveMQComponent"&gt; &lt;property name="configuration" ref="jmsConfig" /&gt; &lt;/bean&gt; &lt;bean id="jmsConfig" class="org.apache.camel.component.jms.JmsConfiguration"&gt; &lt;property name="connectionFactory" ref="jmsConnectionFactory" /&gt; &lt;property name="transacted" value="false" /&gt; &lt;property name="concurrentConsumers" value="1" /&gt; &lt;/bean&gt; &lt;bean id="jmsConnectionFactory" class="org.apache.activemq.ActiveMQConnectionFactory"&gt; &lt;property name="brokerURL" value="vm://localhost" /&gt; &lt;property name="redeliveryPolicy" ref="redeliveryPolicy" /&gt; &lt;property name="prefetchPolicy" ref="prefetchPolicy" /&gt; &lt;/bean&gt; &lt;bean id="prefetchPolicy" class="org.apache.activemq.ActiveMQPrefetchPolicy"&gt; &lt;property name="queuePrefetch" value="5" /&gt; &lt;/bean&gt; &lt;bean id="redeliveryPolicy" class="org.apache.activemq.RedeliveryPolicy"&gt; &lt;property name="maximumRedeliveries" value="1" /&gt; &lt;property name="backOffMultiplier" value="2" /&gt; &lt;property name="initialRedeliveryDelay" value="2000" /&gt; &lt;property name="useExponentialBackOff" value="true" /&gt; &lt;/bean&gt; &lt;!-- creates a java.util.Properties instance with values loaded from the supplied location --&gt; &lt;util:properties id="sensorProperties" location="classpath:/sensor.properties"/&gt; &lt;bean class="sample.SensorGenerator"&gt; &lt;property name="sourceProperties" ref="sensorProperties" /&gt; &lt;/bean&gt; &lt;/beans&gt; </code></pre> <p>Here are the four Java Classes I have (HelloWorldMain.java, HelloWorld.java, Sensor.java, and SensorGenerator.Java):</p> <p>UPDATED: The issue was that I had a constructor in my HelloWorld.java calling SensorGenerator instead of using @Autowired to let Spring do it. The answer by Frederic at the bottom shows the old code Constructor. The @Autowired annotation is shown below in HelloWorld.java:</p> <p>HelloWorldMain.java:</p> <pre><code>package sample; import org.springframework.context.support.AbstractApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class HelloWorldMain { // define context to load properties with Spring public static void main(String[] args) throws Exception { AbstractApplicationContext context = new ClassPathXmlApplicationContext( "applicationContext.xml"); Thread.currentThread().join(); } } </code></pre> <p>HelloWorld.java:</p> <pre><code>package sample; import java.util.*; import org.apache.camel.Handler; import org.springframework.stereotype.Service; /** * POJO that returns Hello World string * */ @Service public class HelloWorld { @AutoWired SensorGenerator sensorGenerator; @Handler public Map&lt;?, ?&gt; returnMap(){ System.out.println(); System.out.println("Returning Map"); // get the map of Sensors Map&lt;String,String&gt; mySensorMap = sensorGenerator.getSensors(); // print out the Sensors in the map on the console Set keys = mySensorMap.keySet(); for (Iterator i = keys.iterator(); i.hasNext();) { String key = (String) i.next(); String value = (String) mySensorMap.get(key); System.out.println("key= " + key + ", value= " + value); } return mySensorMap; } } </code></pre> <p>Sensor.java (which defines the fields I'm reading from sensor.properties):</p> <pre><code>package sample; public class Sensor { private String make; private String makeDataType; private String model; private String modelDataType; private String serialNumber; private String serialNumberDataType; private String sensorType; private String sensorTypeDataType; // getters and setters public String getMake() { return make; } public void setMake(String make) { this.make = make; } public String getMakeDataType() { return makeDataType; } public void setMakeDataType(String makeDataType) { this.makeDataType = makeDataType; } public String getModel() { return model; } public void setModel(String model) { this.model = model; } public String getModelDataType() { return modelDataType; } public void setModelDataType(String modelDataType) { this.modelDataType = modelDataType; } public String getSerialNumber() { return serialNumber; } public void setSerialNumber(String serialNumber) { this.serialNumber = serialNumber; } public String getSerialNumberDataType() { return serialNumberDataType; } public void setSerialNumberDataType(String serialNumberDataType) { this.serialNumberDataType = serialNumberDataType; } public String getSensorType() { return sensorType; } public void setSensorType(String sensorType) { this.sensorType = sensorType; } public String getSensorTypeDataType() { return sensorTypeDataType; } public void setSensorTypeDataType(String sensorTypeDataType) { this.sensorTypeDataType = sensorTypeDataType; } } </code></pre> <p>SensorGenerator.java (the class where I current hard-code the properties but want to have Spring load them from sensor.properties. If I comment out the For loop and any lines referencing sourceProperties I can get the map returned with the hard coded values just fine. That's why I suspect its some sort of Spring/Camel integration issue):</p> <p>package sample;</p> <pre><code>import java.util.HashMap; import java.util.Map; import java.util.Properties; public class SensorGenerator { private Properties sourceProperties; // variable to increment key number for each sensor int sensorNumber = 1; // method to inject sensor.properties into a Map using Spring Map&lt;String, String&gt; getSensors() { Map&lt;String, String&gt; sensorMap = new HashMap&lt;String, String&gt;(); for (Object key : sourceProperties.keySet()) { // Separate out each of the key,value pairs as an entry in the // values array String[] values = sourceProperties.getProperty((String) key).split( ","); System.out.println("values array size= " + values.length); // define string buffer that appends sensor number for each sensor's // keys. Ex: sensor1 would have s1make, s1makeDataType, etc. StringBuffer sensorNumberStringBuffer = new StringBuffer(); sensorNumberStringBuffer.append("s"); sensorNumberStringBuffer.append(sensorNumber); // make and its data type (with sensor number prefix) StringBuffer makeStringBuffer = new StringBuffer(); makeStringBuffer.append(sensorNumberStringBuffer); makeStringBuffer.append("make"); StringBuffer makeDataTypeStringBuffer = new StringBuffer(); makeDataTypeStringBuffer.append(sensorNumberStringBuffer); makeDataTypeStringBuffer.append("makeDataType"); // model and its data type (with sensor number prefix) StringBuffer modelStringBuffer = new StringBuffer(); modelStringBuffer.append(sensorNumberStringBuffer); modelStringBuffer.append("model"); StringBuffer modelDataTypeStringBuffer = new StringBuffer(); modelDataTypeStringBuffer.append(sensorNumberStringBuffer); modelDataTypeStringBuffer.append("modelDataType"); // serialNumber and its data type (with sensor number prefix) StringBuffer serialNumberStringBuffer = new StringBuffer(); serialNumberStringBuffer.append(sensorNumberStringBuffer); serialNumberStringBuffer.append("serialNumber"); StringBuffer serialNumberDataTypeStringBuffer = new StringBuffer(); serialNumberDataTypeStringBuffer.append(sensorNumberStringBuffer); serialNumberDataTypeStringBuffer.append("serialNumberDataType"); // sensorType and its data type (with sensor number prefix) StringBuffer sensorTypeStringBuffer = new StringBuffer(); sensorTypeStringBuffer.append(sensorNumberStringBuffer); sensorTypeStringBuffer.append("sensorType"); StringBuffer sensorTypeDataTypeStringBuffer = new StringBuffer(); sensorTypeDataTypeStringBuffer.append(sensorNumberStringBuffer); sensorTypeDataTypeStringBuffer.append("sensorTypeDataType"); /* put all the key,value pairs for this sensor in the sensorMap */ //TODO: Change all the hard coded values below to be elements // from the values array once Spring can load spring.properties // make and and its data type sensorMap.put(makeStringBuffer.toString(), "DummyMake"); sensorMap.put(makeDataTypeStringBuffer.toString(), "String"); // model and and its data type sensorMap.put(modelStringBuffer.toString(), "DummyModel"); sensorMap.put(modelDataTypeStringBuffer.toString(), "String"); // serialNumber and and its data type sensorMap.put(serialNumberStringBuffer.toString(), "1234567890"); sensorMap.put(serialNumberDataTypeStringBuffer.toString(), "long"); // sensorType and its data type sensorMap.put(sensorTypeStringBuffer.toString(), "DummyType"); sensorMap.put(sensorTypeDataTypeStringBuffer.toString(), "String"); // increment for next sensor sensorNumber++; } return sensorMap; } public void setSourceProperties(Properties properties) { this.sourceProperties = properties; } } </code></pre> <p>Btw: Line 17 of SensorGenerator.java as mentioned in the stack trace above is:</p> <pre><code> for (Object key : sourceProperties.keySet()) { </code></pre> <p>Here is an example sensor.properties file:</p> <pre><code>sensor1=DummySensor1:String,SensorModel1:String,1234567890:long,SensorType1:String sensor2=DummySensor2:String,SensorModel2:String,8675309123:long,SensorType2:String </code></pre>
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