Static methods in concurrency
I have a static method which takes a few String and double parameters and contains only local variables. When it is called by multiple threads there seems to be an exception thrown intermittenly. I got a little paranoid and so I've changed it to an instance method, and now the problem seems to disappear.
Is this just a coincidence? Is my static method intrinsically thread-safe? Or are there any concurrency issues with static methods that I'm not aware of?
Any reply is much appreciated!
public static net.opengis.sos.v_1_0_0.InsertObservationResponse insertObservation(String serverURL, String AssignedSensorId, String dataType, String timeFrom, String timeTo, String srsName, double x, double y, long numElement, String dataString) throws MalformedURLException, IOException, JAXBException, ParserConfigurationException {
OutputStream out = null;
InputStream in = null;
try {
URL url = new URL(serverURL);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-type", "text/xml, application/xml");
out = connection.getOutputStream();
JAXBContext jaxbContext = JAXBContext.newInstance("net.opengis.sos.v_1_0_0:net.opengis.ows.v_1_1_0:net.opengis.sos.v_1_0_0.filter.v_1_1_0:net.opengis.sensorml.v_1_0_1:net.opengis.swe.v_1_0_1:net.opengis.om.v_1_0_0:net.opengis.gml.v_3_1_1:net.opengis.sampling.v_1_0_0");
/////////////////////////////////request
Marshaller marshaller = jaxbContext.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
//////////////////////////////////////object factories
net.opengis.gml.v_3_1_1.ObjectFactory gmlOF = new net.opengis.gml.v_3_1_1.ObjectFactory();
net.opengis.swe.v_1_0_1.ObjectFactory sweOF = new net.opengis.swe.v_1_0_1.ObjectFactory();
net.opengis.sampling.v_1_0_0.ObjectFactory saOF = new net.opengis.sampling.v_1_0_0.ObjectFactory();
////////////////////////////////////////////////////////////////////////////////////////////////getObservation request
net.opengis.sos.v_1_0_0.InsertObservation insertObservation = new net.opengis.sos.v_1_0_0.InsertObservation();
insertObservation.setAssignedSensorId(AssignedSensorId);
net.opengis.om.v_1_0_0.ObservationType observation = new net.opengis.om.v_1_0_0.ObservationType();
///////////////////////////////om:samplingTime
//begin position
net.opengis.gml.v_3_1_1.TimePositionType beginTimePosition = new net.opengis.gml.v_3_1_1.TimePositionType();
beginTimePosition.getValue().add(timeFrom);
//end position
net.opengis.gml.v_3_1_1.TimePositionType endTimePosition = new net.opengis.gml.v_3_1_1.TimePositionType();
endTimePosition.getValue().add(timeTo);
//time period
net.opengis.gml.v_3_1_1.TimePeriodType timePeriod = new net.opengis.gml.v_3_1_1.TimePeriodType();
timePeriod.setBeginPosition(beginTimePosition);
timePeriod.setEndPosition(endTimePosition);
net.opengis.swe.v_1_0_1.TimeObjectPropertyType timeObjectPropertyType = new net.opengis.swe.v_1_0_1.TimeObjectPropertyType();
timeObjectPropertyType.setTimeObject(gmlOF.createTimePeriod(timePeriod));
// timeObjectPropertyType.setTimeObject(new JAXBElement(new QName("http://www.opengis.net/gml", "name"), net.opengis.gml.v_3_1_1.TimePeriodType.class, timePeriod));
observation.setSamplingTime(timeObjectPropertyType);
/////////////////////////////////om:procedure
net.opengis.om.v_1_0_0.ProcessPropertyType processPropertyType = new net.opengis.om.v_1_0_0.ProcessPropertyType();
processPropertyType.setHref(AssignedSensorId);
observation.setProcedure(processPropertyType);
/////////////////////////////////om:observedProperty
net.opengis.swe.v_1_0_1.CompositePhenomenonType compositePhenomenonType = new net.opengis.swe.v_1_0_1.CompositePhenomenonType();
compositePhenomenonType.setId("cpid0");
compositePhenomenonType.setDimension(BigInteger.ONE);
net.opengis.gml.v_3_1_1.CodeType codeType = new net.opengis.gml.v_3_1_1.CodeType();
codeType.setValue("resultComponents");
compositePhenomenonType.getName().add(new JAXBElement(new QName("http://www.opengis.net/gml", "name"), net.opengis.gml.v_3_1_1.CodeType.class, codeType));
net.opengis.swe.v_1_0_1.PhenomenonPropertyType phenomenonPropertyType1 = new net.opengis.swe.v_1_0_1.PhenomenonPropertyType();
phenomenonPropertyType1.setHref("urn:ogc:data:time:iso8601");
compositePhenomenonType.getComponent().add(phenomenonPropertyType1);
net.opengis.swe.v_1_0_1.PhenomenonPropertyType phenomenonPropertyType2 = new net.opengis.swe.v_1_0_1.PhenomenonPropertyType();
phenomenonPropertyType2.setHref("Abfluss");
compositePhenomenonType.getComponent().add(phenomenonPropertyType2);
net.opengis.swe.v_1_0_1.PhenomenonPropertyType observedProperty = new net.opengis.swe.v_1_0_1.PhenomenonPropertyType();
observedProperty.setPhenomenon(sweOF.createCompositePhenomenon(compositePhenomenonType));
observation.setObservedProperty(observedProperty);
////////////////////////////////om:featureOfInterest
net.opengis.sampling.v_1_0_0.SamplingPointType samplingPoint = new net.opengis.sampling.v_1_0_0.SamplingPointType();
samplingPoint.setId(AssignedSensorId);
net.opengis.gml.v_3_1_1.CodeType saName = new net.opengis.gml.v_3_1_1.CodeType();
saName.setValue(AssignedSensorId);
samplingPoint.getName().add(new JAXBElement(new QName("http://www.opengis.net/gml", "name"), net.opengis.gml.v_3_1_1.CodeType.class, saName));
//samplingPoint.getSampledFeature().add(gmlOF.createFeaturePropertyType());
net.opengis.gml.v_3_1_1.DirectPositionType pos = new net.opengis.gml.v_3_1_1.DirectPositionType();
pos.setSrsName(srsName/*"urn:ogc:def:crs:EPSG:4326"*/);
pos.getValue().add(x);
pos.getValue().add(y);
net.opengis.gml.v_3_1_1.PointType point = new net.opengis.gml.v_3_1_1.PointType();
point.setPos(pos);
net.opengis.gml.v_3_1_1.PointPropertyType pointProperty = new net.opengis.gml.v_3_1_1.PointPropertyType();
pointProperty.setPoint(point);
samplingPoint.setPosition(pointProperty);
net.opengis.gml.v_3_1_1.FeaturePropertyType featureMember = new net.opengis.gml.v_3_1_1.FeaturePropertyType();
featureMember.setFeature(saOF.createSamplingPoint(samplingPoint));
net.opengis.gml.v_3_1_1.FeatureCollectionType featureCollectionType = new net.opengis.gml.v_3_1_1.FeatureCollectionType();
featureCollectionType.getFeatureMember().add(featureMember);
net.opengis.gml.v_3_1_1.FeaturePropertyType featureOfInterest = new net.opengis.gml.v_3_1_1.FeaturePropertyType();
featureOfInterest.setFeature(gmlOF.createFeatureCollection(featureCollectionType));
// featureOfInterest.setFeature(new JAXBElement(new QName("http://www.opengis.net/gml", "name"), net.opengis.gml.v_3_1_1.FeatureCollectionType.class, featureCollectionType));
observation.setFeatureOfInterest(featureOfInterest);
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setNamespaceAware(true);
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.newDocument();
final String sweNS = "http://www.opengis.net/swe/1.0.1";
Element dataArray = doc.createElementNS(sweNS, "swe:DataArray");
Element elementCount = doc.createElementNS(sweNS, "swe:elementCount");
Element count = doc.createElementNS(sweNS, "swe:Count");
Element value = doc.createElementNS(sweNS, "swe:value");
dataArray.appendChild(elementCount).appendChild(count).appendChild(value).appendChild(doc.createTextNode(String.valueOf(numElement)));
Element elementType = doc.createElementNS(sweNS, "swe:elementType");
elementType.setAttribute("name", "Components");
Element simpleDataRecord = doc.createElementNS(sweNS, "swe:SimpleDataRecord");
Element timeField = doc.createElementNS(sweNS, "swe:field");
timeField.setAttribute("name", "Time");
Element time = doc.createElementNS(sweNS, "swe:Time");
time.setAttribute("definition", "urn:ogc:data:time:iso8601");
Element featureField = doc.createElementNS(sweNS, "swe:field");
featureField.setAttribute("name", "feature");
Element text = doc.createElementNS(sweNS, "swe:Text");
text.setAttribute("definition", "urn:ogc:data:feature");
Element dataField = doc.createElementNS(sweNS, "swe:field");
dataField.setAttribute("name", dataType);
Element quantity = doc.createElementNS(sweNS, "swe:Quantity");
quantity.setAttribute("definition", dataType);
Element uom = doc.createElementNS(sweNS, "swe:uom");
uom.setAttribute("code", "m3 per s");
simpleDataRecord.appendChild(timeField).appendChild(time);
simpleDataRecord.appendChild(featureField).appendChild(text);
simpleDataRecord.appendChild(dataField).appendChild(quantity).appendChild(uom);
dataArray.appendChild(elementType).appendChild(simpleDataRecord);
Element encoding = doc.createElementNS(sweNS, "swe:encoding");
Element textBlock = doc.createElementNS(sweNS, "swe:TextBlock");
textBlock.setAttribute("decimalSeparator", ".");
textBlock.setAttribute("tokenSeparator", ",");
textBlock.setAttribute("blockSeparator", ";");
dataArray.appendChild(encoding).appendChild(textBlock);
Element sweValues = doc.createElementNS(sweNS, "swe:values");
dataArray.appendChild(sweValues).appendChild((doc.createTextNode(dataString)));
Element result = doc.createElementNS("http://www.opengis.net/om/1.0", "om:result");
result.appendChild(dataArray);
observation.setResult(result);
insertObservation.setObservation(observation);
//handle "ogc" namespace bug
NamespacePrefixMapper mapper = new PreferredMapper();
marshaller.setProperty("com.sun.xml.bind.namespacePrefixMapper", mapper);
marshaller.marshal(insertObservation, System.out);
marshaller.marshal(insertObservation, out);
Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
in = connection.getInputStream();
Object response = unmarshaller.unmarshal(new StreamSource(in));
if (response instanceof net.opengis.sos.v_1_0_0.InsertObservationResponse) {
return (net.opengis.sos.v_1_0_0.InsertObservationResponse) response;
} else if (response instanceof net.opengis.ows.v_1_1_0.ExceptionReport) {
net.opengis.ows.v_1_1_0.ExceptionReport exceptionReport = (net.opengis.ows.v_1_1_0.ExceptionReport) response;
StringBuilder strBuilder = new StringBuilder();
for (net.opengis.ows.v_1_1_0.ExceptionType ex : exceptionReport.getException()) {
StringBuilder tempBuilder = new StringBuilder(ex.getExceptionCode() + ": ");
for (String temp : exceptionReport.getException().get(0).getExceptionText()) {
tempBuilder.append(temp + "\n");
strBuilder.append(tempBuilder.toString() + "\n");
throw new IllegalArgumentException(strBuilder.toString());
} else {
throw new IllegalStateException("Unrecognizeable response type!");
} finally {
if (out != null) {
out.close();
if (in != null) {
in.close();
}Edited by: 808239 on 10-Feb-2011 02:44
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if ((totalRows - (articlesPerPage * page)) > 0) {
int pageNext = page + 1;
request.setAttribute("pageNext", pageNext);
// These will be used by calling code for SQL query.
request.setAttribute("startRow", startRow);
request.setAttribute("endRow", endRow);
// These will be used in JSP page.
request.setAttribute("totalRows", totalRows);
request.setAttribute("numOfPages", numOfPages);
request.setAttribute("page", page);
request.setAttribute("pages", pages);
}I need two parameters from this method (startrow and endrow) so I can perform my SQL queries. Since this is a multithreaded app, I do not want to use class variables that I will later retrieve through methods.
So my solution was to just set the two parameters in the request and grab them later with the calling code like this:
// Set pagination
Pagination.setPagination(request, conf, tl.getTotalRows());
// Grab variables set into request by static method
int startRow = new Integer(request.getAttribute("startRow").toString());
int endRow = new Integer(request.getAttribute("endRow").toString());
// Use startRow and endRow for SQL query below...Does anyone see any problem with this from a resource/performance standpoint? Any idea on what the overhead is in using the HttpServletRequest object like this to pass variables around?
Thanks for any thoughts.You could either
- create instance vars in both controllers and set them accordingly to point to the same object (from the App Delegate) OR
- create an instance variable on the App Delegate and access it from within the view controllers
Hope this helps! -
Can you set a global EntityResolver (via system property, or static method)
I'm trying to set a customized EntityResolver (telling the xml parser where to look for XML schema files).
Usually, you'd use the standard syntax - somehting like:
SaxParser parser=new SaxParser();
parser.parser.setEntityResolver(myResolver);
However, I was wondering whether you can set a "global" EntityResolver, to be used as default for all parsers ?
Maybe this can be done through some system property, or a static method somewhere in the parsing XML ?
(BTW, I need it because I'm using some third-party API, that encapsulates a SaxParser, but won't let me access it, so I can't configure it directly).
thanks.I don't think you can.
What is possible is to set content on the folder resource itself; that would be returned instead of the page you mentioned. -
How to call a static method from an event handler
Hi,
I'm trying to call a static method of class I designed. But I don't know how to do it. This method will be called from an event handler of a web dynpro for Abap application.
Can somebody help me?
Thx in advance.
Hamza.To clearly specify the problem.
I have a big part code that I use many times in my applications. So I decided to put it in a static method to reuse the code. but my method calls functions module of HR module. but just after the declaration ( at the first line of the call function) it thows an exception. So I can't call my method. -
How to call a static method in a class if I have just the object?
Hello. I have an abstract class A where I have a static method blah(). I have 2 classes that extend class A called B and C. In both classes I override method blah(). I have an array with objects of type B and C.
For every instance object of the array, I'm trying to call the static method in the corresponding class. For objects of type B I want to call blah() method in B class and for objects of type C I want to call blah() method in C class. I know it's possible to call a static method with the name of the object, too, but for some reason (?) it calls blah() method in class A if I try this.
So my question is: how do I code this? I guess I need to cast to the class name and then call the method with the class name, but I couldn't do it. I tried to use getClass() method to get the class name and it works, but I didn't know what to do from here...
So any help would be appreciated. Thank you.As somebody already said, to get the behavior you
want, make the methods non-static.You all asked me why I need that method to be
static... I'm not surprised to hear this question
because I asked all my friends before posting here,
and all of them asked me this... It's because some
complicated reasons, I doubt it.
the application I'm writing is
quite big...Irrelevant.
Umm... So what you're saying is there is no way to do
this with that method being static? The behavior you describe cannot be obtained with only static methods in Java. You'd have to explicitly determine the class and then explicitly call the correct class' method. -
Calling a method from a static method
hello all,
I'm calling a non-static method from a static method (from the main method). To overcome this i can make the method i am calling static but is there another way to get this to work without making the method that is being called static?
all replies welcome, thanksWhen you call a non-static method, you are saying you are calling a method on an object. The object is an instance of the class in which the method is defined. It is a non-static method, because the instance holds data in it's instance variables that is needed to perform the method. Therefore to call this kind of method, you need to get (or create an instance of the class. Assuming the two methods are in the same class, you could do
public class Foo
public static void main(String[] args)
Foo f = new Foo();
f.callNonStaticMethod();
}for instance.
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