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I'm using a Spring Boot application. For now, the use of the plugins is very simple. I'm just following the tutorial. My plugin is started, I'm trying to find the extensions like this:
final List<MyExtensionPoint> sections = pluginManager.getExtensions(MyExtensionPoint.class);
but Pf4j doesn't return the extensions.
When I'm following the code execution, I can see this code in the AbstractExtensionFinder:
if (type.isAssignableFrom(extensionClass)) {
ExtensionWrapper extensionWrapper = createExtensionWrapper(extensionClass);
result.add(extensionWrapper);
log.debug("Added extension '{}' with ordinal {}", className, extensionWrapper.getOrdinal());
} else {
log.trace("'{}' is not an extension for extension point '{}'", className, type.getName());
if (RuntimeMode.DEVELOPMENT.equals(pluginManager.getRuntimeMode())) {
checkDifferentClassLoaders(type, extensionClass);
}
}
I can understand the program is not entering inside the condition because I have 2 different classloaders: PluginClassLoader (for the extension) and RestartClassLoader (from Spring for the interface of the extension point).
I don't understand why it will be a problem because I think to instanciate the extension class, the PluginClassloader will use the parent class loader (RestartClassLoader) to find the interface.
Where is my mistake ? How to fix it ?
Thank you.
I extended the DevelopmentPluginLoader to pass the Spring classloader.
public class MyDevelopmentPluginLoader extends DevelopmentPluginLoader {
private ClassLoader parentClassLoader;
/**
* #param pluginManager
*/
public MyDevelopmentPluginLoader(final PluginManager pluginManager, final ClassLoader parentClassLoader) {
super(pluginManager);
this.parentClassLoader = parentClassLoader;
}
#Override
protected PluginClassLoader createPluginClassLoader(final Path pluginPath, final PluginDescriptor pluginDescriptor) {
return new PluginClassLoader(pluginManager, pluginDescriptor, parentClassLoader);
}
}
and in my custom PluginManager, I created and instance of my PluginLoader:
protected PluginLoader createPluginLoader() {
final CompoundPluginLoader compoundPluginLoader = new CompoundPluginLoader();
final PluginLoader developmentPluginLoader = new MyDevelopmentPluginLoader(this, getClass().getClassLoader());
final PluginLoader jarPluginLoader = new JarPluginLoader(this);
final PluginLoader defaultPluginLoader = new DefaultPluginLoader(this);
// #formatter:off
return compoundPluginLoader.
add(developmentPluginLoader, this::isDevelopment).
add(jarPluginLoader, this::isNotDevelopment).
add(defaultPluginLoader, this::isNotDevelopment);
// #formatter:on
}
I'm using Resources.System.GetString(Resource.String.no_of_bags) inside my RecyclerView. This class doesn't contain reference for context/Activity. I'm getting runtime exception.
Like #Digitalsa1nt has said, you need pass the Context to your Adapter.
Here is the official demo about the usage of RecyclerView, but it doesn't refer to the Context when create an instance of PhotoAlbumAdapter.
You can do like this:
1) Add Context in the PhotoAlbumAdapter class
public class PhotoAlbumAdapter : RecyclerView.Adapter
{
Context mContext;
PhotoAlbum mPhotoAlbum;
public PhotoAlbumAdapter(Context context, PhotoAlbum photoAlbum)
{
this.mContext = context;
this.mPhotoAlbum = photoAlbum;
}
...
}
2) Pass this (this is the instance of MainActivity) to PhotoAlbumAdapter
mAdapter = new PhotoAlbumAdapter(this,mphotoAlbum);
3) Use mContext in OnBindViewHolder method
public override void OnBindViewHolder(RecyclerView.ViewHolder holder, int position)
{
mContext.Resources.GetString(Resource.String.no_of_bags);
}
Is it possible to use a map of maps as a Maven plugin parameter?, e.g.
#Parameter
private Map<String, Map<String, String>> converters;
and then to use it like
<converters>
<json>
<indent>true</indent>
<strict>true</strict>
</json>
<yaml>
<stripComments>false</stripComments>
</yaml>
<converters>
If I use it like this, converters only contain the keys json and yaml with null as values.
I know it is possible to have complex objects as values, but is it also somehow possible to use maps for variable element values like in this example?
This is apparently a limitation of the sisu.plexus project internally used by the Mojo API. If you peek inside the MapConverter source, you'll find out that it first tries to fetch the value of the map by trying to interpret the configuration as a String (invoking fromExpression), and when this fails, looks up the expected type of the value. However this method doesn't check for parameterized types, which is our case here (since the type of the map value is Map<String, String>). I filed the bug 498757 on the Bugzilla of this project to track this.
Using a custom wrapper object
One workaround would be to not use a Map<String, String> as value but use a custom object:
#Parameter
private Map<String, Converter> converters;
with a class Converter, located in the same package as the Mojo, being:
public class Converter {
#Parameter
private Map<String, String> properties;
#Override
public String toString() { return properties.toString(); } // to test
}
You can then configure your Mojo with:
<converters>
<json>
<properties>
<indent>true</indent>
<strict>true</strict>
</properties>
</json>
<yaml>
<properties>
<stripComments>false</stripComments>
</properties>
</yaml>
</converters>
This configuration will correctly inject the values in the inner-maps. It also keeps the variable aspect: the object is only introduced as a wrapper around the inner-map. I tested this with a simple test mojo having
public void execute() throws MojoExecutionException, MojoFailureException {
getLog().info(converters.toString());
}
and the output was the expected {json={indent=true, strict=true}, yaml={stripComments=false}}.
Using a custom configurator
I also found a way to keep a Map<String, Map<String, String>> by using a custom ComponentConfigurator.
So we want to fix MapConverter by inhering it, the trouble is how to register this new FixedMapConverter. By default, Maven uses a BasicComponentConfigurator to configure the Mojo and it relies on a DefaultConverterLookup to look-up for converters to use for a specific class. In this case, we want to provide a custom converted for Map that will return our fixed version. Therefore, we need to extend this basic configurator and register our new converter.
import org.codehaus.plexus.classworlds.realm.ClassRealm;
import org.codehaus.plexus.component.configurator.BasicComponentConfigurator;
import org.codehaus.plexus.component.configurator.ComponentConfigurationException;
import org.codehaus.plexus.component.configurator.ConfigurationListener;
import org.codehaus.plexus.component.configurator.expression.ExpressionEvaluator;
import org.codehaus.plexus.configuration.PlexusConfiguration;
public class CustomBasicComponentConfigurator extends BasicComponentConfigurator {
#Override
public void configureComponent(final Object component, final PlexusConfiguration configuration,
final ExpressionEvaluator evaluator, final ClassRealm realm, final ConfigurationListener listener)
throws ComponentConfigurationException {
converterLookup.registerConverter(new FixedMapConverter());
super.configureComponent(component, configuration, evaluator, realm, listener);
}
}
Then we need to tell Maven to use this new configurator instead of the basic one. This is a 2-step process:
Inside your Maven plugin, create a file src/main/resources/META-INF/plexus/components.xml registering the new component:
<?xml version="1.0" encoding="UTF-8"?>
<component-set>
<components>
<component>
<role>org.codehaus.plexus.component.configurator.ComponentConfigurator</role>
<role-hint>custom-basic</role-hint>
<implementation>package.to.CustomBasicComponentConfigurator</implementation>
</component>
</components>
</component-set>
Note a few things: we declare a new component having the hint "custom-basic", this will serve as an id to refer to it and the <implementation> refers to the fully qualified class name of our configurator.
Tell our Mojo to use this configurator with the configurator attribute of the #Mojo annotation:
#Mojo(name = "test", configurator = "custom-basic")
The configurator passed here corresponds to the role-hint specified in the components.xml above.
With such a set-up, you can finally declare
#Parameter
private Map<String, Map<String, String>> converters;
and everything will be injected properly: Maven will use our custom configurator, that will register our fixed version of the map converter and will correctly convert the inner-maps.
Full code of FixedMapConverter (which pretty much copy-pastes MapConverter because we can't override the faulty method):
public class FixedMapConverter extends MapConverter {
public Object fromConfiguration(final ConverterLookup lookup, final PlexusConfiguration configuration,
final Class<?> type, final Type[] typeArguments, final Class<?> enclosingType, final ClassLoader loader,
final ExpressionEvaluator evaluator, final ConfigurationListener listener)
throws ComponentConfigurationException {
final Object value = fromExpression(configuration, evaluator, type);
if (null != value) {
return value;
}
try {
final Map<Object, Object> map = instantiateMap(configuration, type, loader);
final Class<?> elementType = findElementType(typeArguments);
if (Object.class == elementType || String.class == elementType) {
for (int i = 0, size = configuration.getChildCount(); i < size; i++) {
final PlexusConfiguration element = configuration.getChild(i);
map.put(element.getName(), fromExpression(element, evaluator));
}
return map;
}
// handle maps with complex element types...
final ConfigurationConverter converter = lookup.lookupConverterForType(elementType);
for (int i = 0, size = configuration.getChildCount(); i < size; i++) {
Object elementValue;
final PlexusConfiguration element = configuration.getChild(i);
try {
elementValue = converter.fromConfiguration(lookup, element, elementType, enclosingType, //
loader, evaluator, listener);
}
// TEMP: remove when http://jira.codehaus.org/browse/MSHADE-168
// is fixed
catch (final ComponentConfigurationException e) {
elementValue = fromExpression(element, evaluator);
Logs.warn("Map in " + enclosingType + " declares value type as: {} but saw: {} at runtime",
elementType, null != elementValue ? elementValue.getClass() : null);
}
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
map.put(element.getName(), elementValue);
}
return map;
} catch (final ComponentConfigurationException e) {
if (null == e.getFailedConfiguration()) {
e.setFailedConfiguration(configuration);
}
throw e;
}
}
#SuppressWarnings("unchecked")
private Map<Object, Object> instantiateMap(final PlexusConfiguration configuration, final Class<?> type,
final ClassLoader loader) throws ComponentConfigurationException {
final Class<?> implType = getClassForImplementationHint(type, configuration, loader);
if (null == implType || Modifier.isAbstract(implType.getModifiers())) {
return new TreeMap<Object, Object>();
}
final Object impl = instantiateObject(implType);
failIfNotTypeCompatible(impl, type, configuration);
return (Map<Object, Object>) impl;
}
private static Class<?> findElementType( final Type[] typeArguments )
{
if ( null != typeArguments && typeArguments.length > 1 )
{
if ( typeArguments[1] instanceof Class<?> )
{
return (Class<?>) typeArguments[1];
}
// begin fix here
if ( typeArguments[1] instanceof ParameterizedType )
{
return (Class<?>) ((ParameterizedType) typeArguments[1]).getRawType();
}
// end fix here
}
return Object.class;
}
}
One solution is quite simple and works for 1-level nesting. A more sophisticated approach can be found in the alternative answer which possibly also allows for deeper nesting of Maps.
Instead of using an interface as type parameter, simply use a concrete class like TreeMap
#Parameter
private Map<String, TreeMap> converters.
The reason is this check in MapConverter which fails for an interface but suceeds for a concrete class:
private static Class<?> findElementType( final Type[] typeArguments )
{
if ( null != typeArguments && typeArguments.length > 1
&& typeArguments[1] instanceof Class<?> )
{
return (Class<?>) typeArguments[1];
}
return Object.class;
}
As a side-note, an as it is also related to this answer for Maven > 3.3.x it also works to install a custom converter by subclassing BasicComponentConfigurator and using it as a Plexus component. BasicComponentConfigurator has the DefaultConverterLookup as a protected member variable and is hence easily accessible for registering custom converters.
In my Sling app I have data presenting documents, with pages, and content nodes. We mostly server those documents as HTML, but now I would like to have a servlet to serve these documents as PDF and PPT.
Basically, I thought about implementing the factory pattern : in my servlet, dependending on the extension of the request (pdf or ppt), I would get from a DocumentBuilderFactory, the proper DocumentBuilder implementation, either PdfDocumentBuilder or PptDocumentBuilder.
So first I had this:
public class PlanExportBuilderFactory {
public PlanExportBuilder getBuilder(String type) {
PlanExportBuilder builder = null;
switch (type) {
case "pdf":
builder = new PdfPlanExportBuilder();
break;
default:
logger.error("Unsupported plan export builder, type: " + type);
}
return builder;
}
}
In the servlet:
#Component(metatype = false)
#Service(Servlet.class)
#Properties({
#Property(name = "sling.servlet.resourceTypes", value = "myApp/document"),
#Property(name = "sling.servlet.extensions", value = { "ppt", "pdf" }),
#Property(name = "sling.servlet.methods", value = "GET")
})
public class PlanExportServlet extends SlingSafeMethodsServlet {
#Reference
PlanExportBuilderFactory builderFactory;
#Override
protected void doGet(SlingHttpServletRequest request, SlingHttpServletResponse response) throws ServletException, IOException {
Resource resource = request.getResource();
PlanExportBuilder builder = builderFactory.getBuilder(request.getRequestPathInfo().getExtension());
}
}
But the problem is that in the builder I would like to reference other services to access Sling resources, and with this solution, they're not bound.
I looked at Services Factory with OSGi but from what I've understood, you use them to configure differently the same implementation of a service.
Then I found that you can get a specific implementation by naming it, or use a property and a filter.
So I've ended up with this:
public class PlanExportBuilderFactory {
#Reference(target = "(builderType=pdf)")
PlanExportBuilder pdfPlanExportBuilder;
public PlanExportBuilder getBuilder(String type) {
PlanExportBuilder builder = null;
switch (type) {
case "pdf":
return pdfPlanExportBuilder;
default:
logger.error("Unsupported plan export builder, type: " + type);
}
return builder;
}
}
The builder defining a "builderType" property :
// AbstractPlanExportBuilder implements PlanExportBuilder interface
#Component
#Service(value=PlanExportBuilder.class)
public class PdfPlanExportBuilder extends AbstractPlanExportBuilder {
#Property(name="builderType", value="pdf")
public PdfPlanExportBuilder() {
planDocument = new PdfPlanDocument();
}
}
I would like to know if it's a good way to retrieve my PDF builder implementation regarding OSGi good practices.
EDIT 1
From Peter's answer I've tried to add multiple references but with Felix it doesn't seem to work:
#Reference(name = "planExportBuilder", cardinality = ReferenceCardinality.MANDATORY_MULTIPLE, policy = ReferencePolicy.DYNAMIC)
private Map<String, PlanExportBuilder> builders = new ConcurrentHashMap<String, PlanExportBuilder>();
protected final void bindPlanExportBuilder(PlanExportBuilder b, Map<String, Object> props) {
final String type = PropertiesUtil.toString(props.get("type"), null);
if (type != null) {
this.builders.put((String) props.get("type"), b);
}
}
protected final void unbindPlanExportBuilder(final PlanExportBuilder b, Map<String, Object> props) {
final String type = PropertiesUtil.toString(props.get("type"), null);
if (type != null) {
this.builders.remove(type);
}
}
I get these errors :
#Reference(builders) : Missing method bind for reference planExportBuilder
#Reference(builders) : Something went wrong: false - true - MANDATORY_MULTIPLE
#Reference(builders) : Missing method unbind for reference planExportBuilder
The Felix documentation here http://felix.apache.org/documentation/subprojects/apache-felix-maven-scr-plugin/scr-annotations.html#reference says for the bind method:
The default value is the name created by appending the reference name to the string bind. The method must be declared public or protected and take single argument which is declared with the service interface type
So according to this, I understand it cannot work with Felix, as I'm trying to pass two arguments. However, I found an example here that seems to match what you've suggested but I cannot make it work: https://github.com/Adobe-Consulting-Services/acs-aem-samples/blob/master/bundle/src/main/java/com/adobe/acs/samples/services/impl/SampleMultiReferenceServiceImpl.java
EDIT 2
Just had to move the reference above the class to make it work:
#References({
#Reference(
name = "planExportBuilder",
referenceInterface = PlanExportBuilder.class,
policy = ReferencePolicy.DYNAMIC,
cardinality = ReferenceCardinality.OPTIONAL_MULTIPLE)
})
public class PlanExportServlet extends SlingSafeMethodsServlet {
Factories are evil :-) Main reason is of course the yucky class loading hacks that are usually used but also because they tend to have global knowledge. In general, you want to be able to add a bundle with a new DocumentBuilder and then that type should become available.
A more OSGi oriented solution is therefore to use service properties. This could look like:
#Component( property=HTTP_WHITEBOARD_FILTER_REGEX+"=/as")
public class DocumentServlet {
final Map<String,DocBuilder> builders = new ConcurrentHashMap<>();
public void doGet( HttpServletRequest rq, HttpServletResponse rsp )
throws IOException, ServletException {
InputStream in = getInputStream( rq.getPathInfo() );
if ( in == null )
....
String type = toType( rq.getPathInfo(), rq.getParameter("type") );
DocBuilder docbuilder = builders.get( type );
if ( docbuilder == null)
....
docbuilder.convert( type, in, rsp.getOutputStream() );
}
#Reference( cardinality=MULTIPLE, policy=DYNAMIC )
void addDocBuilder( DocBuilder db, Map<String,Object> props ) {
docbuilders.put(props.get("type"), db );
}
void removeDocBuilder(Map<String,Object> props ) {
docbuilders.remove(props.get("type"));
}
}
A DocBuilder could look like:
#Component( property = "type=ppt-pdf" )
public class PowerPointToPdf implements DocBuilder {
...
}
I am working with Spring-websocket and I have the following problem:
I am trying to put a placeholder inside a #MessageMapping annotation in order to get the url from properties. It works with #RequestMapping but not with #MessageMapping.
If I use this placeholder, the URL is null. Any idea or suggestion?
Example:
#RequestMapping(value= "${myProperty}")
#MessageMapping("${myProperty}")
Rossen Stoyanchev added placeholder support for #MessageMapping and #SubscribeMapping methods.
See Jira issue: https://jira.spring.io/browse/SPR-13271
Spring allows you to use property placeholders in #RequestMapping, but not in #MessageMapping. This is 'cause the MessageHandler. So, we need to override the default MessageHandler to do this.
WebSocketAnnotationMethodMessageHandler does not support placeholders and you need add this support yourself.
For simplicity I just created another WebSocketAnnotationMethodMessageHandler class in my project at the same package of the original, org.springframework.web.socket.messaging, and override getMappingForMethod method from SimpAnnotationMethodMessageHandler with same content, changing only how SimpMessageMappingInfo is contructed using this with this methods (private in WebSocketAnnotationMethodMessageHandler):
private SimpMessageMappingInfo createMessageMappingCondition(final MessageMapping annotation) {
return new SimpMessageMappingInfo(SimpMessageTypeMessageCondition.MESSAGE, new DestinationPatternsMessageCondition(
this.resolveAnnotationValues(annotation.value()), this.getPathMatcher()));
}
private SimpMessageMappingInfo createSubscribeCondition(final SubscribeMapping annotation) {
final SimpMessageTypeMessageCondition messageTypeMessageCondition = SimpMessageTypeMessageCondition.SUBSCRIBE;
return new SimpMessageMappingInfo(messageTypeMessageCondition, new DestinationPatternsMessageCondition(
this.resolveAnnotationValues(annotation.value()), this.getPathMatcher()));
}
These methods now will resolve value considering properties (calling resolveAnnotationValues method), so we need use something like this:
private String[] resolveAnnotationValues(final String[] destinationNames) {
final int length = destinationNames.length;
final String[] result = new String[length];
for (int i = 0; i < length; i++) {
result[i] = this.resolveAnnotationValue(destinationNames[i]);
}
return result;
}
private String resolveAnnotationValue(final String name) {
if (!(this.getApplicationContext() instanceof ConfigurableApplicationContext)) {
return name;
}
final ConfigurableApplicationContext applicationContext = (ConfigurableApplicationContext) this.getApplicationContext();
final ConfigurableBeanFactory configurableBeanFactory = applicationContext.getBeanFactory();
final String placeholdersResolved = configurableBeanFactory.resolveEmbeddedValue(name);
final BeanExpressionResolver exprResolver = configurableBeanFactory.getBeanExpressionResolver();
if (exprResolver == null) {
return name;
}
final Object result = exprResolver.evaluate(placeholdersResolved, new BeanExpressionContext(configurableBeanFactory, null));
return result != null ? result.toString() : name;
}
You still need to define a PropertySourcesPlaceholderConfigurer bean in your configuration.
If you are using XML based configuration, include something like this:
<context:property-placeholder location="classpath:/META-INF/spring/url-mapping-config.properties" />
If you are using Java based configuration, you can try in this way:
#Configuration
#PropertySources(value = #PropertySource("classpath:/META-INF/spring/url-mapping-config.properties"))
public class URLMappingConfig {
#Bean
public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
return new PropertySourcesPlaceholderConfigurer();
}
}
Obs.: in this case, url-mapping-config.properties file are in a gradle/maven project in src\main\resources\META-INF\spring folder and content look like this:
myPropertyWS=urlvaluews
This is my sample controller:
#Controller
public class WebSocketController {
#SendTo("/topic/test")
#MessageMapping("${myPropertyWS}")
public String test() throws Exception {
Thread.sleep(4000); // simulated delay
return "OK";
}
}
With default MessageHandler startup log will print something like this:
INFO: Mapped "{[/${myPropertyWS}],messageType=[MESSAGE]}" onto public java.lang.String com.brunocesar.controller.WebSocketController.test() throws java.lang.Exception
And with our MessageHandler now print this:
INFO: Mapped "{[/urlvaluews],messageType=[MESSAGE]}" onto public java.lang.String com.brunocesar.controller.WebSocketController.test() throws java.lang.Exception
See in this gist the full WebSocketAnnotationMethodMessageHandler implementation.
EDIT: this solution resolves the problem for versions before 4.2 GA. For more information, see this jira.
Update :
Now I understood what you mean, but I think that is not possible(yet).
Documentation does not mention anything related to Path mapping URIs.
Old answer
Use
#MessageMapping("/handler/{myProperty}")
instead of
#MessageMapping("/handler/${myProperty}")
And use it like this:
#MessageMapping("/myHandler/{username}")
public void handleTextMessage(#DestinationVariable String username,Message message) {
//do something
}
#MessageMapping("/chat/{roomId}")
public Message handleMessages(#DestinationVariable("roomId") String roomId, #Payload Message message, Traveler traveler) throws Exception {
System.out.println("Message received for room: " + roomId);
System.out.println("User: " + traveler.toString());
// store message in database
message.setAuthor(traveler);
message.setChatRoomId(Integer.parseInt(roomId));
int id = MessageRepository.getInstance().save(message);
message.setId(id);
return message;
}