How do I create a custom directive for Apache Velocity - apache

I am using Apache's Velocity templating engine, and I would like to create a custom Directive. That is, I want to be able to write "#doMyThing()" and have it invoke some java code I wrote in order to generate the text.
I know that I can register a custom directive by adding a line
userdirective=my.package.here.MyDirectiveName
to my velocity.properties file. And I know that I can write such a class by extending the Directive class. What I don't know is how to extend the Directive class -- some sort of documentation for the author of a new Directive. For instance I'd like to know if my getType() method return "BLOCK" or "LINE" and I'd like to know what should my setLocation() method should do?
Is there any documentation out there that is better than just "Use the source, Luke"?

On the Velocity wiki, there's a presentation and sample code from a talk I gave called "Hacking Velocity". It includes an example of a custom directive.

Also was trying to come up with a custom directive. Couldn't find any documentation at all, so I looked at some user created directives: IfNullDirective (nice and easy one), MergeDirective as well as velocity build-in directives.
Here is my simple block directive that returns compressed content (complete project with some directive installation instructions is located here):
import java.io.IOException;
import java.io.StringWriter;
import java.io.Writer;
import org.apache.velocity.context.InternalContextAdapter;
import org.apache.velocity.exception.MethodInvocationException;
import org.apache.velocity.exception.ParseErrorException;
import org.apache.velocity.exception.ResourceNotFoundException;
import org.apache.velocity.exception.TemplateInitException;
import org.apache.velocity.runtime.RuntimeServices;
import org.apache.velocity.runtime.directive.Directive;
import org.apache.velocity.runtime.parser.node.Node;
import org.apache.velocity.runtime.log.Log;
import com.googlecode.htmlcompressor.compressor.HtmlCompressor;
/**
* Velocity directive that compresses an HTML content within #compressHtml ... #end block.
*/
public class HtmlCompressorDirective extends Directive {
private static final HtmlCompressor htmlCompressor = new HtmlCompressor();
private Log log;
public String getName() {
return "compressHtml";
}
public int getType() {
return BLOCK;
}
#Override
public void init(RuntimeServices rs, InternalContextAdapter context, Node node) throws TemplateInitException {
super.init(rs, context, node);
log = rs.getLog();
//set compressor properties
htmlCompressor.setEnabled(rs.getBoolean("userdirective.compressHtml.enabled", true));
htmlCompressor.setRemoveComments(rs.getBoolean("userdirective.compressHtml.removeComments", true));
}
public boolean render(InternalContextAdapter context, Writer writer, Node node)
throws IOException, ResourceNotFoundException, ParseErrorException, MethodInvocationException {
//render content to a variable
StringWriter content = new StringWriter();
node.jjtGetChild(0).render(context, content);
//compress
try {
writer.write(htmlCompressor.compress(content.toString()));
} catch (Exception e) {
writer.write(content.toString());
String msg = "Failed to compress content: "+content.toString();
log.error(msg, e);
throw new RuntimeException(msg, e);
}
return true;
}
}

Block directives always accept a body and must end with #end when used in a template. e.g. #foreach( $i in $foo ) this has a body! #end
Line directives do not have a body or an #end. e.g. #parse( 'foo.vtl' )
You don't need to both with setLocation() at all. The parser uses that.
Any other specifics i can help with?
Also, have you considered using a "tool" approach? Even if you don't use VelocityTools to automatically make your tool available and whatnot, you can just create a tool class that does what you want, put it in the context and either have a method you call to generate content or else just have its toString() method generate the content. e.g. $tool.doMyThing() or just $myThing
Directives are best for when you need to mess with Velocity internals (access to InternalContextAdapter or actual Nodes).

Prior to velocity v1.6 I had a #blockset($v)#end directive to be able to deal with a multiline #set($v) but this function is now handled by the #define directive.
Custom block directives are a pain with modern IDEs because they don't parse the structure correctly, assuming your #end associated with #userBlockDirective is an extra and paints the whole file RED. They should be avoided if possible.
I copied something similar from the velocity source code and created a "blockset" (multiline) directive.
import org.apache.velocity.runtime.directive.Directive;
import org.apache.velocity.runtime.RuntimeServices;
import org.apache.velocity.runtime.parser.node.Node;
import org.apache.velocity.context.InternalContextAdapter;
import org.apache.velocity.exception.MethodInvocationException;
import org.apache.velocity.exception.ResourceNotFoundException;
import org.apache.velocity.exception.ParseErrorException;
import org.apache.velocity.exception.TemplateInitException;
import java.io.Writer;
import java.io.IOException;
import java.io.StringWriter;
public class BlockSetDirective extends Directive {
private String blockKey;
/**
* Return name of this directive.
*/
public String getName() {
return "blockset";
}
/**
* Return type of this directive.
*/
public int getType() {
return BLOCK;
}
/**
* simple init - get the blockKey
*/
public void init( RuntimeServices rs, InternalContextAdapter context,
Node node )
throws TemplateInitException {
super.init( rs, context, node );
/*
* first token is the name of the block. I don't even check the format,
* just assume it looks like this: $block_name. Should check if it has
* a '$' or not like macros.
*/
blockKey = node.jjtGetChild( 0 ).getFirstToken().image.substring( 1 );
}
/**
* Renders node to internal string writer and stores in the context at the
* specified context variable
*/
public boolean render( InternalContextAdapter context, Writer writer,
Node node )
throws IOException, MethodInvocationException,
ResourceNotFoundException, ParseErrorException {
StringWriter sw = new StringWriter(256);
boolean b = node.jjtGetChild( 1 ).render( context, sw );
context.put( blockKey, sw.toString() );
return b;
}
}

Related

Netty client server login, how to have channelRead return a boolean

I'm writing client server applications on top of netty.
I'm starting with a simple client login server that validates info sent from the client with the database. This all works fine.
On the client-side, I want to use If statements once the response is received from the server if the login credentials validate or not. which also works fine. My problem is the ChannelRead method does not return anything. I can not change this. I need it to return a boolean which allows login attempt to succeed or fail.
Once the channelRead() returns, I lose the content of the data.
I tried adding the msg to a List but, for some reason, the message data is not stored in the List.
Any suggestions are welcome. I'm new... This is the only way I've figured out to do this. I have also tried using boolean statements inside channelRead() but these methods are void so once it closes the boolean variables are cleared.
Following is the last attempt I tried to insert the message data into the list I created...
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
public class LoginClientHandler extends ChannelInboundHandlerAdapter {
Player player = new Player();
String response;
public volatile boolean loginSuccess;
// Object message = new Object();
private Object msg;
public static final List<Object> incomingMessage = new List<Object>() {
#Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
// incomingMessage.clear();
response = (String) msg;
System.out.println("channel read response = " + response);
incomingMessage.add(0, msg);
System.out.println("incoming message = " + incomingMessage.get(0));
}
How can I get the message data "out" of the channelRead() method or use this method to create a change in my business logic? I want it to either display a message to tell the client login failed and try again or to succeed and load the next scene. I have the business logic working fine but I can't get it to work with netty because none of the methods return anything I can use to affect my business logic.
ChannelInitializer
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.Delimiters;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
public class LoginClientInitializer extends ChannelInitializer <SocketChannel> {
#Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
pipeline.addLast("framer", new DelimiterBasedFrameDecoder(8192, Delimiters.lineDelimiter()));
pipeline.addLast("decoder", new StringDecoder());
pipeline.addLast("encoder", new StringEncoder());
pipeline.addLast("handler", new LoginClientHandler());
}
}
To get the server to write data to the client, call ctx.write here is a basic echo server and client example from the Netty in Action book. https://github.com/normanmaurer/netty-in-action/blob/2.0-SNAPSHOT/chapter2/Server/src/main/java/nia/chapter2/echoserver/EchoServerHandler.java
There are several other good examples in that repo.
I highly recommend reading the "netty in action" book if you're starting out with netty. It will give you a solid foundational understanding of the framework and how it's intended to be used.

How can the Repast file sink filename be set programmatically?

Does anybody know if there is a simple way to make the filename element path of an file sink variable according to one field in the model?
So instead of using a fix path like :
fixed_path/filename.csv
{variable_path}/filename.csv
The attached ModelInitializer shows how to do this. I also copied the code below in case attachments doesn’t go through. To enable the ModelInitializer, you need to add the following to the scenario.xml file:
<model.initializer class="PredatorPrey.MyInitializer" />
I tested this in the Predator Prey demo so you should change the class package name. In the ModelInitializer example, you need to specify the root context ID which is the same as the context ID in the context.xml file. And you should specify the variable output folder name. This example requires a file name to be specified in the file sink as you would normally do and it inserts the variable path. On caveat is that the variable folder path will be saved in the scenario if the scenario is saved in the GUI, however this code will check for any existing path and simply replace the path with the outputFolder string. So you should put the entire path in the outputFolder string and not just part of it, or change the code behavior as needed.
package PredatorPrey;
import java.io.File;
import repast.simphony.data2.engine.FileSinkComponentControllerAction;
import repast.simphony.data2.engine.FileSinkDescriptor;
import repast.simphony.engine.controller.NullAbstractControllerAction;
import repast.simphony.engine.environment.ControllerAction;
import repast.simphony.engine.environment.RunEnvironmentBuilder;
import repast.simphony.engine.environment.RunState;
import repast.simphony.scenario.ModelInitializer;
import repast.simphony.scenario.Scenario;
import repast.simphony.util.collections.Tree;
public class MyInitializer implements ModelInitializer {
#Override
public void initialize(final Scenario scen, RunEnvironmentBuilder builder) {
scen.addMasterControllerAction(new NullAbstractControllerAction() {
String rootContextID = "Predator Prey";
String outputFolder = "testoutfolder";
#Override
public void batchInitialize(RunState runState, Object contextId) {
Tree<ControllerAction> scenarioTree = scen.getControllerRegistry().getActionTree(rootContextID);
findFileSinkTreeChildren(scenarioTree, scenarioTree.getRoot(), outputFolder);
// Reset the scenario dirty flag so the changes made to the file sink
// descriptors don't prompt a scenario save in the GUI
scen.setDirty(false);
}
});
}
public static void findFileSinkTreeChildren(Tree<ControllerAction> tree,
ControllerAction parent, String outputFolder){
// Check each ControllerAction in the scenario and if it is a FileSink,
// modify the output path to include the folder
for (ControllerAction act : tree.getChildren(parent)){
if (act instanceof FileSinkComponentControllerAction){
FileSinkDescriptor descriptor = ((FileSinkComponentControllerAction)act).getDescriptor();
String fileName = descriptor.getFileName();
// remove any prefix directories from the file name
int lastSeparatorIndex = fileName.lastIndexOf(File.separator);
// Check for backslash separator
if (fileName.lastIndexOf('\\') > lastSeparatorIndex)
lastSeparatorIndex = fileName.lastIndexOf('\\');
// Check for forward slash operator
if (fileName.lastIndexOf('/') > lastSeparatorIndex)
lastSeparatorIndex = fileName.lastIndexOf('/');
if (lastSeparatorIndex > 0){
fileName = fileName.substring(lastSeparatorIndex+1, fileName.length());
}
descriptor.setFileName(outputFolder + File.separator + fileName);
}
else findFileSinkTreeChildren(tree, act, outputFolder);
}
}
}

Dynamic Method Invocation and JAXBElement Type on CXF

I wrote the small application below to list all the methods and of a soap service using Apache CXF library. This application lists all the methods of the service, but as it is seen on the output when you run this application, input parameters and return types of the service methods are JAXBElement for the complex types. I want cxf not to generate JAXBElement, instead I want the complex types in their original classes generated on runtime. As it is said on http://s141.codeinspot.com/q/1455881 , it can be done by setting generateElementProperty property's value to false for wsdl2java utility of cxf library, but I couldn't find the same parameter for dynamic method invocation with cxf library. I want to obtain input parameters and return types in their original types.
import java.lang.reflect.Method;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Collection;
import java.util.List;
import org.apache.cxf.binding.Binding;
import org.apache.cxf.endpoint.Client;
import org.apache.cxf.jaxws.endpoint.dynamic.JaxWsDynamicClientFactory;
import org.apache.cxf.service.model.BindingInfo;
import org.apache.cxf.service.model.BindingMessageInfo;
import org.apache.cxf.service.model.BindingOperationInfo;
import org.apache.cxf.service.model.MessagePartInfo;
import org.apache.cxf.service.model.OperationInfo;
import org.apache.cxf.service.model.ServiceModelUtil;
public class Main {
public static void main(String[] args) {
URL wsdlURL = null;
try {
wsdlURL = new URL("http://path_to_wsdl?wsdl");
} catch (MalformedURLException e) {
e.printStackTrace();
}
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
JaxWsDynamicClientFactory dcf = JaxWsDynamicClientFactory.newInstance();
Client client = dcf.createClient(wsdlURL, classLoader);
Binding binding = client.getEndpoint().getBinding();
BindingInfo bindingInfo = binding.getBindingInfo();
Collection<BindingOperationInfo> operations = bindingInfo.getOperations();
for(BindingOperationInfo boi:operations){
OperationInfo oi = boi.getOperationInfo();
BindingMessageInfo inputMessageInfo = boi.getInput();
List<MessagePartInfo> parts = inputMessageInfo.getMessageParts();
System.out.println("function name: "+oi.getName().getLocalPart());
List<String> inputParams = ServiceModelUtil.getOperationInputPartNames(oi);
System.out.println("input parameters: "+inputParams);
for(MessagePartInfo partInfo:parts){
Class<?> partClass = partInfo.getTypeClass(); //here we have input parameter object on each iteration
Method[] methods = partClass.getMethods();
for(Method method:methods){
System.out.println("method: "+method);
Class<?>[] paramTypes = method.getParameterTypes();
for(Class paramType:paramTypes){
System.out.println("param: "+paramType.getCanonicalName());
}
Class returnType = method.getReturnType();
System.out.println("returns: "+returnType.getCanonicalName());
}
System.out.println("partclass: "+partClass.getCanonicalName());
}
}
System.out.println("binding: " + binding);
}
}
Create a binding file that looks like:
<jaxb:bindings
xmlns:jaxb="http://java.sun.com/xml/ns/jaxb" jaxb:version="2.0"
xmlns:xjc="http://java.sun.com/xml/ns/jaxb/xjc" jaxb:extensionBindingPrefixes="xjc">
<jaxb:globalBindings generateElementProperty="false">
<xjc:simple />
</jaxb:globalBindings>
</jaxb:bindings>
and pass that into the JaxWsDynamicClientFactory via the createClient method that takes the List of binding files.

Only show effective SQL string P6Spy

I'm using p6spy to log the sql statements generated by my program. The format for the outputted spy.log file looks like this:
current time|execution time|category|statement SQL String|effective SQL string
I'm just wondering if anyone knows if there's a way to alter the spy.properties file and have only the last column, the effective SQL string, output to the spy.log file? I've looked through the properties file but haven't found anything that seems to support this.
Thanks!
In spy.properties there is a property called logMessageFormat that you can set to a custom implementation of MessageFormattingStrategy. This works for any type of logger (i.e. file, slf4j etc.).
E.g.
logMessageFormat=my.custom.PrettySqlFormat
An example using Hibernate's pretty-printing SQL formatter:
package my.custom;
import org.hibernate.jdbc.util.BasicFormatterImpl;
import org.hibernate.jdbc.util.Formatter;
import com.p6spy.engine.spy.appender.MessageFormattingStrategy;
public class PrettySqlFormat implements MessageFormattingStrategy {
private final Formatter formatter = new BasicFormatterImpl();
#Override
public String formatMessage(int connectionId, String now, long elapsed, String category, String prepared, String sql) {
return formatter.format(sql);
}
}
There is no such option provided to achieve it via configuration only yet. I think you have 2 options here:
fill a new bug/feature request report (which could bring benefit to others using p6spy as well) on: https://github.com/p6spy/p6spy/issues?state=open or
provide custom implementation.
For the later option, I believe you could achieve it via your own class (depending on the logger you use, let's assume you use Log4jLogger).
Well, if you check relevant part of the Log4jLogger github as well as sourceforge version, your implementation should be rather straightforward:
spy.properties:
appender=com.EffectiveSQLLog4jLogger
Implementation itself could look like this:
package com;
import com.p6spy.engine.logging.appender.Log4jLogger;
public class EffectiveSQLLog4jLogger extends Log4jLogger {
public void logText(String text) {
super.logText(getEffectiveSQL(text));
}
private String getEffectiveSQL(String text) {
if (null == text) {
return null;
}
final int idx = text.lastIndexOf("|");
// non-perfect detection of the exception logged case
if (-1 == idx) {
return text;
}
return text.substring(idx + 1); // not sure about + 1, but check and see :)
}
}
Please note the implementation should cover github (new project home, no version released yet) as well as sourceforge (original project home, released 1.3 version).
Please note: I didn't test the proposal myself, but it could be a good starting point and from the code review itself I'd say it could work.
I agree with #boberj, we are used to having logs with Hibernate formatter, but don't forget about batching, that's why I suggest to use:
import com.p6spy.engine.spy.appender.MessageFormattingStrategy;
import org.hibernate.engine.jdbc.internal.BasicFormatterImpl;
import org.hibernate.engine.jdbc.internal.Formatter;
/**
* Created by Igor Dmitriev on 1/3/16
*/
public class HibernateSqlFormatter implements MessageFormattingStrategy {
private final Formatter formatter = new BasicFormatterImpl();
#Override
public String formatMessage(int connectionId, String now, long elapsed, String category, String prepared, String sql) {
if (sql.isEmpty()) {
return "";
}
String template = "Hibernate: %s %s {elapsed: %sms}";
String batch = "batch".equals(category) ? ((elapsed == 0) ? "add batch" : "execute batch") : "";
return String.format(template, batch, formatter.format(sql), elapsed);
}
}
In p6Spy 3.9 this can be achieved quite simply. In spy.properties set
customLogMessageFormat=%(effectiveSql)
You can patch com.p6spy.engine.spy.appender.SingleLineFormat.java
removing the prepared element and any reference to P6Util like so:
package com.p6spy.engine.spy.appender;
public class SingleLineFormat implements MessageFormattingStrategy {
#Override
public String formatMessage(final int connectionId, final String now, final long elapsed, final String category, final String prepared, final String sql) {
return now + "|" + elapsed + "|" + category + "|connection " + connectionId + "|" + sql;
}
}
Then compile just the file
javac com.p6spy.engine.spy.appender.SingleLineFormat.java
And replace the existing class file in p6spy.jar with the new one.

Lucene 4.1 : How split words that contains "dots" when indexing?

I'l trying to figure out what I should do to index my keywords that contains "." .
ex : this.name
I want to index the terms : this and name in my index.
I use the StandardAnalyser. I try to extends the WhitespaceTokensizer or extends TokenFilter, but I'm not sure if I'm in the right direction.
if I use the StandardAnalyser, I'll obtain "this.name" as a keyword, and that's not what I want, but the analyser do the rest correctly for me.
You can put a CharFilter in front of StandardTokenizer that converts periods and underscores to spaces. MappingCharFilter will work.
Here's MappingCharFilter added to a stripped-down StandardAnalyzer (see the original 4.1 version here):
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.charfilter.MappingCharFilter;
import org.apache.lucene.analysis.charfilter.NormalizeCharMap;
import org.apache.lucene.analysis.core.LowerCaseFilter;
import org.apache.lucene.analysis.core.StopAnalyzer;
import org.apache.lucene.analysis.core.StopFilter;
import org.apache.lucene.analysis.standard.StandardFilter;
import org.apache.lucene.analysis.standard.StandardTokenizer;
import org.apache.lucene.analysis.util.StopwordAnalyzerBase;
import org.apache.lucene.util.Version;
import java.io.IOException;
import java.io.Reader;
public final class MyAnalyzer extends StopwordAnalyzerBase {
private int maxTokenLength = 255;
public MyAnalyzer() {
super(Version.LUCENE_41, StopAnalyzer.ENGLISH_STOP_WORDS_SET);
}
#Override
protected TokenStreamComponents createComponents
(final String fieldName, final Reader reader) {
final StandardTokenizer src = new StandardTokenizer(matchVersion, reader);
src.setMaxTokenLength(maxTokenLength);
TokenStream tok = new StandardFilter(matchVersion, src);
tok = new LowerCaseFilter(matchVersion, tok);
tok = new StopFilter(matchVersion, tok, stopwords);
return new TokenStreamComponents(src, tok) {
#Override
protected void setReader(final Reader reader) throws IOException {
src.setMaxTokenLength(MyAnalyzer.this.maxTokenLength);
super.setReader(reader);
}
};
}
#Override
protected Reader initReader(String fieldName, Reader reader) {
NormalizeCharMap.Builder builder = new NormalizeCharMap.Builder();
builder.add(".", " ");
builder.add("_", " ");
NormalizeCharMap normMap = builder.build();
return new MappingCharFilter(normMap, reader);
}
}
Here's a quick test to demonstrate it works:
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.BaseTokenStreamTestCase;
public class TestMyAnalyzer extends BaseTokenStreamTestCase {
private Analyzer analyzer = new MyAnalyzer();
public void testPeriods() throws Exception {
BaseTokenStreamTestCase.assertAnalyzesTo
(analyzer,
"this.name; here.i.am; sentences ... end with periods.",
new String[] { "name", "here", "i", "am", "sentences", "end", "periods" } );
}
public void testUnderscores() throws Exception {
BaseTokenStreamTestCase.assertAnalyzesTo
(analyzer,
"some_underscore_term _and____ stuff that is_not in it",
new String[] { "some", "underscore", "term", "stuff" } );
}
}
If I understand you correctly, you need to use a tokenizer that removes dots -- that is, any name that contains a dot should be split at that point ("here.i.am" becomes "here" + "i" + "am").
you are getting caught by behavior documented here:
However, a dot that's not followed by whitespace is considered part of a token.
StandardTokenizer introduces some more complex to parsing rules than you may not be looking for. This one, in particular, is intended to prevent tokenization of URLs, IPs, idenifiers, etc. A simpler implementation might suit your needs, like LetterTokenizer.
If that doesn't really suit your needs (and it might well turn out to be throwing the baby out with the bathwater), then you may need to modify StandardTokenizer yourself, which is explicitly encouraged by the Lucene docs:
Many applications have specific tokenizer needs. If this tokenizer does not suit your application, please consider copying this source code directory to your project and maintaining your own grammar-based tokenizer.
Sebastien Dionne: I didn't understand how to split a word, do I have to parse the document char by char ?
Sebastien Dionne: I still want to know how to split a token into multiple part, and index them all
You may have to write a custom analyzer.
Analyzer is a combination of Tokenizer and possibly a chain of TokenFilter instances.
Tokenizer : Takes in the input text passed by you probably as a java.io.Reader. It
JUST breakdowns the text. Doesn't alter, just breaks it down.
TokenFilter : Takes in the token emitted by Tokenizer, adds / removes / alters tokens and emits the same one by one until all are finished.
If it replaces a token with multiple tokens based on requirements, buffers all, emits them one by one to the Indexer.
You may check following resource, unfortunately, you may have to sign-up for a trial membership.
By writing a custom analyzer, you can breakdown the text the way you want to. You may even use some existing components like LowercaseFilter. Fortunately, it is achievable with Lucene to come up with some Analyzer that serves your purpose if you couldn't find that as a built-in or on the web.
" Writing Custom Filters: Lucene in Action 2"