HelpMojo

+
+    package de.juplo.plugins.hibernate4;
+
+    import org.apache.maven.plugin.AbstractMojo;
+    import org.apache.maven.plugin.MojoExecutionException;
+
+    import org.w3c.dom.Document;
+    import org.w3c.dom.Element;
+    import org.w3c.dom.Node;
+    import org.w3c.dom.NodeList;
+    import org.xml.sax.SAXException;
+
+    import javax.xml.parsers.DocumentBuilder;
+    import javax.xml.parsers.DocumentBuilderFactory;
+    import javax.xml.parsers.ParserConfigurationException;
+    import java.io.IOException;
+    import java.io.InputStream;
+    import java.util.ArrayList;
+    import java.util.Iterator;
+    import java.util.List;
+
+    /**
+     * Display help information on hibernate4-maven-plugin.<br/>
+     * Call <code>mvn hibernate4:help -Ddetail=true -Dgoal=&lt;goal-name&gt;</code> to display parameter details.
+     * @author
+     * @version
+     * @goal help
+     * @requiresProject false
+     * @threadSafe
+     */
+    public class HelpMojo
+        extends AbstractMojo
+    {
+        /**
+         * If <code>true</code>, display all settable properties for each goal.
+         *
+         * @parameter property="detail" default-value="false"
+         */
+        private boolean detail;
+
+        /**
+         * The name of the goal for which to show help. If unspecified, all goals will be displayed.
+         *
+         * @parameter property="goal"
+         */
+        private java.lang.String goal;
+
+        /**
+         * The maximum length of a display line, should be positive.
+         *
+         * @parameter property="lineLength" default-value="80"
+         */
+        private int lineLength;
+
+        /**
+         * The number of spaces per indentation level, should be positive.
+         *
+         * @parameter property="indentSize" default-value="2"
+         */
+        private int indentSize;
+
+        // groupId/artifactId/plugin-help.xml
+        private static final String PLUGIN_HELP_PATH = "/META-INF/maven/de.juplo/hibernate4-maven-plugin/plugin-help.xml";
+
+        private Document build()
+            throws MojoExecutionException
+        {
+            getLog().debug( "load plugin-help.xml: " + PLUGIN_HELP_PATH );
+            InputStream is = getClass().getResourceAsStream( PLUGIN_HELP_PATH );
+            try
+            {
+                DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
+                DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
+                return dBuilder.parse( is );
+            }
+            catch ( IOException e )
+            {
+                throw new MojoExecutionException( e.getMessage(), e );
+            }
+            catch ( ParserConfigurationException e )
+            {
+                throw new MojoExecutionException( e.getMessage(), e );
+            }
+            catch ( SAXException e )
+            {
+                throw new MojoExecutionException( e.getMessage(), e );
+            }
+        }
+
+        /**
+         * {@inheritDoc}
+         */
+        public void execute()
+            throws MojoExecutionException
+        {
+            if ( lineLength <= 0 )
+            {
+                getLog().warn( "The parameter 'lineLength' should be positive, using '80' as default." );
+                lineLength = 80;
+            }
+            if ( indentSize <= 0 )
+            {
+                getLog().warn( "The parameter 'indentSize' should be positive, using '2' as default." );
+                indentSize = 2;
+            }
+
+            Document doc = build();
+
+            StringBuilder sb = new StringBuilder();
+            Node plugin = getSingleChild( doc, "plugin" );
+
+
+            String name = getValue( plugin, "name" );
+            String version = getValue( plugin, "version" );
+            String id = getValue( plugin, "groupId" ) + ":" + getValue( plugin, "artifactId" ) + ":" + version;
+            if ( isNotEmpty( name ) && !name.contains( id ) )
+            {
+                append( sb, name + " " + version, 0 );
+            }
+            else
+            {
+                if ( isNotEmpty( name ) )
+                {
+                    append( sb, name, 0 );
+                }
+                else
+                {
+                    append( sb, id, 0 );
+                }
+            }
+            append( sb, getValue( plugin, "description" ), 1 );
+            append( sb, "", 0 );
+
+            //<goalPrefix>plugin</goalPrefix>
+            String goalPrefix = getValue( plugin, "goalPrefix" );
+
+            Node mojos1 = getSingleChild( plugin, "mojos" );
+
+            List<Node> mojos = findNamedChild( mojos1, "mojo" );
+
+            if ( goal == null || goal.length() <= 0 )
+            {
+                append( sb, "This plugin has " + mojos.size() + ( mojos.size() > 1 ? " goals:" : " goal:" ), 0 );
+                append( sb, "", 0 );
+            }
+
+            for ( Node mojo : mojos )
+            {
+                writeGoal( sb, goalPrefix, (Element) mojo );
+            }
+
+            if ( getLog().isInfoEnabled() )
+            {
+                getLog().info( sb.toString() );
+            }
+        }
+
+
+        private static boolean isNotEmpty( String string )
+        {
+            return string != null && string.length() > 0;
+        }
+
+        private String getValue( Node node, String elementName )
+            throws MojoExecutionException
+        {
+            return getSingleChild( node, elementName ).getTextContent();
+        }
+
+        private Node getSingleChild( Node node, String elementName )
+            throws MojoExecutionException
+        {
+            List<Node> namedChild = findNamedChild( node, elementName );
+            if ( namedChild.isEmpty() )
+            {
+                throw new MojoExecutionException( "Could not find " + elementName + " in plugin-help.xml" );
+            }
+            if ( namedChild.size() > 1 )
+            {
+                throw new MojoExecutionException( "Multiple " + elementName + " in plugin-help.xml" );
+            }
+            return namedChild.get( 0 );
+        }
+
+        private List<Node> findNamedChild( Node node, String elementName )
+        {
+            List<Node> result = new ArrayList<Node>();
+            NodeList childNodes = node.getChildNodes();
+            for ( int i = 0; i < childNodes.getLength(); i++ )
+            {
+                Node item = childNodes.item( i );
+                if ( elementName.equals( item.getNodeName() ) )
+                {
+                    result.add( item );
+                }
+            }
+            return result;
+        }
+
+        private Node findSingleChild( Node node, String elementName )
+            throws MojoExecutionException
+        {
+            List<Node> elementsByTagName = findNamedChild( node, elementName );
+            if ( elementsByTagName.isEmpty() )
+            {
+                return null;
+            }
+            if ( elementsByTagName.size() > 1 )
+            {
+                throw new MojoExecutionException( "Multiple " + elementName + "in plugin-help.xml" );
+            }
+            return elementsByTagName.get( 0 );
+        }
+
+        private void writeGoal( StringBuilder sb, String goalPrefix, Element mojo )
+            throws MojoExecutionException
+        {
+            String mojoGoal = getValue( mojo, "goal" );
+            Node configurationElement = findSingleChild( mojo, "configuration" );
+    		Node description = findSingleChild( mojo, "description" );
+            if ( goal == null || goal.length() <= 0 || mojoGoal.equals( goal ) )
+            {
+                append( sb, goalPrefix + ":" + mojoGoal, 0 );
+                Node deprecated = findSingleChild( mojo, "deprecated" );
+                if ( ( deprecated != null ) && isNotEmpty( deprecated.getNodeValue() ) )
+                {
+                    append( sb, "Deprecated. " + deprecated, 1 );
+                    if ( detail && description != null )
+                    {
+                        append( sb, "", 0 );
+                        append( sb, description.getTextContent(), 1 );
+                    }
+                }
+                else if (description != null )
+                {
+                    append( sb, description.getTextContent(), 1 );
+                }
+                append( sb, "", 0 );
+
+                if ( detail )
+                {
+                    Node parametersNode = getSingleChild( mojo, "parameters" );
+                    List<Node> parameters = findNamedChild( parametersNode, "parameter" );
+                    append( sb, "Available parameters:", 1 );
+                    append( sb, "", 0 );
+
+                    for ( Node parameter : parameters )
+                    {
+                        writeParameter( sb, parameter, configurationElement );
+                    }
+                }
+            }
+        }
+
+        private void writeParameter( StringBuilder sb, Node parameter, Node configurationElement )
+            throws MojoExecutionException
+        {
+            String parameterName = getValue( parameter, "name" );
+            String parameterDescription = getValue( parameter, "description" );
+
+            Node fieldConfigurationElement = findSingleChild( configurationElement, parameterName );
+
+            String parameterDefaultValue = "";
+            if ( fieldConfigurationElement != null && fieldConfigurationElement.getNodeValue() != null )
+            {
+                parameterDefaultValue = " (Default: " + ((Element)fieldConfigurationElement).getAttribute( "default-value" ) + ")";
+            }
+            append( sb, parameterName + parameterDefaultValue, 2 );
+            Node deprecated = findSingleChild( parameter, "deprecated" );
+            if ( ( deprecated != null ) && isNotEmpty( deprecated.getNodeValue() ) )
+            {
+                append( sb, "Deprecated. " + deprecated.getNodeValue(), 3 );
+                append( sb, "", 0 );
+            }
+            append( sb, parameterDescription, 3 );
+            if ( "true".equals( getValue( parameter, "required" ) ) )
+            {
+                append( sb, "Required: Yes", 3 );
+            }
+            Node expression = findSingleChild( parameter, "expression" );
+            if ( ( expression != null ) && isNotEmpty( expression.getNodeValue() ) )
+            {
+            	String property = getPropertyFromExpression( expression.getNodeValue() );
+                append( sb, "User property: " + property, 3 );
+            }
+
+            append( sb, "", 0 );
+        }
+
+        /**
+         * <p>Repeat a String <code>n</code> times to form a new string.</p>
+         *
+         * @param str    String to repeat
+         * @param repeat number of times to repeat str
+         * @return String with repeated String
+         * @throws NegativeArraySizeException if <code>repeat < 0</code>
+         * @throws NullPointerException       if str is <code>null</code>
+         */
+        private static String repeat( String str, int repeat )
+        {
+            StringBuilder buffer = new StringBuilder( repeat * str.length() );
+
+            for ( int i = 0; i < repeat; i++ )
+            {
+                buffer.append( str );
+            }
+
+            return buffer.toString();
+        }
+
+        /**
+         * Append a description to the buffer by respecting the indentSize and lineLength parameters.
+         * <b>Note</b>: The last character is always a new line.
+         *
+         * @param sb          The buffer to append the description, not <code>null</code>.
+         * @param description The description, not <code>null</code>.
+         * @param indent      The base indentation level of each line, must not be negative.
+         */
+        private void append( StringBuilder sb, String description, int indent )
+        {
+            for ( String line : toLines( description, indent, indentSize, lineLength ) )
+            {
+                sb.append( line ).append( '\n' );
+            }
+        }
+
+        /**
+         * Splits the specified text into lines of convenient display length.
+         *
+         * @param text       The text to split into lines, must not be <code>null</code>.
+         * @param indent     The base indentation level of each line, must not be negative.
+         * @param indentSize The size of each indentation, must not be negative.
+         * @param lineLength The length of the line, must not be negative.
+         * @return The sequence of display lines, never <code>null</code>.
+         * @throws NegativeArraySizeException if <code>indent < 0</code>
+         */
+        private static List<String> toLines( String text, int indent, int indentSize, int lineLength )
+        {
+            List<String> lines = new ArrayList<String>();
+
+            String ind = repeat( "\t", indent );
+
+            String[] plainLines = text.split( "(\r\n)|(\r)|(\n)" );
+
+            for ( String plainLine : plainLines )
+            {
+                toLines( lines, ind + plainLine, indentSize, lineLength );
+            }
+
+            return lines;
+        }
+
+        /**
+         * Adds the specified line to the output sequence, performing line wrapping if necessary.
+         *
+         * @param lines      The sequence of display lines, must not be <code>null</code>.
+         * @param line       The line to add, must not be <code>null</code>.
+         * @param indentSize The size of each indentation, must not be negative.
+         * @param lineLength The length of the line, must not be negative.
+         */
+        private static void toLines( List<String> lines, String line, int indentSize, int lineLength )
+        {
+            int lineIndent = getIndentLevel( line );
+            StringBuilder buf = new StringBuilder( 256 );
+
+            String[] tokens = line.split( " +" );
+
+            for ( String token : tokens )
+            {
+                if ( buf.length() > 0 )
+                {
+                    if ( buf.length() + token.length() >= lineLength )
+                    {
+                        lines.add( buf.toString() );
+                        buf.setLength( 0 );
+                        buf.append( repeat( " ", lineIndent * indentSize ) );
+                    }
+                    else
+                    {
+                        buf.append( ' ' );
+                    }
+                }
+
+                for ( int j = 0; j < token.length(); j++ )
+                {
+                    char c = token.charAt( j );
+                    if ( c == '\t' )
+                    {
+                        buf.append( repeat( " ", indentSize - buf.length() % indentSize ) );
+                    }
+                    else if ( c == '\u00A0' )
+                    {
+                        buf.append( ' ' );
+                    }
+                    else
+                    {
+                        buf.append( c );
+                    }
+                }
+            }
+            lines.add( buf.toString() );
+        }
+
+        /**
+         * Gets the indentation level of the specified line.
+         *
+         * @param line The line whose indentation level should be retrieved, must not be <code>null</code>.
+         * @return The indentation level of the line.
+         */
+        private static int getIndentLevel( String line )
+        {
+            int level = 0;
+            for ( int i = 0; i < line.length() && line.charAt( i ) == '\t'; i++ )
+            {
+                level++;
+            }
+            for ( int i = level + 1; i <= level + 4 && i < line.length(); i++ )
+            {
+                if ( line.charAt( i ) == '\t' )
+                {
+                    level++;
+                    break;
+                }
+            }
+            return level;
+        }
+
+        private String getPropertyFromExpression( String expression )
+        {
+            if ( expression != null && expression.startsWith( "${" ) && expression.endsWith( "}" )
+                && !expression.substring( 2 ).contains( "${" ) )
+            {
+                // expression="${xxx}" -> property="xxx"
+                return expression.substring( 2, expression.length() - 1 );
+            }
+            // no property can be extracted
+            return null;
+        }
+    }
+