Source code

001
002
003import org.apache.maven.plugin.AbstractMojo;
004import org.apache.maven.plugin.MojoExecutionException;
005import org.apache.maven.plugins.annotations.Mojo;
006import org.apache.maven.plugins.annotations.Parameter;
007
008import org.w3c.dom.Document;
009import org.w3c.dom.Element;
010import org.w3c.dom.Node;
011import org.w3c.dom.NodeList;
012import org.xml.sax.SAXException;
013
014import javax.xml.parsers.DocumentBuilder;
015import javax.xml.parsers.DocumentBuilderFactory;
016import javax.xml.parsers.ParserConfigurationException;
017import java.io.IOException;
018import java.io.InputStream;
019import java.util.ArrayList;
020import java.util.List;
021
022/**
023 * Display help information on maven-plugin-plugin.<br>
024 * Call <code>mvn plugin:help -Ddetail=true -Dgoal=&lt;goal-name&gt;</code> to display parameter details.
025 * @author maven-plugin-tools
026 */
027@Mojo( name = "help", requiresProject = false, threadSafe = true )
028public class HelpMojo
029    extends AbstractMojo
030{
031    /**
032     * If <code>true</code>, display all settable properties for each goal.
033     *
034     */
035    @Parameter( property = "detail", defaultValue = "false" )
036    private boolean detail;
037
038    /**
039     * The name of the goal for which to show help. If unspecified, all goals will be displayed.
040     *
041     */
042    @Parameter( property = "goal" )
043    private java.lang.String goal;
044
045    /**
046     * The maximum length of a display line, should be positive.
047     *
048     */
049    @Parameter( property = "lineLength", defaultValue = "80" )
050    private int lineLength;
051
052    /**
053     * The number of spaces per indentation level, should be positive.
054     *
055     */
056    @Parameter( property = "indentSize", defaultValue = "2" )
057    private int indentSize;
058
059    // groupId/artifactId/plugin-help.xml
060    private static final String PLUGIN_HELP_PATH =
061                    "/META-INF/maven/org.apache.maven.plugins/maven-plugin-plugin/plugin-help.xml";
062
063    private static final int DEFAULT_LINE_LENGTH = 80;
064
065    private Document build()
066        throws MojoExecutionException
067    {
068        getLog().debug( "load plugin-help.xml: " + PLUGIN_HELP_PATH );
069        InputStream is = null;
070        try
071        {
072            is = getClass().getResourceAsStream( PLUGIN_HELP_PATH );
073            DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
074            DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
075            return dBuilder.parse( is );
076        }
077        catch ( IOException e )
078        {
079            throw new MojoExecutionException( e.getMessage(), e );
080        }
081        catch ( ParserConfigurationException e )
082        {
083            throw new MojoExecutionException( e.getMessage(), e );
084        }
085        catch ( SAXException e )
086        {
087            throw new MojoExecutionException( e.getMessage(), e );
088        }
089        finally
090        {
091            if ( is != null )
092            {
093                try
094                {
095                    is.close();
096                }
097                catch ( IOException e )
098                {
099                    throw new MojoExecutionException( e.getMessage(), e );
100                }
101            }
102        }
103    }
104
105    /**
106     * {@inheritDoc}
107     */
108    public void execute()
109        throws MojoExecutionException
110    {
111        if ( lineLength <= 0 )
112        {
113            getLog().warn( "The parameter 'lineLength' should be positive, using '80' as default." );
114            lineLength = DEFAULT_LINE_LENGTH;
115        }
116        if ( indentSize <= 0 )
117        {
118            getLog().warn( "The parameter 'indentSize' should be positive, using '2' as default." );
119            indentSize = 2;
120        }
121
122        Document doc = build();
123
124        StringBuilder sb = new StringBuilder();
125        Node plugin = getSingleChild( doc, "plugin" );
126
127
128        String name = getValue( plugin, "name" );
129        String version = getValue( plugin, "version" );
130        String id = getValue( plugin, "groupId" ) + ":" + getValue( plugin, "artifactId" ) + ":" + version;
131        if ( isNotEmpty( name ) && !name.contains( id ) )
132        {
133            append( sb, name + " " + version, 0 );
134        }
135        else
136        {
137            if ( isNotEmpty( name ) )
138            {
139                append( sb, name, 0 );
140            }
141            else
142            {
143                append( sb, id, 0 );
144            }
145        }
146        append( sb, getValue( plugin, "description" ), 1 );
147        append( sb, "", 0 );
148
149        //<goalPrefix>plugin</goalPrefix>
150        String goalPrefix = getValue( plugin, "goalPrefix" );
151
152        Node mojos1 = getSingleChild( plugin, "mojos" );
153
154        List<Node> mojos = findNamedChild( mojos1, "mojo" );
155
156        if ( goal == null || goal.length() <= 0 )
157        {
158            append( sb, "This plugin has " + mojos.size() + ( mojos.size() > 1 ? " goals:" : " goal:" ), 0 );
159            append( sb, "", 0 );
160        }
161
162        for ( Node mojo : mojos )
163        {
164            writeGoal( sb, goalPrefix, (Element) mojo );
165        }
166
167        if ( getLog().isInfoEnabled() )
168        {
169            getLog().info( sb.toString() );
170        }
171    }
172
173
174    private static boolean isNotEmpty( String string )
175    {
176        return string != null && string.length() > 0;
177    }
178
179    private String getValue( Node node, String elementName )
180        throws MojoExecutionException
181    {
182        return getSingleChild( node, elementName ).getTextContent();
183    }
184
185    private Node getSingleChild( Node node, String elementName )
186        throws MojoExecutionException
187    {
188        List<Node> namedChild = findNamedChild( node, elementName );
189        if ( namedChild.isEmpty() )
190        {
191            throw new MojoExecutionException( "Could not find " + elementName + " in plugin-help.xml" );
192        }
193        if ( namedChild.size() > 1 )
194        {
195            throw new MojoExecutionException( "Multiple " + elementName + " in plugin-help.xml" );
196        }
197        return namedChild.get( 0 );
198    }
199
200    private List<Node> findNamedChild( Node node, String elementName )
201    {
202        List<Node> result = new ArrayList<Node>();
203        NodeList childNodes = node.getChildNodes();
204        for ( int i = 0; i < childNodes.getLength(); i++ )
205        {
206            Node item = childNodes.item( i );
207            if ( elementName.equals( item.getNodeName() ) )
208            {
209                result.add( item );
210            }
211        }
212        return result;
213    }
214
215    private Node findSingleChild( Node node, String elementName )
216        throws MojoExecutionException
217    {
218        List<Node> elementsByTagName = findNamedChild( node, elementName );
219        if ( elementsByTagName.isEmpty() )
220        {
221            return null;
222        }
223        if ( elementsByTagName.size() > 1 )
224        {
225            throw new MojoExecutionException( "Multiple " + elementName + "in plugin-help.xml" );
226        }
227        return elementsByTagName.get( 0 );
228    }
229
230    private void writeGoal( StringBuilder sb, String goalPrefix, Element mojo )
231        throws MojoExecutionException
232    {
233        String mojoGoal = getValue( mojo, "goal" );
234        Node configurationElement = findSingleChild( mojo, "configuration" );
235        Node description = findSingleChild( mojo, "description" );
236        if ( goal == null || goal.length() <= 0 || mojoGoal.equals( goal ) )
237        {
238            append( sb, goalPrefix + ":" + mojoGoal, 0 );
239            Node deprecated = findSingleChild( mojo, "deprecated" );
240            if ( ( deprecated != null ) && isNotEmpty( deprecated.getTextContent() ) )
241            {
242                append( sb, "Deprecated. " + deprecated.getTextContent(), 1 );
243                if ( detail && description != null )
244                {
245                    append( sb, "", 0 );
246                    append( sb, description.getTextContent(), 1 );
247                }
248            }
249            else if ( description != null )
250            {
251                append( sb, description.getTextContent(), 1 );
252            }
253            append( sb, "", 0 );
254
255            if ( detail )
256            {
257                Node parametersNode = getSingleChild( mojo, "parameters" );
258                List<Node> parameters = findNamedChild( parametersNode, "parameter" );
259                append( sb, "Available parameters:", 1 );
260                append( sb, "", 0 );
261
262                for ( Node parameter : parameters )
263                {
264                    writeParameter( sb, parameter, configurationElement );
265                }
266            }
267        }
268    }
269
270    private void writeParameter( StringBuilder sb, Node parameter, Node configurationElement )
271        throws MojoExecutionException
272    {
273        String parameterName = getValue( parameter, "name" );
274        String parameterDescription = getValue( parameter, "description" );
275
276        Element fieldConfigurationElement = (Element) findSingleChild( configurationElement, parameterName );
277
278        String parameterDefaultValue = "";
279        if ( fieldConfigurationElement != null && fieldConfigurationElement.hasAttribute( "default-value" ) )
280        {
281            parameterDefaultValue = " (Default: " + fieldConfigurationElement.getAttribute( "default-value" ) + ")";
282        }
283        append( sb, parameterName + parameterDefaultValue, 2 );
284        Node deprecated = findSingleChild( parameter, "deprecated" );
285        if ( ( deprecated != null ) && isNotEmpty( deprecated.getTextContent() ) )
286        {
287            append( sb, "Deprecated. " + deprecated.getTextContent(), 3 );
288            append( sb, "", 0 );
289        }
290        append( sb, parameterDescription, 3 );
291        if ( "true".equals( getValue( parameter, "required" ) ) )
292        {
293            append( sb, "Required: Yes", 3 );
294        }
295        if ( ( fieldConfigurationElement != null ) && isNotEmpty( fieldConfigurationElement.getTextContent() ) )
296        {
297            String property = getPropertyFromExpression( fieldConfigurationElement.getTextContent() );
298            append( sb, "User property: " + property, 3 );
299        }
300
301        append( sb, "", 0 );
302    }
303
304    /**
305     * <p>Repeat a String <code>n</code> times to form a new string.</p>
306     *
307     * @param str    String to repeat
308     * @param repeat number of times to repeat str
309     * @return String with repeated String
310     * @throws NegativeArraySizeException if <code>repeat < 0</code>
311     * @throws NullPointerException       if str is <code>null</code>
312     */
313    private static String repeat( String str, int repeat )
314    {
315        StringBuilder buffer = new StringBuilder( repeat * str.length() );
316
317        for ( int i = 0; i < repeat; i++ )
318        {
319            buffer.append( str );
320        }
321
322        return buffer.toString();
323    }
324
325    /**
326     * Append a description to the buffer by respecting the indentSize and lineLength parameters.
327     * <b>Note</b>: The last character is always a new line.
328     *
329     * @param sb          The buffer to append the description, not <code>null</code>.
330     * @param description The description, not <code>null</code>.
331     * @param indent      The base indentation level of each line, must not be negative.
332     */
333    private void append( StringBuilder sb, String description, int indent )
334    {
335        for ( String line : toLines( description, indent, indentSize, lineLength ) )
336        {
337            sb.append( line ).append( '\n' );
338        }
339    }
340
341    /**
342     * Splits the specified text into lines of convenient display length.
343     *
344     * @param text       The text to split into lines, must not be <code>null</code>.
345     * @param indent     The base indentation level of each line, must not be negative.
346     * @param indentSize The size of each indentation, must not be negative.
347     * @param lineLength The length of the line, must not be negative.
348     * @return The sequence of display lines, never <code>null</code>.
349     * @throws NegativeArraySizeException if <code>indent < 0</code>
350     */
351    private static List<String> toLines( String text, int indent, int indentSize, int lineLength )
352    {
353        List<String> lines = new ArrayList<String>();
354
355        String ind = repeat( "\t", indent );
356
357        String[] plainLines = text.split( "(\r\n)|(\r)|(\n)" );
358
359        for ( String plainLine : plainLines )
360        {
361            toLines( lines, ind + plainLine, indentSize, lineLength );
362        }
363
364        return lines;
365    }
366
367    /**
368     * Adds the specified line to the output sequence, performing line wrapping if necessary.
369     *
370     * @param lines      The sequence of display lines, must not be <code>null</code>.
371     * @param line       The line to add, must not be <code>null</code>.
372     * @param indentSize The size of each indentation, must not be negative.
373     * @param lineLength The length of the line, must not be negative.
374     */
375    private static void toLines( List<String> lines, String line, int indentSize, int lineLength )
376    {
377        int lineIndent = getIndentLevel( line );
378        StringBuilder buf = new StringBuilder( 256 );
379
380        String[] tokens = line.split( " +" );
381
382        for ( String token : tokens )
383        {
384            if ( buf.length() > 0 )
385            {
386                if ( buf.length() + token.length() >= lineLength )
387                {
388                    lines.add( buf.toString() );
389                    buf.setLength( 0 );
390                    buf.append( repeat( " ", lineIndent * indentSize ) );
391                }
392                else
393                {
394                    buf.append( ' ' );
395                }
396            }
397
398            for ( int j = 0; j < token.length(); j++ )
399            {
400                char c = token.charAt( j );
401                if ( c == '\t' )
402                {
403                    buf.append( repeat( " ", indentSize - buf.length() % indentSize ) );
404                }
405                else if ( c == '\u00A0' )
406                {
407                    buf.append( ' ' );
408                }
409                else
410                {
411                    buf.append( c );
412                }
413            }
414        }
415        lines.add( buf.toString() );
416    }
417
418    /**
419     * Gets the indentation level of the specified line.
420     *
421     * @param line The line whose indentation level should be retrieved, must not be <code>null</code>.
422     * @return The indentation level of the line.
423     */
424    private static int getIndentLevel( String line )
425    {
426        int level = 0;
427        for ( int i = 0; i < line.length() && line.charAt( i ) == '\t'; i++ )
428        {
429            level++;
430        }
431        for ( int i = level + 1; i <= level + 4 && i < line.length(); i++ )
432        {
433            if ( line.charAt( i ) == '\t' )
434            {
435                level++;
436                break;
437            }
438        }
439        return level;
440    }
441    
442    private String getPropertyFromExpression( String expression )
443    {
444        if ( expression != null && expression.startsWith( "${" ) && expression.endsWith( "}" )
445            && !expression.substring( 2 ).contains( "${" ) )
446        {
447            // expression="${xxx}" -> property="xxx"
448            return expression.substring( 2, expression.length() - 1 );
449        }
450        // no property can be extracted
451        return null;
452    }
453}