HelpMojo.java
package org.mybatis.maven.migrations_maven_plugin;
import org.apache.maven.plugin.AbstractMojo;
import org.apache.maven.plugin.MojoExecutionException;
import org.apache.maven.plugins.annotations.Mojo;
import org.apache.maven.plugins.annotations.Parameter;
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.List;
/**
* Display help information on migrations-maven-plugin.<br>
* Call <code>mvn migration:help -Ddetail=true -Dgoal=<goal-name></code> to display parameter details.
* @author maven-plugin-tools
*/
@Mojo( name = "help", requiresProject = false, threadSafe = true )
public class HelpMojo
extends AbstractMojo
{
/**
* If <code>true</code>, display all settable properties for each goal.
*
*/
@Parameter( property = "detail", defaultValue = "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", defaultValue = "80" )
private int lineLength;
/**
* The number of spaces per indentation level, should be positive.
*
*/
@Parameter( property = "indentSize", defaultValue = "2" )
private int indentSize;
// /META-INF/maven/<groupId>/<artifactId>/plugin-help.xml
private static final String PLUGIN_HELP_PATH =
"/META-INF/maven/org.mybatis.maven/migrations-maven-plugin/plugin-help.xml";
private static final int DEFAULT_LINE_LENGTH = 80;
private Document build()
throws MojoExecutionException
{
getLog().debug( "load plugin-help.xml: " + PLUGIN_HELP_PATH );
try ( InputStream is = getClass().getResourceAsStream( PLUGIN_HELP_PATH ) )
{
if ( is == null )
{
throw new MojoExecutionException( "Could not find plugin descriptor at " + PLUGIN_HELP_PATH );
}
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}
*/
@Override
public void execute()
throws MojoExecutionException
{
if ( lineLength <= 0 )
{
getLog().warn( "The parameter 'lineLength' should be positive, using '80' as default." );
lineLength = DEFAULT_LINE_LENGTH;
}
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 static String getValue( Node node, String elementName )
throws MojoExecutionException
{
return getSingleChild( node, elementName ).getTextContent();
}
private static 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 static 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 static 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.getTextContent() ) )
{
append( sb, "Deprecated. " + deprecated.getTextContent(), 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" );
Element fieldConfigurationElement = null;
if ( configurationElement != null )
{
fieldConfigurationElement = (Element) findSingleChild( configurationElement, parameterName );
}
String parameterDefaultValue = "";
if ( fieldConfigurationElement != null && fieldConfigurationElement.hasAttribute( "default-value" ) )
{
parameterDefaultValue = " (Default: " + fieldConfigurationElement.getAttribute( "default-value" ) + ")";
}
append( sb, parameterName + parameterDefaultValue, 2 );
Node deprecated = findSingleChild( parameter, "deprecated" );
if ( ( deprecated != null ) && isNotEmpty( deprecated.getTextContent() ) )
{
append( sb, "Deprecated. " + deprecated.getTextContent(), 3 );
append( sb, "", 0 );
}
if ( isNotEmpty( parameterDescription ) ) {
append( sb, parameterDescription, 3 );
}
if ( "true".equals( getValue( parameter, "required" ) ) )
{
append( sb, "Required: Yes", 3 );
}
if ( ( fieldConfigurationElement != null ) && isNotEmpty( fieldConfigurationElement.getTextContent() ) )
{
String property = getPropertyFromExpression( fieldConfigurationElement.getTextContent() );
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 static 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;
}
}