OptionalPackage


1   /*
2    * Copyright (C) The Apache Software Foundation. All rights reserved.
3    *
4    * This software is published under the terms of the Apache Software License
5    * version 1.1, a copy of which has been included with this distribution in
6    * the LICENSE.txt file.
7    */
8   package org.apache.avalon.excalibur.extension;
9   
10  import java.io.File  ;
11  
12  /**
13   * This contains the required meta-data for an "Optional Package"
14   * (formerly known as "Standard Extension") as described in the manifest
15   * of a JAR file.
16   *
17   * @author <a HREF="mailto:peter@apache.org">Peter Donald</a>
18   */
19  public final class OptionalPackage
20  {
21      private final File            m_file;
22      private final Extension[]   m_available;
23      private final Extension[]   m_required;
24  
25      /**
26       * Convert a list of OptionalPackages into a list of Files.
27       *
28       * @param packages the list of packages
29       * @return the list of files
30       */
31      public static final File  [] toFiles( final OptionalPackage[] packages )
32      {
33          final File  [] results = new File  [ packages.length ];
34  
35          for( int i = 0; i < packages.length; i++ )
36          {
37              results[ i ] = packages[ i ].getFile();
38          }
39  
40          return results;
41      }
42  
43      /**
44       * Constructor for OptionalPackage.
45       * No parameter is allowed to be null.
46       *
47       * @param file absolute location of file
48       * @param available the list of Extensions Optional Package provides
49       * @param required the list of Extensions Optional Package requires
50       */
51      public OptionalPackage( final File   file, 
52                              final Extension[] available, 
53                              final Extension[] required )
54      {
55          if( null == file )
56          {
57              throw new NullPointerException  ( "file property is null" );
58          }
59  
60          if( null == available )
61          {
62              throw new NullPointerException  ( "available property is null" );
63          }
64  
65          if( null == required )
66          {
67              throw new NullPointerException  ( "required property is null" );
68          }
69  
70          m_file = file;
71          m_available = available;
72          m_required = required;
73      }
74  
75      /**
76       * Return <code>File</code> object in which OptionalPackage 
77       * is contained.
78       *
79       * @return the file object for OptionalPackage
80       */
81      public File   getFile()
82      {
83          return m_file;
84      }
85  
86      /**
87       * Return <code>Extension</code>s which OptionalPackage 
88       * requires to operate.
89       *
90       * @return the extensions required by OptionalPackage
91       */
92      public Extension[] getRequiredExtensions()
93      {
94          return m_required;
95      }
96  
97      /**
98       * Return <code>Extension</code>s which OptionalPackage 
99       * makes available.
100      *
101      * @return the extensions made available by OptionalPackage
102      */
103     public Extension[] getAvailableExtensions()
104     {
105         return m_available;
106     }
107 
108     /**
109      * Return <code>true</code> if any of the available <code>Extension</code>s 
110      * are compatible with specified extension. Otherwise return <code>false</code>.
111      *
112      * @param extension the extension
113      * @return true if compatible, false otherwise
114      */
115     public boolean isCompatible( final Extension extension ) 
116     {
117         for( int i = 0; i < m_available.length; i++ )
118         {
119             if( m_available[ i ].isCompatibleWith( extension ) )
120             {
121                 return true;
122             }
123         }
124 
125         return false;
126     }
127 
128     /**
129      * Return a String representation of this object.
130      */
131     public String   toString() 
132     {
133         final StringBuffer   sb = new StringBuffer  ( "OptionalPackage[" );
134         sb.append( m_file );
135 
136         sb.append( ", Available[" );       
137         for( int i = 0; i < m_available.length; i++ )
138         {
139             sb.append( m_available );
140             sb.append( " " );
141         }
142 
143         sb.append( "], Required[" );
144         for( int i = 0; i < m_required.length; i++ )
145         {
146             sb.append( m_required );
147             sb.append( " " );
148         }
149 
150         sb.append( "] ]" );
151 
152         return sb.toString();
153     }
154 }
155
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