|
1
8 package org.apache.avalon.excalibur.property;
9
10 import org.apache.avalon.framework.context.Context;
11 import org.apache.avalon.framework.context.ContextException;
12 import org.apache.avalon.framework.context.Resolvable;
13
14
21 public final class PropertyUtil
22 {
23 private PropertyUtil()
24 {
25 }
26
27
37 public static Object  resolveProperty( final String property,
38 final Context context,
39 final boolean ignoreUndefined )
40 throws PropertyException
41 {
42 int start = findBeginning( property, 0 );
43 if( -1 == start )
44 {
45 return property;
46 }
47
48 int end = findEnding( property, start );
49
50 final int length = property.length();
51
52 if( 0 == start && end == (length - 1) )
53 {
54 return resolveValue( property.substring( start + 2, end ),
55 context,
56 ignoreUndefined );
57 }
58
59 final StringBuffer sb = new StringBuffer ( length * 2 );
60 int lastPlace = 0;
61
62 while( true )
63 {
64 final Object value =
65 resolveValue( property.substring( start + 2, end ),
66 context,
67 ignoreUndefined );
68
69 sb.append( property.substring( lastPlace, start ) );
70 sb.append( value );
71
72 lastPlace = end + 1;
73
74 start = findBeginning( property, lastPlace );
75 if( -1 == start )
76 {
77 break;
78 }
79
80 end = findEnding( property, start );
81 }
82
83 sb.append( property.substring( lastPlace, length ) );
84
85 return sb.toString();
86 }
87
88
89
99 public static Object recursiveResolveProperty( final String property,
100 final Context context,
101 final boolean ignoreUndefined )
102 throws PropertyException
103 {
104 int start = findBeginning( property, 0 );
105 if( -1 == start )
106 {
107 return property;
108 }
109
110 int end = findNestedEnding( property, start );
111
112 final int length = property.length();
113
114 if( 0 == start && end == (length - 1) )
115 {
116 final String propertyName = property.substring( start + 2, end );
117 final Object key = recursiveResolveProperty( propertyName, context, ignoreUndefined );
118 return resolveValue( key.toString(), context, ignoreUndefined );
119 }
120
121 final StringBuffer sb = new StringBuffer ( length * 2 );
122
123 int lastPlace = 0;
124
125 while( true )
126 {
127 final String propertyName = property.substring( start + 2, end );
128 final Object key = recursiveResolveProperty( propertyName, context, ignoreUndefined );
129 final Object value = resolveValue( key.toString(), context, ignoreUndefined );
130
131 sb.append( property.substring( lastPlace, start ) );
132 sb.append( value );
133
134 lastPlace = end + 1;
135
136 start = findBeginning( property, lastPlace );
137 if( -1 == start )
138 {
139 break;
140 }
141
142 end = findNestedEnding( property, start );
143 }
144
145 sb.append( property.substring( lastPlace, length ) );
146
147 return sb.toString();
148 }
149
150 private static int findBeginning( final String property, final int currentPosition )
151 {
152 return property.indexOf( "${", currentPosition );
154 }
155
156 private static int findEnding( final String property, final int currentPosition )
157 throws PropertyException
158 {
159 final int index = property.indexOf( '}', currentPosition );
161 if( -1 == index )
162 {
163 throw new PropertyException( "Malformed property with mismatched }'s" );
164 }
165
166 return index;
167 }
168
169 private static int findNestedEnding( final String property, final int currentPosition )
170 throws PropertyException
171 {
172 final int length = property.length();
173 final int start = currentPosition + 2;
174
175 int weight = 1;
176 for( int i = start; (weight > 0) && (i < length); i++ )
177 {
178 final char ch = property.charAt( i );
179 switch( ch )
180 {
181 case '}':
182 weight--;
184 if( weight == 0 )
185 {
186 return i;
187 }
188 break;
189
190 case '$':
191 {
192 final int next = i + 1;
194 if( next < length && '{' == property.charAt( next ) )
195 {
196 weight++;
197 }
198 }
199 break;
200 }
201 }
202
203 throw new PropertyException( "Malformed property with mismatched }'s" );
204 }
205
206
217 private static Object resolveValue( final String key,
218 final Context context,
219 final boolean ignoreUndefined )
220 throws PropertyException
221 {
222 Object value = null;
223
224 try { value = context.get( key ); }
225 catch( final ContextException ce ) {}
226
227 try
228 {
229 while( null != value && value instanceof Resolvable )
230 {
231 value = ((Resolvable)value).resolve( context );
232 }
233 }
234 catch( final ContextException ce )
235 {
236 throw new PropertyException( "Unable to resolve value for key " + key );
237 }
238
239 if( null == value )
240 {
241 if( ignoreUndefined ) return "";
242 else
243 {
244 throw new PropertyException( "Unable to find " + key + " to expand during " +
245 "property resolution." );
246 }
247 }
248
249 return value;
250 }
251 }
252 |
Popular Tags |
Java API By Example, From Geeks To Geeks.