|
1
10
11 package com.triactive.jdo.util;
12
13 import java.util.Arrays  ;
14 import java.util.Collections ;
15 import java.util.HashMap ;
16 import java.util.HashSet ;
17 import java.util.Iterator ;
18 import java.util.Set ;
19 import java.util.StringTokenizer ;
20 import java.util.WeakHashMap ;
21 import javax.jdo.JDOUserException;
22 import org.apache.log4j.Category;
23
24
25 public class Imports
26 {
27 private static final Category LOG = Category.getInstance(Imports.class);
28
29
30 private static final String [] primitives =
31 { "boolean", "byte", "char", "double", "float", "int", "long", "short" };
32
33
34 private static final Class [] primitiveClasses =
35 { boolean.class, byte.class, char.class, double.class, float.class, int.class, long.class, short.class };
36
37
38 private static final char[] primitiveTypeChars =
39 { 'Z', 'B', 'C', 'D', 'F', 'I', 'J', 'S' };
40
41 private static final WeakHashMap nonExistentClassNamesByLoader = new WeakHashMap ();
42
43 private HashMap importedClassesByName = new HashMap ();
44 private HashSet importedPackageNames = new HashSet ();
45
46
47 public Imports()
48 {
49 importedPackageNames.add("java.lang");
50 }
51
52
53 public void importPackage(Class c)
54 {
55 while (c.isArray())
56 c = c.getComponentType();
57
58 String className = c.getName();
59 int lastDot = className.lastIndexOf('.');
60
61 if (lastDot > 0)
62 importedPackageNames.add(className.substring(0, lastDot));
63 }
64
65
66 public void parseImports(String imports)
67 {
68 StringTokenizer t1 = new StringTokenizer (imports, ";");
69
70 while (t1.hasMoreTokens())
71 {
72 String importDecl = t1.nextToken().trim();
73
74 if (importDecl.length() == 0 && !t1.hasMoreTokens())
75 break;
76
77 StringTokenizer t2 = new StringTokenizer (importDecl, " ");
78
79 if (t2.countTokens() != 2 || !t2.nextToken().equals("import"))
80 throw new JDOUserException("Invalid import declaration: " + importDecl);
81
82 String importName = t2.nextToken();
83 int lastDot = importName.lastIndexOf(".");
84 String lastPart = importName.substring(lastDot + 1);
85
86 if (lastPart.equals("*"))
87 {
88 if (lastDot < 1)
89 throw new JDOUserException("Invalid package import: " + importName);
90
91 importedPackageNames.add(importName.substring(0, lastDot));
92 }
93 else
94 {
95 if (importedClassesByName.get(lastPart) != null)
96 throw new JDOUserException("Duplicate class import: " + importName);
97
98 try
99 {
100 importedClassesByName.put(lastPart, classForName(importName));
101 }
102 catch (ClassNotFoundException e)
103 {
104 throw new JDOUserException("Class named in imports not found: " + importName);
105 }
106 }
107 }
108 }
109
110
111
129
130 private Class classForName(String className) throws ClassNotFoundException
131 {
132 ClassLoader loader = getClass().getClassLoader();
133 Set names;
134
135 synchronized (nonExistentClassNamesByLoader)
136 {
137 names = (Set )nonExistentClassNamesByLoader.get(loader);
138
139 if (names == null)
140 {
141 names = Collections.synchronizedSet(new HashSet ());
142 nonExistentClassNamesByLoader.put(loader, names);
143 }
144 else
145 {
146 if (names.contains(className))
147 throw new ClassNotFoundException (className + " (cached from previous lookup attempt)");
148 }
149 }
150
151 try
152 {
153 return Class.forName(className, true, loader);
154 }
155 catch (ClassNotFoundException e)
156 {
157 LOG.debug("Caching the fact that " + className + " was not found by " + loader);
158 names.add(className);
159 throw e;
160 }
161 }
162
163
164 public Class resolveClassDeclaration(String classDecl) throws ClassNotFoundException
165 {
166 String className;
167 String dims = null;
168 int bktIdx = classDecl.indexOf("[]");
169
170 if (bktIdx > 0)
171 {
172 className = classDecl.substring(0, bktIdx);
173 StringBuffer dimBuf = new StringBuffer ();
174
175 do
176 {
177 dimBuf.append('[');
178 bktIdx += 2;
179 } while (classDecl.startsWith("[]", bktIdx));
180
181 if (bktIdx < classDecl.length())
182 throw new ClassNotFoundException (classDecl);
183
184 dims = dimBuf.toString();
185 }
186 else
187 className = classDecl;
188
189 Class c;
190 int p = Arrays.binarySearch(primitives, className);
191
192 if (p >= 0)
193 {
194 if (dims == null)
195 c = primitiveClasses[p];
196 else
197 c = classForName(dims + primitiveTypeChars[p]);
198 }
199 else
200 {
201 c = (Class )importedClassesByName.get(className);
202
203 if (c == null)
204 {
205 try
206 {
207 c = classForName(className);
208 }
209 catch (ClassNotFoundException e)
210 {
211 Iterator packageNames = importedPackageNames.iterator();
212
213 while (packageNames.hasNext())
214 {
215 String packageName = (String )packageNames.next();
216
217 try
218 {
219 Class c1 = classForName(packageName + '.' + className);
220
221 if (c != null)
222 throw new JDOUserException("Ambiguous class declaration, could be " + c.getName() + " or " + c1.getName());
223
224 c = c1;
225 }
226 catch (ClassNotFoundException e1)
227 {
228 }
229 }
230
231 if (c == null)
232 throw e;
233
234 LOG.warn("Class " + c.getName() + " was not explicitly imported; this may have a noticeable impact on performance", new JDOUserException());
235 }
236 }
237
238 if (dims != null)
239 c = classForName(dims + 'L' + c.getName() + ';');
240 }
241
242 return c;
243 }
244 }
245 |
Popular Tags |
Java API By Example, From Geeks To Geeks.