MetaClassLoader


1   package org.kohsuke.stapler;
2   
3   import java.util.Map  ;
4   import java.util.WeakHashMap  ;
5   import java.io.File  ;
6   import java.net.URLClassLoader  ;
7   import java.net.URL  ;
8   import java.net.MalformedURLException  ;
9   
10  /**
11   * The stapler version of the {@link ClassLoader} object,
12   * that retains some useful cache about a class loader.
13   *
14   * @author Kohsuke Kawaguchi
15   */
16  public class MetaClassLoader extends TearOffSupport {
17      public final MetaClassLoader parent;
18      public final ClassLoader   loader;
19  
20      public MetaClassLoader(ClassLoader   loader) {
21          this.loader = loader;
22          this.parent = get(loader.getParent());
23      }
24  
25      public static MetaClassLoader get(ClassLoader   cl) {
26          if(cl ==null)
27              return null; // if no parent, delegate to the debug loader if available.
28          
29          synchronized(classMap) {
30              MetaClassLoader mc = classMap.get(cl);
31              if(mc==null) {
32                  mc = new MetaClassLoader(cl);
33                  classMap.put(cl,mc);
34              }
35              return mc;
36          }
37      }
38  
39      /**
40       * If non-null, delegate to this classloader.
41       */
42      public static MetaClassLoader debugLoader = null;
43  
44      /**
45       * All {@link MetaClass}es.
46       *
47       * Avoids class leaks by {@link WeakHashMap}.
48       */
49      private static final Map  <ClassLoader  ,MetaClassLoader> classMap = new WeakHashMap  <ClassLoader  ,MetaClassLoader>();
50  
51      static {
52          try {
53              String   path = System.getProperty("stapler.resourcePath");
54              if(path!=null) {
55                  debugLoader = new MetaClassLoader(
56                      new URLClassLoader  (new URL  []{new File  (path).toURL()}));
57              }
58          } catch (MalformedURLException   e) {
59              throw new Error  (e);
60          }
61      }
62  }
63
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