http://www.javassist.org/: Javassist (JAVA programming ASSISTant) makes Java bytecode manipulation simple. It is a class library for editing bytecodes in Java. (Shigeru Chiba, www.javassist.org) 
final class javassist.DirClassPath implements javassist.ClassPath
  minor version: 0
  major version: 59
  flags: flags: (0x0030) ACC_FINAL, ACC_SUPER
  this_class: javassist.DirClassPath
  super_class: java.lang.Object
{
  java.lang.String directory;
    descriptor: Ljava/lang/String;
    flags: (0x0000) 

  void <init>(java.lang.String);
    descriptor: (Ljava/lang/String;)V
    flags: (0x0000) 
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // javassist.DirClassPath this
        start local 1 // java.lang.String dirName
         0: .line 47
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
         1: .line 48
            aload 0 /* this */
            aload 1 /* dirName */
            putfield javassist.DirClassPath.directory:Ljava/lang/String;
         2: .line 49
            return
        end local 1 // java.lang.String dirName
        end local 0 // javassist.DirClassPath this
      LocalVariableTable:
        Start  End  Slot     Name  Signature
            0    3     0     this  Ljavassist/DirClassPath;
            0    3     1  dirName  Ljava/lang/String;
    MethodParameters:
         Name  Flags
      dirName  

  public java.io.InputStream openClassfile(java.lang.String);
    descriptor: (Ljava/lang/String;)Ljava/io/InputStream;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=4, args_size=2
        start local 0 // javassist.DirClassPath this
        start local 1 // java.lang.String classname
         0: .line 54
            getstatic java.io.File.separatorChar:C
            istore 2 /* sep */
        start local 2 // char sep
         1: .line 55
            new java.lang.StringBuilder
            dup
            aload 0 /* this */
            getfield javassist.DirClassPath.directory:Ljava/lang/String;
            invokestatic java.lang.String.valueOf:(Ljava/lang/Object;)Ljava/lang/String;
            invokespecial java.lang.StringBuilder.<init>:(Ljava/lang/String;)V
            iload 2 /* sep */
            invokevirtual java.lang.StringBuilder.append:(C)Ljava/lang/StringBuilder;
         2: .line 56
            aload 1 /* classname */
            bipush 46
            iload 2 /* sep */
            invokevirtual java.lang.String.replace:(CC)Ljava/lang/String;
            invokevirtual java.lang.StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
            ldc ".class"
            invokevirtual java.lang.StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
         3: .line 55
            invokevirtual java.lang.StringBuilder.toString:()Ljava/lang/String;
            astore 3 /* filename */
        start local 3 // java.lang.String filename
         4: .line 57
            new java.io.FileInputStream
            dup
            aload 3 /* filename */
            invokevirtual java.lang.String.toString:()Ljava/lang/String;
            invokespecial java.io.FileInputStream.<init>:(Ljava/lang/String;)V
         5: areturn
        end local 3 // java.lang.String filename
        end local 2 // char sep
         6: .line 59
      StackMap locals:
      StackMap stack: java.io.FileNotFoundException
            pop
            goto 8
         7: .line 60
      StackMap locals:
      StackMap stack: java.lang.SecurityException
            pop
         8: .line 61
      StackMap locals:
      StackMap stack:
            aconst_null
            areturn
        end local 1 // java.lang.String classname
        end local 0 // javassist.DirClassPath this
      LocalVariableTable:
        Start  End  Slot       Name  Signature
            0    9     0       this  Ljavassist/DirClassPath;
            0    9     1  classname  Ljava/lang/String;
            1    6     2        sep  C
            4    6     3   filename  Ljava/lang/String;
      Exception table:
        from    to  target  type
           0     5       6  Class java.io.FileNotFoundException
           0     5       7  Class java.lang.SecurityException
    MethodParameters:
           Name  Flags
      classname  

  public java.net.URL find(java.lang.String);
    descriptor: (Ljava/lang/String;)Ljava/net/URL;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=5, args_size=2
        start local 0 // javassist.DirClassPath this
        start local 1 // java.lang.String classname
         0: .line 66
            getstatic java.io.File.separatorChar:C
            istore 2 /* sep */
        start local 2 // char sep
         1: .line 67
            new java.lang.StringBuilder
            dup
            aload 0 /* this */
            getfield javassist.DirClassPath.directory:Ljava/lang/String;
            invokestatic java.lang.String.valueOf:(Ljava/lang/Object;)Ljava/lang/String;
            invokespecial java.lang.StringBuilder.<init>:(Ljava/lang/String;)V
            iload 2 /* sep */
            invokevirtual java.lang.StringBuilder.append:(C)Ljava/lang/StringBuilder;
         2: .line 68
            aload 1 /* classname */
            bipush 46
            iload 2 /* sep */
            invokevirtual java.lang.String.replace:(CC)Ljava/lang/String;
            invokevirtual java.lang.StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
            ldc ".class"
            invokevirtual java.lang.StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
         3: .line 67
            invokevirtual java.lang.StringBuilder.toString:()Ljava/lang/String;
            astore 3 /* filename */
        start local 3 // java.lang.String filename
         4: .line 69
            new java.io.File
            dup
            aload 3 /* filename */
            invokespecial java.io.File.<init>:(Ljava/lang/String;)V
            astore 4 /* f */
        start local 4 // java.io.File f
         5: .line 70
            aload 4 /* f */
            invokevirtual java.io.File.exists:()Z
            ifeq 10
         6: .line 72
            aload 4 /* f */
            invokevirtual java.io.File.getCanonicalFile:()Ljava/io/File;
            invokevirtual java.io.File.toURI:()Ljava/net/URI;
            invokevirtual java.net.URI.toURL:()Ljava/net/URL;
         7: areturn
         8: .line 74
      StackMap locals: javassist.DirClassPath java.lang.String int java.lang.String java.io.File
      StackMap stack: java.net.MalformedURLException
            pop
            goto 10
         9: .line 75
      StackMap locals:
      StackMap stack: java.io.IOException
            pop
        10: .line 77
      StackMap locals:
      StackMap stack:
            aconst_null
            areturn
        end local 4 // java.io.File f
        end local 3 // java.lang.String filename
        end local 2 // char sep
        end local 1 // java.lang.String classname
        end local 0 // javassist.DirClassPath this
      LocalVariableTable:
        Start  End  Slot       Name  Signature
            0   11     0       this  Ljavassist/DirClassPath;
            0   11     1  classname  Ljava/lang/String;
            1   11     2        sep  C
            4   11     3   filename  Ljava/lang/String;
            5   11     4          f  Ljava/io/File;
      Exception table:
        from    to  target  type
           6     7       8  Class java.net.MalformedURLException
           6     7       9  Class java.io.IOException
    MethodParameters:
           Name  Flags
      classname  

  public java.lang.String toString();
    descriptor: ()Ljava/lang/String;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // javassist.DirClassPath this
         0: .line 82
            aload 0 /* this */
            getfield javassist.DirClassPath.directory:Ljava/lang/String;
            areturn
        end local 0 // javassist.DirClassPath this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Ljavassist/DirClassPath;
}
SourceFile: "ClassPoolTail.java"