jcvm04naming.html

JAVA CARD 开发包规格说明,版本为2.2.2

RID and a PIX for that package. This AID corresponds to the string name
for the package, as shown in <a href="JCVM04naming.html#10025"
 class="XRef">FIGURE 4-1</a>.<br>
<br>
</p>
<a name="pgfId-1002238"> </a><a name="pgfId-1002244"></a><a
 name="10025" style="font-weight: bold;"> </a><span
 style="font-weight: bold;"> FIGURE 4-1 Mapping Package Identifiers To
AIDs</span>
<p class="FigureBox"><img src="figures/JCVM04naming-4.jpg"
 align="bottom">
</p>
<p class="Paragraph"><a name="pgfId-1008049"></a></p>
<p class="Paragraph"><a name="pgfId-998883"></a>Each applet installed
on a Java Card technology enabled device must also have a unique AID.
This AID is constructed similarly to a package AID. It is a
concatenation of the applet provider's RID and PIX for that applet. An
applet AID must not have the same value as the AID of any package or
the AID of any other applet. The RID of each applet in a package must
be the same as the RID of the package.
</p>
<p class="Paragraph"><a name="pgfId-8344"></a>Custom components defined
in a CAP file are also identified using AIDs. Like AIDs for applets and
packages, component AIDs are formed by concatenating a RID and a PIX. </p>
<h2 class="Head1"><a name="pgfId-8004"></a>
<div>
<hr align="left" size="6" width="15%" noshade="noshade"></div>
4.3 <a name="marker-14179"></a>Token-based Linking</h2>
<p class="Paragraph"><a name="pgfId-8011"></a>This section describes a
scheme that allows downloaded software to be linked against APIs on a
Java Card technology enabled device. The scheme represents referenced
items as opaque tokens, instead of Unicode strings as are used in Java
class files. The two basic requirements of this linking scheme are that
it allows linking on the device, and that it does not require internal
implementation details of APIs to be revealed to clients of those APIs.
Secondary requirements are that the scheme be efficient in terms of
resource use on the device, and have acceptable performance for
linking. And of course, it must preserve the semantics of the Java
language.
</p>
<h3 class="Head2"><a name="pgfId-8006"></a>4.3.1 <a name="marker-14180"></a>Externally
Visible Items</h3>
<p class="Paragraph"><a name="pgfId-8007"></a>Classes (including
Interfaces) in Java packages may be declared with public or package
visibility. A class's methods and fields may be declared with public,
protected, package or private visibility. For purposes of this
document, we define public classes, public or protected fields, and
public or protected methods to be externally visible from the package.
</p>
<p class="Paragraph"><a name="pgfId-6956"></a>Each externally visible
item must have a token associated with it to enable references from
other packages to the item to be resolved on a device. There are six
kinds of items in a package that require external identification.
</p>
<ul>
  <li class="Bullet1"><a name="pgfId-6957"></a>Classes (including
Interfaces) </li>
  <p class="Linebreak"> </p>
  <li class="Bullet1-"><a name="pgfId-6958"></a>Static Fields </li>
  <p class="Linebreak"> </p>
  <li class="Bullet1-"><a name="pgfId-6959"></a>Static Methods </li>
  <p class="Linebreak"> </p>
  <li class="Bullet1-"><a name="pgfId-6960"></a>Instance Fields </li>
  <p class="Linebreak"> </p>
  <li class="Bullet1-"><a name="pgfId-6961"></a>Virtual Methods </li>
  <p class="Linebreak"> </p>
  <li class="Bullet1-"><a name="pgfId-6962"></a>Interface Methods </li>
  <p class="Linebreak"> </p>
</ul>
<h3 class="Head2"><a name="pgfId-6963"></a>4.3.2 <a name="marker-14181"></a>Private
Tokens</h3>
<p class="Paragraph"><a name="pgfId-6964"></a>Items that are not
externally visible are internally visible. Internally visible items are
not described in a package's export file, but some such items use
private tokens to represent internal references. External references
are represented by <a name="marker-14182"></a>public tokens. There are
three kinds of items that can be assigned private tokens.
</p>
<ul>
  <li class="Bullet1"><a name="pgfId-6965"></a>Instance Fields </li>
  <p class="Linebreak"> </p>
  <li class="Bullet1-"><a name="pgfId-6966"></a>Virtual Methods </li>
  <p class="Linebreak"> </p>
  <li class="Bullet1-"><a name="pgfId-13632"></a>Packages </li>
  <p class="Linebreak"> </p>
</ul>
<h3 class="Head2"><a name="pgfId-6967"></a>4.3.3 <a name="12405"></a>The
Export File<a name="marker-14183"></a> and Conversion</h3>
<p class="Paragraph"><a name="pgfId-1001549"></a>An export file
contains entries for externally visible items in the package. Each
entry holds the item's name and its token. Some entries may include
additional information as well. For detailed information on the export
file format, see <a href="JCVM05export.html#26841" class="XRef">Chapter
5</a>, "The Export File Format".
</p>
<p class="Paragraph"><a name="pgfId-1001553"></a>The export file is
used to map names for imported items to tokens during package
conversion. The Java Card converter uses these tokens to represent
references to items in an imported package.
</p>
<p class="Paragraph"><a name="pgfId-6971"></a>For example, during the
conversion of the class files of applet A, the export file of
javacard.framework is used to find tokens for items in the API that are
used by the applet. Applet A creates a new instance of framework class
OwnerPIN. The framework export file contains an entry for
javacard.framework.OwnerPIN that holds the token for this class. The
converter places this token in the CAP file's constant pool to
represent an unresolved reference to the class. The token value is
later used to resolve the reference on a device.
</p>
<h3 class="Head2"><a name="pgfId-6972"></a>4.3.4 <a name="marker-14184"></a>References
- External and Internal</h3>
<p class="Paragraph"><a name="pgfId-6973"></a>In the context of a CAP
file, references to items are made indirectly through a package's
constant pool. References to items in other packages are called
external, and are represented in terms of tokens. References to items
in the same CAP file are called internal, and are represented either in
terms of tokens, or in a different internal format.
</p>
<p class="Paragraph"><a name="pgfId-6974"></a>An external reference to
a class is composed of a package token and a class token. Together
those tokens specify a certain class in a certain package. An internal
reference to a class is a 15-bit value that is a pointer to the class
structure's location within the CAP file.
</p>
<p class="Paragraph"><a name="pgfId-6975"></a>An external reference to
a static class member, either a field or method, consists of a package
token, a class token, and a token for the static field or static
method. An internal reference to a static class member is a 16-bit
value that is a pointer to the item's location in the CAP file.
</p>
<p class="Paragraph"><a name="pgfId-6976"></a>References to instance
fields, virtual methods and interface methods consist of a class
reference and a token of the appropriate type. The class reference
determines whether the reference is external or internal.
</p>
<h3 class="Head2"><a name="pgfId-6977"></a>4.3.5 Installation and <a
 name="marker-14185"></a>Linking</h3>
<p class="Paragraph"><a name="pgfId-6978"></a>External references in a
CAP file can be resolved on a device from token form into the internal
representation used by the virtual machine.
</p>
<p class="Paragraph"><a name="pgfId-6979"></a>A token can only be
resolved in the context of the package that defines it. Just as the
export file maps from a package's externally visible names to tokens,
there is a set of link information for each package on the device that
maps from tokens to resolved references.
</p>
<h3 class="Head2"><a name="pgfId-6980"></a>4.3.6 Token <a
 name="marker-14186"></a>Assignment</h3>
<p class="Paragraph"><a name="pgfId-6981"></a>Tokens for an API are
assigned by the API's owner and published in the package export file(s)
for that API. Since the name-to-token mappings are published, an API
owner may choose any order for tokens (subject to the constraints
listed below).
</p>
<p class="Paragraph"><a name="pgfId-6982"></a>A particular device
platform can resolve tokens into whatever internal representation is
most useful for that implementation of a Java Card virtual machine.
Some tokens may be resolved to indices. For example, an instance field
token may be resolved to an index into a class instance's fields. In
such cases, the token value is distinct from and unrelated to the value
of the resolved index.
</p>
<h3 class="Head2"><a name="pgfId-6983"></a>4.3.7 Token <a
 name="marker-14187"></a>Details</h3>
<p class="Paragraph"><a name="pgfId-8356"></a>Each kind of item in a
package has its own independent scope for tokens of that kind. The
token range and assignment rules for each kind are listed in <a
 href="JCVM04naming.html#81010" class="XRef">TABLE 4-2</a>.
</p>
<br>
<table class="Titled" border="1" bordercolorlight="#FFFFFF"
 bordercolordark="#000000" cellpadding="5" cellspacing="0" dir="ltr">
  <caption class="TableCaption"><a name="pgfId-998344"> </a> TABLE 4-2<br>
  <a name="81010"> </a> Token Range, Type and Scope </caption> <thead><tr>
    <th scope="col" rowspan="1" colspan="1" bgcolor="#cccccc">
    <p class="TableHead"><a name="pgfId-998277"></a>Token Type </p>
    </th>
    <th scope="col" rowspan="1" colspan="1" bgcolor="#cccccc">
    <p class="TableHead"><a name="pgfId-998279"></a>Range </p>
    </th>
    <th scope="col" rowspan="1" colspan="1" bgcolor="#cccccc">
    <p class="TableHead"><a name="pgfId-998281"></a>Type </p>
    </th>
    <th scope="col" rowspan="1" colspan="1" bgcolor="#cccccc">
    <p class="TableHead"><a name="pgfId-998283"></a>Scope </p>
    </th>
  </tr>
  </thead> <tbody>
    <tr>
      <td scope="row" rowspan="1" colspan="1">
      <p class="TableText"><a name="pgfId-998285"></a>Package </p>
      </td>
      <td rowspan="1" colspan="1">
      <p class="TableText"><a name="pgfId-998287"></a>0 - 127 </p>
      </td>
      <td rowspan="1" colspan="1">
      <p class="TableText"><a name="pgfId-998289"></a>Private </p>
      </td>
      <td rowspan="1" colspan="1">
      <p class="TableText"><a name="pgfId-998291"></a>Package </p>
      </td>
    </tr>
    <tr>
      <td scope="row" rowspan="1" colspan="1">
      <p class="TableText"><a name="pgfId-998293"></a>Class </p>
      </td>
      <td rowspan="1" colspan="1">
      <p class="TableText"><a name="pgfId-998295"></a>0 - 254 </p>
      </td>
      <td rowspan="1" colspan="1">
      <p class="TableText"><a name="pgfId-998297"></a>Public </p>
      </td>
      <td rowspan="1" colspan="1">
      <p class="TableText"><a name="pgfId-998299"></a>Package </p>
      </td>
    </tr>
    <tr>
      <td scope="row" rowspan="1" colspan="1">
      <p class="TableText"><a name="pgfId-998301"></a>Static Field </p>
      </td>
      <td rowspan="1" colspan="1">
      <p class="TableText"><a name="pgfId-998303"></a>0 - 255 </p>
      </td>
      <td rowspan="1" colspan="1">
      <p class="TableText"><a name="pgfId-998305"></a>Public </p>
      </td>
      <td rowspan="1" colspan="1">
      <p class="TableText"><a name="pgfId-998307"></a>Class </p>
      </td>
    </tr>
    <tr>
      <td scope="row" rowspan="1" colspan="1">
      <p class="TableText"><a name="pgfId-998309"></a>Static Method </p>
      </td>
      <td rowspan="1" colspan="1">
      <p class="TableText"><a name="pgfId-998311"></a>0 - 255 </p>
      </td>
      <td rowspan="1" colspan="1">
      <p class="TableText"><a name="pgfId-998313"></a>Public </p>
      </td>
      <td rowspan="1" colspan="1">
      <p class="TableText"><a name="pgfId-998315"></a>Class </p>
      </td>
    </tr>
    <tr>