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The Package.java Java example source code
/*
* Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.lang;
import java.lang.reflect.AnnotatedElement;
import java.io.InputStream;
import java.util.Enumeration;
import java.util.StringTokenizer;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.URL;
import java.net.MalformedURLException;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.jar.JarInputStream;
import java.util.jar.Manifest;
import java.util.jar.Attributes;
import java.util.jar.Attributes.Name;
import java.util.jar.JarException;
import java.util.Map;
import java.util.HashMap;
import java.util.Iterator;
import sun.net.www.ParseUtil;
import sun.reflect.CallerSensitive;
import sun.reflect.Reflection;
import java.lang.annotation.Annotation;
/**
* {@code Package} objects contain version information
* about the implementation and specification of a Java package.
* This versioning information is retrieved and made available
* by the {@link ClassLoader} instance that
* loaded the class(es). Typically, it is stored in the manifest that is
* distributed with the classes.
*
* <p>The set of classes that make up the package may implement a
* particular specification and if so the specification title, version number,
* and vendor strings identify that specification.
* An application can ask if the package is
* compatible with a particular version, see the {@link
* #isCompatibleWith isCompatibleWith}
* method for details.
*
* <p>Specification version numbers use a syntax that consists of nonnegative
* decimal integers separated by periods ".", for example "2.0" or
* "1.2.3.4.5.6.7". This allows an extensible number to be used to represent
* major, minor, micro, etc. versions. The version specification is described
* by the following formal grammar:
* <blockquote>
* <dl>
* <dt>SpecificationVersion:
* <dd>Digits RefinedVersionopt
* <dt>RefinedVersion:
* <dd>{@code .} Digits
* <dd>{@code .} Digits RefinedVersion
*
* <dt>Digits:
* <dd>Digit
* <dd>Digits
*
* <dt>Digit:
* <dd>any character for which {@link Character#isDigit} returns {@code true},
* e.g. 0, 1, 2, ...
* </dl>
* </blockquote>
*
* <p>The implementation title, version, and vendor strings identify an
* implementation and are made available conveniently to enable accurate
* reporting of the packages involved when a problem occurs. The contents
* all three implementation strings are vendor specific. The
* implementation version strings have no specified syntax and should
* only be compared for equality with desired version identifiers.
*
* <p>Within each {@code ClassLoader} instance all classes from the same
* java package have the same Package object. The static methods allow a package
* to be found by name or the set of all packages known to the current class
* loader to be found.
*
* @see ClassLoader#definePackage
*/
public class Package implements java.lang.reflect.AnnotatedElement {
/**
* Return the name of this package.
*
* @return The fully-qualified name of this package as defined in section 6.5.3 of
* <cite>The Java™ Language Specification,
* for example, {@code java.lang}
*/
public String getName() {
return pkgName;
}
/**
* Return the title of the specification that this package implements.
* @return the specification title, null is returned if it is not known.
*/
public String getSpecificationTitle() {
return specTitle;
}
/**
* Returns the version number of the specification
* that this package implements.
* This version string must be a sequence of nonnegative decimal
* integers separated by "."'s and may have leading zeros.
* When version strings are compared the most significant
* numbers are compared.
* @return the specification version, null is returned if it is not known.
*/
public String getSpecificationVersion() {
return specVersion;
}
/**
* Return the name of the organization, vendor,
* or company that owns and maintains the specification
* of the classes that implement this package.
* @return the specification vendor, null is returned if it is not known.
*/
public String getSpecificationVendor() {
return specVendor;
}
/**
* Return the title of this package.
* @return the title of the implementation, null is returned if it is not known.
*/
public String getImplementationTitle() {
return implTitle;
}
/**
* Return the version of this implementation. It consists of any string
* assigned by the vendor of this implementation and does
* not have any particular syntax specified or expected by the Java
* runtime. It may be compared for equality with other
* package version strings used for this implementation
* by this vendor for this package.
* @return the version of the implementation, null is returned if it is not known.
*/
public String getImplementationVersion() {
return implVersion;
}
/**
* Returns the name of the organization,
* vendor or company that provided this implementation.
* @return the vendor that implemented this package..
*/
public String getImplementationVendor() {
return implVendor;
}
/**
* Returns true if this package is sealed.
*
* @return true if the package is sealed, false otherwise
*/
public boolean isSealed() {
return sealBase != null;
}
/**
* Returns true if this package is sealed with respect to the specified
* code source url.
*
* @param url the code source url
* @return true if this package is sealed with respect to url
*/
public boolean isSealed(URL url) {
return url.equals(sealBase);
}
/**
* Compare this package's specification version with a
* desired version. It returns true if
* this packages specification version number is greater than or equal
* to the desired version number. <p>
*
* Version numbers are compared by sequentially comparing corresponding
* components of the desired and specification strings.
* Each component is converted as a decimal integer and the values
* compared.
* If the specification value is greater than the desired
* value true is returned. If the value is less false is returned.
* If the values are equal the period is skipped and the next pair of
* components is compared.
*
* @param desired the version string of the desired version.
* @return true if this package's version number is greater
* than or equal to the desired version number
*
* @exception NumberFormatException if the desired or current version
* is not of the correct dotted form.
*/
public boolean isCompatibleWith(String desired)
throws NumberFormatException
{
if (specVersion == null || specVersion.length() < 1) {
throw new NumberFormatException("Empty version string");
}
String [] sa = specVersion.split("\\.", -1);
int [] si = new int[sa.length];
for (int i = 0; i < sa.length; i++) {
si[i] = Integer.parseInt(sa[i]);
if (si[i] < 0)
throw NumberFormatException.forInputString("" + si[i]);
}
String [] da = desired.split("\\.", -1);
int [] di = new int[da.length];
for (int i = 0; i < da.length; i++) {
di[i] = Integer.parseInt(da[i]);
if (di[i] < 0)
throw NumberFormatException.forInputString("" + di[i]);
}
int len = Math.max(di.length, si.length);
for (int i = 0; i < len; i++) {
int d = (i < di.length ? di[i] : 0);
int s = (i < si.length ? si[i] : 0);
if (s < d)
return false;
if (s > d)
return true;
}
return true;
}
/**
* Find a package by name in the callers {@code ClassLoader} instance.
* The callers {@code ClassLoader} instance is used to find the package
* instance corresponding to the named class. If the callers
* {@code ClassLoader} instance is null then the set of packages loaded
* by the system {@code ClassLoader} instance is searched to find the
* named package. <p>
*
* Packages have attributes for versions and specifications only if the class
* loader created the package instance with the appropriate attributes. Typically,
* those attributes are defined in the manifests that accompany the classes.
*
* @param name a package name, for example, java.lang.
* @return the package of the requested name. It may be null if no package
* information is available from the archive or codebase.
*/
@CallerSensitive
public static Package getPackage(String name) {
ClassLoader l = ClassLoader.getClassLoader(Reflection.getCallerClass());
if (l != null) {
return l.getPackage(name);
} else {
return getSystemPackage(name);
}
}
/**
* Get all the packages currently known for the caller's {@code ClassLoader}
* instance. Those packages correspond to classes loaded via or accessible by
* name to that {@code ClassLoader} instance. If the caller's
* {@code ClassLoader} instance is the bootstrap {@code ClassLoader}
* instance, which may be represented by {@code null} in some implementations,
* only packages corresponding to classes loaded by the bootstrap
* {@code ClassLoader} instance will be returned.
*
* @return a new array of packages known to the callers {@code ClassLoader}
* instance. An zero length array is returned if none are known.
*/
@CallerSensitive
public static Package[] getPackages() {
ClassLoader l = ClassLoader.getClassLoader(Reflection.getCallerClass());
if (l != null) {
return l.getPackages();
} else {
return getSystemPackages();
}
}
/**
* Get the package for the specified class.
* The class's class loader is used to find the package instance
* corresponding to the specified class. If the class loader
* is the bootstrap class loader, which may be represented by
* {@code null} in some implementations, then the set of packages
* loaded by the bootstrap class loader is searched to find the package.
* <p>
* Packages have attributes for versions and specifications only
* if the class loader created the package
* instance with the appropriate attributes. Typically those
* attributes are defined in the manifests that accompany
* the classes.
*
* @param c the class to get the package of.
* @return the package of the class. It may be null if no package
* information is available from the archive or codebase. */
static Package getPackage(Class<?> c) {
String name = c.getName();
int i = name.lastIndexOf('.');
if (i != -1) {
name = name.substring(0, i);
ClassLoader cl = c.getClassLoader();
if (cl != null) {
return cl.getPackage(name);
} else {
return getSystemPackage(name);
}
} else {
return null;
}
}
/**
* Return the hash code computed from the package name.
* @return the hash code computed from the package name.
*/
public int hashCode(){
return pkgName.hashCode();
}
/**
* Returns the string representation of this Package.
* Its value is the string "package " and the package name.
* If the package title is defined it is appended.
* If the package version is defined it is appended.
* @return the string representation of the package.
*/
public String toString() {
String spec = specTitle;
String ver = specVersion;
if (spec != null && spec.length() > 0)
spec = ", " + spec;
else
spec = "";
if (ver != null && ver.length() > 0)
ver = ", version " + ver;
else
ver = "";
return "package " + pkgName + spec + ver;
}
private Class<?> getPackageInfo() {
if (packageInfo == null) {
try {
packageInfo = Class.forName(pkgName + ".package-info", false, loader);
} catch (ClassNotFoundException ex) {
// store a proxy for the package info that has no annotations
class PackageInfoProxy {}
packageInfo = PackageInfoProxy.class;
}
}
return packageInfo;
}
/**
* @throws NullPointerException {@inheritDoc}
* @since 1.5
*/
public <A extends Annotation> A getAnnotation(Class annotationClass) {
return getPackageInfo().getAnnotation(annotationClass);
}
/**
* {@inheritDoc}
* @throws NullPointerException {@inheritDoc}
* @since 1.5
*/
@Override
public boolean isAnnotationPresent(Class<? extends Annotation> annotationClass) {
return AnnotatedElement.super.isAnnotationPresent(annotationClass);
}
/**
* @throws NullPointerException {@inheritDoc}
* @since 1.8
*/
@Override
public <A extends Annotation> A[] getAnnotationsByType(Class annotationClass) {
return getPackageInfo().getAnnotationsByType(annotationClass);
}
/**
* @since 1.5
*/
public Annotation[] getAnnotations() {
return getPackageInfo().getAnnotations();
}
/**
* @throws NullPointerException {@inheritDoc}
* @since 1.8
*/
@Override
public <A extends Annotation> A getDeclaredAnnotation(Class annotationClass) {
return getPackageInfo().getDeclaredAnnotation(annotationClass);
}
/**
* @throws NullPointerException {@inheritDoc}
* @since 1.8
*/
@Override
public <A extends Annotation> A[] getDeclaredAnnotationsByType(Class annotationClass) {
return getPackageInfo().getDeclaredAnnotationsByType(annotationClass);
}
/**
* @since 1.5
*/
public Annotation[] getDeclaredAnnotations() {
return getPackageInfo().getDeclaredAnnotations();
}
/**
* Construct a package instance with the specified version
* information.
* @param name the name of the package
* @param spectitle the title of the specification
* @param specversion the version of the specification
* @param specvendor the organization that maintains the specification
* @param impltitle the title of the implementation
* @param implversion the version of the implementation
* @param implvendor the organization that maintains the implementation
*/
Package(String name,
String spectitle, String specversion, String specvendor,
String impltitle, String implversion, String implvendor,
URL sealbase, ClassLoader loader)
{
pkgName = name;
implTitle = impltitle;
implVersion = implversion;
implVendor = implvendor;
specTitle = spectitle;
specVersion = specversion;
specVendor = specvendor;
sealBase = sealbase;
this.loader = loader;
}
/*
* Construct a package using the attributes from the specified manifest.
*
* @param name the package name
* @param man the optional manifest for the package
* @param url the optional code source url for the package
*/
private Package(String name, Manifest man, URL url, ClassLoader loader) {
String path = name.replace('.', '/').concat("/");
String sealed = null;
String specTitle= null;
String specVersion= null;
String specVendor= null;
String implTitle= null;
String implVersion= null;
String implVendor= null;
URL sealBase= null;
Attributes attr = man.getAttributes(path);
if (attr != null) {
specTitle = attr.getValue(Name.SPECIFICATION_TITLE);
specVersion = attr.getValue(Name.SPECIFICATION_VERSION);
specVendor = attr.getValue(Name.SPECIFICATION_VENDOR);
implTitle = attr.getValue(Name.IMPLEMENTATION_TITLE);
implVersion = attr.getValue(Name.IMPLEMENTATION_VERSION);
implVendor = attr.getValue(Name.IMPLEMENTATION_VENDOR);
sealed = attr.getValue(Name.SEALED);
}
attr = man.getMainAttributes();
if (attr != null) {
if (specTitle == null) {
specTitle = attr.getValue(Name.SPECIFICATION_TITLE);
}
if (specVersion == null) {
specVersion = attr.getValue(Name.SPECIFICATION_VERSION);
}
if (specVendor == null) {
specVendor = attr.getValue(Name.SPECIFICATION_VENDOR);
}
if (implTitle == null) {
implTitle = attr.getValue(Name.IMPLEMENTATION_TITLE);
}
if (implVersion == null) {
implVersion = attr.getValue(Name.IMPLEMENTATION_VERSION);
}
if (implVendor == null) {
implVendor = attr.getValue(Name.IMPLEMENTATION_VENDOR);
}
if (sealed == null) {
sealed = attr.getValue(Name.SEALED);
}
}
if ("true".equalsIgnoreCase(sealed)) {
sealBase = url;
}
pkgName = name;
this.specTitle = specTitle;
this.specVersion = specVersion;
this.specVendor = specVendor;
this.implTitle = implTitle;
this.implVersion = implVersion;
this.implVendor = implVendor;
this.sealBase = sealBase;
this.loader = loader;
}
/*
* Returns the loaded system package for the specified name.
*/
static Package getSystemPackage(String name) {
synchronized (pkgs) {
Package pkg = pkgs.get(name);
if (pkg == null) {
name = name.replace('.', '/').concat("/");
String fn = getSystemPackage0(name);
if (fn != null) {
pkg = defineSystemPackage(name, fn);
}
}
return pkg;
}
}
/*
* Return an array of loaded system packages.
*/
static Package[] getSystemPackages() {
// First, update the system package map with new package names
String[] names = getSystemPackages0();
synchronized (pkgs) {
for (int i = 0; i < names.length; i++) {
defineSystemPackage(names[i], getSystemPackage0(names[i]));
}
return pkgs.values().toArray(new Package[pkgs.size()]);
}
}
private static Package defineSystemPackage(final String iname,
final String fn)
{
return AccessController.doPrivileged(new PrivilegedAction<Package>() {
public Package run() {
String name = iname;
// Get the cached code source url for the file name
URL url = urls.get(fn);
if (url == null) {
// URL not found, so create one
File file = new File(fn);
try {
url = ParseUtil.fileToEncodedURL(file);
} catch (MalformedURLException e) {
}
if (url != null) {
urls.put(fn, url);
// If loading a JAR file, then also cache the manifest
if (file.isFile()) {
mans.put(fn, loadManifest(fn));
}
}
}
// Convert to "."-separated package name
name = name.substring(0, name.length() - 1).replace('/', '.');
Package pkg;
Manifest man = mans.get(fn);
if (man != null) {
pkg = new Package(name, man, url, null);
} else {
pkg = new Package(name, null, null, null,
null, null, null, null, null);
}
pkgs.put(name, pkg);
return pkg;
}
});
}
/*
* Returns the Manifest for the specified JAR file name.
*/
private static Manifest loadManifest(String fn) {
try (FileInputStream fis = new FileInputStream(fn);
JarInputStream jis = new JarInputStream(fis, false))
{
return jis.getManifest();
} catch (IOException e) {
return null;
}
}
// The map of loaded system packages
private static Map<String, Package> pkgs = new HashMap<>(31);
// Maps each directory or zip file name to its corresponding url
private static Map<String, URL> urls = new HashMap<>(10);
// Maps each code source url for a jar file to its manifest
private static Map<String, Manifest> mans = new HashMap<>(10);
private static native String getSystemPackage0(String name);
private static native String[] getSystemPackages0();
/*
* Private storage for the package name and attributes.
*/
private final String pkgName;
private final String specTitle;
private final String specVersion;
private final String specVendor;
private final String implTitle;
private final String implVersion;
private final String implVendor;
private final URL sealBase;
private transient final ClassLoader loader;
private transient Class<?> packageInfo;
}
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