oracle.ide.net

Class JarUtil

java.lang.Object

oracle.ide.net.JarUtil

public final class JarUtil
extends java.lang.Object

Method Summary

Modifier and Type	Method and Description
static java.lang.String	getClassPath(java.io.File jarFile) Returns the value of the Class-Path attribute in the manifest file of the specified JAR file.
static java.lang.String	getClassPath(java.net.URL jarURL) Returns the value of the Class-Path attribute in the manifest file of the specified JAR URL.
static java.util.List<java.net.URL>	getClassPathURLs(java.net.URL jarURL) Utility method to return the Class-Path attribute from the JAR manifest as a list of URLs.
static java.lang.String	getJarEntry(java.net.URL jarURL) Returns the jar entry name within the specified jar URL.
static java.net.URL	getJarFileURL(java.net.URL jarURL) Returns the jar file part of the specified jar URL.
static JarIndex	getJarIndex(java.net.URL jarURL) Returns the JarIndex object that represents an index of the contents of the specified jar file.
static JarIndex	getJarIndex(java.net.URL jarURL, boolean full) Deprecated. use #getJarIndex(URL)
static ReadWriteLock	getLock(java.net.URL url) Get the lock used to synchronize access to a JAR file across multiple threads in the calling process.
static java.lang.String	getMainClass(java.io.File jarFile) Returns the value of the Main-Class attribute in the manifest file of the specified JAR file.
static java.lang.String	getMainClass(java.net.URL jarURL) Returns the value of the Main-Class attribute in the manifest file of the specified JAR URL.
static java.util.jar.Manifest	getManifest(java.io.File jarFile) Returns the manifest of the specified JAR file.
static java.util.jar.Manifest	getManifest(java.net.URL jarURL) Returns the manifest of the specified JAR URL.
static boolean	isArchive(java.lang.String pathname) Determine if a given URL represents an jar or zip file.
static boolean	isJarURL(java.net.URL jarURL) Returns true if the specified URL has the "jar" protocol.
static void	releaseJarIndex(java.net.URL jarURL) Releases the in-memory jar index corresponding to the specified URL.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getJarEntry

public static java.lang.String getJarEntry(java.net.URL jarURL)

Returns the jar entry name within the specified jar URL. If the jar URL specifies no entry, then the empty string is returned. If the URL is not a jar URL, then null is returned.

getJarFileURL

public static java.net.URL getJarFileURL(java.net.URL jarURL)

Returns the jar file part of the specified jar URL. The specified URL is returned if it is not a jar URL.

getManifest

public static java.util.jar.Manifest getManifest(java.net.URL jarURL)
                                          throws java.io.IOException

Returns the manifest of the specified JAR URL.

Parameters:

jarURL - the URL of a jar

Returns:

The manifest or null if it didn't exist

Throws:

FileNotFoundException - in case the jar doesn't exist

java.io.IOException - if another I/O problem occurs

getManifest

public static java.util.jar.Manifest getManifest(java.io.File jarFile)
                                          throws java.io.IOException

Returns the manifest of the specified JAR file.

Parameters:

jarFile - a Jar file

Returns:

The manifest or null if it didn't exist

Throws:

FileNotFoundException - in case the jar doesn't exist

java.io.IOException - if another I/O problem occurs

getMainClass

public static java.lang.String getMainClass(java.io.File jarFile)
                                     throws java.io.IOException

Returns the value of the Main-Class attribute in the manifest file of the specified JAR file.

Parameters:

jarFile - a Jar file

Returns:

The manifest main-class attribute or null if it didn't exist

Throws:

FileNotFoundException - in case the jar doesn't exist

java.io.IOException - if another I/O problem occurs

getMainClass

public static java.lang.String getMainClass(java.net.URL jarURL)
                                     throws java.io.IOException

Returns the value of the Main-Class attribute in the manifest file of the specified JAR URL.

Parameters:

jarURL - the URL of a jar

Returns:

The manifest main-class attribute or null if it didn't exist

Throws:

FileNotFoundException - in case the jar doesn't exist

java.io.IOException - if another I/O problem occurs

getClassPath

public static java.lang.String getClassPath(java.io.File jarFile)
                                     throws java.io.IOException

Returns the value of the Class-Path attribute in the manifest file of the specified JAR file.

Parameters:

jarFile - a Jar file

Returns:

The manifest class path or null if it didn't exist

Throws:

FileNotFoundException - in case the jar doesn't exist

java.io.IOException - if another I/O problem occurs

getClassPath

public static java.lang.String getClassPath(java.net.URL jarURL)
                                     throws java.io.IOException

Returns the value of the Class-Path attribute in the manifest file of the specified JAR URL.

Parameters:

jarURL - the URL of a jar

Returns:

The manifest class path or null if it didn't exist

Throws:

FileNotFoundException - in case the jar doesn't exist

java.io.IOException - if another I/O problem occurs

getClassPathURLs

public static java.util.List<java.net.URL> getClassPathURLs(java.net.URL jarURL)
                                                     throws java.io.IOException

Utility method to return the Class-Path attribute from the JAR manifest as a list of URLs. Relative path entries are assumed to be relative to the location of the JAR file. URLs are not checked for existence or cyclic references (path entries pointing back to the JAR itself). URLs on the classpath may themselves be JAR URLs, and those JARs may themselves have classpaths. Those classpaths are not included in the classpath returned by this method.

Parameters:

jarURL - the JAR file

Returns:

the list of class path URLs for the JAR

Throws:

FileNotFoundException - in case the jar doesn't exist

java.io.IOException - if another I/O problem occurs

isJarURL

public static boolean isJarURL(java.net.URL jarURL)

Returns true if the specified URL has the "jar" protocol. Returns false if the specified URL is null or has a protocol other than "jar". Alas, Websphere uses "wsjar" as an alias for "jar" protocol.

getJarIndex

public static JarIndex getJarIndex(java.net.URL jarURL)
                            throws java.io.IOException

Returns the JarIndex object that represents an index of the contents of the specified jar file. If the jar file does not exist or if the URL points to content that is not a a jar file, then null is returned.

This method caches its results, so that if an index is requested for the same URL more than once, the previously calculated JarIndex is returned. However, as an implementation detail, this method may use an algorithm for removing cached indexes that have not been accessed recently in order to conserve memory. The details of that algorithm, if one is implemented, are not publically documented. If a previously cached index is removed and is subsequently requested later, it is simply rebuilt.

Parameters:

jarURL - This is the URL of the jar file. If this URL has the "jar" protocol, then the jar file part of the jar URL is extracted and indexed. Otherwise, the URL is assumed to point to a jar/zip file, and that file is indexed.

Throws:

java.io.IOException

getJarIndex

@Deprecated
public static JarIndex getJarIndex(java.net.URL jarURL,
                                               boolean full)
                                        throws java.io.IOException

Deprecated. use #getJarIndex(URL)

Gets the JAR index for the given URL. The full parameter indicates whether a full index is built initially. A full index takes much longer to create. If the caller just needs to check for the existance of entries in the JAR, or open input streams for entries, then a full index is not necessary. A full index is necessary for other operations, such as listing all entries in the JAR or within a directory in the JAR.

Parameters:

jarURL - the URL of the JAR file

full - whether to build a full index

Returns:

the JAR index

Throws:

java.io.IOException - if the JAR file could not be read

releaseJarIndex

public static void releaseJarIndex(java.net.URL jarURL)

Releases the in-memory jar index corresponding to the specified URL. The URL may point to the jar file itself or it may be a jar URL pointing to an entry within a jar. If the URL is null, this method has no effect.

isArchive

public static boolean isArchive(java.lang.String pathname)

Determine if a given URL represents an jar or zip file. The method does a simple check to determine if the pathname ends with .jar or .zip.

getLock

public static ReadWriteLock getLock(java.net.URL url)

Get the lock used to synchronize access to a JAR file across multiple threads in the calling process. The lock is used internally by JarIndex and URLFileSystem, but it may be necessary to acquire this lock manually in cases where the JAR file is read or written without going through those APIs. For example, using the JarFile class to read or write a JAR file would require manually acquiring this lock.

The caller must hold a strong reference to the lock while it is locked. This is necessary because locks are weakly cached.

Note that the locking mechanism provided by this method is different than native file system locking (such as that provided by FileLock), which synchronizes access to a file across different processes, but does not synchronize access to the file across threads in the same process.

Parameters:

url - the URL of the JAR file or an entry in the JAR file

Returns:

the lock for the JAR file