A URL Connection to a Java ARchive (JAR) file or an entry in a JAR file.
The syntax of a JAR URL is:
jar:<url>!/{entry}
for example:
jar:http://www.foo.com/bar/baz.jar!/COM/foo/Quux.class
Jar URLs should be used to refer to a JAR file or entries in
a JAR file. The example above is a JAR URL which refers to a JAR
entry. If the entry name is omitted, the URL refers to the whole
JAR file:
jar:http://www.foo.com/bar/baz.jar!/
Users should cast the generic URLConnection to a JarURLConnection when they know that the URL they created is a JAR URL, and they need JAR-specific functionality. For example:
URL url = new URL("jar:file:/home/duke/duke.jar!/"); JarURLConnection jarConnection = (JarURLConnection)url.openConnection(); Manifest manifest = jarConnection.getManifest();
JarURLConnection instances can only be used to read from JAR files.
It is not possible to get a OutputStream
to modify or write
to the underlying JAR file using this class.
Examples:
- A Jar entry
jar:http://www.foo.com/bar/baz.jar!/COM/foo/Quux.class
- A Jar file
jar:http://www.foo.com/bar/baz.jar!/
- A Jar directory
jar:http://www.foo.com/bar/baz.jar!/COM/foo/
!/
is referred to as the separator.
When constructing a JAR url via new URL(context, spec)
,
the following rules apply:
- if there is no context URL and the specification passed to the URL constructor doesn't contain a separator, the URL is considered to refer to a JarFile.
- if there is a context URL, the context URL is assumed to refer to a JAR file or a Jar directory.
- if the specification begins with a '/', the Jar directory is
ignored, and the spec is considered to be at the root of the Jar
file.
Examples:
- context: jar:http://www.foo.com/bar/jar.jar!/, spec:baz/entry.txt
- url:jar:http://www.foo.com/bar/jar.jar!/baz/entry.txt
- context: jar:http://www.foo.com/bar/jar.jar!/baz, spec:entry.txt
- url:jar:http://www.foo.com/bar/jar.jar!/baz/entry.txt
- context: jar:http://www.foo.com/bar/jar.jar!/baz, spec:/entry.txt
- url:jar:http://www.foo.com/bar/jar.jar!/entry.txt
Field Summary
protected URLConnection | jarFileURLConnection | The connection to the JAR file URL, if the connection has been initiated. |
Inherited Field Summary
Protected Constructor Summary
Public Method Summary
Attributes |
getAttributes()
Return the Attributes object for this connection if the URL
for it points to a JAR file entry, null otherwise.
|
Certificate[] |
getCertificates()
Return the Certificate object for this connection if the URL
for it points to a JAR file entry, null otherwise.
|
String |
getEntryName()
Return the entry name for this connection.
|
JarEntry |
getJarEntry()
Return the JAR entry object for this connection, if any.
|
abstract JarFile |
getJarFile()
Return the JAR file for this connection.
|
URL |
getJarFileURL()
Returns the URL for the Jar file for this connection.
|
Attributes |
getMainAttributes()
Returns the main Attributes for the JAR file for this
connection.
|
Manifest |
getManifest()
Returns the Manifest for this connection, or null if none.
|
Inherited Method Summary
Fields
protected URLConnection jarFileURLConnection
The connection to the JAR file URL, if the connection has been initiated. This should be set by connect.
Protected Constructors
protected JarURLConnection (URL url)
Creates the new JarURLConnection to the specified URL.
Parameters
url | the URL |
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Throws
MalformedURLException | if no legal protocol could be found in a specification string or the string could not be parsed. |
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Public Methods
public Attributes getAttributes ()
Return the Attributes object for this connection if the URL for it points to a JAR file entry, null otherwise.
Returns
- the Attributes object for this connection if the URL for it points to a JAR file entry, null otherwise.
Throws
IOException | if getting the JAR entry causes an IOException to be thrown. |
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See Also
public Certificate[] getCertificates ()
Return the Certificate object for this connection if the URL
for it points to a JAR file entry, null otherwise. This method
can only be called once
the connection has been completely verified by reading
from the input stream until the end of the stream has been
reached. Otherwise, this method will return null
Returns
- the Certificate object for this connection if the URL for it points to a JAR file entry, null otherwise.
Throws
IOException | if getting the JAR entry causes an IOException to be thrown. |
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See Also
public String getEntryName ()
Return the entry name for this connection. This method returns null if the JAR file URL corresponding to this connection points to a JAR file and not a JAR file entry.
Returns
- the entry name for this connection, if any.
public JarEntry getJarEntry ()
Return the JAR entry object for this connection, if any. This method returns null if the JAR file URL corresponding to this connection points to a JAR file and not a JAR file entry.
Returns
- the JAR entry object for this connection, or null if the JAR URL for this connection points to a JAR file.
Throws
IOException | if getting the JAR file for this connection causes an IOException to be thrown. |
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See Also
public abstract JarFile getJarFile ()
Return the JAR file for this connection.
Returns
- the JAR file for this connection. If the connection is a connection to an entry of a JAR file, the JAR file object is returned
Throws
IOException | if an IOException occurs while trying to connect to the JAR file for this connection. |
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See Also
public URL getJarFileURL ()
Returns the URL for the Jar file for this connection.
Returns
- the URL for the Jar file for this connection.
public Attributes getMainAttributes ()
Returns the main Attributes for the JAR file for this connection.
Returns
- the main Attributes for the JAR file for this connection.
Throws
IOException | if getting the manifest causes an IOException to be thrown. |
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See Also
public Manifest getManifest ()
Returns the Manifest for this connection, or null if none.
Returns
- the manifest object corresponding to the JAR file object for this connection.
Throws
IOException | if getting the JAR file for this connection causes an IOException to be thrown. |
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