Package com.portal.pfc.util.nestedjars

Class NestedJarURLConnection

java.lang.Object

java.net.URLConnection

com.portal.pfc.util.nestedjars.NestedJarURLConnection

public class NestedJarURLConnection
extends URLConnection

NestedJarURLConnection is a subclass of the URLConnection. It supports opening a connection to a file that is packaged in a JAR file, which in turn is inside another JAR file. There is support for a single level of nesting.

It is expected that the outer JAR is available on the local filesystem and accessible via standard java.io.File operations.

This class knows how to handle URLs using a custom nestedjar protocol. The URL should be of the form:

nestedjar://file:/C:/TEMP/apps.jar!/innerapps.jar!/myapp/nested.gif

The different parts of the URL are:

nestedjar://	Custom protocol for loading resources from nested jar files.
/C:/TEMP/	Path to the toplevel jar file. Should be accessible via standard java.io.File.
apps.jar	Outer jar file. This jar file is on the classpath. It contains nested jar file(s).
innerapps.jar	Jar file nested inside the outer jar file. This Jar file contains the actual resources.
myapp/nested.gif	Resource in the inner jar file that is to be loaded
!/	Separator. Separates a jar file and the components it contains.

Author:

Max Spivak

Field Summary

Fields inherited from class java.net.URLConnection

allowUserInteraction, connected, doInput, doOutput, ifModifiedSince, url, useCaches

Constructor Summary

Constructors

Constructor	Description
NestedJarURLConnection(URL url)	Constructor.

Method Summary

Modifier and Type	Method	Description
void	connect()	Opens a communications link to the resource referenced by this URL, if such a connection has not already been established.
String	getContentType()	Determine the content type of the resource
InputStream	getInputStream()	Returns an input stream that reads from this open connection.

Methods inherited from class java.net.URLConnection

addRequestProperty, getAllowUserInteraction, getConnectTimeout, getContent, getContent, getContentEncoding, getContentLength, getContentLengthLong, getDate, getDefaultAllowUserInteraction, getDefaultRequestProperty, getDefaultUseCaches, getDefaultUseCaches, getDoInput, getDoOutput, getExpiration, getFileNameMap, getHeaderField, getHeaderField, getHeaderFieldDate, getHeaderFieldInt, getHeaderFieldKey, getHeaderFieldLong, getHeaderFields, getIfModifiedSince, getLastModified, getOutputStream, getPermission, getReadTimeout, getRequestProperties, getRequestProperty, getURL, getUseCaches, guessContentTypeFromName, guessContentTypeFromStream, setAllowUserInteraction, setConnectTimeout, setContentHandlerFactory, setDefaultAllowUserInteraction, setDefaultRequestProperty, setDefaultUseCaches, setDefaultUseCaches, setDoInput, setDoOutput, setFileNameMap, setIfModifiedSince, setReadTimeout, setRequestProperty, setUseCaches, toString

Methods inherited from class java.lang.Object

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

Constructor Details

NestedJarURLConnection

public NestedJarURLConnection(URL url)

Constructor. See class comment regarding URL structure this class knows how to handle.

Method Details

connect

public void connect()
             throws IOException

Opens a communications link to the resource referenced by this URL, if such a connection has not already been established. More specifically, this method will attempt to open the outer jar file and locate the inner, nested jar file as specified by the URL.

If the connect method is called when the connection has already been opened the call is ignored.

Specified by:

connect in class URLConnection

Throws:

IOException - if an I/O error occurs while opening the connection.

getInputStream

public InputStream getInputStream()
                           throws IOException

Returns an input stream that reads from this open connection.

Overrides:

getInputStream in class URLConnection

Returns:

an input stream that reads from this open connection.

Throws:

IOException - if an I/O error occurs while creating the input stream.

UnknownServiceException - if the protocol does not support input.

getContentType

public String getContentType()

Determine the content type of the resource

Overrides:

getContentType in class URLConnection