JarURLConnection

public abstract class JarURLConnection
extends URLConnection

java.lang.Object
   ↳ java.net.URLConnection
     ↳ java.net.JarURLConnection


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

Summary

Fields

protected URLConnection jarFileURLConnection

The connection to the JAR file URL, if the connection has been initiated.

Inherited fields

protected boolean allowUserInteraction

If true, this URL is being examined in a context in which it makes sense to allow user interactions such as popping up an authentication dialog.

protected boolean connected

If false, this connection object has not created a communications link to the specified URL.

protected boolean doInput

This variable is set by the setDoInput method.

protected boolean doOutput

This variable is set by the setDoOutput method.

protected long ifModifiedSince

Some protocols support skipping the fetching of the object unless the object has been modified more recently than a certain time.

protected URL url

The URL represents the remote object on the World Wide Web to which this connection is opened.

protected boolean useCaches

If true, the protocol is allowed to use caching whenever it can.

Protected constructors

JarURLConnection(URL url)

Creates the new JarURLConnection to the specified URL.

Public methods

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 methods

void addRequestProperty(String key, String value)

Adds a general request property specified by a key-value pair.

abstract void connect()

Opens a communications link to the resource referenced by this URL, if such a connection has not already been established.

boolean getAllowUserInteraction()

Returns the value of the allowUserInteraction field for this object.

int getConnectTimeout()

Returns setting for connect timeout.

Object getContent()

Retrieves the contents of this URL connection.

Object getContent(Class[] classes)

Retrieves the contents of this URL connection.

String getContentEncoding()

Returns the value of the content-encoding header field.

int getContentLength()

Returns the value of the content-length header field.

long getContentLengthLong()

Returns the value of the content-length header field as a long.

String getContentType()

Returns the value of the content-type header field.

long getDate()

Returns the value of the date header field.

static boolean getDefaultAllowUserInteraction()

Returns the default value of the allowUserInteraction field.

static String getDefaultRequestProperty(String key)

This method was deprecated in API level 15. The instance specific getRequestProperty method should be used after an appropriate instance of URLConnection is obtained.

boolean getDefaultUseCaches()

Returns the default value of a URLConnection's useCaches flag.

boolean getDoInput()

Returns the value of this URLConnection's doInput flag.

boolean getDoOutput()

Returns the value of this URLConnection's doOutput flag.

long getExpiration()

Returns the value of the expires header field.

static FileNameMap getFileNameMap()

Returns a FileNameMap implementation suitable for guessing a content type based on a URL's "file" component.

String getHeaderField(String name)

Returns the value of the named header field.

String getHeaderField(int n)

Returns the value for the nth header field.

long getHeaderFieldDate(String name, long Default)

Returns the value of the named field parsed as date.

int getHeaderFieldInt(String name, int Default)

Returns the value of the named field parsed as a number.

String getHeaderFieldKey(int n)

Returns the key for the nth header field.

long getHeaderFieldLong(String name, long Default)

Returns the value of the named field parsed as a number.

Map<StringList<String>> getHeaderFields()

Returns an unmodifiable Map of the header fields.

long getIfModifiedSince()

Returns the value of this object's ifModifiedSince field.

InputStream getInputStream()

Returns an input stream that reads from this open connection.

long getLastModified()

Returns the value of the last-modified header field.

OutputStream getOutputStream()

Returns an output stream that writes to this connection.

Permission getPermission()

Returns a permission object representing the permission necessary to make the connection represented by this object.

int getReadTimeout()

Returns setting for read timeout.

Map<StringList<String>> getRequestProperties()

Returns an unmodifiable Map of general request properties for this connection.

String getRequestProperty(String key)

Returns the value of the named general request property for this connection.

URL getURL()

Returns the value of this URLConnection's URL field.

boolean getUseCaches()

Returns the value of this URLConnection's useCaches field.

static String guessContentTypeFromName(String fname)

Tries to determine the content type of an object, based on the specified "file" component of a URL.

static String guessContentTypeFromStream(InputStream is)

Tries to determine the type of an input stream based on the characters at the beginning of the input stream.

void setAllowUserInteraction(boolean allowuserinteraction)

Set the value of the allowUserInteraction field of this URLConnection.

void setConnectTimeout(int timeout)

Sets a specified timeout value, in milliseconds, to be used when opening a communications link to the resource referenced by this URLConnection.

static void setContentHandlerFactory(ContentHandlerFactory fac)

Sets the ContentHandlerFactory of an application.

static void setDefaultAllowUserInteraction(boolean defaultallowuserinteraction)

Sets the default value of the allowUserInteraction field for all future URLConnection objects to the specified value.

static void setDefaultRequestProperty(String key, String value)

This method was deprecated in API level 15. The instance specific setRequestProperty method should be used after an appropriate instance of URLConnection is obtained. Invoking this method will have no effect.

void setDefaultUseCaches(boolean defaultusecaches)

Sets the default value of the useCaches field to the specified value.

void setDoInput(boolean doinput)

Sets the value of the doInput field for this URLConnection to the specified value.

void setDoOutput(boolean dooutput)

Sets the value of the doOutput field for this URLConnection to the specified value.

static void setFileNameMap(FileNameMap map)

Sets the FileNameMap.

void setIfModifiedSince(long ifmodifiedsince)

Sets the value of the ifModifiedSince field of this URLConnection to the specified value.

void setReadTimeout(int timeout)

Sets the read timeout to a specified timeout, in milliseconds.

void setRequestProperty(String key, String value)

Sets the general request property.

void setUseCaches(boolean usecaches)

Sets the value of the useCaches field of this URLConnection to the specified value.

String toString()

Returns a String representation of this URL connection.

Object clone()

Creates and returns a copy of this object.

boolean equals(Object obj)

Indicates whether some other object is "equal to" this one.

void finalize()

Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.

final Class<?> getClass()

Returns the runtime class of this Object.

int hashCode()

Returns a hash code value for the object.

final void notify()

Wakes up a single thread that is waiting on this object's monitor.

final void notifyAll()

Wakes up all threads that are waiting on this object's monitor.

String toString()

Returns a string representation of the object.

final void wait(long timeoutMillis, int nanos)

Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

final void wait(long timeoutMillis)

Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

final void wait()

Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

Fields

jarFileURLConnection

Added in API level 1
protected URLConnection jarFileURLConnection

The connection to the JAR file URL, if the connection has been initiated. This should be set by connect.

Protected constructors

JarURLConnection

Added in API level 1
protected JarURLConnection (URL url)

Creates the new JarURLConnection to the specified URL.

Parameters
url URL: the URL

Throws
MalformedURLException if no legal protocol could be found in a specification string or the string could not be parsed.

Public methods

getAttributes

Added in API level 1
public Attributes getAttributes ()

Return the Attributes object for this connection if the URL for it points to a JAR file entry, null otherwise.

Returns
Attributes 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.

See also:

getCertificates

Added in API level 1
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
Certificate[] 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.

See also:

getEntryName

Added in API level 1
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
String the entry name for this connection, if any.

getJarEntry

Added in API level 1
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
JarEntry 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.

getJarFile

Added in API level 1
public abstract JarFile getJarFile ()

Return the JAR file for this connection.

Returns
JarFile 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.

getJarFileURL

Added in API level 1
public URL getJarFileURL ()

Returns the URL for the Jar file for this connection.

Returns
URL the URL for the Jar file for this connection.

getMainAttributes

Added in API level 1
public Attributes getMainAttributes ()

Returns the main Attributes for the JAR file for this connection.

Returns
Attributes the main Attributes for the JAR file for this connection.

Throws
IOException if getting the manifest causes an IOException to be thrown.

getManifest

Added in API level 1
public Manifest getManifest ()

Returns the Manifest for this connection, or null if none.

Returns
Manifest 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.

See also: