OpenJDK 27 · java.net.JarURLConnection · APIdia, the JavaDoc alternative

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 java.io.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

Modifier and Type	Field and Description
private final String	entryName
private final URL	jarFileURL
protected URLConnection	jarFileURLConnection The connection to the JAR file URL, if the connection has been initiated.

Inherited from java.net.URLConnection:: allowUserInteraction connected doInput doOutput ifModifiedSince url useCaches

Access	Constructor and Description
protected	JarURLConnection(URL the URL url) Creates the new JarURLConnection to the specified URL.

Method Summary

Modifier and Type	Method and Description
public Attributes	Returns: the Attributes object for this connection if the URL for it points to a JAR file entry, null otherwise. getAttributes() Return the Attributes object for this connection if the URL for it points to a JAR file entry, null otherwise.
public Certificate[]	Returns: the Certificate objects for this connection if the URL for it points to a JAR file entry, null otherwise. getCertificates() Returns the Certificate objects for this connection if the URL for it points to a JAR file entry, null otherwise.
public String	Returns: the entry name for this connection, if any. getEntryName() Return the entry name for this connection.
public JarEntry	Returns: the JAR entry object for this connection, or null if the JAR URL for this connection points to a JAR file. getJarEntry() Return the JAR entry object for this connection, if any.
public abstract JarFile	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 getJarFile() Return the JAR file for this connection.
public URL	Returns: the URL for the Jar file for this connection. getJarFileURL() Returns the URL for the Jar file for this connection.
public Attributes	Returns: the main Attributes for the JAR file for this connection. getMainAttributes() Returns the main Attributes for the JAR file for this connection.
public Manifest	Returns: the manifest object corresponding to the JAR file object for this connection. getManifest() Returns the Manifest for this connection, or null if none.
private static String	Returns: the decoded entry name, or null if this URL has no entry name parseEntryName(String the URL spec of this connection spec, int the index of the '!/' separator separatorIndex) Parse the entry name (if any) of this JarURLConnection
private static URL	Returns: a URL to the JAR file this connection reads from parseJarFileURL(String the URL spec of this connection spec, int the index of the '!/' separator separatorIndex, URL the URL passed to the constructor connectionURL) Parse the URL of the JAR file backing this JarURLConnection, appending any #runtime fragment as neccessary

Inherited from java.net.URLConnection:: addRequestProperty connect getAllowUserInteraction getConnectTimeout getContent getContent getContentEncoding getContentLength getContentLengthLong getContentType getDate getDefaultAllowUserInteraction getDefaultRequestProperty getDefaultUseCaches getDefaultUseCaches getDoInput getDoOutput getExpiration getFileNameMap getHeaderField getHeaderField getHeaderFieldDate getHeaderFieldInt getHeaderFieldKey getHeaderFieldLong getHeaderFields getIfModifiedSince getInputStream 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

Field Detail

entryName	back to summary
private final String entryName

jarFileURL	back to summary
private final URL jarFileURL

jarFileURLConnection	back to summary
protected URLConnection jarFileURLConnection The connection to the JAR file URL, if the connection has been initiated. This should be set by connect.

Constructor Detail

JarURLConnection	back to summary
protected JarURLConnection(URL url) throws MalformedURLException Creates the new JarURLConnection to the specified URL. Parameters url:URL the URL Exceptions MalformedURLException: if no legal protocol could be found in a specification string or the string could not be parsed.

JarURLConnection

back to summary

protected JarURLConnection(URL url) throws MalformedURLException

Creates the new JarURLConnection to the specified URL.

Parameters

url:URL: the URL

Exceptions

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

Method Detail

getAttributes back to summary

getAttributes	back to summary
public Attributes getAttributes() throws IOException 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. Exceptions IOException: if getting the JAR entry causes an IOException to be thrown. See Also `getJarEntry`

public Attributes getAttributes() throws IOException

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.

Exceptions

IOException:: if getting the JAR entry causes an IOException to be thrown.

See Also

getJarEntry

getCertificates back to summary

getCertificates	back to summary
public Certificate[] getCertificates() throws IOException Returns the Certificate objects 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`. The returned certificate array comprises all the signer certificates that were used to verify this entry. Each signer certificate is followed by its supporting certificate chain (which may be empty). Each signer certificate and its supporting certificate chain are ordered bottom-to-top (i.e., with the signer certificate first and the (root) certificate authority last). API Note The verification process does not include validating or establishing trust in the code signers. A caller should perform additional checks, such as using a `java.security.cert.CertPathValidator` to validate each signer's certificate chain, and determining whether to trust the entry signed by the signers. Returns:Certificate[] the Certificate objects for this connection if the URL for it points to a JAR file entry, null otherwise. Exceptions IOException: if getting the JAR entry causes an IOException to be thrown. See Also `getJarEntry`

public Certificate[] getCertificates() throws IOException

Returns the Certificate objects 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.

The returned certificate array comprises all the signer certificates that were used to verify this entry. Each signer certificate is followed by its supporting certificate chain (which may be empty). Each signer certificate and its supporting certificate chain are ordered bottom-to-top (i.e., with the signer certificate first and the (root) certificate authority last).

API Note

The verification process does not include validating or establishing trust in the code signers. A caller should perform additional checks, such as using a java.security.cert.CertPathValidator to validate each signer's certificate chain, and determining whether to trust the entry signed by the signers.

Returns:Certificate[]

the Certificate objects for this connection if the URL for it points to a JAR file entry, null otherwise.

Exceptions

IOException:: if getting the JAR entry causes an IOException to be thrown.

See Also

getJarEntry

getEntryName	back to summary
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.

getEntryName

back to summary

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 back to summary

getJarEntry	back to summary
public JarEntry getJarEntry() throws IOException 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. Exceptions IOException: if getting the JAR file for this connection causes an IOException to be thrown. See Also `getJarFile`, `getJarEntry`

public JarEntry getJarEntry() throws IOException

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.

Exceptions

IOException:: if getting the JAR file for this connection causes an IOException to be thrown.

See Also

getJarFile, getJarEntry

getJarFile back to summary

getJarFile	back to summary
public abstract JarFile getJarFile() throws IOException 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 Exceptions IOException: if an IOException occurs while trying to connect to the JAR file for this connection. See Also `connect`

public abstract JarFile getJarFile() throws IOException

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

Exceptions

IOException:: if an IOException occurs while trying to connect to the JAR file for this connection.

See Also

connect

getJarFileURL	back to summary
public URL getJarFileURL() Returns the URL for the Jar file for this connection. Returns:URL the URL for the Jar file for this connection.

getJarFileURL

back to summary

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 back to summary

getMainAttributes	back to summary
public Attributes getMainAttributes() throws IOException Returns the main Attributes for the JAR file for this connection. Returns:Attributes the main Attributes for the JAR file for this connection. Exceptions IOException: if getting the manifest causes an IOException to be thrown. See Also `getJarFile`, `getManifest`

public Attributes getMainAttributes() throws IOException

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

Returns:Attributes

the main Attributes for the JAR file for this connection.

Exceptions

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

See Also

getJarFile, getManifest

getManifest back to summary

getManifest	back to summary
public Manifest getManifest() throws IOException Returns the Manifest for this connection, or null if none. Returns:Manifest the manifest object corresponding to the JAR file object for this connection. Exceptions IOException: if getting the JAR file for this connection causes an IOException to be thrown. See Also `getJarFile`

public Manifest getManifest() throws IOException

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

Returns:Manifest

the manifest object corresponding to the JAR file object for this connection.

Exceptions

IOException:: if getting the JAR file for this connection causes an IOException to be thrown.

See Also

getJarFile

parseEntryName	back to summary
private static String parseEntryName(String spec, int separatorIndex) Parse the entry name (if any) of this JarURLConnection Parameters spec:String the URL spec of this connection separatorIndex:int the index of the '!/' separator Returns:String the decoded entry name, or null if this URL has no entry name

parseEntryName

back to summary

private static String parseEntryName(String spec, int separatorIndex)

Parse the entry name (if any) of this JarURLConnection

Parameters

spec:String: the URL spec of this connection
separatorIndex:int: the index of the '!/' separator

Returns:String

the decoded entry name, or null if this URL has no entry name

parseJarFileURL	back to summary
private static URL parseJarFileURL(String spec, int separatorIndex, URL connectionURL) throws MalformedURLException Parse the URL of the JAR file backing this JarURLConnection, appending any #runtime fragment as neccessary Parameters spec:String the URL spec of this connection separatorIndex:int the index of the '!/' separator connectionURL:URL the URL passed to the constructor Returns:URL a URL to the JAR file this connection reads from Annotations @SuppressWarnings:deprecation Exceptions MalformedURLException: if a malformed URL is found

parseJarFileURL

back to summary

private static URL parseJarFileURL(String spec, int separatorIndex, URL connectionURL) throws MalformedURLException

Parse the URL of the JAR file backing this JarURLConnection, appending any #runtime fragment as neccessary

Parameters

spec:String: the URL spec of this connection
separatorIndex:int: the index of the '!/' separator
connectionURL:URL: the URL passed to the constructor

Returns:URL

a URL to the JAR file this connection reads from

Annotations

@SuppressWarnings:deprecation

Exceptions

MalformedURLException:: if a malformed URL is found

public abstract Class JarURLConnection

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail