Package java.net

Class JarURLConnection

  • Direct Known Subclasses:
    JarURLConnectionImpl
    public abstract class JarURLConnection
extends URLConnection
    This class establishes a connection to a jar: URL using the JAR protocol. A JarURLConnection instance can refer to either a JAR archive file or to an entry of such a file. jar: URLs are specified as follows: jar:{archive-url}!/{entry} where "!/" is called a separator. This separator is important to determine if an archive or an entry of an archive is referred.

    Examples:

    • Archive: jar:http://www.example.com/applets/archive.jar!/
    • File Entry: jar:http://www.example.com/applets/archive.jar!/test.class
    • Directory Entry: jar:http://www.example.com/applets/archive.jar!/applets/

    This class has different behavior depending on the URLConnection.getUseCaches() setting. When caching is enabled the underlying JarFile returned from getJarFile() is cached and shared between connections. It must not be closed by the caller. Disabling caching using URLConnection.setUseCaches(boolean) will prevent sharing but in the absence of a JarURLConnection.disconnect() method the only way to close the underlying JarFile is to call getJarFile().close() or getInputStream().close(). For uncached connections, closing the JarFile can prevent various other URLConnection methods from working.

    • Field Detail

      • jarFileURLConnection

        protected URLConnection jarFileURLConnection
        The location part of the represented URL.

    • Constructor Detail

      • JarURLConnection

        protected JarURLConnection​(URL url)
                    throws MalformedURLException
        Constructs an instance of JarURLConnection that refers to the specified URL.
        Parameters:
        url - the URL that contains the location to connect to.
        Throws:
        MalformedURLException - if an invalid URL has been entered.

    • Method Detail

      • getAttributes

        public Attributes getAttributes()
                         throws IOException
        Returns all attributes of the JarEntry referenced by this JarURLConnection.
        Returns:
        the attributes of the referenced JarEntry.
        Throws:
        IOException - if an I/O exception occurs while retrieving the JAR-entries.

      • getCertificates

        public Certificate[] getCertificates()
                              throws IOException
        Returns all certificates of the JarEntry referenced by this JarURLConnection instance. This method will return null until the InputStream has been completely verified.
        Returns:
        the certificates of the JarEntry as an array.
        Throws:
        IOException - if there is an I/O exception occurs while getting the JarEntry.

      • getEntryName

        public String getEntryName()
        Gets the name of the entry referenced by this JarURLConnection. The return value will be null if this instance refers to a JAR file rather than an JAR file entry.
        Returns:
        the JarEntry name this instance refers to.

      • getJarEntry

        public JarEntry getJarEntry()
                     throws IOException
        Gets the JarEntry object of the entry referenced by this JarURLConnection.
        Returns:
        the referenced JarEntry object or null if no entry name is specified.
        Throws:
        IOException - if an error occurs while getting the file or file-entry.

      • getManifest

        public Manifest getManifest()
                     throws IOException
        Gets the manifest file associated with this JAR-URL.
        Returns:
        the manifest of the referenced JAR-file.
        Throws:
        IOException - if an error occurs while getting the manifest file.

      • getJarFile

        public abstract JarFile getJarFile()
                            throws IOException
        Gets the JarFile object referenced by this JarURLConnection.
        Returns:
        the referenced JarFile object.
        Throws:
        IOException - if an I/O exception occurs while retrieving the JAR-file.

      • getJarFileURL

        public URL getJarFileURL()
        Gets the URL to the JAR-file referenced by this JarURLConnection.
        Returns:
        the URL to the JAR-file or null if there was an error retrieving the URL.

      • getMainAttributes

        public Attributes getMainAttributes()
                             throws IOException
        Gets all attributes of the manifest file referenced by this JarURLConnection. If this instance refers to a JAR-file rather than a JAR-file entry, null will be returned.
        Returns:
        the attributes of the manifest file or null.
        Throws:
        IOException - if an I/O exception occurs while retrieving the JarFile.