This class is a specialized URLConnection that represents a connection to a jar : URL. A jar : URL is a compound URL that includes the URL of a JAR archive and, optionally , a reference to a file or directory within the JAR archive. The jar : URL syntax uses the ! character to separate the pathname of the JAR archive from the filename within the JAR archive. Note that a jar : URL contains a subprotocol that specifies the protocol that retrieves the JAR file itself. For example: jar:http://my.jar.com/my.jar!/ // The whole archive jar:file:/usr/java/lib/my.jar!/com/jar/ // A directory of the archive jar:ftp://ftp.jar.com/pub/my.jar!/com/jar/Jar.class // A file in the archive To obtain a JarURLConnection , define a URL object for a jar : URL, open a connection to it with openConnection( ) , and cast the returned URLConnection object to a JarURLConnection . The various methods defined by JarURLConnection allow you to read the manifest file of the JAR archive and look up attributes from that manifest for the archive as a whole or for individual entries in the archive. These methods make use of various classes from the java.util.jar package. Figure 12-10. java.net.JarURLConnectionpublic abstract class JarURLConnection extends URLConnection { // Protected Constructors protected JarURLConnection (URL url ) throws MalformedURLException; // Public Instance Methods public java.util.jar.Attributes getAttributes ( ) throws java.io.IOException; public java.security.cert.Certificate[ ] getCertificates ( ) throws java.io.IOException; public String getEntryName ( ); public java.util.jar.JarEntry getJarEntry ( ) throws java.io.IOException; public abstract java.util.jar.JarFile getJarFile ( ) throws java.io.IOException; public URL getJarFileURL ( ); public java.util.jar.Attributes getMainAttributes ( ) throws java.io.IOException; public java.util.jar.Manifest getManifest ( ) throws java.io.IOException; // Protected Instance Fields protected URLConnection jarFileURLConnection ; } |