Package net.jini.url.httpmd

Class Handler

java.lang.Object
java.net.URLStreamHandler
net.jini.url.httpmd.Handler
public class Handler extends URLStreamHandler
A stream handler for URLs with the HTTPMD protocol. HTTPMD URLs provide a way to insure the integrity of data retrieved from an HTTP URL. The HTTPMD URL includes a message digest for the data to be retrieved from the URL. The URL input stream insures that the data has the correct message digest when the end of file for the stream is reached. If the data has the wrong message digest, a WrongMessageDigestException is thrown.

HTTPMD URLs may be used to guarantee the integrity of a downloaded object's codebase if used when specifying the URLs for the JAR files containing the object's classes. Because HTTPMD URLs specify a message digest for a single item, they should not be used for directories of classes.

HTTPMD URLs have a syntax similar to that of HTTP URLs, but include a message digest as the last parameter stored in the last segment of the path. The parameter is introduced by the ';' character, and includes the name of the message digest algorithm, a '=', the message digest, and an optional comment introduced by the ',' character. In addition, a comment by itself may be specified in a relative HTTPMD URL. Comments are ignored when using equals to compare HTTPMD URLs. The comment specified in the context URL is ignored when parsing a relative HTTPMD URL. Adding a comment to an HTTPMD URL is useful in cases where the URL is required to have a particular suffix, for example the ".jar" file extension. A comment-only relative HTTPMD URL is useful when specifying the URL of the containing document from within the contents of the document, where the message digest cannot be specified because it is not yet known.

The message digest algorithm is case-insensitive, and may include ASCII letters and numbers, as well as the following characters: 

 - _ . ~ * ' ( ) : @ & + $ ,

The value specifies the name of the MessageDigest algorithm to use. For the URL syntax to be valid, the value must be the name of a MessageDigest algorithm as determined by calling MessageDigest.getInstance(String).

The message digest is represented as a positive hexadecimal integer, using digits, and the letters 'a' through 'f', in either lowercase or uppercase.

The characters following the ',' comment character may include ASCII letters and numbers, as well as the following characters: 

 - _ . ~ * ' ( ) : @ & = + $ ,

Here are some examples of HTTPMD URLs:

  • An absolute URL:
    httpmd://www.sun.com/index.html;md5=7be207c7111e459eeea1c9b3d04f1667
  • A relative URL:
    index.html;sha=99f6837808c0a79398bf69d83cfb1b82d20cf0cf,Comment
  • A comment-only relative URL:
    ,.jar
Since:
2.0 This implementation of HTTPMD URLs uses the Logger named net.jini.url.httpmd to log information at the following logging levels:

net.jini.url.httpmd
Level Description
FINE URL input stream detects an incorrect message digest

Author:
Sun Microsystems, Inc.
See Also:

  • Constructor Details

    • Handler

      public Handler()
      Creates a URL stream handler for HTTPMD URLs.

  • Method Details

    • getDefaultPort

      protected int getDefaultPort()
      Returns the default port for a URL parsed by this handler, which is 80.
      Overrides:
      getDefaultPort in class URLStreamHandler
      Returns:
      the default port for a URL parsed by this handler

    • openConnection

      protected URLConnection openConnection(URL u) throws IOException
      Creates a HTTP URL connection for an HTTPMD URL.
      Specified by:
      openConnection in class URLStreamHandler
      Throws:
      IOException

    • parseURL

      protected void parseURL(URL url, String spec, int start, int limit)
      Parses the string representation of an HTTPMD URL object.
      Overrides:
      parseURL in class URLStreamHandler
      Throws:
      IllegalArgumentException - if the URL is malformed

    • sameFile

      protected boolean sameFile(URL u1, URL u2)
      Compares two HTTPMD URLs to see if they refer to the same file. Performs case-insensitive comparison of the protocols and of the message digest parameters (ignoring the comment), calls hostsEqual to compare the hosts, compares the ports, with -1 matching the default HTTP port (80), and performs case-sensitive comparison on the remaining portions.
      Overrides:
      sameFile in class URLStreamHandler

    • hashCode

      protected int hashCode(URL u)
      Computes the hash code for the specified URL. This method ignores the comment portion of the message digest parameter, and ignores the case of characters in the message digest and algorithm.
      Overrides:
      hashCode in class URLStreamHandler