Java(TM) 2 Platform, Standard Edition, v1.2.2 API Specification: Class URLStreamHandler - JDK 5 Documentation v1.2.2, Java 2 SDK 英文文档

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java.net
Class URLStreamHandler

java.lang.Object
  |
  +--java.net.URLStreamHandler

public abstract class URLStreamHandler
extends Object

The abstract class URLStreamHandler is the common superclass for all stream protocol handlers. A stream protocol handler knows how to make a connection for a particular protocol type, such as http, ftp, or gopher.

In most cases, an instance of a URLStreamHandler subclass is not created directly by an application. Rather, the first time a protocol name is encountered when constructing a URL, the appropriate stream protocol handler is automatically loaded.

Since:: JDK1.0
See Also:: URL.URL(java.lang.String, java.lang.String, int, java.lang.String)

Constructor Summary

URLStreamHandler()


Method Summary

protected abstract URLConnection openConnection(URL u)
          Opens a connection to the object referenced by the URL argument.

protected void parseURL(URL u, String spec, int start, int limit)
          Parses the string representation of a URL into a URL object.

protected void setURL(URL u, String protocol, String host, int port, String file, String ref)
          Sets the fields of the URL argument to the indicated values.

protected String toExternalForm(URL u)
          Converts a URL of a specific protocol to a String.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

URLStreamHandler

public URLStreamHandler()

Method Detail

openConnection

protected abstract URLConnection openConnection(URL u)
                                         throws IOException

Opens a connection to the object referenced by the URL argument. This method should be overridden by a subclass.

If for the handler's protocol (such as HTTP or JAR), there exists a public, specialized URLConnection subclass belonging to one of the following packages or one of their subpackages: java.lang, java.io, java.util, java.net, the connection returned will be of that subclass. For example, for HTTP an HttpURLConnection will be returned, and for JAR a JarURLConnection will be returned.

Parameters:: u - the URL that this connects to.
Returns:: a URLConnection object for the URL.
Throws:: IOException - if an I/O error occurs while opening the connection.

parseURL

protected void parseURL(URL u,
                        String spec,
                        int start,
                        int limit)

Parses the string representation of a URL into a URL object.

If there is any inherited context, then it has already been copied into the URL argument.

The parseURL method of URLStreamHandler parses the string representation as if it were an http specification. Most URL protocol families have a similar parsing. A stream protocol handler for a protocol that has a different syntax must override this routine.

Parameters:: u - the URL to receive the result of parsing the spec.; spec - the String representing the URL that must be parsed.; start - the character index at which to begin parsing. This is just past the ':' (if there is one) that specifies the determination of the protocol name.; limit - the character position to stop parsing at. This is the end of the string or the position of the "#" character, if present. All information after the sharp sign indicates an anchor.

toExternalForm

protected String toExternalForm(URL u)

Converts a URL of a specific protocol to a String.

Parameters:: u - the URL.
Returns:: a string representation of the URL argument.

setURL

protected void setURL(URL u,
                      String protocol,
                      String host,
                      int port,
                      String file,
                      String ref)

Sets the fields of the URL argument to the indicated values. Only classes derived from URLStreamHandler are supposed to be able to call the set method on a URL.

Parameters:: u - the URL to modify.; protocol - the protocol name.; host - the remote host value for the URL.; port - the port on the remote machine.; file - the file.; ref - the reference.
See Also:: URL.set(java.lang.String, java.lang.String, int, java.lang.String, java.lang.String)