- java.lang.Object
-
- java.net.URLStreamHandler
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public abstract class URLStreamHandler extends Object
The abstract classURLStreamHandler
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 ashttp
,ftp
, orgopher
.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 aURL
, 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)
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Constructor Summary
Constructors Constructor and Description URLStreamHandler()
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Method Summary
Methods Modifier and Type Method and Description protected boolean
equals(URL u1, URL u2)
Provides the default equals calculation.protected int
getDefaultPort()
Returns the default port for a URL parsed by this handler.protected InetAddress
getHostAddress(URL u)
Get the IP address of our host.protected int
hashCode(URL u)
Provides the default hash calculation.protected boolean
hostsEqual(URL u1, URL u2)
Compares the host components of two URLs.protected abstract URLConnection
openConnection(URL u)
Opens a connection to the object referenced by theURL
argument.protected URLConnection
openConnection(URL u, Proxy p)
Same as openConnection(URL), except that the connection will be made through the specified proxy; Protocol handlers that do not support proxying will ignore the proxy parameter and make a normal connection.protected void
parseURL(URL u, String spec, int start, int limit)
Parses the string representation of aURL
into aURL
object.protected boolean
sameFile(URL u1, URL u2)
Compare two urls to see whether they refer to the same file, i.e., having the same protocol, host, port, and path.protected void
setURL(URL u, String protocol, String host, int port, String file, String ref)
Deprecated.Use setURL(URL, String, String, int, String, String, String, String);protected void
setURL(URL u, String protocol, String host, int port, String authority, String userInfo, String path, String query, String ref)
Sets the fields of theURL
argument to the indicated values.protected String
toExternalForm(URL u)
Converts aURL
of a specific protocol to aString
.
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Method Detail
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openConnection
protected abstract URLConnection openConnection(URL u) throws IOException
Opens a connection to the object referenced by theURL
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 theURL
. - Throws:
IOException
- if an I/O error occurs while opening the connection.
-
openConnection
protected URLConnection openConnection(URL u, Proxy p) throws IOException
Same as openConnection(URL), except that the connection will be made through the specified proxy; Protocol handlers that do not support proxying will ignore the proxy parameter and make a normal connection. Calling this method preempts the system's default ProxySelector settings.- Parameters:
u
- the URL that this connects to.p
- the proxy through which the connection will be made. If direct connection is desired, Proxy.NO_PROXY should be specified.- Returns:
- a
URLConnection
object for theURL
. - Throws:
IOException
- if an I/O error occurs while opening the connection.IllegalArgumentException
- if either u or p is null, or p has the wrong type.UnsupportedOperationException
- if the subclass that implements the protocol doesn't support this method.- Since:
- 1.5
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parseURL
protected void parseURL(URL u, String spec, int start, int limit)
Parses the string representation of aURL
into aURL
object.If there is any inherited context, then it has already been copied into the
URL
argument.The
parseURL
method ofURLStreamHandler
parses the string representation as if it were anhttp
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
- theURL
to receive the result of parsing the spec.spec
- theString
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.
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getDefaultPort
protected int getDefaultPort()
Returns the default port for a URL parsed by this handler. This method is meant to be overidden by handlers with default port numbers.- Returns:
- the default port for a
URL
parsed by this handler. - Since:
- 1.3
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equals
protected boolean equals(URL u1, URL u2)
Provides the default equals calculation. May be overidden by handlers for other protocols that have different requirements for equals(). This method requires that none of its arguments is null. This is guaranteed by the fact that it is only called by java.net.URL class.- Parameters:
u1
- a URL objectu2
- a URL object- Returns:
- true if the two urls are considered equal, ie. they refer to the same fragment in the same file.
- Since:
- 1.3
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hashCode
protected int hashCode(URL u)
Provides the default hash calculation. May be overidden by handlers for other protocols that have different requirements for hashCode calculation.- Parameters:
u
- a URL object- Returns:
- an int suitable for hash table indexing
- Since:
- 1.3
-
sameFile
protected boolean sameFile(URL u1, URL u2)
Compare two urls to see whether they refer to the same file, i.e., having the same protocol, host, port, and path. This method requires that none of its arguments is null. This is guaranteed by the fact that it is only called indirectly by java.net.URL class.- Parameters:
u1
- a URL objectu2
- a URL object- Returns:
- true if u1 and u2 refer to the same file
- Since:
- 1.3
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getHostAddress
protected InetAddress getHostAddress(URL u)
Get the IP address of our host. An empty host field or a DNS failure will result in a null return.- Parameters:
u
- a URL object- Returns:
- an
InetAddress
representing the host IP address. - Since:
- 1.3
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hostsEqual
protected boolean hostsEqual(URL u1, URL u2)
Compares the host components of two URLs.- Parameters:
u1
- the URL of the first host to compareu2
- the URL of the second host to compare- Returns:
- true if and only if they are equal, false otherwise.
- Since:
- 1.3
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toExternalForm
protected String toExternalForm(URL u)
Converts aURL
of a specific protocol to aString
.- Parameters:
u
- the URL.- Returns:
- a string representation of the
URL
argument.
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setURL
protected void setURL(URL u, String protocol, String host, int port, String authority, String userInfo, String path, String query, String ref)
Sets the fields of theURL
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.authority
- the authority part for the URL.userInfo
- the userInfo part of the URL.path
- the path component of the URL.query
- the query part for the URL.ref
- the reference.- Throws:
SecurityException
- if the protocol handler of the URL is different from this one- Since:
- 1.3
- See Also:
URL.set(java.lang.String, java.lang.String, int, java.lang.String, java.lang.String)
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setURL
@Deprecated protected void setURL(URL u, String protocol, String host, int port, String file, String ref)
Deprecated. Use setURL(URL, String, String, int, String, String, String, String);Sets the fields of theURL
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. This value is ignored since 1.2.host
- the remote host value for the URL.port
- the port on the remote machine.file
- the file.ref
- the reference.- Throws:
SecurityException
- if the protocol handler of the URL is different from this one
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