Class URLStreamHandler
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 or https.
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:
- 1.0
- See Also:
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionprotected booleanProvides the default equals calculation.protected intReturns the default port for a URL parsed by this handler.protected InetAddressGet the IP address of our host.protected intProvides the default hash calculation.protected booleanhostsEqual(URL u1, URL u2) Compares the host components of two URLs.protected abstract URLConnectionOpens a connection to the object referenced by theURLargument.protected URLConnectionopenConnection(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 voidParses the string representation of aURLinto aURLobject.protected booleanCompare two urls to see whether they refer to the same file, i.e., having the same protocol, host, port, and path.protected voidDeprecated.Use setURL(URL, String, String, int, String, String, String, String);protected voidsetURL(URL u, String protocol, String host, int port, String authority, String userInfo, String path, String query, String ref) Sets the fields of theURLargument to the indicated values.protected StringConverts aURLof a specific protocol to aString.
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Constructor Details
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URLStreamHandler
public URLStreamHandler()Constructor for subclasses to call.
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Method Details
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openConnection
Opens a connection to the object referenced by theURLargument. 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
URLConnectionobject for theURL. - Throws:
IOException- if an I/O error occurs while opening the connection.
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openConnection
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
ProxySelectorsettings.- Implementation Requirements:
- The default implementation of this method first checks that the given
URLandProxyare not null, then throwsUnsupportedOperationException. Subclasses should override this method with an appropriate implementation. - 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
URLConnectionobject 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
Parses the string representation of aURLinto aURLobject.If there is any inherited context, then it has already been copied into the
URLargument.The
parseURLmethod ofURLStreamHandlerparses the string representation as if it were anhttpspecification. 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- theURLto receive the result of parsing the spec.spec- theStringrepresenting 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.- Throws:
IllegalArgumentException- if the implementation of the protocol handler rejects any of the given parametersNullPointerException- ifuisnull, or ifstart < limitandspecisnull
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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 overridden by handlers with default port numbers.- Returns:
- the default port for a
URLparsed by this handler. - Since:
- 1.3
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equals
Provides the default equals calculation. May be overridden 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:
trueif the two urls are considered equal, i.e. they refer to the same fragment in the same file.- Since:
- 1.3
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hashCode
Provides the default hash calculation. May be overridden by handlers for other protocols that have different requirements for hashCode calculation.- Parameters:
u- a URL object- Returns:
- an
intsuitable for hash table indexing - Since:
- 1.3
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sameFile
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
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
InetAddressrepresenting the host IP address. - Since:
- 1.3
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hostsEqual
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toExternalForm
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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 theURLargument to the indicated values. Only classes derived from URLStreamHandler are able to use this method to set the values of the URL fields.- 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 oneIllegalArgumentException- if the implementation of the protocol handler rejects any of the given parametersNullPointerException- ifuisnull- Since:
- 1.3
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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 theURLargument to the indicated values. Only classes derived from URLStreamHandler are able to use this method to set the values of the URL fields.- 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 oneIllegalArgumentException- if the implementation of the protocol handler rejects any of the given parametersNullPointerException- ifuisnull
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