The URL.java Java example source code
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package java.net;
import java.io.IOException;
import java.io.InputStream;
import java.util.Hashtable;
import java.util.StringTokenizer;
import sun.security.util.SecurityConstants;
/**
* Class {@code URL} represents a Uniform Resource
* Locator, a pointer to a "resource" on the World
* Wide Web. A resource can be something as simple as a file or a
* directory, or it can be a reference to a more complicated object,
* such as a query to a database or to a search engine. More
* information on the types of URLs and their formats can be found at:
* <a href=
* "http://web.archive.org/web/20051219043731/http://archive.ncsa.uiuc.edu/SDG/Software/Mosaic/Demo/url-primer.html">
* <i>Types of URL
* <p>
* In general, a URL can be broken into several parts. Consider the
* following example:
* <blockquote> * http://www.example.com/docs/resource1.html
* </pre>
* <p>
* The URL above indicates that the protocol to use is
* {@code http} (HyperText Transfer Protocol) and that the
* information resides on a host machine named
* {@code www.example.com}. The information on that host
* machine is named {@code /docs/resource1.html}. The exact
* meaning of this name on the host machine is both protocol
* dependent and host dependent. The information normally resides in
* a file, but it could be generated on the fly. This component of
* the URL is called the <i>path component.
* <p>
* A URL can optionally specify a "port", which is the
* port number to which the TCP connection is made on the remote host
* machine. If the port is not specified, the default port for
* the protocol is used instead. For example, the default port for
* {@code http} is {@code 80}. An alternative port could be
* specified as:
* <blockquote> * http://www.example.com:1080/docs/resource1.html
* </pre>
* <p>
* The syntax of {@code URL} is defined by <a
* href="http://www.ietf.org/rfc/rfc2396.txt"><i>RFC 2396: Uniform
* Resource Identifiers (URI): Generic Syntax</i>, amended by RFC 2732: Format for
* Literal IPv6 Addresses in URLs</i>. The Literal IPv6 address format
* also supports scope_ids. The syntax and usage of scope_ids is described
* <a href="Inet6Address.html#scoped">here.
* <p>
* A URL may have appended to it a "fragment", also known
* as a "ref" or a "reference". The fragment is indicated by the sharp
* sign character "#" followed by more characters. For example,
* <blockquote> * http://java.sun.com/index.html#chapter1
* </pre>
* <p>
* This fragment is not technically part of the URL. Rather, it
* indicates that after the specified resource is retrieved, the
* application is specifically interested in that part of the
* document that has the tag {@code chapter1} attached to it. The
* meaning of a tag is resource specific.
* <p>
* An application can also specify a "relative URL",
* which contains only enough information to reach the resource
* relative to another URL. Relative URLs are frequently used within
* HTML pages. For example, if the contents of the URL:
* <blockquote> * http://java.sun.com/index.html
* </pre>
* contained within it the relative URL:
* <blockquote> * FAQ.html
* </pre>
* it would be a shorthand for:
* <blockquote> * http://java.sun.com/FAQ.html
* </pre>
* <p>
* The relative URL need not specify all the components of a URL. If
* the protocol, host name, or port number is missing, the value is
* inherited from the fully specified URL. The file component must be
* specified. The optional fragment is not inherited.
* <p>
* The URL class does not itself encode or decode any URL components
* according to the escaping mechanism defined in RFC2396. It is the
* responsibility of the caller to encode any fields, which need to be
* escaped prior to calling URL, and also to decode any escaped fields,
* that are returned from URL. Furthermore, because URL has no knowledge
* of URL escaping, it does not recognise equivalence between the encoded
* or decoded form of the same URL. For example, the two URLs:<br>
* <pre> http://foo.com/hello world/ and http://foo.com/hello%20world
* would be considered not equal to each other.
* <p>
* Note, the {@link java.net.URI} class does perform escaping of its
* component fields in certain circumstances. The recommended way
* to manage the encoding and decoding of URLs is to use {@link java.net.URI},
* and to convert between these two classes using {@link #toURI()} and
* {@link URI#toURL()}.
* <p>
* The {@link URLEncoder} and {@link URLDecoder} classes can also be
* used, but only for HTML form encoding, which is not the same
* as the encoding scheme defined in RFC2396.
*
* @author James Gosling
* @since JDK1.0
*/
public final class URL implements java.io.Serializable {
static final long serialVersionUID = -7627629688361524110L;
/**
* The property which specifies the package prefix list to be scanned
* for protocol handlers. The value of this property (if any) should
* be a vertical bar delimited list of package names to search through
* for a protocol handler to load. The policy of this class is that
* all protocol handlers will be in a class called <protocolname>.Handler,
* and each package in the list is examined in turn for a matching
* handler. If none are found (or the property is not specified), the
* default package prefix, sun.net.www.protocol, is used. The search
* proceeds from the first package in the list to the last and stops
* when a match is found.
*/
private static final String protocolPathProp = "java.protocol.handler.pkgs";
/**
* The protocol to use (ftp, http, nntp, ... etc.) .
* @serial
*/
private String protocol;
/**
* The host name to connect to.
* @serial
*/
private String host;
/**
* The protocol port to connect to.
* @serial
*/
private int port = -1;
/**
* The specified file name on that host. {@code file} is
* defined as {@code path[?query]}
* @serial
*/
private String file;
/**
* The query part of this URL.
*/
private transient String query;
/**
* The authority part of this URL.
* @serial
*/
private String authority;
/**
* The path part of this URL.
*/
private transient String path;
/**
* The userinfo part of this URL.
*/
private transient String userInfo;
/**
* # reference.
* @serial
*/
private String ref;
/**
* The host's IP address, used in equals and hashCode.
* Computed on demand. An uninitialized or unknown hostAddress is null.
*/
transient InetAddress hostAddress;
/**
* The URLStreamHandler for this URL.
*/
transient URLStreamHandler handler;
/* Our hash code.
* @serial
*/
private int hashCode = -1;
/**
* Creates a {@code URL} object from the specified
* {@code protocol}, {@code host}, {@code port}
* number, and {@code file}.<p>
*
* {@code host} can be expressed as a host name or a literal
* IP address. If IPv6 literal address is used, it should be
* enclosed in square brackets ({@code '['} and {@code ']'}), as
* specified by <a
* href="http://www.ietf.org/rfc/rfc2732.txt">RFC 2732</a>;
* However, the literal IPv6 address format defined in <a
* href="http://www.ietf.org/rfc/rfc2373.txt"><i>RFC 2373: IP
* Version 6 Addressing Architecture</i> is also accepted.
*
* Specifying a {@code port} number of {@code -1}
* indicates that the URL should use the default port for the
* protocol.<p>
*
* If this is the first URL object being created with the specified
* protocol, a <i>stream protocol handler object, an instance of
* class {@code URLStreamHandler}, is created for that protocol:
* <ol>
* <li>If the application has previously set up an instance of
* {@code URLStreamHandlerFactory} as the stream handler factory,
* then the {@code createURLStreamHandler} method of that instance
* is called with the protocol string as an argument to create the
* stream protocol handler.
* <li>If no {@code URLStreamHandlerFactory} has yet been set up,
* or if the factory's {@code createURLStreamHandler} method
* returns {@code null}, then the constructor finds the
* value of the system property:
* <blockquote>
* java.protocol.handler.pkgs
* </pre>
* If the value of that system property is not {@code null},
* it is interpreted as a list of packages separated by a vertical
* slash character '{@code |}'. The constructor tries to load
* the class named:
* <blockquote> * <<i>package>.<protocol>.Handler
* </pre>
* where <<i>package> is replaced by the name of the package
* and <<i>protocol> is replaced by the name of the protocol.
* If this class does not exist, or if the class exists but it is not
* a subclass of {@code URLStreamHandler}, then the next package
* in the list is tried.
* <li>If the previous step fails to find a protocol handler, then the
* constructor tries to load from a system default package.
* <blockquote> * <<i>system default package>.<protocol>.Handler
* </pre>
* If this class does not exist, or if the class exists but it is not a
* subclass of {@code URLStreamHandler}, then a
* {@code MalformedURLException} is thrown.
* </ol>
*
* <p>Protocol handlers for the following protocols are guaranteed
* to exist on the search path :-
* <blockquote> * http, https, file, and jar
* </pre>
* Protocol handlers for additional protocols may also be
* available.
*
* <p>No validation of the inputs is performed by this constructor.
*
* @param protocol the name of the protocol to use.
* @param host the name of the host.
* @param port the port number on the host.
* @param file the file on the host
* @exception MalformedURLException if an unknown protocol is specified.
* @see java.lang.System#getProperty(java.lang.String)
* @see java.net.URL#setURLStreamHandlerFactory(
* java.net.URLStreamHandlerFactory)
* @see java.net.URLStreamHandler
* @see java.net.URLStreamHandlerFactory#createURLStreamHandler(
* java.lang.String)
*/
public URL(String protocol, String host, int port, String file)
throws MalformedURLException
{
this(protocol, host, port, file, null);
}
/**
* Creates a URL from the specified {@code protocol}
* name, {@code host} name, and {@code file} name. The
* default port for the specified protocol is used.
* <p>
* This method is equivalent to calling the four-argument
* constructor with the arguments being {@code protocol},
* {@code host}, {@code -1}, and {@code file}.
*
* No validation of the inputs is performed by this constructor.
*
* @param protocol the name of the protocol to use.
* @param host the name of the host.
* @param file the file on the host.
* @exception MalformedURLException if an unknown protocol is specified.
* @see java.net.URL#URL(java.lang.String, java.lang.String,
* int, java.lang.String)
*/
public URL(String protocol, String host, String file)
throws MalformedURLException {
this(protocol, host, -1, file);
}
/**
* Creates a {@code URL} object from the specified
* {@code protocol}, {@code host}, {@code port}
* number, {@code file}, and {@code handler}. Specifying
* a {@code port} number of {@code -1} indicates that
* the URL should use the default port for the protocol. Specifying
* a {@code handler} of {@code null} indicates that the URL
* should use a default stream handler for the protocol, as outlined
* for:
* java.net.URL#URL(java.lang.String, java.lang.String, int,
* java.lang.String)
*
* <p>If the handler is not null and there is a security manager,
* the security manager's {@code checkPermission}
* method is called with a
* {@code NetPermission("specifyStreamHandler")} permission.
* This may result in a SecurityException.
*
* No validation of the inputs is performed by this constructor.
*
* @param protocol the name of the protocol to use.
* @param host the name of the host.
* @param port the port number on the host.
* @param file the file on the host
* @param handler the stream handler for the URL.
* @exception MalformedURLException if an unknown protocol is specified.
* @exception SecurityException
* if a security manager exists and its
* {@code checkPermission} method doesn't allow
* specifying a stream handler explicitly.
* @see java.lang.System#getProperty(java.lang.String)
* @see java.net.URL#setURLStreamHandlerFactory(
* java.net.URLStreamHandlerFactory)
* @see java.net.URLStreamHandler
* @see java.net.URLStreamHandlerFactory#createURLStreamHandler(
* java.lang.String)
* @see SecurityManager#checkPermission
* @see java.net.NetPermission
*/
public URL(String protocol, String host, int port, String file,
URLStreamHandler handler) throws MalformedURLException {
if (handler != null) {
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
// check for permission to specify a handler
checkSpecifyHandler(sm);
}
}
protocol = protocol.toLowerCase();
this.protocol = protocol;
if (host != null) {
/**
* if host is a literal IPv6 address,
* we will make it conform to RFC 2732
*/
if (host.indexOf(':') >= 0 && !host.startsWith("[")) {
host = "["+host+"]";
}
this.host = host;
if (port < -1) {
throw new MalformedURLException("Invalid port number :" +
port);
}
this.port = port;
authority = (port == -1) ? host : host + ":" + port;
}
Parts parts = new Parts(file);
path = parts.getPath();
query = parts.getQuery();
if (query != null) {
this.file = path + "?" + query;
} else {
this.file = path;
}
ref = parts.getRef();
// Note: we don't do validation of the URL here. Too risky to change
// right now, but worth considering for future reference. -br
if (handler == null &&
(handler = getURLStreamHandler(protocol)) == null) {
throw new MalformedURLException("unknown protocol: " + protocol);
}
this.handler = handler;
}
/**
* Creates a {@code URL} object from the {@code String}
* representation.
* <p>
* This constructor is equivalent to a call to the two-argument
* constructor with a {@code null} first argument.
*
* @param spec the {@code String} to parse as a URL.
* @exception MalformedURLException if no protocol is specified, or an
* unknown protocol is found, or {@code spec} is {@code null}.
* @see java.net.URL#URL(java.net.URL, java.lang.String)
*/
public URL(String spec) throws MalformedURLException {
this(null, spec);
}
/**
* Creates a URL by parsing the given spec within a specified context.
*
* The new URL is created from the given context URL and the spec
* argument as described in
* RFC2396 "Uniform Resource Identifiers : Generic * Syntax" :
* <blockquote> * <scheme>://<authority><path>?<query>#<fragment>
* </pre>
* The reference is parsed into the scheme, authority, path, query and
* fragment parts. If the path component is empty and the scheme,
* authority, and query components are undefined, then the new URL is a
* reference to the current document. Otherwise, the fragment and query
* parts present in the spec are used in the new URL.
* <p>
* If the scheme component is defined in the given spec and does not match
* the scheme of the context, then the new URL is created as an absolute
* URL based on the spec alone. Otherwise the scheme component is inherited
* from the context URL.
* <p>
* If the authority component is present in the spec then the spec is
* treated as absolute and the spec authority and path will replace the
* context authority and path. If the authority component is absent in the
* spec then the authority of the new URL will be inherited from the
* context.
* <p>
* If the spec's path component begins with a slash character
* "/" then the
* path is treated as absolute and the spec path replaces the context path.
* <p>
* Otherwise, the path is treated as a relative path and is appended to the
* context path, as described in RFC2396. Also, in this case,
* the path is canonicalized through the removal of directory
* changes made by occurrences of ".." and ".".
* <p>
* For a more detailed description of URL parsing, refer to RFC2396.
*
* @param context the context in which to parse the specification.
* @param spec the {@code String} to parse as a URL.
* @exception MalformedURLException if no protocol is specified, or an
* unknown protocol is found, or {@code spec} is {@code null}.
* @see java.net.URL#URL(java.lang.String, java.lang.String,
* int, java.lang.String)
* @see java.net.URLStreamHandler
* @see java.net.URLStreamHandler#parseURL(java.net.URL,
* java.lang.String, int, int)
*/
public URL(URL context, String spec) throws MalformedURLException {
this(context, spec, null);
}
/**
* Creates a URL by parsing the given spec with the specified handler
* within a specified context. If the handler is null, the parsing
* occurs as with the two argument constructor.
*
* @param context the context in which to parse the specification.
* @param spec the {@code String} to parse as a URL.
* @param handler the stream handler for the URL.
* @exception MalformedURLException if no protocol is specified, or an
* unknown protocol is found, or {@code spec} is {@code null}.
* @exception SecurityException
* if a security manager exists and its
* {@code checkPermission} method doesn't allow
* specifying a stream handler.
* @see java.net.URL#URL(java.lang.String, java.lang.String,
* int, java.lang.String)
* @see java.net.URLStreamHandler
* @see java.net.URLStreamHandler#parseURL(java.net.URL,
* java.lang.String, int, int)
*/
public URL(URL context, String spec, URLStreamHandler handler)
throws MalformedURLException
{
String original = spec;
int i, limit, c;
int start = 0;
String newProtocol = null;
boolean aRef=false;
boolean isRelative = false;
// Check for permission to specify a handler
if (handler != null) {
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
checkSpecifyHandler(sm);
}
}
try {
limit = spec.length();
while ((limit > 0) && (spec.charAt(limit - 1) <= ' ')) {
limit--; //eliminate trailing whitespace
}
while ((start < limit) && (spec.charAt(start) <= ' ')) {
start++; // eliminate leading whitespace
}
if (spec.regionMatches(true, start, "url:", 0, 4)) {
start += 4;
}
if (start < spec.length() && spec.charAt(start) == '#') {
/* we're assuming this is a ref relative to the context URL.
* This means protocols cannot start w/ '#', but we must parse
* ref URL's like: "hello:there" w/ a ':' in them.
*/
aRef=true;
}
for (i = start ; !aRef && (i < limit) &&
((c = spec.charAt(i)) != '/') ; i++) {
if (c == ':') {
String s = spec.substring(start, i).toLowerCase();
if (isValidProtocol(s)) {
newProtocol = s;
start = i + 1;
}
break;
}
}
// Only use our context if the protocols match.
protocol = newProtocol;
if ((context != null) && ((newProtocol == null) ||
newProtocol.equalsIgnoreCase(context.protocol))) {
// inherit the protocol handler from the context
// if not specified to the constructor
if (handler == null) {
handler = context.handler;
}
// If the context is a hierarchical URL scheme and the spec
// contains a matching scheme then maintain backwards
// compatibility and treat it as if the spec didn't contain
// the scheme; see 5.2.3 of RFC2396
if (context.path != null && context.path.startsWith("/"))
newProtocol = null;
if (newProtocol == null) {
protocol = context.protocol;
authority = context.authority;
userInfo = context.userInfo;
host = context.host;
port = context.port;
file = context.file;
path = context.path;
isRelative = true;
}
}
if (protocol == null) {
throw new MalformedURLException("no protocol: "+original);
}
// Get the protocol handler if not specified or the protocol
// of the context could not be used
if (handler == null &&
(handler = getURLStreamHandler(protocol)) == null) {
throw new MalformedURLException("unknown protocol: "+protocol);
}
this.handler = handler;
i = spec.indexOf('#', start);
if (i >= 0) {
ref = spec.substring(i + 1, limit);
limit = i;
}
/*
* Handle special case inheritance of query and fragment
* implied by RFC2396 section 5.2.2.
*/
if (isRelative && start == limit) {
query = context.query;
if (ref == null) {
ref = context.ref;
}
}
handler.parseURL(this, spec, start, limit);
} catch(MalformedURLException e) {
throw e;
} catch(Exception e) {
MalformedURLException exception = new MalformedURLException(e.getMessage());
exception.initCause(e);
throw exception;
}
}
/*
* Returns true if specified string is a valid protocol name.
*/
private boolean isValidProtocol(String protocol) {
int len = protocol.length();
if (len < 1)
return false;
char c = protocol.charAt(0);
if (!Character.isLetter(c))
return false;
for (int i = 1; i < len; i++) {
c = protocol.charAt(i);
if (!Character.isLetterOrDigit(c) && c != '.' && c != '+' &&
c != '-') {
return false;
}
}
return true;
}
/*
* Checks for permission to specify a stream handler.
*/
private void checkSpecifyHandler(SecurityManager sm) {
sm.checkPermission(SecurityConstants.SPECIFY_HANDLER_PERMISSION);
}
/**
* Sets the fields of the URL. This is not a public method so that
* only URLStreamHandlers can modify URL fields. URLs are
* otherwise constant.
*
* @param protocol the name of the protocol to use
* @param host the name of the host
@param port the port number on the host
* @param file the file on the host
* @param ref the internal reference in the URL
*/
void set(String protocol, String host, int port,
String file, String ref) {
synchronized (this) {
this.protocol = protocol;
this.host = host;
authority = port == -1 ? host : host + ":" + port;
this.port = port;
this.file = file;
this.ref = ref;
/* This is very important. We must recompute this after the
* URL has been changed. */
hashCode = -1;
hostAddress = null;
int q = file.lastIndexOf('?');
if (q != -1) {
query = file.substring(q+1);
path = file.substring(0, q);
} else
path = file;
}
}
/**
* Sets the specified 8 fields of the URL. This is not a public method so
* that only URLStreamHandlers can modify URL fields. URLs are otherwise
* constant.
*
* @param protocol the name of the protocol to use
* @param host the name of the host
* @param port the port number on the host
* @param authority the authority part for the url
* @param userInfo the username and password
* @param path the file on the host
* @param ref the internal reference in the URL
* @param query the query part of this URL
* @since 1.3
*/
void set(String protocol, String host, int port,
String authority, String userInfo, String path,
String query, String ref) {
synchronized (this) {
this.protocol = protocol;
this.host = host;
this.port = port;
this.file = query == null ? path : path + "?" + query;
this.userInfo = userInfo;
this.path = path;
this.ref = ref;
/* This is very important. We must recompute this after the
* URL has been changed. */
hashCode = -1;
hostAddress = null;
this.query = query;
this.authority = authority;
}
}
/**
* Gets the query part of this {@code URL}.
*
* @return the query part of this {@code URL},
* or <CODE>null if one does not exist
* @since 1.3
*/
public String getQuery() {
return query;
}
/**
* Gets the path part of this {@code URL}.
*
* @return the path part of this {@code URL}, or an
* empty string if one does not exist
* @since 1.3
*/
public String getPath() {
return path;
}
/**
* Gets the userInfo part of this {@code URL}.
*
* @return the userInfo part of this {@code URL}, or
* <CODE>null if one does not exist
* @since 1.3
*/
public String getUserInfo() {
return userInfo;
}
/**
* Gets the authority part of this {@code URL}.
*
* @return the authority part of this {@code URL}
* @since 1.3
*/
public String getAuthority() {
return authority;
}
/**
* Gets the port number of this {@code URL}.
*
* @return the port number, or -1 if the port is not set
*/
public int getPort() {
return port;
}
/**
* Gets the default port number of the protocol associated
* with this {@code URL}. If the URL scheme or the URLStreamHandler
* for the URL do not define a default port number,
* then -1 is returned.
*
* @return the port number
* @since 1.4
*/
public int getDefaultPort() {
return handler.getDefaultPort();
}
/**
* Gets the protocol name of this {@code URL}.
*
* @return the protocol of this {@code URL}.
*/
public String getProtocol() {
return protocol;
}
/**
* Gets the host name of this {@code URL}, if applicable.
* The format of the host conforms to RFC 2732, i.e. for a
* literal IPv6 address, this method will return the IPv6 address
* enclosed in square brackets ({@code '['} and {@code ']'}).
*
* @return the host name of this {@code URL}.
*/
public String getHost() {
return host;
}
/**
* Gets the file name of this {@code URL}.
* The returned file portion will be
* the same as <CODE>getPath(), plus the concatenation of
* the value of <CODE>getQuery(), if any. If there is
* no query portion, this method and <CODE>getPath() will
* return identical results.
*
* @return the file name of this {@code URL},
* or an empty string if one does not exist
*/
public String getFile() {
return file;
}
/**
* Gets the anchor (also known as the "reference") of this
* {@code URL}.
*
* @return the anchor (also known as the "reference") of this
* {@code URL}, or <CODE>null if one does not exist
*/
public String getRef() {
return ref;
}
/**
* Compares this URL for equality with another object.<p>
*
* If the given object is not a URL then this method immediately returns
* {@code false}.<p>
*
* Two URL objects are equal if they have the same protocol, reference
* equivalent hosts, have the same port number on the host, and the same
* file and fragment of the file.<p>
*
* Two hosts are considered equivalent if both host names can be resolved
* into the same IP addresses; else if either host name can't be
* resolved, the host names must be equal without regard to case; or both
* host names equal to null.<p>
*
* Since hosts comparison requires name resolution, this operation is a
* blocking operation. <p>
*
* Note: The defined behavior for {@code equals} is known to
* be inconsistent with virtual hosting in HTTP.
*
* @param obj the URL to compare against.
* @return {@code true} if the objects are the same;
* {@code false} otherwise.
*/
public boolean equals(Object obj) {
if (!(obj instanceof URL))
return false;
URL u2 = (URL)obj;
return handler.equals(this, u2);
}
/**
* Creates an integer suitable for hash table indexing.<p>
*
* The hash code is based upon all the URL components relevant for URL
* comparison. As such, this operation is a blocking operation.<p>
*
* @return a hash code for this {@code URL}.
*/
public synchronized int hashCode() {
if (hashCode != -1)
return hashCode;
hashCode = handler.hashCode(this);
return hashCode;
}
/**
* Compares two URLs, excluding the fragment component.<p>
*
* Returns {@code true} if this {@code URL} and the
* {@code other} argument are equal without taking the
* fragment component into consideration.
*
* @param other the {@code URL} to compare against.
* @return {@code true} if they reference the same remote object;
* {@code false} otherwise.
*/
public boolean sameFile(URL other) {
return handler.sameFile(this, other);
}
/**
* Constructs a string representation of this {@code URL}. The
* string is created by calling the {@code toExternalForm}
* method of the stream protocol handler for this object.
*
* @return a string representation of this object.
* @see java.net.URL#URL(java.lang.String, java.lang.String, int,
* java.lang.String)
* @see java.net.URLStreamHandler#toExternalForm(java.net.URL)
*/
public String toString() {
return toExternalForm();
}
/**
* Constructs a string representation of this {@code URL}. The
* string is created by calling the {@code toExternalForm}
* method of the stream protocol handler for this object.
*
* @return a string representation of this object.
* @see java.net.URL#URL(java.lang.String, java.lang.String,
* int, java.lang.String)
* @see java.net.URLStreamHandler#toExternalForm(java.net.URL)
*/
public String toExternalForm() {
return handler.toExternalForm(this);
}
/**
* Returns a {@link java.net.URI} equivalent to this URL.
* This method functions in the same way as {@code new URI (this.toString())}.
* <p>Note, any URL instance that complies with RFC 2396 can be converted
* to a URI. However, some URLs that are not strictly in compliance
* can not be converted to a URI.
*
* @exception URISyntaxException if this URL is not formatted strictly according to
* to RFC2396 and cannot be converted to a URI.
*
* @return a URI instance equivalent to this URL.
* @since 1.5
*/
public URI toURI() throws URISyntaxException {
return new URI (toString());
}
/**
* Returns a {@link java.net.URLConnection URLConnection} instance that
* represents a connection to the remote object referred to by the
* {@code URL}.
*
* <P>A new instance of {@linkplain java.net.URLConnection URLConnection} is
* created every time when invoking the
* {@linkplain java.net.URLStreamHandler#openConnection(URL)
* URLStreamHandler.openConnection(URL)} method of the protocol handler for
* this URL.</P>
*
* <P>It should be noted that a URLConnection instance does not establish
* the actual network connection on creation. This will happen only when
* calling {@linkplain java.net.URLConnection#connect() URLConnection.connect()}.</P>
*
* <P>If for the URL'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.</P>
*
* @return a {@link java.net.URLConnection URLConnection} linking
* to the URL.
* @exception IOException if an I/O exception occurs.
* @see java.net.URL#URL(java.lang.String, java.lang.String,
* int, java.lang.String)
*/
public URLConnection openConnection() throws java.io.IOException {
return handler.openConnection(this);
}
/**
* Same as {@link #openConnection()}, except that the connection will be
* made through the specified proxy; Protocol handlers that do not
* support proxing will ignore the proxy parameter and make a
* normal connection.
*
* Invoking this method preempts the system's default ProxySelector
* settings.
*
* @param proxy the Proxy through which this connection
* will be made. If direct connection is desired,
* Proxy.NO_PROXY should be specified.
* @return a {@code URLConnection} to the URL.
* @exception IOException if an I/O exception occurs.
* @exception SecurityException if a security manager is present
* and the caller doesn't have permission to connect
* to the proxy.
* @exception IllegalArgumentException will be thrown if proxy is null,
* or proxy has the wrong type
* @exception UnsupportedOperationException if the subclass that
* implements the protocol handler doesn't support
* this method.
* @see java.net.URL#URL(java.lang.String, java.lang.String,
* int, java.lang.String)
* @see java.net.URLConnection
* @see java.net.URLStreamHandler#openConnection(java.net.URL,
* java.net.Proxy)
* @since 1.5
*/
public URLConnection openConnection(Proxy proxy)
throws java.io.IOException {
if (proxy == null) {
throw new IllegalArgumentException("proxy can not be null");
}
// Create a copy of Proxy as a security measure
Proxy p = proxy == Proxy.NO_PROXY ? Proxy.NO_PROXY : sun.net.ApplicationProxy.create(proxy);
SecurityManager sm = System.getSecurityManager();
if (p.type() != Proxy.Type.DIRECT && sm != null) {
InetSocketAddress epoint = (InetSocketAddress) p.address();
if (epoint.isUnresolved())
sm.checkConnect(epoint.getHostName(), epoint.getPort());
else
sm.checkConnect(epoint.getAddress().getHostAddress(),
epoint.getPort());
}
return handler.openConnection(this, p);
}
/**
* Opens a connection to this {@code URL} and returns an
* {@code InputStream} for reading from that connection. This
* method is a shorthand for:
* <blockquote> * openConnection().getInputStream()
* </pre>
*
* @return an input stream for reading from the URL connection.
* @exception IOException if an I/O exception occurs.
* @see java.net.URL#openConnection()
* @see java.net.URLConnection#getInputStream()
*/
public final InputStream openStream() throws java.io.IOException {
return openConnection().getInputStream();
}
/**
* Gets the contents of this URL. This method is a shorthand for:
* <blockquote> * openConnection().getContent()
* </pre>
*
* @return the contents of this URL.
* @exception IOException if an I/O exception occurs.
* @see java.net.URLConnection#getContent()
*/
public final Object getContent() throws java.io.IOException {
return openConnection().getContent();
}
/**
* Gets the contents of this URL. This method is a shorthand for:
* <blockquote> * openConnection().getContent(Class[])
* </pre>
*
* @param classes an array of Java types
* @return the content object of this URL that is the first match of
* the types specified in the classes array.
* null if none of the requested types are supported.
* @exception IOException if an I/O exception occurs.
* @see java.net.URLConnection#getContent(Class[])
* @since 1.3
*/
public final Object getContent(Class[] classes)
throws java.io.IOException {
return openConnection().getContent(classes);
}
/**
* The URLStreamHandler factory.
*/
static URLStreamHandlerFactory factory;
/**
* Sets an application's {@code URLStreamHandlerFactory}.
* This method can be called at most once in a given Java Virtual
* Machine.
*
*<p> The {@code URLStreamHandlerFactory} instance is used to
*construct a stream protocol handler from a protocol name.
*
* <p> If there is a security manager, this method first calls
* the security manager's {@code checkSetFactory} method
* to ensure the operation is allowed.
* This could result in a SecurityException.
*
* @param fac the desired factory.
* @exception Error if the application has already set a factory.
* @exception SecurityException if a security manager exists and its
* {@code checkSetFactory} method doesn't allow
* the operation.
* @see java.net.URL#URL(java.lang.String, java.lang.String,
* int, java.lang.String)
* @see java.net.URLStreamHandlerFactory
* @see SecurityManager#checkSetFactory
*/
public static void setURLStreamHandlerFactory(URLStreamHandlerFactory fac) {
synchronized (streamHandlerLock) {
if (factory != null) {
throw new Error("factory already defined");
}
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkSetFactory();
}
handlers.clear();
factory = fac;
}
}
/**
* A table of protocol handlers.
*/
static Hashtable<String,URLStreamHandler> handlers = new Hashtable<>();
private static Object streamHandlerLock = new Object();
/**
* Returns the Stream Handler.
* @param protocol the protocol to use
*/
static URLStreamHandler getURLStreamHandler(String protocol) {
URLStreamHandler handler = handlers.get(protocol);
if (handler == null) {
boolean checkedWithFactory = false;
// Use the factory (if any)
if (factory != null) {
handler = factory.createURLStreamHandler(protocol);
checkedWithFactory = true;
}
// Try java protocol handler
if (handler == null) {
String packagePrefixList = null;
packagePrefixList
= java.security.AccessController.doPrivileged(
new sun.security.action.GetPropertyAction(
protocolPathProp,""));
if (packagePrefixList != "") {
packagePrefixList += "|";
}
// REMIND: decide whether to allow the "null" class prefix
// or not.
packagePrefixList += "sun.net.www.protocol";
StringTokenizer packagePrefixIter =
new StringTokenizer(packagePrefixList, "|");
while (handler == null &&
packagePrefixIter.hasMoreTokens()) {
String packagePrefix =
packagePrefixIter.nextToken().trim();
try {
String clsName = packagePrefix + "." + protocol +
".Handler";
Class<?> cls = null;
try {
cls = Class.forName(clsName);
} catch (ClassNotFoundException e) {
ClassLoader cl = ClassLoader.getSystemClassLoader();
if (cl != null) {
cls = cl.loadClass(clsName);
}
}
if (cls != null) {
handler =
(URLStreamHandler)cls.newInstance();
}
} catch (Exception e) {
// any number of exceptions can get thrown here
}
}
}
synchronized (streamHandlerLock) {
URLStreamHandler handler2 = null;
// Check again with hashtable just in case another
// thread created a handler since we last checked
handler2 = handlers.get(protocol);
if (handler2 != null) {
return handler2;
}
// Check with factory if another thread set a
// factory since our last check
if (!checkedWithFactory && factory != null) {
handler2 = factory.createURLStreamHandler(protocol);
}
if (handler2 != null) {
// The handler from the factory must be given more
// importance. Discard the default handler that
// this thread created.
handler = handler2;
}
// Insert this handler into the hashtable
if (handler != null) {
handlers.put(protocol, handler);
}
}
}
return handler;
}
/**
* WriteObject is called to save the state of the URL to an
* ObjectOutputStream. The handler is not saved since it is
* specific to this system.
*
* @serialData the default write object value. When read back in,
* the reader must ensure that calling getURLStreamHandler with
* the protocol variable returns a valid URLStreamHandler and
* throw an IOException if it does not.
*/
private synchronized void writeObject(java.io.ObjectOutputStream s)
throws IOException
{
s.defaultWriteObject(); // write the fields
}
/**
* readObject is called to restore the state of the URL from the
* stream. It reads the components of the URL and finds the local
* stream handler.
*/
private synchronized void readObject(java.io.ObjectInputStream s)
throws IOException, ClassNotFoundException
{
s.defaultReadObject(); // read the fields
if ((handler = getURLStreamHandler(protocol)) == null) {
throw new IOException("unknown protocol: " + protocol);
}
// Construct authority part
if (authority == null &&
((host != null && host.length() > 0) || port != -1)) {
if (host == null)
host = "";
authority = (port == -1) ? host : host + ":" + port;
// Handle hosts with userInfo in them
int at = host.lastIndexOf('@');
if (at != -1) {
userInfo = host.substring(0, at);
host = host.substring(at+1);
}
} else if (authority != null) {
// Construct user info part
int ind = authority.indexOf('@');
if (ind != -1)
userInfo = authority.substring(0, ind);
}
// Construct path and query part
path = null;
query = null;
if (file != null) {
// Fix: only do this if hierarchical?
int q = file.lastIndexOf('?');
if (q != -1) {
query = file.substring(q+1);
path = file.substring(0, q);
} else
path = file;
}
}
}
class Parts {
String path, query, ref;
Parts(String file) {
int ind = file.indexOf('#');
ref = ind < 0 ? null: file.substring(ind + 1);
file = ind < 0 ? file: file.substring(0, ind);
int q = file.lastIndexOf('?');
if (q != -1) {
query = file.substring(q+1);
path = file.substring(0, q);
} else {
path = file;
}
}
String getPath() {
return path;
}
String getQuery() {
return query;
}
String getRef() {
return ref;
}
}
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