Serializablepublic final class URL extends Object implements Serializable
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: Types of URL In general, a URL can be broken into several parts. Consider the following example:
http://www.example.com/docs/resource1.html
The URL above indicates that the protocol to use is http (HyperText Transfer Protocol) and that the information resides on a host machine named www.example.com. The information on that host machine is named /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 path component.
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 http is 80. An alternative port could be specified as:
http://www.example.com:1080/docs/resource1.html
The syntax of URL is defined by RFC 2396: Uniform Resource Identifiers (URI): Generic Syntax, amended by RFC 2732: Format for Literal IPv6 Addresses in URLs. The Literal IPv6 address format also supports scope_ids. The syntax and usage of scope_ids is described here.
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,
http://www.example.com/index.html#chapter1
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 chapter1 attached to it. The meaning of a tag is resource specific.
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:
http://www.example.com/index.html
FAQ.html
http://www.example.com/FAQ.html
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.
URL
java.net.URL constructors are deprecated. Developers are encouraged to use java.net.URI to parse or construct a URL. In cases where an instance of
java.net.URL is needed to open a connection, URI can be used to construct or parse the URL string, possibly calling URI.parseServerAuthority() to validate that the authority component can be parsed as a server-based authority, and then calling URI.toURL() to create the URL instance. The URL constructors are specified to throw MalformedURLException but the actual parsing/validation that is performed is implementation dependent. Some parsing/validation may be delayed until later, when the underlying stream handler's implementation is called. Being able to construct an instance of URL doesn't provide any guarantee about its conformance to the URL syntax specification.
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:
http://foo.com/hello world/ and http://foo.com/hello%20worldwould be considered not equal to each other.
Note, the 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 URI, and to convert between these two classes using toURI() and URI.toURL().
The URLEncoder and URLDecoder classes can also be used, but only for HTML form encoding, which is not the same as the encoding scheme defined in RFC2396.
Path.of(URI) factory method and the File(URI) constructor can be used to create Path or File objects from a file URI. Path.toUri() and File.toURI() can be used to create a URI from a file path, which can be converted to URL using URI.toURL(). Applications should never try to construct or parse a URL from the direct string representation of a File or Path instance. Before constructing a URL from a URI, and depending on the protocol involved, applications should consider validating whether the URI authority can be parsed as server-based.
Some components of a URL or URI, such as userinfo, may be abused to construct misleading URLs or URIs. Applications that deal with URLs or URIs should take into account the recommendations advised in RFC3986, Section 7, Security Considerations.
All URL constructors may throw MalformedURLException. In particular, if the underlying URLStreamHandler implementation rejects, or is known to reject, any of the parameters, MalformedURLException may be thrown. Typically, a constructor that calls the stream handler's parseURL method may throw MalformedURLException if the underlying stream handler implementation of that method throws IllegalArgumentException. However, which checks are performed, or not, by the stream handlers is implementation dependent, and callers should not rely on such checks for full URL validation.
| Constructor | Description |
|---|---|
URL |
Deprecated. |
URL |
Deprecated. Use URI.toURL() to construct an instance of URL. |
URL |
Deprecated. Use of(URI, URLStreamHandler) to construct an instance of URL associated with a custom protocol handler. |
URL |
Deprecated. Use URI.toURL() to construct an instance of URL. |
URL |
Deprecated. Use URI.toURL() to construct an instance of URL. |
URL |
Deprecated. Use of(URI, URLStreamHandler) to construct an instance of URL associated with a custom protocol handler. |
| Modifier and Type | Method | Description |
|---|---|---|
boolean |
equals |
Compares this URL for equality with another object. |
String |
getAuthority() |
Gets the authority part of this URL. |
final Object |
getContent() |
Gets the contents of this URL. |
final Object |
getContent |
Gets the contents of this URL. |
int |
getDefaultPort() |
Gets the default port number of the protocol associated with this URL. |
String |
getFile() |
Gets the file name of this URL. |
String |
getHost() |
Gets the host name of this URL, if applicable. |
String |
getPath() |
Gets the path part of this URL. |
int |
getPort() |
Gets the port number of this URL. |
String |
getProtocol() |
Gets the protocol name of this URL. |
String |
getQuery() |
Gets the query part of this URL. |
String |
getRef() |
Gets the anchor (also known as the "reference") of this URL. |
String |
getUserInfo() |
Gets the userInfo part of this URL. |
int |
hashCode() |
Creates an integer suitable for hash table indexing. |
static URL |
of |
Creates a URL from a URI, as if by invoking uri.toURL(), but associating it with the given URLStreamHandler, if allowed. |
URLConnection |
openConnection() |
Returns a URLConnection instance that represents a connection to the remote object referred to by the URL. |
URLConnection |
openConnection |
Same as openConnection(), 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. |
final InputStream |
openStream() |
Opens a connection to this URL and returns an InputStream for reading from that connection. |
boolean |
sameFile |
Compares two URLs, excluding the fragment component. |
static void |
setURLStreamHandlerFactory |
Sets an application's URLStreamHandlerFactory. |
String |
toExternalForm() |
Constructs a string representation of this URL. |
String |
toString() |
Constructs a string representation of this URL. |
URI |
toURI() |
Returns a URI equivalent to this URL. |
@Deprecated(since="20") public URL(String protocol, String host, int port, String file) throws MalformedURLException
URI.toURL() to construct an instance of URL. See the note on constructor deprecation for more details.URL object from the specified protocol, host, port number, and file. 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 ('[' and ']'), as specified by RFC 2732; However, the literal IPv6 address format defined in RFC 2373: IP Version 6 Addressing Architecture is also accepted.
Specifying a port number of -1 indicates that the URL should use the default port for the protocol.
If this is the first URL object being created with the specified protocol, a stream protocol handler object, an instance of class URLStreamHandler, is created for that protocol:
URLStreamHandlerFactory as the stream handler factory, then the createURLStreamHandler method of that instance is called with the protocol string as an argument to create the stream protocol handler. URLStreamHandlerFactory has yet been set up, or if the factory's createURLStreamHandler method returns null, then the ServiceLoader mechanism is used to locate URLStreamHandlerProvider implementations using the system class loader. The order that providers are located is implementation specific, and an implementation is free to cache the located providers. A ServiceConfigurationError, Error or RuntimeException thrown from the createURLStreamHandler, if encountered, will be propagated to the calling thread. The
createURLStreamHandler method of each provider, if instantiated, is invoked, with the protocol string, until a provider returns non-null, or all providers have been exhausted. java.protocol.handler.pkgsnull, it is interpreted as a list of packages separated by a vertical slash character '|'. The constructor tries to load the class named:
<package>.<protocol>.Handler
<package> is replaced by the name of the package and <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 URLStreamHandler, then the next package in the list is tried. URLStreamHandler, then a MalformedURLException is thrown. Protocol handlers for the following protocols are guaranteed to exist on the search path:
httphttpsfilejarNo validation of the inputs is performed by this constructor.
protocol - the name of the protocol to use.host - the name of the host.port - the port number on the host.file - the file on the hostMalformedURLException - if an unknown protocol or the port is a negative number other than -1, or if the underlying stream handler implementation rejects, or is known to reject, the URL
@Deprecated(since="20") public URL(String protocol, String host, String file) throws MalformedURLException
URI.toURL() to construct an instance of URL. See the note on constructor deprecation for more details.protocol name, host name, and file name. The default port for the specified protocol is used. This constructor is equivalent to the four-argument constructor with the only difference of using the default port for the specified protocol. No validation of the inputs is performed by this constructor.
protocol - the name of the protocol to use.host - the name of the host.file - the file on the host.MalformedURLException - if an unknown protocol is specified, or if the underlying stream handler implementation rejects, or is known to reject, the URL
@Deprecated(since="20") public URL(String protocol, String host, int port, String file, URLStreamHandler handler) throws MalformedURLException
of(URI, URLStreamHandler) to construct an instance of URL associated with a custom protocol handler. See the note on constructor deprecation for more details.URL object from the specified protocol, host, port number, file, and handler. Specifying a port number of -1 indicates that the URL should use the default port for the protocol. Specifying a handler of null indicates that the URL should use a default stream handler for the protocol, as outlined for: URL(java.lang.String, java.lang.String, int, java.lang.String) If the handler is not null and there is a security manager, the security manager's checkPermission method is called with a NetPermission("specifyStreamHandler") permission. This may result in a SecurityException. No validation of the inputs is performed by this constructor.
protocol - the name of the protocol to use.host - the name of the host.port - the port number on the host.file - the file on the hosthandler - the stream handler for the URL.MalformedURLException - if an unknown protocol or the port is a negative number other than -1, or if the underlying stream handler implementation rejects, or is known to reject, the URL
SecurityException - if a security manager exists and its checkPermission method doesn't allow specifying a stream handler explicitly.@Deprecated(since="20") public URL(String spec) throws MalformedURLException
URI.toURL() to construct an instance of URL. See the note on constructor deprecation for more details.URL object from the String representation. This constructor is equivalent to a call to the two-argument constructor with a null first argument.
spec - the String to parse as a URL.MalformedURLException - if no protocol is specified, or an unknown protocol is found, or spec is null, or the parsed URL fails to comply with the specific syntax of the associated protocol, or the underlying stream handler's parseURL method throws IllegalArgumentException
@Deprecated(since="20") public URL(URL context, String spec) throws MalformedURLException
URI.toURL() to construct an instance of URL. See the note on constructor deprecation for more details.
<scheme>://<authority><path>?<query>#<fragment>
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.
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.
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.
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 ".".
For a more detailed description of URL parsing, refer to RFC2396.
parseURL method on the selected handler.context - the context in which to parse the specification.spec - the String to parse as a URL.MalformedURLException - if no protocol is specified, or an unknown protocol is found, or spec is null, or the parsed URL fails to comply with the specific syntax of the associated protocol, or the underlying stream handler's parseURL method throws IllegalArgumentException
@Deprecated(since="20") public URL(URL context, String spec, URLStreamHandler handler) throws MalformedURLException
of(URI, URLStreamHandler) to construct an instance of URL associated with a custom protocol handler. See the note on constructor deprecation for more details.parseURL method on the selected handler.context - the context in which to parse the specification.spec - the String to parse as a URL.handler - the stream handler for the URL.MalformedURLException - if no protocol is specified, or an unknown protocol is found, or spec is null, or the parsed URL fails to comply with the specific syntax of the associated protocol, or the underlying stream handler's parseURL method throws IllegalArgumentException
SecurityException - if a security manager exists and its checkPermission method doesn't allow specifying a stream handler.public static URL of(URI uri, URLStreamHandler handler) throws MalformedURLException
uri.toURL(), but associating it with the given URLStreamHandler, if allowed.URL and opening a connection. See the API note in the class level API documentation.parseURL method on the selected handler.uri - the URI from which the returned URL should be builthandler - a custom protocol stream handler for the returned URL. Can be null, in which case the default stream handler for the protocol if any, will be used.URL instance created from the given URI and associated with the given URLStreamHandler, if anyNullPointerException - if uri is null
IllegalArgumentException - if no protocol is specified (the uri scheme is null), or if the URLStreamHandler is not null and can not be set for the given protocolMalformedURLException - if an unknown protocol is found, or the given URI fails to comply with the specific syntax of the associated protocol, or the underlying stream handler's parseURL method throws IllegalArgumentException
SecurityException - if a security manager exists and its checkPermission method doesn't allow specifying a stream handlerpublic String getQuery()
URL.URL, or null if one does not existpublic String getPath()
URL.URL, or an empty string if one does not existpublic String getUserInfo()
URL.URL, or null if one does not existpublic String getAuthority()
URL.URL
public int getPort()
URL.public int getDefaultPort()
URL. If the URL scheme or the URLStreamHandler for the URL do not define a default port number, then -1 is returned.public String getProtocol()
URL.URL.public String getHost()
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 ('[' and ']').URL.public String getFile()
URL. The returned file portion will be the same as getPath(), plus the concatenation of the value of getQuery(), if any. If there is no query portion, this method and getPath() will return identical results.URL, or an empty string if one does not existpublic String getRef()
URL.URL, or null if one does not existpublic boolean equals(Object obj)
If the given object is not a URL then this method immediately returns false.
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.
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.
Since hosts comparison requires name resolution, this operation is a blocking operation.
Note: The defined behavior for equals is known to be inconsistent with virtual hosting in HTTP.
public int hashCode()
The hash code is based upon all the URL components relevant for URL comparison. As such, this operation is a blocking operation.
public boolean sameFile(URL other)
Returns true if this URL and the other argument are equal without taking the fragment component into consideration.
other - the URL to compare against.true if they reference the same remote object; false otherwise.public String toString()
URL. The string is created by calling the toExternalForm method of the stream protocol handler for this object.public String toExternalForm()
URL. The string is created by calling the toExternalForm method of the stream protocol handler for this object.public URI toURI() throws URISyntaxException
URI equivalent to this URL. This method functions in the same way as new URI (this.toString()). 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.
URISyntaxException - if this URL is not formatted strictly according to RFC2396 and cannot be converted to a URI.public URLConnection openConnection() throws IOException
URLConnection instance that represents a connection to the remote object referred to by the URL. A new instance of URLConnection is created every time when invoking the URLStreamHandler.openConnection(URL) method of the protocol handler for this URL.
It should be noted that a URLConnection instance does not establish the actual network connection on creation. This will happen only when calling URLConnection.connect().
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.
URLConnection linking to the URL.IOException - if an I/O exception occurs.public URLConnection openConnection(Proxy proxy) throws IOException
openConnection(), 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. Invoking this method preempts the system's default ProxySelector settings.proxy - the Proxy through which this connection will be made. If direct connection is desired, Proxy.NO_PROXY should be specified.URLConnection to the URL.IOException - if an I/O exception occurs.SecurityException - if a security manager is present and the caller doesn't have permission to connect to the proxy.IllegalArgumentException - will be thrown if proxy is null, or proxy has the wrong typeUnsupportedOperationException - if the subclass that implements the protocol handler doesn't support this method.public final InputStream openStream() throws IOException
URL and returns an InputStream for reading from that connection. This method is a shorthand for:
openConnection().getInputStream()
IOException - if an I/O exception occurs.public final Object getContent() throws IOException
openConnection().getContent()
IOException - if an I/O exception occurs.public final Object getContent(Class<?>[] classes) throws IOException
openConnection().getContent(classes)
classes - an array of Java typesIOException - if an I/O exception occurs.public static void setURLStreamHandlerFactory(URLStreamHandlerFactory fac)
URLStreamHandlerFactory. This method can be called at most once in a given Java Virtual Machine. The URLStreamHandlerFactory instance is used to construct a stream protocol handler from a protocol name.
If there is a security manager, this method first calls the security manager's checkSetFactory method to ensure the operation is allowed. This could result in a SecurityException.
fac - the desired factory.Error - if the application has already set a factory.SecurityException - if a security manager exists and its checkSetFactory method doesn't allow the operation.
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https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/net/URL.html
URI.toURL()to construct an instance of URL.