Package java.net

Class URL

java.lang.Object
java.net.URL
All Implemented Interfaces:
Serializable
public final class URL
extends Object
implements Serializable
A Uniform Resource Locator that identifies the location of an Internet resource as specified by RFC 1738.

Parts of a URL

A URL is composed of many parts. This class can both parse URL strings into parts and compose URL strings from parts. For example, consider the parts of this URL: http://username:password@host:8080/directory/file?query#ref:
ComponentExample valueAlso known as
Protocolhttpscheme
Authorityusername:password@host:8080
User Infousername:password
Hosthost
Port8080
File/directory/file?query
Path/directory/file
Queryquery
Refreffragment

Supported Protocols

This class may be used to construct URLs with the following protocols: In general, attempts to create URLs with any other protocol will fail with a MalformedURLException. Applications may install handlers for other schemes using setURLStreamHandlerFactory(java.net.URLStreamHandlerFactory) or with the java.protocol.handler.pkgs system property.

The URI class can be used to manipulate URLs of any protocol.

See Also:
Serialized Form

  • Constructor Details

    • URL

      public URL​(String spec) throws MalformedURLException
      Creates a new URL instance by parsing spec.
      Throws:
      MalformedURLException - if spec could not be parsed as a URL.

    • URL

      public URL​(URL context, String spec) throws MalformedURLException
      Creates a new URL by resolving spec relative to context.
      Parameters:
      context - the URL to which spec is relative, or null for no context in which case spec must be an absolute URL.
      Throws:
      MalformedURLException - if spec could not be parsed as a URL or has an unsupported protocol.

    • URL

      public URL​(URL context, String spec, URLStreamHandler handler) throws MalformedURLException
      Creates a new URL by resolving spec relative to context.
      Parameters:
      context - the URL to which spec is relative, or null for no context in which case spec must be an absolute URL.
      handler - the stream handler for this URL, or null for the protocol's default stream handler.
      Throws:
      MalformedURLException - if the given string spec could not be parsed as a URL or an invalid protocol has been found.

    • URL

      public URL​(String protocol, String host, String file) throws MalformedURLException
      Creates a new URL of the given component parts. The URL uses the protocol's default port.
      Throws:
      MalformedURLException - if the combination of all arguments do not represent a valid URL or if the protocol is invalid.

    • URL

      public URL​(String protocol, String host, int port, String file) throws MalformedURLException
      Creates a new URL of the given component parts. The URL uses the protocol's default port.
      Parameters:
      host - the host name or IP address of the new URL.
      port - the port, or -1 for the protocol's default port.
      file - the name of the resource.
      Throws:
      MalformedURLException - if the combination of all arguments do not represent a valid URL or if the protocol is invalid.

    • URL

      public URL​(String protocol, String host, int port, String file, URLStreamHandler handler) throws MalformedURLException
      Creates a new URL of the given component parts. The URL uses the protocol's default port.
      Parameters:
      host - the host name or IP address of the new URL.
      port - the port, or -1 for the protocol's default port.
      file - the name of the resource.
      handler - the stream handler for this URL, or null for the protocol's default stream handler.
      Throws:
      MalformedURLException - if the combination of all arguments do not represent a valid URL or if the protocol is invalid.

  • Method Details

    • setURLStreamHandlerFactory

      public static void setURLStreamHandlerFactory​(URLStreamHandlerFactory factory)
      Sets the stream handler factory for this VM.
      Throws:
      Error - if a URLStreamHandlerFactory has already been installed for the current VM.

    • set

      protected void set​(String protocol, String host, int port, String file, String ref)
      Sets the properties of this URL using the provided arguments. Only a URLStreamHandler can use this method to set fields of the existing URL instance. A URL is generally constant.

    • equals

      public boolean equals​(Object o)
      Returns true if this URL equals o. URLs are equal if they have the same protocol, host, port, file, and reference.

      Network I/O Warning

      Some implementations of URL.equals() resolve host names over the network. This is problematic:

      • The network may be slow. Many classes, including core collections like Map and Set expect that equals and hashCode will return quickly. By violating this assumption, this method posed potential performance problems.
      • Equal IP addresses do not imply equal content. Virtual hosting permits unrelated sites to share an IP address. This method could report two otherwise unrelated URLs to be equal because they're hosted on the same server.
      • The network many not be available. Two URLs could be equal when a network is available and unequal otherwise.
      • The network may change. The IP address for a given host name varies by network and over time. This is problematic for mobile devices. Two URLs could be equal on some networks and unequal on others.

      This problem is fixed in Android 4.0 (Ice Cream Sandwich). In that release, URLs are only equal if their host names are equal (ignoring case).

      Overrides:
      equals in class Object
      Parameters:
      o - the object to compare this instance with.
      Returns:
      true if the specified object is equal to this Object; false otherwise.
      See Also:
      Object.hashCode()

    • sameFile

      public boolean sameFile​(URL otherURL)
      Returns true if this URL refers to the same resource as otherURL. All URL components except the reference field are compared.

    • hashCode

      public int hashCode()
      Description copied from class: Object
      Returns an integer hash code for this object. By contract, any two objects for which Object.equals(java.lang.Object) returns true must return the same hash code value. This means that subclasses of Object usually override both methods or neither method.

      Note that hash values must not change over time unless information used in equals comparisons also changes.

      See Writing a correct hashCode method if you intend implementing your own hashCode method.

      Overrides:
      hashCode in class Object
      Returns:
      this object's hash code.
      See Also:
      Object.equals(java.lang.Object)

    • getContent

      public final Object getContent() throws IOException
      Returns the content of the resource which is referred by this URL. By default this returns an InputStream, or null if the content type of the response is unknown.
      Throws:
      IOException

    • getContent

      public final Object getContent​(Class[] types) throws IOException
      Equivalent to openConnection().getContent(types).
      Throws:
      IOException

    • openStream

      public final InputStream openStream() throws IOException
      Equivalent to openConnection().getInputStream(types).
      Throws:
      IOException

    • openConnection

      public URLConnection openConnection() throws IOException
      Returns a new connection to the resource referred to by this URL.
      Throws:
      IOException - if an error occurs while opening the connection.

    • openConnection

      public URLConnection openConnection​(Proxy proxy) throws IOException
      Returns a new connection to the resource referred to by this URL.
      Parameters:
      proxy - the proxy through which the connection will be established.
      Throws:
      IOException - if an I/O error occurs while opening the connection.
      IllegalArgumentException - if the argument proxy is null or of is an invalid type.
      UnsupportedOperationException - if the protocol handler does not support opening connections through proxies.

    • toURI

      public URI toURI() throws URISyntaxException
      Returns the URI equivalent to this URL.
      Throws:
      URISyntaxException - if this URL cannot be converted into a URI.

    • toURILenient

      public URI toURILenient() throws URISyntaxException
      Encodes this URL to the equivalent URI after escaping characters that are not permitted by URI.
      Throws:
      URISyntaxException

    • toString

      public String toString()
      Returns a string containing a concise, human-readable representation of this URL. The returned string is the same as the result of the method toExternalForm().
      Overrides:
      toString in class Object
      Returns:
      a printable representation of this object.

    • toExternalForm

      public String toExternalForm()
      Returns a string containing a concise, human-readable representation of this URL.

    • getEffectivePort

      public int getEffectivePort()

    • getProtocol

      public String getProtocol()
      Returns the protocol of this URL like "http" or "file". This is also known as the scheme. The returned string is lower case.

    • getAuthority

      public String getAuthority()
      Returns the authority part of this URL, or null if this URL has no authority.

    • getUserInfo

      public String getUserInfo()
      Returns the user info of this URL, or null if this URL has no user info.

    • getHost

      public String getHost()
      Returns the host name or IP address of this URL.

    • getPort

      public int getPort()
      Returns the port number of this URL or -1 if this URL has no explicit port.

      If this URL has no explicit port, connections opened using this URL will use its default port.

    • getDefaultPort

      public int getDefaultPort()
      Returns the default port number of the protocol used by this URL. If no default port is defined by the protocol or the URLStreamHandler, -1 will be returned.
      See Also:
      URLStreamHandler.getDefaultPort()

    • getFile

      public String getFile()
      Returns the file of this URL.

    • getPath

      public String getPath()
      Returns the path part of this URL.

    • getQuery

      public String getQuery()
      Returns the query part of this URL, or null if this URL has no query.

    • getRef

      public String getRef()
      Returns the value of the reference part of this URL, or null if this URL has no reference part. This is also known as the fragment.

    • set

      protected void set​(String protocol, String host, int port, String authority, String userInfo, String path, String query, String ref)
      Sets the properties of this URL using the provided arguments. Only a URLStreamHandler can use this method to set fields of the existing URL instance. A URL is generally constant.