IT. Expert System.

Android Reference

URL

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:

Component	Example value	Also known as
`Protocol`	`http`	scheme
`Authority`	`username:password@host:8080`
`User Info`	`username:password`
`Host`	`host`
`Port`	`8080`
`File`	`/directory/file?query`
`Path`	`/directory/file`
`Query`	`query`
`Ref`	`ref`	fragment

Supported Protocols

This class may be used to construct URLs with the following protocols:

file: read files from the local filesystem.
ftp: File Transfer Protocol
http: Hypertext Transfer Protocol
https: HTTP over TLS
jar: read Jar files from the filesystem

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 Summary

Constructors
Constructor and Description
`URL(String spec)` Creates a new URL instance by parsing `spec`.
`URL(String protocol, String host, int port, String file)` Creates a new URL of the given component parts.
`URL(String protocol, String host, int port, String file, URLStreamHandler handler)` Creates a new URL of the given component parts.
`URL(String protocol, String host, String file)` Creates a new URL of the given component parts.
`URL(URL context, String spec)` Creates a new URL by resolving `spec` relative to `context`.
`URL(URL context, String spec, URLStreamHandler handler)` Creates a new URL by resolving `spec` relative to `context`.

Method Summary

Methods
Modifier and Type	Method and Description
`boolean`	`equals(Object o)` Returns true if this URL equals `o`.
`String`	`getAuthority()` Returns the authority part of this URL, or null if this URL has no authority.
`Object`	`getContent()` Returns the content of the resource which is referred by this URL.
`Object`	`getContent(Class[] types)` Equivalent to `openConnection().getContent(types)`.
`int`	`getDefaultPort()` Returns the default port number of the protocol used by this URL.
`int`	`getEffectivePort()`
`String`	`getFile()` Returns the file of this URL.
`String`	`getHost()` Returns the host name or IP address of this URL.
`String`	`getPath()` Returns the path part of this URL.
`int`	`getPort()` Returns the port number of this URL or `-1` if this URL has no explicit port.
`String`	`getProtocol()` Returns the protocol of this URL like "http" or "file".
`String`	`getQuery()` Returns the query part of this URL, or null if this URL has no query.
`String`	`getRef()` Returns the value of the reference part of this URL, or null if this URL has no reference part.
`String`	`getUserInfo()` Returns the user info of this URL, or null if this URL has no user info.
`int`	`hashCode()` Returns an integer hash code for this object.
`URLConnection`	`openConnection()` Returns a new connection to the resource referred to by this URL.
`URLConnection`	`openConnection(Proxy proxy)` Returns a new connection to the resource referred to by this URL.
`InputStream`	`openStream()` Equivalent to `openConnection().getInputStream(types)`.
`boolean`	`sameFile(URL otherURL)` Returns true if this URL refers to the same resource as `otherURL`.
`protected void`	`set(String protocol, String host, int port, String file, String ref)` Sets the properties of this URL using the provided arguments.
`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.
`static void`	`setURLStreamHandlerFactory(URLStreamHandlerFactory factory)` Sets the stream handler factory for this VM.
`String`	`toExternalForm()` Returns a string containing a concise, human-readable representation of this URL.
`String`	`toString()` Returns a string containing a concise, human-readable representation of this URL.
`URI`	`toURI()` Returns the URI equivalent to this URL.
`URI`	`toURILenient()` Encodes this URL to the equivalent URI after escaping characters that are not permitted by URI.

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - 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 Detail
  - 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.

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IT. Expert System.

Android Reference

URL

Class URL

Parts of a URL

Supported Protocols

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

URL

URL

URL

URL

URL

URL

Method Detail

setURLStreamHandlerFactory

set

equals

Network I/O Warning

sameFile

hashCode

getContent

getContent

openStream

openConnection

openConnection

toURI

toURILenient

toString

toExternalForm

getEffectivePort

getProtocol

getAuthority

getUserInfo

getHost

getPort

getDefaultPort

getFile

getPath

getQuery

getRef

set

Android Reference

Java basics

Java Enterprise Edition (EE)

Java Standard Edition (SE)

SQL

HTML

PHP

CSS

Java Script

MYSQL

JQUERY

VBS

REGEX

C

C++

C#

Design patterns

RFC (standard status)

RFC (proposed standard status)

RFC (draft standard status)

RFC (informational status)

RFC (experimental status)

RFC (best current practice status)

RFC (historic status)

RFC (unknown status)

IT dictionary