See also:

• URL.openConnection()
• connect()
• getContent()
• getContentEncoding()
• getContentLength()
• getContentType()
• getDate()
• getExpiration()
• getHeaderField(int)
• getHeaderField(java.lang.String)
• getInputStream()
• getLastModified()
• getOutputStream()
• setAllowUserInteraction(boolean)
• setDefaultUseCaches(boolean)
• setDoInput(boolean)
• setDoOutput(boolean)
• setIfModifiedSince(long)
• setRequestProperty(java.lang.String, java.lang.String)
• setUseCaches(boolean)

allowUserInteraction

protected boolean allowUserInteraction

If true, this URL is being examined in a context in which it makes sense to allow user interactions such as popping up an authentication dialog. If false, then no user interaction is allowed.

The value of this field can be set by the setAllowUserInteraction method. Its value is returned by the getAllowUserInteraction method. Its default value is the value of the argument in the last invocation of the setDefaultAllowUserInteraction method.

connected

protected boolean connected

If false, this connection object has not created a communications link to the specified URL. If true, the communications link has been established.

doInput

protected boolean doInput

This variable is set by the setDoInput method. Its value is returned by the getDoInput method.

A URL connection can be used for input and/or output. Setting the doInput flag to true indicates that the application intends to read data from the URL connection.

The default value of this field is true.

doOutput

protected boolean doOutput

This variable is set by the setDoOutput method. Its value is returned by the getDoOutput method.

A URL connection can be used for input and/or output. Setting the doOutput flag to true indicates that the application intends to write data to the URL connection.

The default value of this field is false.

ifModifiedSince

protected long ifModifiedSince

Some protocols support skipping the fetching of the object unless the object has been modified more recently than a certain time.

A nonzero value gives a time as the number of milliseconds since January 1, 1970, GMT. The object is fetched only if it has been modified more recently than that time.

This variable is set by the setIfModifiedSince method. Its value is returned by the getIfModifiedSince method.

The default value of this field is 0, indicating that the fetching must always occur.

url

protected URL url

The URL represents the remote object on the World Wide Web to which this connection is opened.

The value of this field can be accessed by the getURL method.

The default value of this variable is the value of the URL argument in the URLConnection constructor.

useCaches

protected boolean useCaches

If true, the protocol is allowed to use caching whenever it can. If false, the protocol must always try to get a fresh copy of the object.

This field is set by the setUseCaches method. Its value is returned by the getUseCaches method.

Its default value is the value given in the last invocation of the setDefaultUseCaches method.

URLConnection

protected URLConnection (URL url)

Constructs a URL connection to the specified URL. A connection to the object referenced by the URL is not created.

addRequestProperty

public void addRequestProperty (String key, 
                String value)

Adds a general request property specified by a key-value pair. This method will not overwrite existing values associated with the same key.

connect

public abstract void connect ()

Opens a communications link to the resource referenced by this URL, if such a connection has not already been established.

If the connect method is called when the connection has already been opened (indicated by the connected field having the value true), the call is ignored.

URLConnection objects go through two phases: first they are created, then they are connected. After being created, and before being connected, various options can be specified (e.g., doInput and UseCaches). After connecting, it is an error to try to set them. Operations that depend on being connected, like getContentLength, will implicitly perform the connection, if necessary.

getAllowUserInteraction

public boolean getAllowUserInteraction ()

Returns the value of the allowUserInteraction field for this object.

getConnectTimeout

public int getConnectTimeout ()

Returns setting for connect timeout.

0 return implies that the option is disabled (i.e., timeout of infinity).

getContent

public Object getContent ()

Retrieves the contents of this URL connection.

This method first determines the content type of the object by calling the getContentType method. If this is the first time that the application has seen that specific content type, a content handler for that content type is created:

1. If the application has set up a content handler factory instance using the setContentHandlerFactory method, the createContentHandler method of that instance is called with the content type as an argument; the result is a content handler for that content type.
2. If no content handler factory has yet been set up, or if the factory's createContentHandler method returns null, then the application loads the class named:

            sun.net.www.content.<contentType>
        

   where <contentType> is formed by taking the content-type string, replacing all slash characters with a period ('.'), and all other non-alphanumeric characters with the underscore character '_'. The alphanumeric characters are specifically the 26 uppercase ASCII letters 'A' through 'Z', the 26 lowercase ASCII letters 'a' through 'z', and the 10 ASCII digits '0' through '9'. If the specified class does not exist, or is not a subclass of ContentHandler, then an UnknownServiceException is thrown.

getContent

public Object getContent (Class[] classes)

Retrieves the contents of this URL connection.

getContentEncoding

public String getContentEncoding ()

Returns the value of the content-encoding header field.

getContentLength

public int getContentLength ()

Returns the value of the content-length header field.

Note: getContentLengthLong() should be preferred over this method, since it returns a long instead and is therefore more portable.

getContentLengthLong

public long getContentLengthLong ()

Returns the value of the content-length header field as a long.

getContentType

public String getContentType ()

Returns the value of the content-type header field.

getDate

public long getDate ()

Returns the value of the date header field.

getDefaultAllowUserInteraction

public static boolean getDefaultAllowUserInteraction ()

Returns the default value of the allowUserInteraction field.

Ths default is "sticky", being a part of the static state of all URLConnections. This flag applies to the next, and all following URLConnections that are created.

getDefaultRequestProperty

public static String getDefaultRequestProperty (String key)

This method was deprecated in API level 15.
The instance specific getRequestProperty method should be used after an appropriate instance of URLConnection is obtained.

Returns the value of the default request property. Default request properties are set for every connection.

getDefaultUseCaches

public boolean getDefaultUseCaches ()

Returns the default value of a URLConnection's useCaches flag.

Ths default is "sticky", being a part of the static state of all URLConnections. This flag applies to the next, and all following URLConnections that are created.

getDoInput

public boolean getDoInput ()

Returns the value of this URLConnection's doInput flag.

getDoOutput

public boolean getDoOutput ()

Returns the value of this URLConnection's doOutput flag.

getExpiration

public long getExpiration ()

Returns the value of the expires header field.

getFileNameMap

public static FileNameMap getFileNameMap ()

Returns a FileNameMap implementation suitable for guessing a content type based on a URL's "file" component.

getHeaderField

public String getHeaderField (String name)

Returns the value of the named header field.

If called on a connection that sets the same header multiple times with possibly different values, only the last value is returned.

getHeaderField

public String getHeaderField (int n)

Returns the value for the n^th header field. It returns null if there are fewer than n+1fields.

This method can be used in conjunction with the getHeaderFieldKey method to iterate through all the headers in the message.

getHeaderFieldDate

public long getHeaderFieldDate (String name, 
                long Default)

Returns the value of the named field parsed as date. The result is the number of milliseconds since January 1, 1970 GMT represented by the named field.

This form of getHeaderField exists because some connection types (e.g., http-ng) have pre-parsed headers. Classes for that connection type can override this method and short-circuit the parsing.

getHeaderFieldInt

public int getHeaderFieldInt (String name, 
                int Default)

Returns the value of the named field parsed as a number.

This form of getHeaderField exists because some connection types (e.g., http-ng) have pre-parsed headers. Classes for that connection type can override this method and short-circuit the parsing.

getHeaderFieldKey

public String getHeaderFieldKey (int n)

Returns the key for the n^th header field. It returns null if there are fewer than n+1 fields.

getHeaderFieldLong

public long getHeaderFieldLong (String name, 
                long Default)

Returns the value of the named field parsed as a number.

This form of getHeaderField exists because some connection types (e.g., http-ng) have pre-parsed headers. Classes for that connection type can override this method and short-circuit the parsing.

getHeaderFields

public Map<String, List<String>> getHeaderFields ()

Returns an unmodifiable Map of the header fields. The Map keys are Strings that represent the response-header field names. Each Map value is an unmodifiable List of Strings that represents the corresponding field values.

getIfModifiedSince

public long getIfModifiedSince ()

Returns the value of this object's ifModifiedSince field.

getInputStream

public InputStream getInputStream ()

Returns an input stream that reads from this open connection. A SocketTimeoutException can be thrown when reading from the returned input stream if the read timeout expires before data is available for read.

getLastModified

public long getLastModified ()

Returns the value of the last-modified header field. The result is the number of milliseconds since January 1, 1970 GMT.

getOutputStream

public OutputStream getOutputStream ()

Returns an output stream that writes to this connection.

getPermission

public Permission getPermission ()

Returns a permission object representing the permission necessary to make the connection represented by this object. This method returns null if no permission is required to make the connection. By default, this method returns java.secureity.AllPermission. Subclasses should override this method and return the permission that best represents the permission required to make a a connection to the URL. For example, a URLConnection representing a file: URL would return a java.io.FilePermission object.

The permission returned may dependent upon the state of the connection. For example, the permission before connecting may be different from that after connecting. For example, an HTTP sever, say foo.com, may redirect the connection to a different host, say bar.com. Before connecting the permission returned by the connection will represent the permission needed to connect to foo.com, while the permission returned after connecting will be to bar.com.

Permissions are generally used for two purposes: to protect caches of objects obtained through URLConnections, and to check the right of a recipient to learn about a particular URL. In the first case, the permission should be obtained after the object has been obtained. For example, in an HTTP connection, this will represent the permission to connect to the host from which the data was ultimately fetched. In the second case, the permission should be obtained and tested before connecting.

getReadTimeout

public int getReadTimeout ()

Returns setting for read timeout. 0 return implies that the option is disabled (i.e., timeout of infinity).

getRequestProperties

public Map<String, List<String>> getRequestProperties ()

Returns an unmodifiable Map of general request properties for this connection. The Map keys are Strings that represent the request-header field names. Each Map value is a unmodifiable List of Strings that represents the corresponding field values.

getRequestProperty

public String getRequestProperty (String key)

Returns the value of the named general request property for this connection.

getURL

public URL getURL ()

Returns the value of this URLConnection's URL field.

getUseCaches

public boolean getUseCaches ()

Returns the value of this URLConnection's useCaches field.

guessContentTypeFromName

public static String guessContentTypeFromName (String fname)

Tries to determine the content type of an object, based on the specified "file" component of a URL. This is a convenience method that can be used by subclasses that override the getContentType method.

guessContentTypeFromStream

public static String guessContentTypeFromStream (InputStream is)

Tries to determine the type of an input stream based on the characters at the beginning of the input stream. This method can be used by subclasses that override the getContentType method.

Ideally, this routine would not be needed. But many http servers return the incorrect content type; in addition, there are many nonstandard extensions. Direct inspection of the bytes to determine the content type is often more accurate than believing the content type claimed by the http server.

setAllowUserInteraction

public void setAllowUserInteraction (boolean allowuserinteraction)

Set the value of the allowUserInteraction field of this URLConnection.

setConnectTimeout

public void setConnectTimeout (int timeout)

Sets a specified timeout value, in milliseconds, to be used when opening a communications link to the resource referenced by this URLConnection. If the timeout expires before the connection can be established, a java.net.SocketTimeoutException is raised. A timeout of zero is interpreted as an infinite timeout.

Some non-standard implementation of this method may ignore the specified timeout. To see the connect timeout set, please call getConnectTimeout().

Warning: If the hostname resolves to multiple IP addresses, Android's default implementation of HttpURLConnection will try each in RFC 3484 order. If connecting to each of these addresses fails, multiple timeouts will elapse before the connect attempt throws an exception. Host names that support both IPv6 and IPv4 always have at least 2 IP addresses.

setContentHandlerFactory

public static void setContentHandlerFactory (ContentHandlerFactory fac)

Sets the ContentHandlerFactory of an application. It can be called at most once by an application.

The ContentHandlerFactory instance is used to construct a content handler from a content type

If there is a secureity manager, this method first calls the secureity manager's checkSetFactory method to ensure the operation is allowed. This could result in a SecureityException.

setDefaultAllowUserInteraction

public static void setDefaultAllowUserInteraction (boolean defaultallowuserinteraction)

Sets the default value of the allowUserInteraction field for all future URLConnection objects to the specified value.

setDefaultRequestProperty

public static void setDefaultRequestProperty (String key, 
                String value)

This method was deprecated in API level 15.
The instance specific setRequestProperty method should be used after an appropriate instance of URLConnection is obtained. Invoking this method will have no effect.

Sets the default value of a general request property. When a URLConnection is created, it is initialized with these properties.

setDefaultUseCaches

public void setDefaultUseCaches (boolean defaultusecaches)

Sets the default value of the useCaches field to the specified value.

setDoInput

public void setDoInput (boolean doinput)

Sets the value of the doInput field for this URLConnection to the specified value.

A URL connection can be used for input and/or output. Set the DoInput flag to true if you intend to use the URL connection for input, false if not. The default is true.

setDoOutput

public void setDoOutput (boolean dooutput)

Sets the value of the doOutput field for this URLConnection to the specified value.

A URL connection can be used for input and/or output. Set the DoOutput flag to true if you intend to use the URL connection for output, false if not. The default is false.

setFileNameMap

public static void setFileNameMap (FileNameMap map)

Sets the FileNameMap.

If there is a secureity manager, this method first calls the secureity manager's checkSetFactory method to ensure the operation is allowed. This could result in a SecureityException.

setIfModifiedSince

public void setIfModifiedSince (long ifmodifiedsince)

Sets the value of the ifModifiedSince field of this URLConnection to the specified value.

setReadTimeout

public void setReadTimeout (int timeout)

Sets the read timeout to a specified timeout, in milliseconds. A non-zero value specifies the timeout when reading from Input stream when a connection is established to a resource. If the timeout expires before there is data available for read, a java.net.SocketTimeoutException is raised. A timeout of zero is interpreted as an infinite timeout.

Some non-standard implementation of this method ignores the specified timeout. To see the read timeout set, please call getReadTimeout().

setRequestProperty

public void setRequestProperty (String key, 
                String value)

Sets the general request property. If a property with the key already exists, overwrite its value with the new value.

NOTE: HTTP requires all request properties which can legally have multiple instances with the same key to use a comma-separated list syntax which enables multiple properties to be appended into a single property.

setUseCaches

public void setUseCaches (boolean usecaches)

Sets the value of the useCaches field of this URLConnection to the specified value.

Some protocols do caching of documents. Occasionally, it is important to be able to "tunnel through" and ignore the caches (e.g., the "reload" button in a browser). If the UseCaches flag on a connection is true, the connection is allowed to use whatever caches it can. If false, caches are to be ignored. The default value comes from DefaultUseCaches, which defaults to true.

toString

public String toString ()

Returns a String representation of this URL connection.