URLConnection
  public
  
  
  abstract
  class
  URLConnection
  
    extends Object
  
  
  
  
  
  
| java.lang.Object | |
| ↳ | java.net.URLConnection | 
The abstract class URLConnection is the superclass
 of all classes that represent a communications link between the
 application and a URL. Instances of this class can be used both to
 read from and to write to the resource referenced by the URL. In
 general, creating a connection to a URL is a multistep process:
 
| openConnection() | connect() | 
|---|---|
| Manipulate parameters that affect the connection to the remote resource. | Interact with the resource; query header fields and contents. | 
time
- The connection object is created by invoking the
     openConnectionmethod on a URL.
- The setup parameters and general request properties are manipulated.
- The actual connection to the remote object is made, using the
    connectmethod.
- The remote object becomes available. The header fields and the contents of the remote object can be accessed.
The setup parameters are modified using the following methods:
- setAllowUserInteraction
- setDoInput
- setDoOutput
- setIfModifiedSince
- setUseCaches
and the general request properties are modified using the method:
- setRequestProperty
 Default values for the AllowUserInteraction and
 UseCaches parameters can be set using the methods
 setDefaultAllowUserInteraction and
 setDefaultUseCaches.
 
 Each of the above set methods has a corresponding
 get method to retrieve the value of the parameter or
 general request property. The specific parameters and general
 request properties that are applicable are protocol specific.
 
The following methods are used to access the header fields and the contents after the connection is made to the remote object:
- getContent
- getHeaderField
- getInputStream
- getOutputStream
Certain header fields are accessed frequently. The methods:
- getContentEncoding
- getContentLength
- getContentType
- getDate
- getExpiration
- getLastModifed
 provide convenient access to these fields. The
 getContentType method is used by the
 getContent method to determine the type of the remote
 object; subclasses may find it convenient to override the
 getContentType method.
 
 In the common case, all of the pre-connection parameters and
 general request properties can be ignored: the pre-connection
 parameters and request properties default to sensible values. For
 most clients of this interface, there are only two interesting
 methods: getInputStream and getContent,
 which are mirrored in the URL class by convenience methods.
 
 More information on the request properties and header fields of
 an http connection can be found at:
 
Invoking the
close() methods on the InputStream or OutputStream of an
 URLConnection after a request may free network resources associated with this
 instance, unless particular protocol specifications specify different behaviours
 for it.
  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)
Summary
| Fields | |
|---|---|
| 
    protected
    
    
    boolean | allowUserInteractionIf  | 
| 
    protected
    
    
    boolean | connectedIf  | 
| 
    protected
    
    
    boolean | doInputThis variable is set by the  | 
| 
    protected
    
    
    boolean | doOutputThis variable is set by the  | 
| 
    protected
    
    
    long | ifModifiedSinceSome protocols support skipping the fetching of the object unless the object has been modified more recently than a certain time. | 
| 
    protected
    
    
    URL | urlThe URL represents the remote object on the World Wide Web to which this connection is opened. | 
| 
    protected
    
    
    boolean | useCachesIf  | 
| Protected constructors | |
|---|---|
| 
      URLConnection(URL url)
      Constructs a URL connection to the specified URL. | |
| Public methods | |
|---|---|
| 
        
        
        
        
        
        void | 
      addRequestProperty(String key, String value)
      Adds a general request property specified by a key-value pair. | 
| 
        abstract
        
        
        
        
        void | 
      connect()
      Opens a communications link to the resource referenced by this URL, if such a connection has not already been established. | 
| 
        
        
        
        
        
        boolean | 
      getAllowUserInteraction()
      Returns the value of the  | 
| 
        
        
        
        
        
        int | 
      getConnectTimeout()
      Returns setting for connect timeout. | 
| 
        
        
        
        
        
        Object | 
      getContent()
      Retrieves the contents of this URL connection. | 
| 
        
        
        
        
        
        Object | 
      getContent(Class[] classes)
      Retrieves the contents of this URL connection. | 
| 
        
        
        
        
        
        String | 
      getContentEncoding()
      Returns the value of the  | 
| 
        
        
        
        
        
        int | 
      getContentLength()
      Returns the value of the  | 
| 
        
        
        
        
        
        long | 
      getContentLengthLong()
      Returns the value of the  | 
| 
        
        
        
        
        
        String | 
      getContentType()
      Returns the value of the  | 
| 
        
        
        
        
        
        long | 
      getDate()
      Returns the value of the  | 
| 
        
        
        static
        
        
        boolean | 
      getDefaultAllowUserInteraction()
      Returns the default value of the  | 
| 
        
        
        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. | 
| 
        
        
        
        
        
        boolean | 
      getDefaultUseCaches()
      Returns the default value of a  | 
| 
        
        
        
        
        
        boolean | 
      getDoInput()
      Returns the value of this  | 
| 
        
        
        
        
        
        boolean | 
      getDoOutput()
      Returns the value of this  | 
| 
        
        
        
        
        
        long | 
      getExpiration()
      Returns the value of the  | 
| 
        
        
        static
        
        
        FileNameMap | 
      getFileNameMap()
      Returns a  | 
| 
        
        
        
        
        
        String | 
      getHeaderField(String name)
      Returns the value of the named header field. | 
| 
        
        
        
        
        
        String | 
      getHeaderField(int n)
      Returns the value for the  | 
| 
        
        
        
        
        
        long | 
      getHeaderFieldDate(String name, long Default)
      Returns the value of the named field parsed as date. | 
| 
        
        
        
        
        
        int | 
      getHeaderFieldInt(String name, int Default)
      Returns the value of the named field parsed as a number. | 
| 
        
        
        
        
        
        String | 
      getHeaderFieldKey(int n)
      Returns the key for the  | 
| 
        
        
        
        
        
        long | 
      getHeaderFieldLong(String name, long Default)
      Returns the value of the named field parsed as a number. | 
| 
        
        
        
        
        
        Map<String, List<String>> | 
      getHeaderFields()
      Returns an unmodifiable Map of the header fields. | 
| 
        
        
        
        
        
        long | 
      getIfModifiedSince()
      Returns the value of this object's  | 
| 
        
        
        
        
        
        InputStream | 
      getInputStream()
      Returns an input stream that reads from this open connection. | 
| 
        
        
        
        
        
        long | 
      getLastModified()
      Returns the value of the  | 
| 
        
        
        
        
        
        OutputStream | 
      getOutputStream()
      Returns an output stream that writes to this connection. | 
| 
        
        
        
        
        
        Permission | 
      getPermission()
      Returns a permission object representing the permission necessary to make the connection represented by this object. | 
| 
        
        
        
        
        
        int | 
      getReadTimeout()
      Returns setting for read timeout. | 
| 
        
        
        
        
        
        Map<String, List<String>> | 
      getRequestProperties()
      Returns an unmodifiable Map of general request properties for this connection. | 
| 
        
        
        
        
        
        String | 
      getRequestProperty(String key)
      Returns the value of the named general request property for this connection. | 
| 
        
        
        
        
        
        URL | 
      getURL()
      Returns the value of this  | 
| 
        
        
        
        
        
        boolean | 
      getUseCaches()
      Returns the value of this  | 
| 
        
        
        static
        
        
        String | 
      guessContentTypeFromName(String fname)
      Tries to determine the content type of an object, based on the specified "file" component of a URL. | 
| 
        
        
        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. | 
| 
        
        
        
        
        
        void | 
      setAllowUserInteraction(boolean allowuserinteraction)
      Set the value of the  | 
| 
        
        
        
        
        
        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. | 
| 
        
        
        static
        
        
        void | 
      setContentHandlerFactory(ContentHandlerFactory fac)
      Sets the  | 
| 
        
        
        static
        
        
        void | 
      setDefaultAllowUserInteraction(boolean defaultallowuserinteraction)
      Sets the default value of the
  | 
| 
        
        
        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. | 
| 
        
        
        
        
        
        void | 
      setDefaultUseCaches(boolean defaultusecaches)
      Sets the default value of the  | 
| 
        
        
        
        
        
        void | 
      setDoInput(boolean doinput)
      Sets the value of the  | 
| 
        
        
        
        
        
        void | 
      setDoOutput(boolean dooutput)
      Sets the value of the  | 
| 
        
        
        static
        
        
        void | 
      setFileNameMap(FileNameMap map)
      Sets the FileNameMap. | 
| 
        
        
        
        
        
        void | 
      setIfModifiedSince(long ifmodifiedsince)
      Sets the value of the  | 
| 
        
        
        
        
        
        void | 
      setReadTimeout(int timeout)
      Sets the read timeout to a specified timeout, in milliseconds. | 
| 
        
        
        
        
        
        void | 
      setRequestProperty(String key, String value)
      Sets the general request property. | 
| 
        
        
        
        
        
        void | 
      setUseCaches(boolean usecaches)
      Sets the value of the  | 
| 
        
        
        
        
        
        String | 
      toString()
      Returns a  | 
| Inherited methods | |
|---|---|
Fields
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.
See also:
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.
See also:
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.
Protected constructors
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.
| Parameters | |
|---|---|
| url | URL: the specified URL. | 
Public methods
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.
| Parameters | |
|---|---|
| key | String: the keyword by which the request is known
                  (e.g., "Accept"). | 
| value | String: the value associated with it. | 
| Throws | |
|---|---|
| IllegalStateException | if already connected | 
| NullPointerException | if key is null | 
See also:
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.
| Throws | |
|---|---|
| SocketTimeoutException | if the timeout expires before the connection can be established | 
| IOException | if an I/O error occurs while opening the connection. | 
getAllowUserInteraction
public boolean getAllowUserInteraction ()
Returns the value of the allowUserInteraction field for
 this object.
| Returns | |
|---|---|
| boolean | the value of the allowUserInteractionfield for
          this object. | 
See also:
getConnectTimeout
public int getConnectTimeout ()
Returns setting for connect timeout.
0 return implies that the option is disabled (i.e., timeout of infinity).
| Returns | |
|---|---|
| int | an intthat indicates the connect timeout
         value in milliseconds | 
See also:
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:
 
- If the application has set up a content handler factory instance
     using the setContentHandlerFactorymethod, thecreateContentHandlermethod of that instance is called with the content type as an argument; the result is a content handler for that content type.
- If no content handler factory has yet been set up, or if the
     factory's createContentHandlermethod returnsnull, then the application loads the class named:
 where <contentType> is formed by taking the content-type string, replacing all slash characters with asun.net.www.content.<contentType>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 ofContentHandler, then anUnknownServiceExceptionis thrown.
| Returns | |
|---|---|
| Object | the object fetched. The instanceofoperator
               should be used to determine the specific kind of object
               returned. | 
| Throws | |
|---|---|
| IOException | if an I/O error occurs while getting the content. | 
| UnknownServiceException | if the protocol does not support the content type. | 
getContent
public Object getContent (Class[] classes)
Retrieves the contents of this URL connection.
| Parameters | |
|---|---|
| classes | Class: theClassarray
 indicating the requested types | 
| Returns | |
|---|---|
| Object | the object fetched that is the first match of the type
               specified in the classes array. null if none of
               the requested types are supported.
               The instanceofoperator should be used to
               determine the specific kind of object returned. | 
| Throws | |
|---|---|
| IOException | if an I/O error occurs while getting the content. | 
| UnknownServiceException | if the protocol does not support the content type. | 
getContentEncoding
public String getContentEncoding ()
Returns the value of the content-encoding header field.
| Returns | |
|---|---|
| String | the content encoding of the resource that the URL references,
          or nullif not known. | 
See also:
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.
| Returns | |
|---|---|
| int | the content length of the resource that this connection's URL
          references, -1if the content length is not known,
          or if the content length is greater than Integer.MAX_VALUE. | 
getContentLengthLong
public long getContentLengthLong ()
Returns the value of the content-length header field as a
 long.
| Returns | |
|---|---|
| long | the content length of the resource that this connection's URL
          references, or -1if the content length is
          not known. | 
getContentType
public String getContentType ()
Returns the value of the content-type header field.
| Returns | |
|---|---|
| String | the content type of the resource that the URL references,
          or nullif not known. | 
See also:
getDate
public long getDate ()
Returns the value of the date header field.
| Returns | |
|---|---|
| long | the sending date of the resource that the URL references,
          or 0if not known. The value returned is the
          number of milliseconds since January 1, 1970 GMT. | 
See also:
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.
| Returns | |
|---|---|
| boolean | the default value of the allowUserInteractionfield. | 
See also:
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.
| Parameters | |
|---|---|
| key | String: the keyword by which the request is known (e.g., "Accept"). | 
| Returns | |
|---|---|
| String | the value of the default request property for the specified key. | 
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.
| Returns | |
|---|---|
| boolean | the default value of a URLConnection'suseCachesflag. | 
See also:
getDoInput
public boolean getDoInput ()
Returns the value of this URLConnection's
 doInput flag.
| Returns | |
|---|---|
| boolean | the value of this URLConnection'sdoInputflag. | 
See also:
getDoOutput
public boolean getDoOutput ()
Returns the value of this URLConnection's
 doOutput flag.
| Returns | |
|---|---|
| boolean | the value of this URLConnection'sdoOutputflag. | 
See also:
getExpiration
public long getExpiration ()
Returns the value of the expires header field.
| Returns | |
|---|---|
| long | the expiration date of the resource that this URL references, or 0 if not known. The value is the number of milliseconds since January 1, 1970 GMT. | 
See also:
getFileNameMap
public static FileNameMap getFileNameMap ()
Returns a FileNameMap implementation suitable for guessing a
 content type based on a URL's "file" component.
| Returns | |
|---|---|
| FileNameMap | |
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.
| Parameters | |
|---|---|
| name | String: the name of a header field. | 
| Returns | |
|---|---|
| String | the value of the named header field, or nullif there is no such field in the header. | 
getHeaderField
public String getHeaderField (int n)
Returns the value for the nth 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.
| Parameters | |
|---|---|
| n | int: an index, wheren>=0 | 
| Returns | |
|---|---|
| String | the value of the nth header field
          ornullif there are fewer thann+1fields | 
See also:
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.
| Parameters | |
|---|---|
| name | String: the name of the header field. | 
| Default | long: a default value. | 
| Returns | |
|---|---|
| long | the value of the field, parsed as a date. The value of the Defaultargument is returned if the field is
          missing or malformed. | 
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.
| Parameters | |
|---|---|
| name | String: the name of the header field. | 
| Default | int: the default value. | 
| Returns | |
|---|---|
| int | the value of the named field, parsed as an integer. The Defaultvalue is returned if the field is
          missing or malformed. | 
getHeaderFieldKey
public String getHeaderFieldKey (int n)
Returns the key for the nth header field.
 It returns null if there are fewer than n+1 fields.
| Parameters | |
|---|---|
| n | int: an index, wheren>=0 | 
| Returns | |
|---|---|
| String | the key for the nth header field,
          ornullif there are fewer thann+1fields. | 
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.
| Parameters | |
|---|---|
| name | String: the name of the header field. | 
| Default | long: the default value. | 
| Returns | |
|---|---|
| long | the value of the named field, parsed as a long. The Defaultvalue is returned if the field is
          missing or malformed. | 
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.
| Returns | |
|---|---|
| Map<String, List<String>> | a Map of header fields | 
getIfModifiedSince
public long getIfModifiedSince ()
Returns the value of this object's ifModifiedSince field.
| Returns | |
|---|---|
| long | the value of this object's ifModifiedSincefield. | 
See also:
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.
| Returns | |
|---|---|
| InputStream | an input stream that reads from this open connection. | 
| Throws | |
|---|---|
| IOException | if an I/O error occurs while creating the input stream. | 
| UnknownServiceException | if the protocol does not support input. | 
See also:
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.
| Returns | |
|---|---|
| long | the date the resource referenced by this URLConnectionwas last modified, or 0 if not known. | 
See also:
getOutputStream
public OutputStream getOutputStream ()
Returns an output stream that writes to this connection.
| Returns | |
|---|---|
| OutputStream | an output stream that writes to this connection. | 
| Throws | |
|---|---|
| IOException | if an I/O error occurs while creating the output stream. | 
| UnknownServiceException | if the protocol does not support output. | 
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.security.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.
| Returns | |
|---|---|
| Permission | the permission object representing the permission necessary to make the connection represented by this URLConnection. | 
| Throws | |
|---|---|
| IOException | if the computation of the permission requires network or file I/O and an exception occurs while computing it. | 
getReadTimeout
public int getReadTimeout ()
Returns setting for read timeout. 0 return implies that the option is disabled (i.e., timeout of infinity).
| Returns | |
|---|---|
| int | an intthat indicates the read timeout
         value in milliseconds | 
See also:
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.
| Returns | |
|---|---|
| Map<String, List<String>> | a Map of the general request properties for this connection. | 
| Throws | |
|---|---|
| IllegalStateException | if already connected | 
getRequestProperty
public String getRequestProperty (String key)
Returns the value of the named general request property for this connection.
| Parameters | |
|---|---|
| key | String: the keyword by which the request is known (e.g., "Accept"). | 
| Returns | |
|---|---|
| String | the value of the named general request property for this connection. If key is null, then null is returned. | 
| Throws | |
|---|---|
| IllegalStateException | if already connected | 
getURL
public URL getURL ()
Returns the value of this URLConnection's URL
 field.
| Returns | |
|---|---|
| URL | the value of this URLConnection'sURLfield. | 
See also:
getUseCaches
public boolean getUseCaches ()
Returns the value of this URLConnection's
 useCaches field.
| Returns | |
|---|---|
| boolean | the value of this URLConnection'suseCachesfield. | 
See also:
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.
| Parameters | |
|---|---|
| fname | String: a filename. | 
| Returns | |
|---|---|
| String | a guess as to what the content type of the object is, based upon its file name. | 
See also:
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.
| Parameters | |
|---|---|
| is | InputStream: an input stream that supports marks. | 
| Returns | |
|---|---|
| String | a guess at the content type, or nullif none
             can be determined. | 
| Throws | |
|---|---|
| IOException | if an I/O error occurs while reading the input stream. | 
setAllowUserInteraction
public void setAllowUserInteraction (boolean allowuserinteraction)
Set the value of the allowUserInteraction field of
 this URLConnection.
| Parameters | |
|---|---|
| allowuserinteraction | boolean: the new value. | 
| Throws | |
|---|---|
| IllegalStateException | if already connected | 
See also:
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.
| Parameters | |
|---|---|
| timeout | int: anintthat specifies the connect
               timeout value in milliseconds | 
| Throws | |
|---|---|
| IllegalArgumentException | if the timeout parameter is negative | 
See also:
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 security manager, this method first calls
 the security manager's checkSetFactory method
 to ensure the operation is allowed.
 This could result in a SecurityException.
| Parameters | |
|---|---|
| fac | ContentHandlerFactory: the desired factory. | 
| Throws | |
|---|---|
| Error | if the factory has already been defined. | 
| SecurityException | if a security manager exists and its checkSetFactorymethod doesn't allow the operation. | 
setDefaultAllowUserInteraction
public static void setDefaultAllowUserInteraction (boolean defaultallowuserinteraction)
Sets the default value of the
 allowUserInteraction field for all future
 URLConnection objects to the specified value.
| Parameters | |
|---|---|
| defaultallowuserinteraction | boolean: the new value. | 
See also:
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.
| Parameters | |
|---|---|
| key | String: the keyword by which the request is known
                  (e.g., "Accept"). | 
| value | String: the value associated with the key. | 
setDefaultUseCaches
public void setDefaultUseCaches (boolean defaultusecaches)
Sets the default value of the useCaches field to the
 specified value.
| Parameters | |
|---|---|
| defaultusecaches | boolean: the new value. | 
See also:
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.
| Parameters | |
|---|---|
| doinput | boolean: the new value. | 
| Throws | |
|---|---|
| IllegalStateException | if already connected | 
See also:
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.
| Parameters | |
|---|---|
| dooutput | boolean: the new value. | 
| Throws | |
|---|---|
| IllegalStateException | if already connected | 
See also:
setFileNameMap
public static void setFileNameMap (FileNameMap map)
Sets the FileNameMap.
 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.
| Parameters | |
|---|---|
| map | FileNameMap: the FileNameMap to be set | 
| Throws | |
|---|---|
| SecurityException | if a security manager exists and its checkSetFactorymethod doesn't allow the operation. | 
setIfModifiedSince
public void setIfModifiedSince (long ifmodifiedsince)
Sets the value of the ifModifiedSince field of
 this URLConnection to the specified value.
| Parameters | |
|---|---|
| ifmodifiedsince | long: the new value. | 
| Throws | |
|---|---|
| IllegalStateException | if already connected | 
See also:
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().
| Parameters | |
|---|---|
| timeout | int: anintthat specifies the timeout
 value to be used in milliseconds | 
| Throws | |
|---|---|
| IllegalArgumentException | if the timeout parameter is negative | 
See also:
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.
| Parameters | |
|---|---|
| key | String: the keyword by which the request is known
                  (e.g., "Accept"). | 
| value | String: the value associated with it. | 
| Throws | |
|---|---|
| IllegalStateException | if already connected | 
| NullPointerException | if key is null | 
See also:
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.
| Parameters | |
|---|---|
| usecaches | boolean: abooleanindicating whether
 or not to allow caching | 
| Throws | |
|---|---|
| IllegalStateException | if already connected | 
See also:
toString
public String toString ()
Returns a String representation of this URL connection.
| Returns | |
|---|---|
| String | a string representation of this URLConnection. | 
