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Summary: Nested | Field | Method | Constr | Detail: Nested | Field | Method | Constr |
java.lang.Object
java.net.URLConnection
public abstract class URLConnection
extends Object
Field Summary | |
protected boolean |
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protected boolean |
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protected boolean |
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protected boolean |
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protected long |
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protected URL |
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protected boolean |
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Constructor Summary | |
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Method Summary | |
void |
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abstract void |
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boolean |
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int |
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Object |
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Object |
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String |
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int |
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String |
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long |
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static boolean |
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static String |
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boolean |
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boolean |
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boolean |
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long |
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static FileNameMap |
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String |
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String |
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long |
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int |
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String |
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Map |
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long |
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InputStream |
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long |
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OutputStream |
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Permission |
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int |
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Map |
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String |
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URL |
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boolean |
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static String |
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static String |
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void |
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void |
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static void |
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static void |
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static void |
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void |
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void |
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void |
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static void |
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void |
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void |
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void |
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void |
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String |
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Methods inherited from class java.lang.Object | |
clone , equals , extends Object> getClass , finalize , hashCode , notify , notifyAll , toString , wait , wait , wait |
protected boolean allowUserInteraction
This variable determines whether or not interaction is allowed with the user. For example, to prompt for a username and password.
protected boolean connected
Indicates whether or not a connection has been established to the destination specified in the URL
protected long ifModifiedSince
If this value is non-zero, then the connection will only attempt to fetch the document pointed to by the URL if the document has been modified more recently than the date set in this variable. That date should be specified as the number of seconds since 1/1/1970 GMT.
protected boolean useCaches
If this flag is set, the protocol is allowed to cache data whenever it can (caching is not guaranteed). If it is not set, the protocol must a get a fresh copy of the data. This field is set by the setUseCaches method and returned by the getUseCaches method. Its default value is that determined by the last invocation of setDefaultUseCaches
protected URLConnection(URL url)
Creates a URL connection to a given URL. A real connection is not made. Useconnect()
to do this.
- Parameters:
url
- The Object to create the URL connection to
- See Also:
connect()
public void addRequestProperty(String key, String value)
Adds a new request property by a key/value pair. This method does not overwrite existing properties with the same key.
- Parameters:
key
- Key of the property to addvalue
- Value of the Property to add
- Throws:
IllegalStateException
- If already connectedNullPointerException
- If key is null
- Since:
- 1.4
public abstract void connect() throws IOException
Establishes the actual connection to the URL associated with this connection object
- Throws:
IOException
- if an error occurs
public boolean getAllowUserInteraction()
Returns a boolean flag indicating whether or not user interaction is allowed for this connection. (For example, in order to prompt for username and password info.
- Returns:
- true if user interaction is allowed, false otherwise
public int getConnectTimeout()
Returns the connection timeout speed, in milliseconds, or zero if the timeout is infinite or not set.
- Returns:
- The timeout.
- Since:
- 1.5
public Object getContent() throws IOException
This method returns the content of the document pointed to by the URL as an Object. The type of object depends on the MIME type of the object and particular content hander loaded. Most text type content handlers will return a subclass ofInputStream
. Images usually return a class that implementsImageProducer
. There is not guarantee what type of object will be returned, however. This class first determines the MIME type of the content, then creates a ContentHandler object to process the input. If theContentHandlerFactory
is set, then that object is called to load a content handler, otherwise a class called gnu.java.net.content.<content_type> is tried. If this handler does not exist, the method will simple return theInputStream
returned bygetInputStream()
. Note that the default implementation ofgetInputStream()
throws aUnknownServiceException
so subclasses are encouraged to override this method.
- Returns:
- the content
- Throws:
IOException
- If an error with the connection occurs.
public Object getContent(Class<T>[] classes) throws IOException
Retrieves the content of this URLConnection
- Parameters:
classes
- The allowed classes for the content
- Returns:
- the content
- Throws:
IOException
- If an error occurs
public String getContentEncoding()
Returns the value of the content-encoding field or null if it is not known or not present.
- Returns:
- The content-encoding field
public int getContentLength()
Returns the value of the content-length header field or -1 if the value is not known or not present.
- Returns:
- The content-length field
public String getContentType()
Returns the the content-type of the data pointed to by the URL. This method first tries looking for a content-type header. If that is not present, it attempts to use the file name to determine the content's MIME type. If that is unsuccessful, the method returns null. The caller may then still attempt to determine the MIME type by a call to guessContentTypeFromStream()
- Returns:
- The content MIME type
public long getDate()
Returns the date of the document pointed to by the URL as reported in the date field of the header or 0 if the value is not present or not known. If populated, the return value is number of seconds since midnight on 1/1/1970 GMT.
- Returns:
- The document date
public static boolean getDefaultAllowUserInteraction()
Returns the default flag for whether or not interaction with a user is allowed. This will be used for all connections unless overridden
- Returns:
- true if user interaction is allowed, false otherwise
public static String getDefaultRequestProperty(String key)
Deprecated. 1.3 The method getRequestProperty should be used instead. This method does nothing now.
Returns the default value of a request property. This will be used for all connections unless the value of the property is manually overridden.
- Parameters:
key
- The request property to return the default value of
- Returns:
- The value of the default property or null if not available
- See Also:
getRequestProperty(String)
public boolean getDefaultUseCaches()
Returns the default value used to determine whether or not caching of documents will be done when possible.
- Returns:
- true if caches will be used, false otherwise
public boolean getDoInput()
Returns the value of a flag indicating whether or not input is going to be done for this connection. This default to true unless the doOutput flag is set to false, in which case this defaults to false.
- Returns:
- true if input is to be done, false otherwise
public boolean getDoOutput()
Returns a boolean flag indicating whether or not output will be done on this connection. This defaults to false.
- Returns:
- true if output is to be done, false otherwise
public long getExpiration()
Returns the value of the expires header or 0 if not known or present. If populated, the return value is number of seconds since midnight on 1/1/1970 GMT.
- Returns:
- The expiration time.
public static FileNameMap getFileNameMap()
This method returns theFileNameMap
object being used to decode MIME types by file extension.
- Returns:
- The
FileNameMap
.
- Since:
- 1.2
public String getHeaderField(int index)
Return a String representing the header value at the specified index. This allows the caller to walk the list of header fields. The analogousgetHeaderField(int)
method allows access to the corresponding key for this header field
- Parameters:
index
- The index into the header field list to retrieve the value for
- Returns:
- The header value or null if index is past the end of the headers
public String getHeaderField(String name)
Returns a String representing the value of the header field having the named key. Returns null if the header field does not exist.
- Parameters:
name
- The key of the header field
- Returns:
- The value of the header field as a String
public long getHeaderFieldDate(String name, long defaultValue)
Returns the value of the named header field as a date. This date will be the number of seconds since midnight 1/1/1970 GMT or the default value if the field is not present or cannot be converted to a date.
- Parameters:
name
- The name of the header fielddefaultValue
- The default date if the header field is not found or can't be converted.
- Returns:
- The date value of the header filed or the default value if the field is missing or malformed
public int getHeaderFieldInt(String name, int defaultValue)
Returns the value of the named header field as an int. If the field is not present or cannot be parsed as an integer, the default value will be returned.
- Parameters:
name
- The header field key to lookupdefaultValue
- The defaule value if the header field is not found or can't be parsed.
- Returns:
- The value of the header field or the default value if the field is missing or malformed
public String getHeaderFieldKey(int index)
Returns a String representing the header key at the specified index. This allows the caller to walk the list of header fields. The analogousgetHeaderField(int)
method allows access to the corresponding value for this tag.
- Parameters:
index
- The index into the header field list to retrieve the key for.
- Returns:
- The header field key or null if index is past the end of the headers.
public Map> getHeaderFields()
Returns an unmodifiable Map containing all sent header fields.
- Returns:
- The map of header fields. The map consists of String keys with an unmodifiable List of String objects as value.
- Since:
- 1.4
public long getIfModifiedSince()
Returns the ifModified since instance variable. If this value is non zero and the underlying protocol supports it, the actual document will not be fetched unless it has been modified since this time. The value returned will be 0 if this feature is disabled or the time expressed as the number of seconds since midnight 1/1/1970 GMT otherwise
- Returns:
- The ifModifiedSince value
public InputStream getInputStream() throws IOException
Returns an InputStream for this connection. As this default implementation returns null, subclasses should override this method
- Returns:
- An InputStream for this connection
- Throws:
IOException
- If an error occurs
public long getLastModified()
Returns the value of the last-modified header field or 0 if not known known or not present. If populated, the return value is the number of seconds since midnight on 1/1/1970.
- Returns:
- The last modified time
public OutputStream getOutputStream() throws IOException
Returns an OutputStream for this connection. As this default implementation returns null, subclasses should override this method
- Returns:
- An OutputStream for this connection
- Throws:
IOException
- If an error occurs
public Permission getPermission() throws IOException
This method returns aPermission
object representing the permissions required to access this URL. This method returnsjava.security.AllPermission
by default. Subclasses should override it to return a more specific permission. For example, an HTTP URL should return an instance ofSocketPermission
for the appropriate host and port. Note that because of items such as HTTP redirects, the permission object returned might be different before and after connecting.
- Returns:
- A Permission object
- Throws:
IOException
- If the computation of the permission requires network or file I/O and an exception occurs while computing it
public int getReadTimeout()
Returns the read timeout, in milliseconds, or zero if the timeout is infinite or not set.
- Returns:
- The timeout.
- Since:
- 1.5
- See Also:
setReadTimeout(int)
public Map> getRequestProperties()
Returns an unmodifiable Map containing the request properties.
- Returns:
- The map of properties. The map consists of String keys with an unmodifiable List of String objects as value.
- Throws:
IllegalStateException
- If already connected
- Since:
- 1.4
public String getRequestProperty(String key)
Returns the value of the named request property.
- Parameters:
key
- The name of the property
- Returns:
- Value of the property, or
null
if key is null.
- Throws:
IllegalStateException
- If already connected
public URL getURL()
Returns the URL object associated with this connection
- Returns:
- The URL for this connection.
public boolean getUseCaches()
Returns a boolean flag indicating whether or not caching will be used (if possible) to store data downloaded via the connection.
- Returns:
- true if caching should be used if possible, false otherwise
public static String guessContentTypeFromName(String filename)
Returns the MIME type of a file based on the name of the file. This works by searching for the file's extension in a list of file extensions and returning the MIME type associated with it. If no type is found, then a MIME type of "application/octet-stream" will be returned.
- Parameters:
filename
- The filename to determine the MIME type for
- Returns:
- The MIME type String
public static String guessContentTypeFromStream(InputStream is) throws IOException
Returns the MIME type of a stream based on the first few characters at the beginning of the stream. This routine can be used to determine the MIME type if a server is believed to be returning an incorrect MIME type. This method returns "application/octet-stream" if it cannot determine the MIME type. NOTE: Overriding MIME types sent from the server can be obnoxious to user's. See Internet Exploder 4 if you don't believe me.
- Parameters:
is
- The InputStream to determine the MIME type from
- Returns:
- The MIME type
- Throws:
IOException
- If an error occurs
public void setAllowUserInteraction(boolean allow)
Sets a boolean flag indicating whether or not user interaction is allowed for this connection. (For example, in order to prompt for username and password info.
- Parameters:
allow
- true if user interaction should be allowed, false otherwise.
- Throws:
IllegalStateException
- If already connected
public void setConnectTimeout(int timeout) throws IllegalArgumentException
Set the connection timeout speed, in milliseconds, or zero if the timeout is to be considered infinite. Note that in certain socket implementations/platforms this method may not have any effect. Throws anIllegalArgumentException
if timeout <320.
- Parameters:
timeout
- the timeout, in milliseconds.
- Since:
- 1.5
public static void setContentHandlerFactory(ContentHandlerFactory factory)
Sets the ContentHandlerFactory for an application. This can be called once and only once. If it is called again, then an Error is thrown. Unlike for other set factory methods, this one does not do a security check prior to setting the factory.
- Parameters:
factory
- The ContentHandlerFactory for this application
- Throws:
SecurityException
- If a security manager exists and its checkSetFactory method doesn't allow the operation
public static void setDefaultAllowUserInteraction(boolean allow)
Sets the default flag for whether or not interaction with a user is allowed. This will be used for all connections unless overridden
- Parameters:
allow
- true to allow user interaction, false otherwise
public static void setDefaultRequestProperty(String key, String value)
Deprecated. 1.3 The method setRequestProperty should be used instead. This method does nothing now.
Sets the default value of a request property. This will be used for all connections unless the value of the property is manually overridden.
- Parameters:
key
- The request property name the default is being set forvalue
- The value to set the default to
- See Also:
setRequestProperty(String,String)
public void setDefaultUseCaches(boolean use)
Sets the default value used to determine whether or not caching of documents will be done when possible.
- Parameters:
use
- true to use caches if possible by default, false otherwise
public void setDoInput(boolean input)
Sets the value of a flag indicating whether or not input is going to be done for this connection. This default to true unless the doOutput flag is set to false, in which case this defaults to false.
- Parameters:
input
-true
if input is to be done,false
otherwise
- Throws:
IllegalStateException
- If already connected
public void setDoOutput(boolean output)
Sets a boolean flag indicating whether or not output will be done on this connection. The default value is false, so this method can be used to override the default
- Parameters:
output
- ture if output is to be done, false otherwise
- Throws:
IllegalStateException
- If already connected
public static void setFileNameMap(FileNameMap map)
This method sets theFileNameMap
object being used to decode MIME types by file extension.
- Parameters:
map
- TheFileNameMap
.
- Throws:
SecurityException
- If a security manager exists and its checkSetFactory method doesn't allow the operation
- Since:
- 1.2
public void setIfModifiedSince(long ifmodifiedsince)
Sets the ifModified since instance variable. If this value is non zero and the underlying protocol supports it, the actual document will not be fetched unless it has been modified since this time. The value passed should be 0 if this feature is to be disabled or the time expressed as the number of seconds since midnight 1/1/1970 GMT otherwise.
- Parameters:
ifmodifiedsince
- The new value in milliseconds since January 1, 1970 GMT
- Throws:
IllegalStateException
- If already connected
public void setReadTimeout(int timeout) throws IllegalArgumentException
Set the read timeout, in milliseconds, or zero if the timeout is to be considered infinite. Note that in certain socket implementations/platforms this method may not have any effect. Throws anIllegalArgumentException
if timeout <320.
- Parameters:
timeout
- - The timeout, in milliseconds.
- Throws:
IllegalArgumentException
- if timeout is negative.
- Since:
- 1.5
- See Also:
getReadTimeout()
public void setRequestProperty(String key, String value)
Sets the value of the named request property. This method does overwrite the value of existing properties with the new value.
- Parameters:
key
- The name of the propertyvalue
- The value of the property
- Throws:
IllegalStateException
- If already connectedNullPointerException
- If key is null
- Since:
- 1.4
- See Also:
URLConnection.getRequestProperty(String key)
,URLConnection.addRequestProperty(String key, String value)
public void setUseCaches(boolean usecaches)
Sets a boolean flag indicating whether or not caching will be used (if possible) to store data downloaded via the connection.
- Parameters:
usecaches
- The new value
- Throws:
IllegalStateException
- If already connected
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