Class HttpURLConnection
- Direct Known Subclasses:
HttpsURLConnection
Each HttpURLConnection instance is used to make a single request but the underlying network connection to the HTTP server may be transparently shared by other instances. Calling the close() methods on the InputStream or OutputStream of an HttpURLConnection after a request may free network resources associated with this instance but has no effect on any shared persistent connection. Calling the disconnect() method may close the underlying socket if a persistent connection is otherwise idle at that time.
The HTTP protocol handler has a few settings that can be accessed through System Properties. This covers Proxy settings as well as various other settings.
Security permissions
If a security manager is installed, and if a method is called which results in an attempt to open a connection, the caller must possess either:
- a "connect"
SocketPermission
to the host/port combination of the destination URL or - a
URLPermission
that permits this request.
If automatic redirection is enabled, and this request is redirected to another destination, then the caller must also have permission to connect to the redirected host/URL.
- Since:
- 1.1
- See Also:
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Field Summary
Modifier and TypeFieldDescriptionprotected int
The chunk-length when using chunked encoding streaming mode for output.protected int
The fixed content-length when using fixed-length streaming mode.protected long
The fixed content-length when using fixed-length streaming mode.static final int
HTTP Status-Code 202: Accepted.static final int
HTTP Status-Code 502: Bad Gateway.static final int
HTTP Status-Code 405: Method Not Allowed.static final int
HTTP Status-Code 400: Bad Request.static final int
HTTP Status-Code 408: Request Time-Out.static final int
HTTP Status-Code 409: Conflict.static final int
HTTP Status-Code 201: Created.static final int
HTTP Status-Code 413: Request Entity Too Large.static final int
HTTP Status-Code 403: Forbidden.static final int
HTTP Status-Code 504: Gateway Timeout.static final int
HTTP Status-Code 410: Gone.static final int
HTTP Status-Code 500: Internal Server Error.static final int
HTTP Status-Code 411: Length Required.static final int
HTTP Status-Code 301: Moved Permanently.static final int
HTTP Status-Code 302: Temporary Redirect.static final int
HTTP Status-Code 300: Multiple Choices.static final int
HTTP Status-Code 204: No Content.static final int
HTTP Status-Code 406: Not Acceptable.static final int
HTTP Status-Code 203: Non-Authoritative Information.static final int
HTTP Status-Code 404: Not Found.static final int
HTTP Status-Code 501: Not Implemented.static final int
HTTP Status-Code 304: Not Modified.static final int
HTTP Status-Code 200: OK.static final int
HTTP Status-Code 206: Partial Content.static final int
HTTP Status-Code 402: Payment Required.static final int
HTTP Status-Code 412: Precondition Failed.static final int
HTTP Status-Code 407: Proxy Authentication Required.static final int
HTTP Status-Code 414: Request-URI Too Large.static final int
HTTP Status-Code 205: Reset Content.static final int
HTTP Status-Code 303: See Other.static final int
Deprecated.it is misplaced and shouldn't have existed.static final int
HTTP Status-Code 401: Unauthorized.static final int
HTTP Status-Code 503: Service Unavailable.static final int
HTTP Status-Code 415: Unsupported Media Type.static final int
HTTP Status-Code 305: Use Proxy.static final int
HTTP Status-Code 505: HTTP Version Not Supported.protected boolean
Iftrue
, the protocol will automatically follow redirects.protected String
The HTTP method (GET,POST,PUT,etc.).protected int
Anint
representing the three digit HTTP Status-Code.protected String
The HTTP response message.Fields declared in class java.net.URLConnection
allowUserInteraction, connected, doInput, doOutput, ifModifiedSince, url, useCaches
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Constructor Summary
ModifierConstructorDescriptionprotected
Constructor for the HttpURLConnection. -
Method Summary
Modifier and TypeMethodDescriptionabstract void
Indicates that other requests to the server are unlikely in the near future.Returns the error stream if the connection failed but the server sent useful data nonetheless.static boolean
Returns aboolean
indicating whether or not HTTP redirects (3xx) should be automatically followed.getHeaderField
(int n) Returns the value for then
th header field.getHeaderFieldKey
(int n) Returns the key for then
th header field.boolean
Returns the value of thisHttpURLConnection
'sinstanceFollowRedirects
field.Returns aSocketPermission
object representing the permission necessary to connect to the destination host and port.Get the request method.int
Gets the status code from an HTTP response message.Gets the HTTP response message, if any, returned along with the response code from a server.void
Supplies anAuthenticator
to be used when authentication is requested through the HTTP protocol for thisHttpURLConnection
.void
setChunkedStreamingMode
(int chunklen) This method is used to enable streaming of a HTTP request body without internal buffering, when the content length is not known in advance.void
setFixedLengthStreamingMode
(int contentLength) This method is used to enable streaming of a HTTP request body without internal buffering, when the content length is known in advance.void
setFixedLengthStreamingMode
(long contentLength) This method is used to enable streaming of a HTTP request body without internal buffering, when the content length is known in advance.static void
setFollowRedirects
(boolean set) Sets whether HTTP redirects (requests with response code 3xx) should be automatically followed by this class.void
setInstanceFollowRedirects
(boolean followRedirects) Sets whether HTTP redirects (requests with response code 3xx) should be automatically followed by thisHttpURLConnection
instance.void
setRequestMethod
(String method) Set the method for the URL request, one of: GET POST HEAD OPTIONS PUT DELETE TRACE are legal, subject to protocol restrictions.abstract boolean
Indicates if the connection is going through a proxy.Methods declared in class java.net.URLConnection
addRequestProperty, connect, getAllowUserInteraction, getConnectTimeout, getContent, getContent, getContentEncoding, getContentLength, getContentLengthLong, getContentType, getDate, getDefaultAllowUserInteraction, getDefaultRequestProperty, getDefaultUseCaches, getDefaultUseCaches, getDoInput, getDoOutput, getExpiration, getFileNameMap, getHeaderField, getHeaderFieldDate, getHeaderFieldInt, getHeaderFieldLong, getHeaderFields, getIfModifiedSince, getInputStream, getLastModified, getOutputStream, getReadTimeout, getRequestProperties, getRequestProperty, getURL, getUseCaches, guessContentTypeFromName, guessContentTypeFromStream, setAllowUserInteraction, setConnectTimeout, setContentHandlerFactory, setDefaultAllowUserInteraction, setDefaultRequestProperty, setDefaultUseCaches, setDefaultUseCaches, setDoInput, setDoOutput, setFileNameMap, setIfModifiedSince, setReadTimeout, setRequestProperty, setUseCaches, toString
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Field Details
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method
The HTTP method (GET,POST,PUT,etc.). -
chunkLength
protected int chunkLengthThe chunk-length when using chunked encoding streaming mode for output. A value of-1
means chunked encoding is disabled for output.- Since:
- 1.5
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fixedContentLength
protected int fixedContentLengthThe fixed content-length when using fixed-length streaming mode. A value of-1
means fixed-length streaming mode is disabled for output.NOTE:
fixedContentLengthLong
is recommended instead of this field, as it allows larger content lengths to be set.- Since:
- 1.5
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fixedContentLengthLong
protected long fixedContentLengthLongThe fixed content-length when using fixed-length streaming mode. A value of-1
means fixed-length streaming mode is disabled for output.- Since:
- 1.7
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responseCode
protected int responseCodeAnint
representing the three digit HTTP Status-Code.- 1xx: Informational
- 2xx: Success
- 3xx: Redirection
- 4xx: Client Error
- 5xx: Server Error
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responseMessage
The HTTP response message. -
instanceFollowRedirects
protected boolean instanceFollowRedirectsIftrue
, the protocol will automatically follow redirects. Iffalse
, the protocol will not automatically follow redirects.This field is set by the
setInstanceFollowRedirects
method. Its value is returned by thegetInstanceFollowRedirects
method.Its default value is based on the value of the static followRedirects at HttpURLConnection construction time.
- See Also:
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HTTP_OK
public static final int HTTP_OKHTTP Status-Code 200: OK.- See Also:
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HTTP_CREATED
public static final int HTTP_CREATEDHTTP Status-Code 201: Created.- See Also:
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HTTP_ACCEPTED
public static final int HTTP_ACCEPTEDHTTP Status-Code 202: Accepted.- See Also:
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HTTP_NOT_AUTHORITATIVE
public static final int HTTP_NOT_AUTHORITATIVEHTTP Status-Code 203: Non-Authoritative Information.- See Also:
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HTTP_NO_CONTENT
public static final int HTTP_NO_CONTENTHTTP Status-Code 204: No Content.- See Also:
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HTTP_RESET
public static final int HTTP_RESETHTTP Status-Code 205: Reset Content.- See Also:
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HTTP_PARTIAL
public static final int HTTP_PARTIALHTTP Status-Code 206: Partial Content.- See Also:
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HTTP_MULT_CHOICE
public static final int HTTP_MULT_CHOICEHTTP Status-Code 300: Multiple Choices.- See Also:
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HTTP_MOVED_PERM
public static final int HTTP_MOVED_PERMHTTP Status-Code 301: Moved Permanently.- See Also:
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HTTP_MOVED_TEMP
public static final int HTTP_MOVED_TEMPHTTP Status-Code 302: Temporary Redirect.- See Also:
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HTTP_SEE_OTHER
public static final int HTTP_SEE_OTHERHTTP Status-Code 303: See Other.- See Also:
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HTTP_NOT_MODIFIED
public static final int HTTP_NOT_MODIFIEDHTTP Status-Code 304: Not Modified.- See Also:
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HTTP_USE_PROXY
public static final int HTTP_USE_PROXYHTTP Status-Code 305: Use Proxy.- See Also:
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HTTP_BAD_REQUEST
public static final int HTTP_BAD_REQUESTHTTP Status-Code 400: Bad Request.- See Also:
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HTTP_UNAUTHORIZED
public static final int HTTP_UNAUTHORIZEDHTTP Status-Code 401: Unauthorized.- See Also:
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HTTP_PAYMENT_REQUIRED
public static final int HTTP_PAYMENT_REQUIREDHTTP Status-Code 402: Payment Required.- See Also:
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HTTP_FORBIDDEN
public static final int HTTP_FORBIDDENHTTP Status-Code 403: Forbidden.- See Also:
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HTTP_NOT_FOUND
public static final int HTTP_NOT_FOUNDHTTP Status-Code 404: Not Found.- See Also:
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HTTP_BAD_METHOD
public static final int HTTP_BAD_METHODHTTP Status-Code 405: Method Not Allowed.- See Also:
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HTTP_NOT_ACCEPTABLE
public static final int HTTP_NOT_ACCEPTABLEHTTP Status-Code 406: Not Acceptable.- See Also:
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HTTP_PROXY_AUTH
public static final int HTTP_PROXY_AUTHHTTP Status-Code 407: Proxy Authentication Required.- See Also:
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HTTP_CLIENT_TIMEOUT
public static final int HTTP_CLIENT_TIMEOUTHTTP Status-Code 408: Request Time-Out.- See Also:
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HTTP_CONFLICT
public static final int HTTP_CONFLICTHTTP Status-Code 409: Conflict.- See Also:
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HTTP_GONE
public static final int HTTP_GONEHTTP Status-Code 410: Gone.- See Also:
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HTTP_LENGTH_REQUIRED
public static final int HTTP_LENGTH_REQUIREDHTTP Status-Code 411: Length Required.- See Also:
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HTTP_PRECON_FAILED
public static final int HTTP_PRECON_FAILEDHTTP Status-Code 412: Precondition Failed.- See Also:
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HTTP_ENTITY_TOO_LARGE
public static final int HTTP_ENTITY_TOO_LARGEHTTP Status-Code 413: Request Entity Too Large.- See Also:
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HTTP_REQ_TOO_LONG
public static final int HTTP_REQ_TOO_LONGHTTP Status-Code 414: Request-URI Too Large.- See Also:
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HTTP_UNSUPPORTED_TYPE
public static final int HTTP_UNSUPPORTED_TYPEHTTP Status-Code 415: Unsupported Media Type.- See Also:
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HTTP_SERVER_ERROR
Deprecated.it is misplaced and shouldn't have existed.HTTP Status-Code 500: Internal Server Error.- See Also:
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HTTP_INTERNAL_ERROR
public static final int HTTP_INTERNAL_ERRORHTTP Status-Code 500: Internal Server Error.- See Also:
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HTTP_NOT_IMPLEMENTED
public static final int HTTP_NOT_IMPLEMENTEDHTTP Status-Code 501: Not Implemented.- See Also:
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HTTP_BAD_GATEWAY
public static final int HTTP_BAD_GATEWAYHTTP Status-Code 502: Bad Gateway.- See Also:
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HTTP_UNAVAILABLE
public static final int HTTP_UNAVAILABLEHTTP Status-Code 503: Service Unavailable.- See Also:
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HTTP_GATEWAY_TIMEOUT
public static final int HTTP_GATEWAY_TIMEOUTHTTP Status-Code 504: Gateway Timeout.- See Also:
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HTTP_VERSION
public static final int HTTP_VERSIONHTTP Status-Code 505: HTTP Version Not Supported.- See Also:
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Constructor Details
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HttpURLConnection
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Method Details
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setAuthenticator
Supplies anAuthenticator
to be used when authentication is requested through the HTTP protocol for thisHttpURLConnection
. If no authenticator is supplied, the default authenticator will be used.- Implementation Requirements:
- The default behavior of this method is to unconditionally
throw
UnsupportedOperationException
. Concrete implementations ofHttpURLConnection
which support supplying anAuthenticator
for a specificHttpURLConnection
instance should override this method to implement a different behavior. - Implementation Note:
- Depending on authentication schemes, an implementation
may or may not need to use the provided authenticator
to obtain a password. For instance, an implementation that
relies on third-party security libraries may still invoke the
default authenticator if these libraries are configured
to do so.
Likewise, an implementation that supports transparent
NTLM authentication may let the system attempt
to connect using the system user credentials first,
before invoking the provided authenticator.
However, if an authenticator is specifically provided, then the underlying connection may only be reused forHttpURLConnection
instances which share the sameAuthenticator
instance, and authentication information, if cached, may only be reused for anHttpURLConnection
sharing that sameAuthenticator
. - Parameters:
auth
- TheAuthenticator
that should be used by thisHttpURLConnection
.- Throws:
UnsupportedOperationException
- if setting an Authenticator is not supported by the underlying implementation.IllegalStateException
- if URLConnection is already connected.NullPointerException
- if the suppliedauth
isnull
.- Since:
- 9
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getHeaderFieldKey
Returns the key for then
th header field. Some implementations may treat the0
th header field as special, i.e. as the status line returned by the HTTP server. In this case,getHeaderField(0)
returns the status line, butgetHeaderFieldKey(0)
returns null.- Overrides:
getHeaderFieldKey
in classURLConnection
- Parameters:
n
- an index, wheren >=0
.- Returns:
- the key for the
n
th header field, ornull
if the key does not exist.
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setFixedLengthStreamingMode
public void setFixedLengthStreamingMode(int contentLength) This method is used to enable streaming of a HTTP request body without internal buffering, when the content length is known in advance.An exception will be thrown if the application attempts to write more data than the indicated content-length, or if the application closes the OutputStream before writing the indicated amount.
When output streaming is enabled, authentication and redirection cannot be handled automatically. A HttpRetryException will be thrown when reading the response if authentication or redirection are required. This exception can be queried for the details of the error.
This method must be called before the URLConnection is connected.
NOTE:
setFixedLengthStreamingMode(long)
is recommended instead of this method as it allows larger content lengths to be set.- Parameters:
contentLength
- The number of bytes which will be written to the OutputStream.- Throws:
IllegalStateException
- if URLConnection is already connected or if a different streaming mode is already enabled.IllegalArgumentException
- if a content length less than zero is specified.- Since:
- 1.5
- See Also:
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setFixedLengthStreamingMode
public void setFixedLengthStreamingMode(long contentLength) This method is used to enable streaming of a HTTP request body without internal buffering, when the content length is known in advance.An exception will be thrown if the application attempts to write more data than the indicated content-length, or if the application closes the OutputStream before writing the indicated amount.
When output streaming is enabled, authentication and redirection cannot be handled automatically. A HttpRetryException will be thrown when reading the response if authentication or redirection are required. This exception can be queried for the details of the error.
This method must be called before the URLConnection is connected.
The content length set by invoking this method takes precedence over any value set by
setFixedLengthStreamingMode(int)
.- Parameters:
contentLength
- The number of bytes which will be written to the OutputStream.- Throws:
IllegalStateException
- if URLConnection is already connected or if a different streaming mode is already enabled.IllegalArgumentException
- if a content length less than zero is specified.- Since:
- 1.7
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setChunkedStreamingMode
public void setChunkedStreamingMode(int chunklen) This method is used to enable streaming of a HTTP request body without internal buffering, when the content length is not known in advance. In this mode, chunked transfer encoding is used to send the request body. Note, not all HTTP servers support this mode.When output streaming is enabled, authentication and redirection cannot be handled automatically. A HttpRetryException will be thrown when reading the response if authentication or redirection are required. This exception can be queried for the details of the error.
This method must be called before the URLConnection is connected.
- Parameters:
chunklen
- The number of bytes to be written in each chunk, including a chunk size header as a hexadecimal string (minimum of 1 byte), two CRLF's (4 bytes) and a minimum payload length of 1 byte. If chunklen is less than or equal to 5, a higher default value will be used.- Throws:
IllegalStateException
- if URLConnection is already connected or if a different streaming mode is already enabled.- Since:
- 1.5
- See Also:
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getHeaderField
Returns the value for then
th header field. Some implementations may treat the0
th header field as special, i.e. as the status line returned by the HTTP server.This method can be used in conjunction with the
getHeaderFieldKey
method to iterate through all the headers in the message.- Overrides:
getHeaderField
in classURLConnection
- Parameters:
n
- an index, wheren>=0
.- Returns:
- the value of the
n
th header field, ornull
if the value does not exist. - See Also:
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setFollowRedirects
public static void setFollowRedirects(boolean set) Sets whether HTTP redirects (requests with response code 3xx) should be automatically followed by this class. True by default.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:
set
- aboolean
indicating whether or not to follow HTTP redirects.- Throws:
SecurityException
- if a security manager exists and itscheckSetFactory
method doesn't allow the operation.- See Also:
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getFollowRedirects
public static boolean getFollowRedirects()Returns aboolean
indicating whether or not HTTP redirects (3xx) should be automatically followed.- Returns:
true
if HTTP redirects should be automatically followed,false
if not.- See Also:
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setInstanceFollowRedirects
public void setInstanceFollowRedirects(boolean followRedirects) Sets whether HTTP redirects (requests with response code 3xx) should be automatically followed by thisHttpURLConnection
instance.The default value comes from followRedirects, which defaults to true.
- Parameters:
followRedirects
- aboolean
indicating whether or not to follow HTTP redirects.- Since:
- 1.3
- See Also:
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getInstanceFollowRedirects
public boolean getInstanceFollowRedirects()Returns the value of thisHttpURLConnection
'sinstanceFollowRedirects
field.- Returns:
- the value of this
HttpURLConnection
'sinstanceFollowRedirects
field. - Since:
- 1.3
- See Also:
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setRequestMethod
Set the method for the URL request, one of:- GET
- POST
- HEAD
- OPTIONS
- PUT
- DELETE
- TRACE
- Parameters:
method
- the HTTP method- Throws:
ProtocolException
- if the method cannot be reset or if the requested method isn't valid for HTTP.SecurityException
- if a security manager is set and the method is "TRACE", but the "allowHttpTrace" NetPermission is not granted.- See Also:
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getRequestMethod
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getResponseCode
Gets the status code from an HTTP response message. For example, in the case of the following status lines:HTTP/1.0 200 OK HTTP/1.0 401 Unauthorized
It will return 200 and 401 respectively. Returns -1 if no code can be discerned from the response (i.e., the response is not valid HTTP).- Returns:
- the HTTP Status-Code, or -1
- Throws:
IOException
- if an error occurred connecting to the server.
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getResponseMessage
Gets the HTTP response message, if any, returned along with the response code from a server. From responses like:HTTP/1.0 200 OK HTTP/1.0 404 Not Found
Extracts the Strings "OK" and "Not Found" respectively. Returns null if none could be discerned from the responses (the result was not valid HTTP).- Returns:
- the HTTP response message, or
null
- Throws:
IOException
- if an error occurred connecting to the server.
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disconnect
public abstract void disconnect()Indicates that other requests to the server are unlikely in the near future. Calling disconnect() should not imply that this HttpURLConnection instance can be reused for other requests. -
usingProxy
public abstract boolean usingProxy()Indicates if the connection is going through a proxy. This method returnstrue
if the connection is known to be going or has gone through proxies, and returnsfalse
if the connection will never go through a proxy or if the use of a proxy cannot be determined.- Returns:
- a boolean indicating if the connection is using a proxy.
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getPermission
Returns aSocketPermission
object representing the permission necessary to connect to the destination host and port.- Overrides:
getPermission
in classURLConnection
- Returns:
- a
SocketPermission
object representing the permission necessary to connect to the destination host and port. - Throws:
IOException
- if an error occurs while computing the permission.
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getErrorStream
Returns the error stream if the connection failed but the server sent useful data nonetheless. The typical example is when an HTTP server responds with a 404, which will cause a FileNotFoundException to be thrown in connect, but the server sent an HTML help page with suggestions as to what to do.This method will not cause a connection to be initiated. If the connection was not connected, or if the server did not have an error while connecting or if the server had an error but no error data was sent, this method will return null. This is the default.
- Returns:
- an error stream if any, null if there have been no errors, the connection is not connected or the server sent no useful data.
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