- 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"
SocketPermissionto the host/port combination of the destination URL or - a
URLPermissionthat 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
FieldsModifier and TypeFieldDescriptionprotected intThe chunk-length when using chunked encoding streaming mode for output.protected intThe fixed content-length when using fixed-length streaming mode.protected longThe fixed content-length when using fixed-length streaming mode.static final intHTTP Status-Code 202: Accepted.static final intHTTP Status-Code 502: Bad Gateway.static final intHTTP Status-Code 405: Method Not Allowed.static final intHTTP Status-Code 400: Bad Request.static final intHTTP Status-Code 408: Request Time-Out.static final intHTTP Status-Code 409: Conflict.static final intHTTP Status-Code 201: Created.static final intHTTP Status-Code 413: Request Entity Too Large.static final intHTTP Status-Code 403: Forbidden.static final intHTTP Status-Code 504: Gateway Timeout.static final intHTTP Status-Code 410: Gone.static final intHTTP Status-Code 500: Internal Server Error.static final intHTTP Status-Code 411: Length Required.static final intHTTP Status-Code 301: Moved Permanently.static final intHTTP Status-Code 302: Temporary Redirect.static final intHTTP Status-Code 300: Multiple Choices.static final intHTTP Status-Code 204: No Content.static final intHTTP Status-Code 406: Not Acceptable.static final intHTTP Status-Code 203: Non-Authoritative Information.static final intHTTP Status-Code 404: Not Found.static final intHTTP Status-Code 501: Not Implemented.static final intHTTP Status-Code 304: Not Modified.static final intHTTP Status-Code 200: OK.static final intHTTP Status-Code 206: Partial Content.static final intHTTP Status-Code 402: Payment Required.static final intHTTP Status-Code 412: Precondition Failed.static final intHTTP Status-Code 407: Proxy Authentication Required.static final intHTTP Status-Code 414: Request-URI Too Large.static final intHTTP Status-Code 205: Reset Content.static final intHTTP Status-Code 303: See Other.static final intDeprecated.it is misplaced and shouldn't have existed.static final intHTTP Status-Code 401: Unauthorized.static final intHTTP Status-Code 503: Service Unavailable.static final intHTTP Status-Code 415: Unsupported Media Type.static final intHTTP Status-Code 305: Use Proxy.static final intHTTP Status-Code 505: HTTP Version Not Supported.protected booleanIftrue, the protocol will automatically follow redirects.protected StringThe HTTP method (GET,POST,PUT,etc.).protected intAnintrepresenting the three digit HTTP Status-Code.protected StringThe HTTP response message.Fields declared in class java.net.URLConnection
allowUserInteraction, connected, doInput, doOutput, ifModifiedSince, url, useCaches -
Constructor Summary
ConstructorsModifierConstructorDescriptionprotectedConstructor for the HttpURLConnection. -
Method Summary
Modifier and TypeMethodDescriptionabstract voidIndicates 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 booleanReturns abooleanindicating whether or not HTTP redirects (3xx) should be automatically followed.getHeaderField(int n) Returns the value for thenth header field.getHeaderFieldKey(int n) Returns the key for thenth header field.booleanReturns the value of thisHttpURLConnection'sinstanceFollowRedirectsfield.Returns aSocketPermissionobject representing the permission necessary to connect to the destination host and port.Get the request method.intGets the status code from an HTTP response message.Gets the HTTP response message, if any, returned along with the response code from a server.voidSupplies anAuthenticatorto be used when authentication is requested through the HTTP protocol for thisHttpURLConnection.voidsetChunkedStreamingMode(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.voidsetFixedLengthStreamingMode(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.voidsetFixedLengthStreamingMode(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 voidsetFollowRedirects(boolean set) Sets whether HTTP redirects (requests with response code 3xx) should be automatically followed by this class.voidsetInstanceFollowRedirects(boolean followRedirects) Sets whether HTTP redirects (requests with response code 3xx) should be automatically followed by thisHttpURLConnectioninstance.voidsetRequestMethod(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 booleanIndicates 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-1means 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-1means fixed-length streaming mode is disabled for output.NOTE:
fixedContentLengthLongis 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-1means fixed-length streaming mode is disabled for output.- Since:
- 1.7
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responseCode
protected int responseCodeAnintrepresenting 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
setInstanceFollowRedirectsmethod. Its value is returned by thegetInstanceFollowRedirectsmethod.Its default value is based on the value of the static followRedirects at HttpURLConnection construction time.
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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
Constructor for the HttpURLConnection.- Parameters:
u- the URL
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Method Details
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setAuthenticator
Supplies anAuthenticatorto 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 ofHttpURLConnectionwhich support supplying anAuthenticatorfor a specificHttpURLConnectioninstance 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 forHttpURLConnectioninstances which share the sameAuthenticatorinstance, and authentication information, if cached, may only be reused for anHttpURLConnectionsharing that sameAuthenticator. - Parameters:
auth- TheAuthenticatorthat 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 suppliedauthisnull.- Since:
- 9
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getHeaderFieldKey
Returns the key for thenth header field. Some implementations may treat the0th 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:
getHeaderFieldKeyin classURLConnection- Parameters:
n- an index, wheren >=0.- Returns:
- the key for the
nth header field, ornullif 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 write in each chunk. If chunklen is less than or equal to zero, a 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 thenth header field. Some implementations may treat the0th header field as special, i.e. as the status line returned by the HTTP server.This method can be used in conjunction with the
getHeaderFieldKeymethod to iterate through all the headers in the message.- Overrides:
getHeaderFieldin classURLConnection- Parameters:
n- an index, wheren>=0.- Returns:
- the value of the
nth header field, ornullif 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. Applets cannot change this variable.If there is a security manager, this method first calls the security manager's
checkSetFactorymethod to ensure the operation is allowed. This could result in a SecurityException.- Parameters:
set- abooleanindicating whether or not to follow HTTP redirects.- Throws:
SecurityException- if a security manager exists and itscheckSetFactorymethod doesn't allow the operation.- See Also:
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getFollowRedirects
public static boolean getFollowRedirects()Returns abooleanindicating whether or not HTTP redirects (3xx) should be automatically followed.- Returns:
trueif HTTP redirects should be automatically followed,falseif 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 thisHttpURLConnectioninstance.The default value comes from followRedirects, which defaults to true.
- Parameters:
followRedirects- abooleanindicating 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'sinstanceFollowRedirectsfield.- Returns:
- the value of this
HttpURLConnection'sinstanceFollowRedirectsfield. - 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
Get the request method.- Returns:
- the HTTP request method
- See Also:
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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 returnstrueif the connection is known to be going or has gone through proxies, and returnsfalseif 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 aSocketPermissionobject representing the permission necessary to connect to the destination host and port.- Overrides:
getPermissionin classURLConnection- Returns:
- a
SocketPermissionobject 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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