java.net
Class HttpURLConnection

java.lang.Object
  extended by java.net.URLConnection
      extended by java.net.HttpURLConnection
Direct Known Subclasses:
HttpsURLConnection

public abstract class HttpURLConnection
extends URLConnection

This class provides a common abstract implementation for those URL connection classes that will connect using the HTTP protocol. In addition to the functionality provided by the URLConnection class, it defines constants for HTTP return code values and methods for setting the HTTP request method and determining whether or not to follow redirects.

Since:
1.1

Field Summary
static int HTTP_ACCEPTED
          The request has been accepted for processing but has not completed.
static int HTTP_BAD_GATEWAY
          The proxy encountered a bad response from the server it was proxy-ing for
static int HTTP_BAD_METHOD
          The specified request method is not allowed for this resource.
static int HTTP_BAD_REQUEST
          The request was misformed or could not be understood.
static int HTTP_CLIENT_TIMEOUT
          The request timed out.
static int HTTP_CONFLICT
          There is a conflict between the current state of the resource and the requested action.
static int HTTP_CREATED
          The requested resource has been created.
static int HTTP_ENTITY_TOO_LARGE
          The request sent was too large for the server to handle.
static int HTTP_FORBIDDEN
          There is no permission to access the requested resource.
static int HTTP_GATEWAY_TIMEOUT
          The proxy timed out getting a reply from the remote server it was proxy-ing for.
static int HTTP_GONE
          The requested resource is no longer available.
static int HTTP_INTERNAL_ERROR
          The server encountered an unexpected error (such as a CGI script crash) that prevents the request from being fulfilled.
static int HTTP_LENGTH_REQUIRED
          A Content-Length header is required for this request, but was not supplied.
static int HTTP_MOVED_PERM
          The resource has been permanently moved to a new location.
static int HTTP_MOVED_TEMP
          The resource requested has been temporarily moved to a new location.
static int HTTP_MULT_CHOICE
          There is a list of choices available for the requested resource.
static int HTTP_NO_CONTENT
          The server performed the request, but there is no data to send back.
static int HTTP_NOT_ACCEPTABLE
          Based on the input headers sent, the resource returned in response to the request would not be acceptable to the client.
static int HTTP_NOT_AUTHORITATIVE
          The meta-information returned in the header is not the actual data from the original server, but may be from a local or other copy.
static int HTTP_NOT_FOUND
          The requested resource was not found.
static int HTTP_NOT_IMPLEMENTED
          The server does not support the requested functionality.
static int HTTP_NOT_MODIFIED
          The document has not been modified since the criteria specified in a conditional GET.
static int HTTP_OK
          Indicates the request succeeded.
static int HTTP_PARTIAL
          The server completed the partial GET request for the resource.
static int HTTP_PAYMENT_REQUIRED
          Code reserved for future use - I hope way in the future.
static int HTTP_PRECON_FAILED
          A client specified pre-condition was not met on the server.
static int HTTP_PROXY_AUTH
          The client must authenticate with a proxy prior to attempting this request.
static int HTTP_REQ_TOO_LONG
          The name of the resource specified was too long.
static int HTTP_RESET
          The server performed the request, but there is no data to sent back, however, the user's display should be "reset" to clear out any form fields entered.
static int HTTP_SEE_OTHER
          The response to the request issued is available at another location.
static int HTTP_SERVER_ERROR
          Deprecated.  
static int HTTP_UNAUTHORIZED
          The request made requires user authorization.
static int HTTP_UNAVAILABLE
          The HTTP service is not availalble, such as because it is overloaded and does not want additional requests.
static int HTTP_UNSUPPORTED_TYPE
          The request is in a format not supported by the requested resource.
static int HTTP_USE_PROXY
          The requested resource needs to be accessed through a proxy.
static int HTTP_VERSION
          This server does not support the protocol version requested.
protected  boolean instanceFollowRedirects
          If this instance should follow redirect requests.
protected  String method
          The requested method in use for this connection.
protected  int responseCode
          The response code received from the server
protected  String responseMessage
          The response message string received from the server.
 
Fields inherited from class java.net.URLConnection
allowUserInteraction, connected, doInput, doOutput, ifModifiedSince, url, useCaches
 
Constructor Summary
protected HttpURLConnection(URL url)
          Create an HttpURLConnection for the specified URL
 
Method Summary
abstract  void disconnect()
          Closes the connection to the server.
 InputStream getErrorStream()
          This method allows the caller to retrieve any data that might have been sent despite the fact that an error occurred.
static boolean getFollowRedirects()
          Returns a boolean indicating whether or not HTTP redirects will automatically be followed or not.
 long getHeaderFieldDate(String key, long value)
          Returns the value of the named field parsed as date
 boolean getInstanceFollowRedirects()
          Returns the value of this HttpURLConnection's instanceFollowRedirects field
 Permission getPermission()
          Returns a permission object representing the permission necessary to make the connection represented by this object
 String getRequestMethod()
          The request method currently in use for this connection.
 int getResponseCode()
          Gets the status code from an HTTP response message, or -1 if the response code could not be determined.
 String getResponseMessage()
          Gets the HTTP response message, if any, returned along with the response code from a server.
static void setFollowRedirects(boolean set)
          Sets whether HTTP redirects (requests with response code 3xx) should be automatically followed by this class.
 void setInstanceFollowRedirects(boolean follow)
          Sets the value of this HttpURLConnection's instanceFollowRedirects field
 void setRequestMethod(String method)
          Set the method for the URL request, one of: GET POST HEAD OPTIONS PUT DELETE TRACE are legal
abstract  boolean usingProxy()
          Returns a boolean indicating whether or not this connection is going through a proxy
 
Methods inherited from class java.net.URLConnection
addRequestProperty, connect, getAllowUserInteraction, getConnectTimeout, getContent, getContent, getContentEncoding, getContentLength, getContentType, getDate, getDefaultAllowUserInteraction, getDefaultRequestProperty, getDefaultUseCaches, getDoInput, getDoOutput, getExpiration, getFileNameMap, getHeaderField, getHeaderField, getHeaderFieldInt, getHeaderFieldKey, getHeaderFields, getIfModifiedSince, getInputStream, getLastModified, getOutputStream, getReadTimeout, getRequestProperties, getRequestProperty, getURL, getUseCaches, guessContentTypeFromName, guessContentTypeFromStream, setAllowUserInteraction, setConnectTimeout, setContentHandlerFactory, setDefaultAllowUserInteraction, setDefaultRequestProperty, setDefaultUseCaches, setDoInput, setDoOutput, setFileNameMap, setIfModifiedSince, setReadTimeout, setRequestProperty, setUseCaches, toString
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

HTTP_OK

public static final int HTTP_OK
Indicates the request succeeded.

See Also:
Constant Field Values

HTTP_CREATED

public static final int HTTP_CREATED
The requested resource has been created.

See Also:
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HTTP_ACCEPTED

public static final int HTTP_ACCEPTED
The request has been accepted for processing but has not completed. There is no guarantee that the requested action will actually ever be completed succesfully, but everything is ok so far.

See Also:
Constant Field Values

HTTP_NOT_AUTHORITATIVE

public static final int HTTP_NOT_AUTHORITATIVE
The meta-information returned in the header is not the actual data from the original server, but may be from a local or other copy. Normally this still indicates a successful completion.

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HTTP_NO_CONTENT

public static final int HTTP_NO_CONTENT
The server performed the request, but there is no data to send back. This indicates that the user's display should not be changed.

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HTTP_RESET

public static final int HTTP_RESET
The server performed the request, but there is no data to sent back, however, the user's display should be "reset" to clear out any form fields entered.

See Also:
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HTTP_PARTIAL

public static final int HTTP_PARTIAL
The server completed the partial GET request for the resource.

See Also:
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HTTP_MULT_CHOICE

public static final int HTTP_MULT_CHOICE
There is a list of choices available for the requested resource.

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HTTP_MOVED_PERM

public static final int HTTP_MOVED_PERM
The resource has been permanently moved to a new location.

See Also:
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HTTP_MOVED_TEMP

public static final int HTTP_MOVED_TEMP
The resource requested has been temporarily moved to a new location.

See Also:
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HTTP_SEE_OTHER

public static final int HTTP_SEE_OTHER
The response to the request issued is available at another location.

See Also:
Constant Field Values

HTTP_NOT_MODIFIED

public static final int HTTP_NOT_MODIFIED
The document has not been modified since the criteria specified in a conditional GET.

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HTTP_USE_PROXY

public static final int HTTP_USE_PROXY
The requested resource needs to be accessed through a proxy.

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HTTP_BAD_REQUEST

public static final int HTTP_BAD_REQUEST
The request was misformed or could not be understood.

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HTTP_UNAUTHORIZED

public static final int HTTP_UNAUTHORIZED
The request made requires user authorization. Try again with a correct authentication header.

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HTTP_PAYMENT_REQUIRED

public static final int HTTP_PAYMENT_REQUIRED
Code reserved for future use - I hope way in the future.

See Also:
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HTTP_FORBIDDEN

public static final int HTTP_FORBIDDEN
There is no permission to access the requested resource.

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HTTP_NOT_FOUND

public static final int HTTP_NOT_FOUND
The requested resource was not found.

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HTTP_BAD_METHOD

public static final int HTTP_BAD_METHOD
The specified request method is not allowed for this resource.

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HTTP_NOT_ACCEPTABLE

public static final int HTTP_NOT_ACCEPTABLE
Based on the input headers sent, the resource returned in response to the request would not be acceptable to the client.

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HTTP_PROXY_AUTH

public static final int HTTP_PROXY_AUTH
The client must authenticate with a proxy prior to attempting this request.

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HTTP_CLIENT_TIMEOUT

public static final int HTTP_CLIENT_TIMEOUT
The request timed out.

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HTTP_CONFLICT

public static final int HTTP_CONFLICT
There is a conflict between the current state of the resource and the requested action.

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HTTP_GONE

public static final int HTTP_GONE
The requested resource is no longer available. This ususally indicates a permanent condition.

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HTTP_LENGTH_REQUIRED

public static final int HTTP_LENGTH_REQUIRED
A Content-Length header is required for this request, but was not supplied.

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HTTP_PRECON_FAILED

public static final int HTTP_PRECON_FAILED
A client specified pre-condition was not met on the server.

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HTTP_ENTITY_TOO_LARGE

public static final int HTTP_ENTITY_TOO_LARGE
The request sent was too large for the server to handle.

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HTTP_REQ_TOO_LONG

public static final int HTTP_REQ_TOO_LONG
The name of the resource specified was too long.

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HTTP_UNSUPPORTED_TYPE

public static final int HTTP_UNSUPPORTED_TYPE
The request is in a format not supported by the requested resource.

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HTTP_SERVER_ERROR

public static final int HTTP_SERVER_ERROR
Deprecated. 
This error code indicates that some sort of server error occurred.

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HTTP_INTERNAL_ERROR

public static final int HTTP_INTERNAL_ERROR
The server encountered an unexpected error (such as a CGI script crash) that prevents the request from being fulfilled.

See Also:
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HTTP_NOT_IMPLEMENTED

public static final int HTTP_NOT_IMPLEMENTED
The server does not support the requested functionality.

Since:
1.3
See Also:
Constant Field Values

HTTP_BAD_GATEWAY

public static final int HTTP_BAD_GATEWAY
The proxy encountered a bad response from the server it was proxy-ing for

See Also:
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HTTP_UNAVAILABLE

public static final int HTTP_UNAVAILABLE
The HTTP service is not availalble, such as because it is overloaded and does not want additional requests.

See Also:
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HTTP_GATEWAY_TIMEOUT

public static final int HTTP_GATEWAY_TIMEOUT
The proxy timed out getting a reply from the remote server it was proxy-ing for.

See Also:
Constant Field Values

HTTP_VERSION

public static final int HTTP_VERSION
This server does not support the protocol version requested.

See Also:
Constant Field Values

method

protected String method
The requested method in use for this connection. Default is GET.


responseCode

protected int responseCode
The response code received from the server


responseMessage

protected String responseMessage
The response message string received from the server.


instanceFollowRedirects

protected boolean instanceFollowRedirects
If this instance should follow redirect requests.

Constructor Detail

HttpURLConnection

protected HttpURLConnection(URL url)
Create an HttpURLConnection for the specified URL

Parameters:
url - The URL to create this connection for.
Method Detail

disconnect

public abstract void disconnect()
Closes the connection to the server.


usingProxy

public abstract boolean usingProxy()
Returns a boolean indicating whether or not this connection is going through a proxy

Returns:
true if through a proxy, false otherwise

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

Parameters:
set - true if redirects should be followed, false otherwis.
Throws:
SecurityException - If a security manager exists and its checkSetFactory method doesn't allow the operation

getFollowRedirects

public static boolean getFollowRedirects()
Returns a boolean indicating whether or not HTTP redirects will automatically be followed or not.

Returns:
true if redirects will be followed, false otherwise

getInstanceFollowRedirects

public boolean getInstanceFollowRedirects()
Returns the value of this HttpURLConnection's instanceFollowRedirects field

Returns:
true if following redirects is enabled, false otherwise

setInstanceFollowRedirects

public void setInstanceFollowRedirects(boolean follow)
Sets the value of this HttpURLConnection's instanceFollowRedirects field

Parameters:
follow - true to enable following redirects, false otherwise

setRequestMethod

public void setRequestMethod(String method)
                      throws ProtocolException
Set the method for the URL request, one of: GET POST HEAD OPTIONS PUT DELETE TRACE are legal

Parameters:
method - the method to use
Throws:
ProtocolException - If the method cannot be reset or if the requested method isn't valid for HTTP

getRequestMethod

public String getRequestMethod()
The request method currently in use for this connection.

Returns:
The request method

getResponseCode

public int getResponseCode()
                    throws IOException
Gets the status code from an HTTP response message, or -1 if the response code could not be determined. Note that all valid response codes have class variables defined for them in this class.

Returns:
The response code
Throws:
IOException - If an error occurs

getResponseMessage

public String getResponseMessage()
                          throws IOException
Gets the HTTP response message, if any, returned along with the response code from a server. Null if no response message was set or an error occured while connecting.

Returns:
The response message
Throws:
IOException - If an error occurs

getPermission

public Permission getPermission()
                         throws IOException
Returns a permission object representing the permission necessary to make the connection represented by this object

Overrides:
getPermission in class URLConnection
Returns:
the permission necessary for this connection
Throws:
IOException - If an error occurs

getErrorStream

public InputStream getErrorStream()
This method allows the caller to retrieve any data that might have been sent despite the fact that an error occurred. For example, the HTML page sent along with a 404 File Not Found error. If the socket is not connected, or if no error occurred or no data was returned, this method returns null.

Returns:
An InputStream for reading error data.

getHeaderFieldDate

public long getHeaderFieldDate(String key,
                               long value)
Returns the value of the named field parsed as date

Overrides:
getHeaderFieldDate in class URLConnection
Parameters:
key - the key of the header field
value - the default value if the header field is not present
Returns:
the value of the header field