java.net
Class HttpURLConnection

java.lang.Object
  |
  +--java.net.URLConnection
        |
        +--java.net.HttpURLConnection
Direct Known Subclasses:
HttpsURLConnection
public abstract class HttpURLConnection
extends URLConnection

A URLConnection with support for HTTP-specific features. See the spec for details.

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.

Since:
JDK1.1
See Also:
disconnect()

 

Field Summary

static int HTTP_ACCEPTED
    HTTP Status-Code 202: Accepted.
static int HTTP_BAD_GATEWAY
    HTTP Status-Code 502: Bad Gateway.
static int HTTP_BAD_METHOD
    HTTP Status-Code 405: Method Not Allowed.
static int HTTP_BAD_REQUEST
    HTTP Status-Code 400: Bad Request.
static int HTTP_CLIENT_TIMEOUT
    HTTP Status-Code 408: Request Time-Out.
static int HTTP_CONFLICT
    HTTP Status-Code 409: Conflict.
static int HTTP_CREATED
    HTTP Status-Code 201: Created.
static int HTTP_ENTITY_TOO_LARGE
    HTTP Status-Code 413: Request Entity Too Large.
static int HTTP_FORBIDDEN
    HTTP Status-Code 403: Forbidden.
static int HTTP_GATEWAY_TIMEOUT
    HTTP Status-Code 504: Gateway Timeout.
static int HTTP_GONE
    HTTP Status-Code 410: Gone.
static int HTTP_INTERNAL_ERROR
    HTTP Status-Code 500: Internal Server Error.
static int HTTP_LENGTH_REQUIRED
    HTTP Status-Code 411: Length Required.
static int HTTP_MOVED_PERM
    HTTP Status-Code 301: Moved Permanently.
static int HTTP_MOVED_TEMP
    HTTP Status-Code 302: Temporary Redirect.
static int HTTP_MULT_CHOICE
    HTTP Status-Code 300: Multiple Choices.
static int HTTP_NO_CONTENT
    HTTP Status-Code 204: No Content.
static int HTTP_NOT_ACCEPtable
    HTTP Status-Code 406: Not Acceptable.
static int HTTP_NOT_AUTHORITATIVE
    HTTP Status-Code 203: Non-Authoritative Information.
static int HTTP_NOT_FOUND
    HTTP Status-Code 404: Not Found.
static int HTTP_NOT_IMPLEMENTED
    HTTP Status-Code 501: Not Implemented.
static int HTTP_NOT_MODIFIED
    HTTP Status-Code 304: Not Modified.
static int HTTP_OK
    HTTP Status-Code 200: OK.
static int HTTP_PARTIAL
    HTTP Status-Code 206: Partial Content.
static int HTTP_PAYMENT_REQUIRED
    HTTP Status-Code 402: Payment Required.
static int HTTP_PRECON_FAILED
    HTTP Status-Code 412: Precondition Failed.
static int HTTP_PROXY_AUTH
    HTTP Status-Code 407: Proxy Authentication Required.
static int HTTP_REQ_TOO_LONG
    HTTP Status-Code 414: Request-URI Too Large.
static int HTTP_RESET
    HTTP Status-Code 205: Reset Content.
static int HTTP_SEE_OTHER
    HTTP Status-Code 303: See Other.
static int HTTP_SERVER_ERROR
    Deprecated. it is misplaced and shouldn't have existed.
static int HTTP_UNAUTHORIZED
    HTTP Status-Code 401: Unauthorized.
static int HTTP_UNAVAILABLE
    HTTP Status-Code 503: Service Unavailable.
static int HTTP_UNSUPPORTED_TYPE
    HTTP Status-Code 415: Unsupported Media Type.
static int HTTP_USE_PROXY
    HTTP Status-Code 305: Use Proxy.
static int HTTP_VERSION
    HTTP Status-Code 505: HTTP Version Not Supported.
protected  boolean instanceFollowRedirects
    If true, the protocol will automatically follow redirects.
protected  String method
    The HTTP method (GET,POST,PUT,etc.).
protected  int responseCode
    An int representing the three digit HTTP Status-Code.
protected  String responseMessage
    The HTTP response message.
 
Fields inherited from class java.net.URLConnection
allowUserInteraction, connected, doInput, doOutput, ifModifiedSince, url, useCaches
 

 

Constructor Summary

protected HttpURLConnection(URL u)
    Constructor for the HttpURLConnection.
 

 

Method Summary

abstract  void disconnect()
    Indicates that other requests to the server are unlikely in the near future.
 InputStream getErrorStream()
    Returns the error stream if the connection failed but the server sent useful data nonetheless.
static boolean getFollowRedirects()
    Returns a boolean indicating whether or not HTTP redirects (3xx) should be automatically followed.
 long getHeaderFieldDate(String name, long Default)
    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()
    Get the request method.
 int getResponseCode()
    Gets the status code from an HTTP response message.
 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 followRedirects)
    Sets whether HTTP redirects (requests with response code 3xx) should be automatically followed by this HttpURLConnection 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 usingProxy()
    Indicates if the connection is going through a proxy.
 
Methods inherited from class java.net.URLConnection
addRequestProperty, connect, getAllowUserInteraction, getContent, getContent, getContentEncoding, getContentLength, getContentType, getDate, getDefaultAllowUserInteraction, getDefaultRequestProperty, getDefaultUseCaches, getDoInput, getDoOutput, getExpiration, getFileNameMap, getHeaderField, getHeaderField, getHeaderFieldInt, getHeaderFieldKey, getHeaderFields, getIfModifiedSince, getInputStream, getLastModified, getOutputStream, getRequestProperties, getRequestProperty, getURL, getUseCaches, guessContentTypeFromName, guessContentTypeFromStream, setAllowUserInteraction, setContentHandlerFactory, setDefaultAllowUserInteraction, setDefaultRequestProperty, setDefaultUseCaches, setDoInput, setDoOutput, setFileNameMap, setIfModifiedSince, setRequestProperty, setUseCaches, toString
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

 

Field Detail

 

method

protected String method
The HTTP method (GET,POST,PUT,etc.).

 

responseCode

protected int responseCode
An int representing the three digit HTTP Status-Code.
  • 1xx: Informational
  • 2xx: Success
  • 3xx: Redirection
  • 4xx: Client Error
  • 5xx: Server Error

 

responseMessage

protected String responseMessage
The HTTP response message.

 

instanceFollowRedirects

protected boolean instanceFollowRedirects
If true, the protocol will automatically follow redirects. If false, the protocol will not automatically follow redirects.

This field is set by the setInstanceFollowRedirects method. Its value is returned by the getInstanceFollowRedirects method.

Its default value is based on the value of the static followRedirects at HttpURLConnection construction time.

See Also:
setInstanceFollowRedirects(boolean), getInstanceFollowRedirects(), setFollowRedirects(boolean)

 

HTTP_OK

public static final int HTTP_OK
HTTP Status-Code 200: OK.

See Also:
Constant Field Values

 

HTTP_CREATED

public static final int HTTP_CREATED
HTTP Status-Code 201: Created.

See Also:
Constant Field Values

 

HTTP_ACCEPTED

public static final int HTTP_ACCEPTED
HTTP Status-Code 202: Accepted.

See Also:
Constant Field Values

 

HTTP_NOT_AUTHORITATIVE

public static final int HTTP_NOT_AUTHORITATIVE
HTTP Status-Code 203: Non-Authoritative Information.

See Also:
Constant Field Values

 

HTTP_NO_CONTENT

public static final int HTTP_NO_CONTENT
HTTP Status-Code 204: No Content.

See Also:
Constant Field Values

 

HTTP_RESET

public static final int HTTP_RESET
HTTP Status-Code 205: Reset Content.

See Also:
Constant Field Values

 

HTTP_PARTIAL

public static final int HTTP_PARTIAL
HTTP Status-Code 206: Partial Content.

See Also:
Constant Field Values

 

HTTP_MULT_CHOICE

public static final int HTTP_MULT_CHOICE
HTTP Status-Code 300: Multiple Choices.

See Also:
Constant Field Values

 

HTTP_MOVED_PERM

public static final int HTTP_MOVED_PERM
HTTP Status-Code 301: Moved Permanently.

See Also:
Constant Field Values

 

HTTP_MOVED_TEMP

public static final int HTTP_MOVED_TEMP
HTTP Status-Code 302: Temporary Redirect.

See Also:
Constant Field Values

 

HTTP_SEE_OTHER

public static final int HTTP_SEE_OTHER
HTTP Status-Code 303: See Other.

See Also:
Constant Field Values

 

HTTP_NOT_MODIFIED

public static final int HTTP_NOT_MODIFIED
HTTP Status-Code 304: Not Modified.

See Also:
Constant Field Values

 

HTTP_USE_PROXY

public static final int HTTP_USE_PROXY
HTTP Status-Code 305: Use Proxy.

See Also:
Constant Field Values

 

HTTP_BAD_REQUEST

public static final int HTTP_BAD_REQUEST
HTTP Status-Code 400: Bad Request.

See Also:
Constant Field Values

 

HTTP_UNAUTHORIZED

public static final int HTTP_UNAUTHORIZED
HTTP Status-Code 401: Unauthorized.

See Also:
Constant Field Values

 

HTTP_PAYMENT_REQUIRED

public static final int HTTP_PAYMENT_REQUIRED
HTTP Status-Code 402: Payment Required.

See Also:
Constant Field Values

 

HTTP_FORBIDDEN

public static final int HTTP_FORBIDDEN
HTTP Status-Code 403: Forbidden.

See Also:
Constant Field Values

 

HTTP_NOT_FOUND

public static final int HTTP_NOT_FOUND
HTTP Status-Code 404: Not Found.

See Also:
Constant Field Values

 

HTTP_BAD_METHOD

public static final int HTTP_BAD_METHOD
HTTP Status-Code 405: Method Not Allowed.

See Also:
Constant Field Values

 

HTTP_NOT_ACCEPtable

public static final int HTTP_NOT_ACCEPtable
HTTP Status-Code 406: Not Acceptable.

See Also:
Constant Field Values

 

HTTP_PROXY_AUTH

public static final int HTTP_PROXY_AUTH
HTTP Status-Code 407: Proxy Authentication Required.

See Also:
Constant Field Values

 

HTTP_CLIENT_TIMEOUT

public static final int HTTP_CLIENT_TIMEOUT
HTTP Status-Code 408: Request Time-Out.

See Also:
Constant Field Values

 

HTTP_CONFLICT

public static final int HTTP_CONFLICT
HTTP Status-Code 409: Conflict.

See Also:
Constant Field Values

 

HTTP_GONE

public static final int HTTP_GONE
HTTP Status-Code 410: Gone.

See Also:
Constant Field Values

 

HTTP_LENGTH_REQUIRED

public static final int HTTP_LENGTH_REQUIRED
HTTP Status-Code 411: Length Required.

See Also:
Constant Field Values

 

HTTP_PRECON_FAILED

public static final int HTTP_PRECON_FAILED
HTTP Status-Code 412: Precondition Failed.

See Also:
Constant Field Values

 

HTTP_ENTITY_TOO_LARGE

public static final int HTTP_ENTITY_TOO_LARGE
HTTP Status-Code 413: Request Entity Too Large.

See Also:
Constant Field Values

 

HTTP_REQ_TOO_LONG

public static final int HTTP_REQ_TOO_LONG
HTTP Status-Code 414: Request-URI Too Large.

See Also:
Constant Field Values

 

HTTP_UNSUPPORTED_TYPE

public static final int HTTP_UNSUPPORTED_TYPE
HTTP Status-Code 415: Unsupported Media Type.

See Also:
Constant Field Values

 

HTTP_SERVER_ERROR

public static final int HTTP_SERVER_ERROR
Deprecated. it is misplaced and shouldn't have existed.

HTTP Status-Code 500: Internal Server Error.

See Also:
Constant Field Values

 

HTTP_INTERNAL_ERROR

public static final int HTTP_INTERNAL_ERROR
HTTP Status-Code 500: Internal Server Error.

See Also:
Constant Field Values

 

HTTP_NOT_IMPLEMENTED

public static final int HTTP_NOT_IMPLEMENTED
HTTP Status-Code 501: Not Implemented.

See Also:
Constant Field Values

 

HTTP_BAD_GATEWAY

public static final int HTTP_BAD_GATEWAY
HTTP Status-Code 502: Bad Gateway.

See Also:
Constant Field Values

 

HTTP_UNAVAILABLE

public static final int HTTP_UNAVAILABLE
HTTP Status-Code 503: Service Unavailable.

See Also:
Constant Field Values

 

HTTP_GATEWAY_TIMEOUT

public static final int HTTP_GATEWAY_TIMEOUT
HTTP Status-Code 504: Gateway Timeout.

See Also:
Constant Field Values

 

HTTP_VERSION

public static final int HTTP_VERSION
HTTP Status-Code 505: HTTP Version Not Supported.

See Also:
Constant Field Values

 

Constructor Detail

 

HttpURLConnection

protected HttpURLConnection(URL u)
Constructor for the HttpURLConnection.

Parameters:
u - the URL

 

Method Detail

 

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 checkSetFactory method to ensure the operation is allowed. This could result in a SecurityException.

Parameters:
set - a boolean indicating whether or not to follow HTTP redirects.
Throws:
SecurityException - if a security manager exists and its checkSetFactory method doesn't allow the operation.
See Also:
SecurityManager.checkSetFactory(), getFollowRedirects()

 

getFollowRedirects

public static boolean getFollowRedirects()
Returns a boolean 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:
setFollowRedirects(boolean)

 

setInstanceFollowRedirects

public void setInstanceFollowRedirects(boolean followRedirects)
Sets whether HTTP redirects (requests with response code 3xx) should be automatically followed by this HttpURLConnection instance.

The default value comes from followRedirects, which defaults to true.

Parameters:
followRedirects - a boolean indicating whether or not to follow HTTP redirects.
See Also:
instanceFollowRedirects, getInstanceFollowRedirects()

 

getInstanceFollowRedirects

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

Returns:
the value of this HttpURLConnection's instanceFollowRedirects field.
See Also:
instanceFollowRedirects, setInstanceFollowRedirects(boolean)

 

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, subject to protocol restrictions. The default method is GET.

Parameters:
method - the HTTP method
Throws:
ProtocolException - if the method cannot be reset or if the requested method isn't valid for HTTP.
See Also:
getRequestMethod()

 

getRequestMethod

public String getRequestMethod()
Get the request method.

Returns:
the HTTP request method
See Also:
setRequestMethod(java.lang.String)

 

getResponseCode

public int getResponseCode()
                    throws IOException
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.

 

getResponseMessage

public String getResponseMessage()
                          throws IOException
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.

 

getHeaderFieldDate

public long getHeaderFieldDate(String name,
                               long Default)
Description copied from class: URLConnection
Returns the value of the named field parsed as date. The result is the number of milliseconds since January 1, 1970 GMT represented by the named field.

This form of getHeaderField exists because some connection types (e.g., http-ng) have pre-parsed headers. Classes for that connection type can override this method and short-circuit the parsing.

Overrides:
getHeaderFieldDate in class URLConnection
Parameters:
name - the name of the header field.
Default - a default value.
Returns:
the value of the field, parsed as a date. The value of the Default argument is returned if the field is missing or malformed.

 

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.

Returns:
a boolean indicating if the connection is using a proxy.

 

getPermission

public Permission getPermission()
                         throws IOException
Description copied from class: URLConnection
Returns a permission object representing the permission necessary to make the connection represented by this object. This method returns null if no permission is required to make the connection. By default, this method returns java.security.AllPermission. Subclasses should override this method and return the permission that best represents the permission required to make a a connection to the URL. For example, a URLConnection representing a file: URL would return a java.io.FilePermission object.

The permission returned may dependent upon the state of the connection. For example, the permission before connecting may be different from that after connecting. For example, an HTTP sever, say foo.com, may redirect the connection to a different host, say bar.com. Before connecting the permission returned by the connection will represent the permission needed to connect to foo.com, while the permission returned after connecting will be to bar.com.

Permissions are generally used for two purposes: to protect caches of objects obtained through URLConnections, and to check the right of a recipient to learn about a particular URL. In the first case, the permission should be obtained after the object has been obtained. For example, in an HTTP connection, this will represent the permission to connect to the host from which the data was ultimately fetched. In the second case, the permission should be obtained and tested before connecting.

Overrides:
getPermission in class URLConnection
Returns:
the permission object representing the permission necessary to make the connection represented by this URLConnection.
Throws:
IOException - if the computation of the permission requires network or file I/O and an exception occurs while computing it.

 

getErrorStream

public InputStream 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.