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abstract public class: HttpURLConnection [javadoc | source]
java.lang.Object
   java.net.URLConnection
      java.net.HttpURLConnection

Direct Known Subclasses:
    HttpsURLConnection

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.

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.

Field Summary
protected  String method    The HTTP method (GET,POST,PUT,etc.). 
protected  int chunkLength    The chunk-length when using chunked encoding streaming mode for output. A value of -1 means chunked encoding is disabled for output.
    since: 1.5 -
 
protected  int fixedContentLength    The 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 -
 
protected  long fixedContentLengthLong    The fixed content-length when using fixed-length streaming mode. A value of {@code -1} means fixed-length streaming mode is disabled for output.
    since: 1.7 -
 
protected  int responseCode    An int representing the three digit HTTP Status-Code.
  • 1xx: Informational
  • 2xx: Success
  • 3xx: Redirection
  • 4xx: Client Error
  • 5xx: Server Error
 
protected  String responseMessage    The HTTP response message. 
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.

    Also see:
    java.net.HttpURLConnection#setInstanceFollowRedirects(boolean)
    java.net.HttpURLConnection#getInstanceFollowRedirects()
    java.net.HttpURLConnection#setFollowRedirects(boolean)
 
public static final  int HTTP_OK    HTTP Status-Code 200: OK. 
public static final  int HTTP_CREATED    HTTP Status-Code 201: Created. 
public static final  int HTTP_ACCEPTED    HTTP Status-Code 202: Accepted. 
public static final  int HTTP_NOT_AUTHORITATIVE    HTTP Status-Code 203: Non-Authoritative Information. 
public static final  int HTTP_NO_CONTENT    HTTP Status-Code 204: No Content. 
public static final  int HTTP_RESET    HTTP Status-Code 205: Reset Content. 
public static final  int HTTP_PARTIAL    HTTP Status-Code 206: Partial Content. 
public static final  int HTTP_MULT_CHOICE    HTTP Status-Code 300: Multiple Choices. 
public static final  int HTTP_MOVED_PERM    HTTP Status-Code 301: Moved Permanently. 
public static final  int HTTP_MOVED_TEMP    HTTP Status-Code 302: Temporary Redirect. 
public static final  int HTTP_SEE_OTHER    HTTP Status-Code 303: See Other. 
public static final  int HTTP_NOT_MODIFIED    HTTP Status-Code 304: Not Modified. 
public static final  int HTTP_USE_PROXY    HTTP Status-Code 305: Use Proxy. 
public static final  int HTTP_BAD_REQUEST    HTTP Status-Code 400: Bad Request. 
public static final  int HTTP_UNAUTHORIZED    HTTP Status-Code 401: Unauthorized. 
public static final  int HTTP_PAYMENT_REQUIRED    HTTP Status-Code 402: Payment Required. 
public static final  int HTTP_FORBIDDEN    HTTP Status-Code 403: Forbidden. 
public static final  int HTTP_NOT_FOUND    HTTP Status-Code 404: Not Found. 
public static final  int HTTP_BAD_METHOD    HTTP Status-Code 405: Method Not Allowed. 
public static final  int HTTP_NOT_ACCEPTABLE    HTTP Status-Code 406: Not Acceptable. 
public static final  int HTTP_PROXY_AUTH    HTTP Status-Code 407: Proxy Authentication Required. 
public static final  int HTTP_CLIENT_TIMEOUT    HTTP Status-Code 408: Request Time-Out. 
public static final  int HTTP_CONFLICT    HTTP Status-Code 409: Conflict. 
public static final  int HTTP_GONE    HTTP Status-Code 410: Gone. 
public static final  int HTTP_LENGTH_REQUIRED    HTTP Status-Code 411: Length Required. 
public static final  int HTTP_PRECON_FAILED    HTTP Status-Code 412: Precondition Failed. 
public static final  int HTTP_ENTITY_TOO_LARGE    HTTP Status-Code 413: Request Entity Too Large. 
public static final  int HTTP_REQ_TOO_LONG    HTTP Status-Code 414: Request-URI Too Large. 
public static final  int HTTP_UNSUPPORTED_TYPE    HTTP Status-Code 415: Unsupported Media Type. 
public static final  int HTTP_SERVER_ERROR    HTTP Status-Code 500: Internal Server Error.
     
    public static final  int HTTP_INTERNAL_ERROR    HTTP Status-Code 500: Internal Server Error. 
    public static final  int HTTP_NOT_IMPLEMENTED    HTTP Status-Code 501: Not Implemented. 
    public static final  int HTTP_BAD_GATEWAY    HTTP Status-Code 502: Bad Gateway. 
    public static final  int HTTP_UNAVAILABLE    HTTP Status-Code 503: Service Unavailable. 
    public static final  int HTTP_GATEWAY_TIMEOUT    HTTP Status-Code 504: Gateway Timeout. 
    public static final  int HTTP_VERSION    HTTP Status-Code 505: HTTP Version Not Supported. 
    Fields inherited from java.net.URLConnection:
    url,  doInput,  doOutput,  allowUserInteraction,  useCaches,  ifModifiedSince,  connected,  factory
    Constructor:
     protected HttpURLConnection(URL u) 
      Constructor for the HttpURLConnection.
      Parameters:
      u - the URL
    Method from java.net.HttpURLConnection Summary:
    disconnect,   getErrorStream,   getFollowRedirects,   getHeaderField,   getHeaderFieldDate,   getHeaderFieldKey,   getInstanceFollowRedirects,   getPermission,   getRequestMethod,   getResponseCode,   getResponseMessage,   setChunkedStreamingMode,   setFixedLengthStreamingMode,   setFixedLengthStreamingMode,   setFollowRedirects,   setInstanceFollowRedirects,   setRequestMethod,   usingProxy
    Methods from java.net.URLConnection:
    addRequestProperty,   connect,   getAllowUserInteraction,   getConnectTimeout,   getContent,   getContent,   getContentEncoding,   getContentHandler,   getContentLength,   getContentLengthLong,   getContentType,   getDate,   getDefaultAllowUserInteraction,   getDefaultRequestProperty,   getDefaultUseCaches,   getDoInput,   getDoOutput,   getExpiration,   getFileNameMap,   getHeaderField,   getHeaderField,   getHeaderFieldDate,   getHeaderFieldInt,   getHeaderFieldKey,   getHeaderFieldLong,   getHeaderFields,   getIfModifiedSince,   getInputStream,   getLastModified,   getOutputStream,   getPermission,   getReadTimeout,   getRequestProperties,   getRequestProperty,   getURL,   getUseCaches,   guessContentTypeFromName,   guessContentTypeFromStream,   setAllowUserInteraction,   setConnectTimeout,   setContentHandlerFactory,   setDefaultAllowUserInteraction,   setDefaultRequestProperty,   setDefaultUseCaches,   setDoInput,   setDoOutput,   setFileNameMap,   setIfModifiedSince,   setReadTimeout,   setRequestProperty,   setUseCaches,   toString
    Methods from java.lang.Object:
    clone,   equals,   finalize,   getClass,   hashCode,   notify,   notifyAll,   toString,   wait,   wait,   wait
    Method from java.net.HttpURLConnection Detail:
     abstract public  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.
     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.

     public static boolean getFollowRedirects() 
      Returns a boolean indicating whether or not HTTP redirects (3xx) should be automatically followed.
     public String getHeaderField(int n) 
      Returns the value for the nth header field. Some implementations may treat the 0th 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.

     public long getHeaderFieldDate(String name,
        long Default) 
     public String getHeaderFieldKey(int n) 
      Returns the key for the nth header field. Some implementations may treat the 0th header field as special, i.e. as the status line returned by the HTTP server. In this case, getHeaderField(0) returns the status line, but getHeaderFieldKey(0) returns null.
     public boolean getInstanceFollowRedirects() 
      Returns the value of this HttpURLConnection's instanceFollowRedirects field.
     public Permission getPermission() throws IOException 
      Returns a SocketPermission object representing the permission necessary to connect to the destination host and port.
     public String getRequestMethod() 
      Get the request method.
     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).
     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).
     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.

     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.

     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 {@linkplain 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) .

     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.

     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.

     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.
     abstract public boolean usingProxy()
      Indicates if the connection is going through a proxy.