home | O'Reilly's CD bookshelfs | FreeBSD | Linux | Cisco | Cisco Exam

Previous

Chapter 15
The java.net Package

Next

HttpURLConnection

Name

HttpURLConnection

Synopsis

Class Name:

java.net.HttpURLConnection

Superclass:

java.net.URLConnection

Immediate Subclasses:

None

Interfaces Implemented:

None

Availability:

New as of JDK 1.1

Description

The HttpURLConnection class is an abstract class that is a subclass of URLConnection. HttpURLConnection defines many of the HTTP server response codes as constants and provides methods for parsing server responses.

An HttpURLConnection object defines a network connection to a resource specified by a URL. Essentially, the HttpURLConnection object represents the HTTP request for that resource.

Class Summary

public abstract class java.net.HttpURLConnection
                      extends java.net.URLConnection {
  // Constants
  public final static int HTTP_ACCEPTED;
  public final static int HTTP_BAD_GATEWAY;
  public final static int HTTP_BAD_METHOD;
  public final static int HTTP_BAD_REQUEST;
  public final static int HTTP_CLIENT_TIMEOUT;
  public final static int HTTP_CONFLICT;
  public final static int HTTP_CREATED;
  public final static int HTTP_ENTITY_TOO_LARGE;
  public final static int HTTP_FORBIDDEN;
  public final static int HTTP_GATEWAY_TIMEOUT;
  public final static int HTTP_GONE;
  public final static int HTTP_INTERNAL_ERROR;
  public final static int HTTP_LENGTH_REQUIRED;
  public final static int HTTP_MOVED_PERM;
  public final static int HTTP_MOVED_TEMP;
  public final static int HTTP_MULT_CHOICE;
  public final static int HTTP_NOT_ACCEPTABLE;
  public final static int HTTP_NOT_AUTHORITATIVE;
  public final static int HTTP_NOT_FOUND;
  public final static int HTTP_NOT_MODIFIED;
  public final static int HTTP_NO_CONTENT;
  public final static int HTTP_OK;
  public final static int HTTP_PARTIAL;
  public final static int HTTP_PAYMENT_REQUIRED;
  public final static int HTTP_PRECON_FAILED;
  public final static int HTTP_PROXY_AUTH;
  public final static int HTTP_REQ_TOO_LONG;
  public final static int HTTP_RESET;
  public final static int HTTP_SEE_OTHER;
  public final static int HTTP_SERVER_ERROR;
  public final static int HTTP_UNAUTHORIZED;
  public final static int HTTP_UNAVAILABLE;
  public final static int HTTP_UNSUPPORTED_TYPE;
  public final static int HTTP_USE_PROXY;
  public final static int HTTP_VERSION;
  // Variables
  protected String method;
  protected int responseCode;
  protected String responseMessage;
  // Constructors
  protected HttpURLConnection(URL u);
  // Class Methods
  public static boolean getFollowRedirects();
  public static void setFollowRedirects(boolean set);
  // Instance Methods
  public abstract void disconnect();
  public String getRequestMethod();
  public int getResponseCode();
  public String getResponseMessage();
  public void setRequestMethod(String method);
  public abstract boolean usingProxy();
}

Constants

HTTP_ACCEPTED

public final static int HTTP_ACCEPTED = 202

Description: The HTTP response code that means the request has been accepted by the server.

HTTP_BAD_GATEWAY

public final static int HTTP_BAD_GATEWAY = 502

Description: The HTTP response code that means the server, acting as a gateway, has received a bad response from another server.

HTTP_BAD_METHOD

public final static int HTTP_BAD_METHOD = 405

Description: The HTTP response code that means the requested method is not allowed for the requested resource.

HTTP_BAD_REQUEST

public final static int HTTP_BAD_REQUEST = 400

Description: The HTTP response code that means the request was syntactically incorrect.

HTTP_CLIENT_TIMEOUT

public final static int HTTP_CLIENT_TIMEOUT = 408

Description: The HTTP response code that means the server has not received a request from the client in the time it expected.

HTTP_CONFLICT

public final static int HTTP_CONFLICT = 409

Description: The HTTP response code that means there is a conflict with the state of the requested resource.

HTTP_CREATED

public final static int HTTP_CREATED = 201

Description: The HTTP response code that means a new resource has been created as the result of the request.

HTTP_ENTITY_TOO_LARGE

public final static int HTTP_ENTITY_TOO_LARGE = 413

Description: The HTTP response code that means the request contains an entity that is too large for the server.

HTTP_FORBIDDEN

public final static int HTTP_FORBIDDEN = 403

Description: The HTTP response code that means the client does not have permission to access the requested resource.

HTTP_GATEWAY_TIMEOUT

public final static int HTTP_GATEWAY_TIMEOUT = 504

Description: The HTTP response code that means the server, acting as a gateway, has not received a response from an upstream server in the time it expected.

HTTP_GONE

public final static int HTTP_GONE = 410

Description: The HTTP response code that means the requested resource is no longer available.

HTTP_INTERNAL_ERROR

public final static int HTTP_INTERNAL_ERROR = 501

Description: The HTTP response code that means the server does not or cannot support the client's request.

HTTP_LENGTH_REQUIRED

public final static int HTTP_LENGTH_REQUIRED = 411

Description: The HTTP response code that means the server won't accept the request without a length indication.

HTTP_MOVED_PERM

public final static int HTTP_MOVED_PERM = 301

Description: The HTTP response code that means the requested resource has moved permanently.

HTTP_MOVED_TEMP

public final static int HTTP_MOVED_TEMP = 302

Description: The HTTP response code that means the requested resource has moved temporarily.

HTTP_MULT_CHOICE

public final static int HTTP_MULT_CHOICE = 300

Description: The HTTP response code that means the requested resource is available in multiple representations.

HTTP_NOT_ACCEPTABLE

public final static int HTTP_NOT_ACCEPTABLE = 406

Description: The HTTP response code that means the requested resource is not available in a representation that is acceptable to the client.

HTTP_NOT_AUTHORITATIVE

public final static int HTTP_NOT_AUTHORITATIVE = 203

Description: The HTTP response code that means the information returned may be a copy.

HTTP_NOT_FOUND

public final static int HTTP_NOT_FOUND = 404

Description: The HTTP response code that means the server could not find the requested resource.

HTTP_NOT_MODIFIED

public final static int HTTP_NOT_MODIFIED = 304

Description: The HTTP response code that means the requested resource has not been modified.

HTTP_NO_CONTENT

public final static int HTTP_NO_CONTENT = 204

Description: The HTTP response code that means the request has been processed, but there is no new information.

HTTP_OK

public final static int HTTP_OK = 200

Description: The HTTP response code that means the request succeeded.

HTTP_PARTIAL

public final static int HTTP_PARTIAL = 206

Description: The HTTP response code that means the partial request has been fulfilled.

HTTP_PAYMENT_REQUIRED

public final static int HTTP_PAYMENT_REQUIRED = 402

Description: An HTTP response code that is reserved for future use.

HTTP_PRECON_FAILED

public final static int HTTP_PRECON_FAILED = 412

Description: The HTTP response code that means the precondition in the request has failed.

HTTP_PROXY_AUTH

public final static int HTTP_PROXY_AUTH = 407

Description: The HTTP response code that means the client needs to authenticate itself with the proxy.

HTTP_REQ_TOO_LONG

public final static int HTTP_REQ_TOO_LONG = 414

Description: The HTTP response code that means the client request is too long.

HTTP_RESET

public final static int HTTP_RESET = 205

Description: The HTTP response code that means the request has been fulfilled, and the client should reset its view.

HTTP_SEE_OTHER

public final static int HTTP_SEE_OTHER = 303

Description: The HTTP response code that means the requested resource is available at another URL.

HTTP_SERVER_ERROR

public final static int HTTP_SERVER_ERROR = 500

Description: The HTTP response code that means the server encountered a problem and could not fulfill the request.

HTTP_UNAUTHORIZED

public final static int HTTP_UNAUTHORIZED = 401

Description: The HTTP response code that means the client is not authenticated for the requested resource.

HTTP_UNAVAILABLE

public final static int HTTP_UNAVAILABLE = 503

Description: The HTTP response code that means the server is temporarily unable to fulfill the request.

HTTP_UNSUPPORTED_TYPE

public final static int HTTP_UNSUPPORTED_TYPE = 415

Description: The HTTP response code that means the server cannot process the type of the request.

HTTP_USE_PROXY

public final static int HTTP_USE_PROXY = 305

Description: The HTTP response code that means a proxy must be used to access the requested resource.

HTTP_VERSION

public final static int HTTP_VERSION = 505

Description: The HTTP response code that means the server does not support the HTTP version used in the request.

Variables

method

protected String method = "GET"

Description: The method of this request. Valid values are: "DELETE", "GET", "HEAD", "OPTIONS", "POST", "PUT", and "TRACE".

responseCode

protected int responseCode = -1

Description: The response code from the server, which may be one of the HTTP_ constants.

responseMessage

protected String responseMessage = null

Description: The response message from the server that corresponds to responseCode.

Constructors

HttpURLConnection

protected HttpURLConnection(URL u)

Parameters

u: A URL object that represents a resource.

Description

This constructor creates an HttpURLConnection for the given URL object.

Class Methods

getFollowRedirects

public static boolean getFollowRedirects()

Returns

A boolean value that indicates whether or not HTTP redirect codes are automatically followed.

Description

This method indicates whether or not this HttpURLConnection follows HTTP redirects. The default value is false.

setFollowRedirects

public static void setFollowRedirects(boolean set)

Parameters

set: A boolean value that specifies whether or not HTTP redirects should be followed.

Throws

SecurityException: If there is a SecurityManager installed and its checkSetFactory() method throws a SecurityException.

Description

This method specifies whether or not this HttpURLConnection follows HTTP redirects.

Instance Methods

disconnect

public abstract void disconnect()

Description: This method closes the connection to the server.

getRequestMethod

public String getRequestMethod()

Returns

The method of this request.

Description

This method returns the method of this request.

getResponseCode

public int getResponseCode() throws IOException

Returns

The response code from the server.

Throws

IOException: If any kind of I/O error occurs.

Description

This method returns the code the server sent in response to this request. For example, suppose the server response is:

HTTP/1.0 404 Not Found

In this case, the method returns integer value 404.

getResponseMessage

public int getResponseMessage() throws IOException

Returns

The response message from the server.

Throws

IOException: If any kind of I/O error occurs.

Description

This method returns the message the server sent in response to this request. For example, suppose the server response is:

HTTP/1.0 404 Not Found

In this case, the method returns the string "Not Found".

setRequestMethod

 public void setRequestMethod(String method) throws ProtocolException

Parameters

method: The new method for this request.

Throws

ProtocolException: If the connection has already been made or if method is invalid.

Description

This method sets the method of this request. Valid values are: "DELETE", "GET", "HEAD", "OPTIONS", "POST", "PUT", and "TRACE".

usingProxy

public abstract boolean usingProxy()

Returns

A boolean value that indicates whether or not this HttpURLConnection is using a proxy.

Throws

IOException: If any kind of I/O error occurs.

Description

This method returns a flag that indicates if this connection is going through a proxy or not.

Inherited Variables

Variable	Inherited From	Variable	Inherited From
`allowUserInteraction`	`URLConnection`	`connected`	`URLConnection`
`doInput`	`URLConnection`	`doOutput`	`URLConnection`
`ifModifiedSince`	`URLConnection`	`url`	`URLConnection`
`useCaches`	`URLConnection`

Inherited Methods

Method	Inherited From	Method	Inherited From
`clone()`	`Object`	`connect()`	`URLConnection`
`equals(Object)`	`Object`	`finalize()`	`Object`
`getAllowUserInteraction()`	`URLConnection`	`getClass()`	`Object`
`getContent()`	`URLConnection`	`getContentEncoding()`	`URLConnection`
`getContentLength()`	`URLConnection`	`getContentType()`	`URLConnection`
`getDate()`	`URLConnection`	`getDefaultUseCaches()`	`URLConnection`
`getDoInput()`	`URLConnection`	`getDoOutput()`	`URLConnection`
`getExpiration()`	`URLConnection`	`getHeaderField(String)`	`URLConnection`
`getHeaderField(int)`	`URLConnection`	`getHeaderFieldDate(String, long)`	`URLConnection`
`getHeaderFieldInt(String, int)`	`URLConnection`	`getHeaderFieldKey(int)`	`URLConnection`
`getIfModifiedSince()`	`URLConnection`	`getInputStream()`	`URLConnection`
`getLastModified()`	`URLConnection`	`getOutputStream()`	`URLConnection`
`getRequestProperty(String)`	`URLConnection`	`getURL()`	`URLConnection`
`getUseCaches()`	`URLConnection`	`hashCode()`	`Object`
`notify()`	`Object`	`notifyAll()`	`Object`
`setAllowUserInteraction(boolean)`	`URLConnection`	`setDefaultUseCaches(boolean)`	`URLConnection`
`setDoInput(boolean)`	`URLConnection`	`setDoOutput(boolean)`	`URLConnection`
`setIfModifiedSince(long)`	`URLConnection`	`setRequestProperty(String, String)`	`URLConnection`
`setUseCaches(boolean)`	`URLConnection`	`toString()`	`URLConnection`
`wait()`	`Object`	`wait(long)`	`Object`
`wait(long, int)`	`Object`

See Also

IOException, ProtocolException, SecurityException, SecurityManager, URL, URLConnection


FileNameMap		InetAddress