HttpURLConnection
public
abstract
class
HttpURLConnection
extends URLConnection
java.lang.Object | ||
↳ | java.net.URLConnection | |
↳ | java.net.HttpURLConnection |
A URLConnection with support for HTTP-specific features. See the spec for details.
Uses of this class follow a pattern:
- Obtain a new
HttpURLConnection
by callingURL.openConnection()
and casting the result toHttpURLConnection
. - Prepare the request. The primary property of a request is its URI. Request headers may also include metadata such as credentials, preferred content types, and session cookies.
- Optionally upload a request body. Instances must be configured with
setDoOutput(true)
if they include a request body. Transmit data by writing to the stream returned byURLConnection.getOutputStream()
. - Read the response. Response headers typically include metadata such as
the response body's content type and length, modified dates and session
cookies. The response body may be read from the stream returned by
URLConnection.getInputStream()
. If the response has no body, that method returns an empty stream. - Disconnect. Once the response body has been read, the
HttpURLConnection
should be closed by callingdisconnect()
. Disconnecting releases the resources held by a connection so they may be closed or reused.
For example, to retrieve the webpage at http://www.android.com/
:
URL url = new URL("http://www.android.com/");
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
try {
InputStream in = new BufferedInputStream(urlConnection.getInputStream());
readStream(in);
} finally {
urlConnection.disconnect();
}
Secure Communication with HTTPS
CallingURL#openConnection()
on a URL with the "https"
scheme will return an HttpsURLConnection
, which allows for
overriding the default HostnameVerifier
and SSLSocketFactory
. An application-supplied SSLSocketFactory
created from an SSLContext
can
provide a custom X509TrustManager
for verifying certificate chains and a custom
X509KeyManager
for supplying
client certificates. See HttpsURLConnection
for more details.
Response Handling
HttpURLConnection
will follow up to five HTTP redirects. It will
follow redirects from one origin server to another. This implementation
doesn't follow redirects from HTTPS to HTTP or vice versa.
If the HTTP response indicates that an error occurred, URLConnection.getInputStream()
will throw an IOException
. Use getErrorStream()
to read the error response. The headers can be read in
the normal way using URLConnection.getHeaderFields()
,
Posting Content
To upload data to a web server, configure the connection for output usingsetDoOutput(true)
.
For best performance, you should call either setFixedLengthStreamingMode(int)
when the body length is known in advance,
or setChunkedStreamingMode(int)
when it is not. Otherwise HttpURLConnection
will be forced to buffer the complete request body in
memory before it is transmitted, wasting (and possibly exhausting) heap and
increasing latency.
For example, to perform an upload:
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
try {
urlConnection.setDoOutput(true);
urlConnection.setChunkedStreamingMode(0);
OutputStream out = new BufferedOutputStream(urlConnection.getOutputStream());
writeStream(out);
InputStream in = new BufferedInputStream(urlConnection.getInputStream());
readStream(in);
} finally {
urlConnection.disconnect();
}
Performance
The input and output streams returned by this class are not buffered. Most callers should wrap the returned streams withBufferedInputStream
or BufferedOutputStream
. Callers that do only bulk
reads or writes may omit buffering.
When transferring large amounts of data to or from a server, use streams to limit how much data is in memory at once. Unless you need the entire body to be in memory at once, process it as a stream (rather than storing the complete body as a single byte array or string).
To reduce latency, this class may reuse the same underlying Socket
for multiple request/response pairs. As a result, HTTP connections may be
held open longer than necessary. Calls to disconnect()
may return
the socket to a pool of connected sockets.
By default, this implementation of HttpURLConnection
requests that
servers use gzip compression and it automatically decompresses the data for
callers of URLConnection.getInputStream()
. The Content-Encoding and Content-Length
response headers are cleared in this case. Gzip compression can be disabled by
setting the acceptable encodings in the request header:
urlConnection.setRequestProperty("Accept-Encoding", "identity");
Setting the Accept-Encoding request header explicitly disables automatic decompression and leaves the response headers intact; callers must handle decompression as needed, according to the Content-Encoding header of the response.
URLConnection.getContentLength()
returns the number of bytes transmitted and
cannot be used to predict how many bytes can be read from
URLConnection.getInputStream()
for compressed streams. Instead, read that stream
until it is exhausted, i.e. when InputStream#read
returns -1.
Handling Network Sign-On
Some Wi-Fi networks block Internet access until the user clicks through a sign-on page. Such sign-on pages are typically presented by using HTTP redirects. You can useURLConnection.getURL()
to test if your connection has been
unexpectedly redirected. This check is not valid until after
the response headers have been received, which you can trigger by calling
URLConnection.getHeaderFields()
or URLConnection.getInputStream()
. For example, to
check that a response was not redirected to an unexpected host:
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
try {
InputStream in = new BufferedInputStream(urlConnection.getInputStream());
if (!url.getHost().equals(urlConnection.getURL().getHost())) {
// we were redirected! Kick the user out to the browser to sign on?
}
...
} finally {
urlConnection.disconnect();
}
HTTP Authentication
HttpURLConnection
supports HTTP basic authentication. Use
Authenticator
to set the VM-wide authentication handler:
Authenticator.setDefault(new Authenticator() {
protected PasswordAuthentication getPasswordAuthentication() {
return new PasswordAuthentication(username, password.toCharArray());
}
});
Sessions with Cookies
To establish and maintain a potentially long-lived session between client and server,HttpURLConnection
includes an extensible cookie manager.
Enable VM-wide cookie management using CookieHandler
and CookieManager
: CookieManager cookieManager = new CookieManager();
CookieHandler.setDefault(cookieManager);
CookieManager
accepts cookies from the origin
server only. Two other policies are included: CookiePolicy.ACCEPT_ALL
and CookiePolicy#ACCEPT_NONE
. Implement
CookiePolicy
to define a custom policy.
The default CookieManager
keeps all accepted cookies in memory. It
will forget these cookies when the VM exits. Implement CookieStore
to
define a custom cookie store.
In addition to the cookies set by HTTP responses, you may set cookies programmatically. To be included in HTTP request headers, cookies must have the domain and path properties set.
By default, new instances of HttpCookie
work only with servers
that support RFC 2965
cookies. Many web servers support only the older specification, RFC 2109. For compatibility
with the most web servers, set the cookie version to 0.
For example, to receive www.twitter.com
in French:
HttpCookie cookie = new HttpCookie("lang", "fr");
cookie.setDomain("twitter.com");
cookie.setPath("/");
cookie.setVersion(0);
cookieManager.getCookieStore().add(new URI("http://twitter.com/"), cookie);
HTTP Methods
HttpURLConnection
uses the GET
method by default. It will
use POST
if setDoOutput(true)
has been called.
Other HTTP methods (OPTIONS
, HEAD
, PUT
, DELETE
and TRACE
) can be used with setRequestMethod(String)
.
Proxies
By default, this class will connect directly to the origin server. It can also connect via anHTTP
or SOCKS
proxy. To use a proxy, use URL.openConnection(Proxy)
when creating the
connection.
IPv6 Support
This class includes transparent support for IPv6. For hosts with both IPv4 and IPv6 addresses, it will attempt to connect to each of a host's addresses until a connection is established.
Response Caching
Android 4.0 (Ice Cream Sandwich, API level 15) includes a response cache. Seeandroid.net.http.HttpResponseCache
for instructions on enabling HTTP
caching in your application.
Avoiding Bugs In Earlier Releases
Prior to Android 2.2 (Froyo), this class had some frustrating bugs. In particular, callingclose()
on a readable InputStream
could
poison the
connection pool. Work around this by disabling connection pooling:
private void disableConnectionReuseIfNecessary() {
// Work around pre-Froyo bugs in HTTP connection reuse.
if (Integer.parseInt(Build.VERSION.SDK) < Build.VERSION_CODES.FROYO) {
System.setProperty("http.keepAlive", "false");
}
}
Each instance of HttpURLConnection
may be used for one
request/response pair. Instances of this class are not thread safe.
See also:
Summary
Constants | |
---|---|
int |
HTTP_ACCEPTED
HTTP Status-Code 202: Accepted. |
int |
HTTP_BAD_GATEWAY
HTTP Status-Code 502: Bad Gateway. |
int |
HTTP_BAD_METHOD
HTTP Status-Code 405: Method Not Allowed. |
int |
HTTP_BAD_REQUEST
HTTP Status-Code 400: Bad Request. |
int |
HTTP_CLIENT_TIMEOUT
HTTP Status-Code 408: Request Time-Out. |
int |
HTTP_CONFLICT
HTTP Status-Code 409: Conflict. |
int |
HTTP_CREATED
HTTP Status-Code 201: Created. |
int |
HTTP_ENTITY_TOO_LARGE
HTTP Status-Code 413: Request Entity Too Large. |
int |
HTTP_FORBIDDEN
HTTP Status-Code 403: Forbidden. |
int |
HTTP_GATEWAY_TIMEOUT
HTTP Status-Code 504: Gateway Timeout. |
int |
HTTP_GONE
HTTP Status-Code 410: Gone. |
int |
HTTP_INTERNAL_ERROR
HTTP Status-Code 500: Internal Server Error. |
int |
HTTP_LENGTH_REQUIRED
HTTP Status-Code 411: Length Required. |
int |
HTTP_MOVED_PERM
HTTP Status-Code 301: Moved Permanently. |
int |
HTTP_MOVED_TEMP
HTTP Status-Code 302: Temporary Redirect. |
int |
HTTP_MULT_CHOICE
HTTP Status-Code 300: Multiple Choices. |
int |
HTTP_NOT_ACCEPTABLE
HTTP Status-Code 406: Not Acceptable. |
int |
HTTP_NOT_AUTHORITATIVE
HTTP Status-Code 203: Non-Authoritative Information. |
int |
HTTP_NOT_FOUND
HTTP Status-Code 404: Not Found. |
int |
HTTP_NOT_IMPLEMENTED
HTTP Status-Code 501: Not Implemented. |
int |
HTTP_NOT_MODIFIED
HTTP Status-Code 304: Not Modified. |
int |
HTTP_NO_CONTENT
HTTP Status-Code 204: No Content. |
int |
HTTP_OK
HTTP Status-Code 200: OK. |
int |
HTTP_PARTIAL
HTTP Status-Code 206: Partial Content. |
int |
HTTP_PAYMENT_REQUIRED
HTTP Status-Code 402: Payment Required. |
int |
HTTP_PRECON_FAILED
HTTP Status-Code 412: Precondition Failed. |
int |
HTTP_PROXY_AUTH
HTTP Status-Code 407: Proxy Authentication Required. |
int |
HTTP_REQ_TOO_LONG
HTTP Status-Code 414: Request-URI Too Large. |
int |
HTTP_RESET
HTTP Status-Code 205: Reset Content. |
int |
HTTP_SEE_OTHER
HTTP Status-Code 303: See Other. |
int |
HTTP_SERVER_ERROR
This constant was deprecated in API level 15. it is misplaced and shouldn't have existed. |
int |
HTTP_UNAUTHORIZED
HTTP Status-Code 401: Unauthorized. |
int |
HTTP_UNAVAILABLE
HTTP Status-Code 503: Service Unavailable. |
int |
HTTP_UNSUPPORTED_TYPE
HTTP Status-Code 415: Unsupported Media Type. |
int |
HTTP_USE_PROXY
HTTP Status-Code 305: Use Proxy. |
int |
HTTP_VERSION
HTTP Status-Code 505: HTTP Version Not Supported. |
Fields | |
---|---|
protected
int |
chunkLength
The chunk-length when using chunked encoding streaming mode for output. |
protected
int |
fixedContentLength
The fixed content-length when using fixed-length streaming mode. |
protected
long |
fixedContentLengthLong
The fixed content-length when using fixed-length streaming mode. |
protected
boolean |
instanceFollowRedirects
If |
protected
String |
method
The HTTP method (GET,POST,PUT,etc.). |
protected
int |
responseCode
An |
protected
String |
responseMessage
The HTTP response message. |
Inherited fields |
---|
Protected constructors | |
---|---|
HttpURLConnection(URL u)
Constructor for the HttpURLConnection. |
Public methods | |
---|---|
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 |
String
|
getHeaderField(int n)
Returns the value for the |
long
|
getHeaderFieldDate(String name, long Default)
Returns the value of the named field parsed as date. |
String
|
getHeaderFieldKey(int n)
Returns the key for the |
boolean
|
getInstanceFollowRedirects()
Returns the value of this |
Permission
|
getPermission()
Returns a |
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. |
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. |
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. |
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. |
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 |
void
|
setRequestMethod(String method)
Set the method for the URL request, one of:
|
abstract
boolean
|
usingProxy()
Indicates if the connection is going through a proxy. |
Inherited methods | |
---|---|
Constants
HTTP_ACCEPTED
public static final int HTTP_ACCEPTED
HTTP Status-Code 202: Accepted.
Constant Value: 202 (0x000000ca)
HTTP_BAD_GATEWAY
public static final int HTTP_BAD_GATEWAY
HTTP Status-Code 502: Bad Gateway.
Constant Value: 502 (0x000001f6)
HTTP_BAD_METHOD
public static final int HTTP_BAD_METHOD
HTTP Status-Code 405: Method Not Allowed.
Constant Value: 405 (0x00000195)
HTTP_BAD_REQUEST
public static final int HTTP_BAD_REQUEST
HTTP Status-Code 400: Bad Request.
Constant Value: 400 (0x00000190)
HTTP_CLIENT_TIMEOUT
public static final int HTTP_CLIENT_TIMEOUT
HTTP Status-Code 408: Request Time-Out.
Constant Value: 408 (0x00000198)
HTTP_CONFLICT
public static final int HTTP_CONFLICT
HTTP Status-Code 409: Conflict.
Constant Value: 409 (0x00000199)
HTTP_CREATED
public static final int HTTP_CREATED
HTTP Status-Code 201: Created.
Constant Value: 201 (0x000000c9)
HTTP_ENTITY_TOO_LARGE
public static final int HTTP_ENTITY_TOO_LARGE
HTTP Status-Code 413: Request Entity Too Large.
Constant Value: 413 (0x0000019d)
HTTP_FORBIDDEN
public static final int HTTP_FORBIDDEN
HTTP Status-Code 403: Forbidden.
Constant Value: 403 (0x00000193)
HTTP_GATEWAY_TIMEOUT
public static final int HTTP_GATEWAY_TIMEOUT
HTTP Status-Code 504: Gateway Timeout.
Constant Value: 504 (0x000001f8)
HTTP_GONE
public static final int HTTP_GONE
HTTP Status-Code 410: Gone.
Constant Value: 410 (0x0000019a)
HTTP_INTERNAL_ERROR
public static final int HTTP_INTERNAL_ERROR
HTTP Status-Code 500: Internal Server Error.
Constant Value: 500 (0x000001f4)
HTTP_LENGTH_REQUIRED
public static final int HTTP_LENGTH_REQUIRED
HTTP Status-Code 411: Length Required.
Constant Value: 411 (0x0000019b)
HTTP_MOVED_PERM
public static final int HTTP_MOVED_PERM
HTTP Status-Code 301: Moved Permanently.
Constant Value: 301 (0x0000012d)
HTTP_MOVED_TEMP
public static final int HTTP_MOVED_TEMP
HTTP Status-Code 302: Temporary Redirect.
Constant Value: 302 (0x0000012e)
HTTP_MULT_CHOICE
public static final int HTTP_MULT_CHOICE
HTTP Status-Code 300: Multiple Choices.
Constant Value: 300 (0x0000012c)
HTTP_NOT_ACCEPTABLE
public static final int HTTP_NOT_ACCEPTABLE
HTTP Status-Code 406: Not Acceptable.
Constant Value: 406 (0x00000196)
HTTP_NOT_AUTHORITATIVE
public static final int HTTP_NOT_AUTHORITATIVE
HTTP Status-Code 203: Non-Authoritative Information.
Constant Value: 203 (0x000000cb)
HTTP_NOT_FOUND
public static final int HTTP_NOT_FOUND
HTTP Status-Code 404: Not Found.
Constant Value: 404 (0x00000194)
HTTP_NOT_IMPLEMENTED
public static final int HTTP_NOT_IMPLEMENTED
HTTP Status-Code 501: Not Implemented.
Constant Value: 501 (0x000001f5)
HTTP_NOT_MODIFIED
public static final int HTTP_NOT_MODIFIED
HTTP Status-Code 304: Not Modified.
Constant Value: 304 (0x00000130)
HTTP_NO_CONTENT
public static final int HTTP_NO_CONTENT
HTTP Status-Code 204: No Content.
Constant Value: 204 (0x000000cc)
HTTP_OK
public static final int HTTP_OK
HTTP Status-Code 200: OK.
Constant Value: 200 (0x000000c8)
HTTP_PARTIAL
public static final int HTTP_PARTIAL
HTTP Status-Code 206: Partial Content.
Constant Value: 206 (0x000000ce)
HTTP_PAYMENT_REQUIRED
public static final int HTTP_PAYMENT_REQUIRED
HTTP Status-Code 402: Payment Required.
Constant Value: 402 (0x00000192)
HTTP_PRECON_FAILED
public static final int HTTP_PRECON_FAILED
HTTP Status-Code 412: Precondition Failed.
Constant Value: 412 (0x0000019c)
HTTP_PROXY_AUTH
public static final int HTTP_PROXY_AUTH
HTTP Status-Code 407: Proxy Authentication Required.
Constant Value: 407 (0x00000197)
HTTP_REQ_TOO_LONG
public static final int HTTP_REQ_TOO_LONG
HTTP Status-Code 414: Request-URI Too Large.
Constant Value: 414 (0x0000019e)
HTTP_RESET
public static final int HTTP_RESET
HTTP Status-Code 205: Reset Content.
Constant Value: 205 (0x000000cd)
HTTP_SEE_OTHER
public static final int HTTP_SEE_OTHER
HTTP Status-Code 303: See Other.
Constant Value: 303 (0x0000012f)
HTTP_SERVER_ERROR
public static final int HTTP_SERVER_ERROR
This constant was deprecated
in API level 15.
it is misplaced and shouldn't have existed.
HTTP Status-Code 500: Internal Server Error.
Constant Value: 500 (0x000001f4)
HTTP_UNAUTHORIZED
public static final int HTTP_UNAUTHORIZED
HTTP Status-Code 401: Unauthorized.
Constant Value: 401 (0x00000191)
HTTP_UNAVAILABLE
public static final int HTTP_UNAVAILABLE
HTTP Status-Code 503: Service Unavailable.
Constant Value: 503 (0x000001f7)
HTTP_UNSUPPORTED_TYPE
public static final int HTTP_UNSUPPORTED_TYPE
HTTP Status-Code 415: Unsupported Media Type.
Constant Value: 415 (0x0000019f)
HTTP_USE_PROXY
public static final int HTTP_USE_PROXY
HTTP Status-Code 305: Use Proxy.
Constant Value: 305 (0x00000131)
HTTP_VERSION
public static final int HTTP_VERSION
HTTP Status-Code 505: HTTP Version Not Supported.
Constant Value: 505 (0x000001f9)
Fields
chunkLength
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.
fixedContentLength
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.
fixedContentLengthLong
protected long fixedContentLengthLong
The fixed content-length when using fixed-length streaming mode.
A value of -1
means fixed-length streaming mode is disabled
for output.
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.
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
Protected constructors
HttpURLConnection
protected HttpURLConnection (URL u)
Constructor for the HttpURLConnection.
Parameters | |
---|---|
u |
URL : the URL |
Public methods
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.
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 | |
---|---|
InputStream |
an error stream if any, null if there have been no errors, the connection is not connected or the server sent no useful data. |
getFollowRedirects
public static boolean getFollowRedirects ()
Returns a boolean
indicating
whether or not HTTP redirects (3xx) should
be automatically followed.
Returns | |
---|---|
boolean |
true if HTTP redirects should
be automatically followed, false if not. |
See also:
getHeaderField
public String getHeaderField (int n)
Returns the value for the n
th header field.
Some implementations may treat the 0
th
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.
Parameters | |
---|---|
n |
int : an index, where n>=0 . |
Returns | |
---|---|
String |
the value of the n th header field,
or null if the value does not exist. |
See also:
getHeaderFieldDate
public long getHeaderFieldDate (String name, long Default)
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.
Parameters | |
---|---|
name |
String : the name of the header field. |
Default |
long : a default value. |
Returns | |
---|---|
long |
the value of the field, parsed as a date. The value of the
Default argument is returned if the field is
missing or malformed. |
getHeaderFieldKey
public String getHeaderFieldKey (int n)
Returns the key for the n
th header field.
Some implementations may treat the 0
th
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.
Parameters | |
---|---|
n |
int : an index, where n >=0 . |
Returns | |
---|---|
String |
the key for the n th header field,
or null if the key does not exist. |
getInstanceFollowRedirects
public boolean getInstanceFollowRedirects ()
Returns the value of this HttpURLConnection
's
instanceFollowRedirects
field.
Returns | |
---|---|
boolean |
the value of this HttpURLConnection 's
instanceFollowRedirects field. |
getPermission
public Permission getPermission ()
Returns a SocketPermission
object representing the
permission necessary to connect to the destination host and port.
Returns | |
---|---|
Permission |
a SocketPermission object representing the
permission necessary to connect to the destination
host and port. |
Throws | |
---|---|
IOException |
if an error occurs while computing the permission. |
getRequestMethod
public String getRequestMethod ()
Get the request method.
Returns | |
---|---|
String |
the HTTP request method |
See also:
getResponseCode
public int 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
Returns | |
---|---|
int |
the HTTP Status-Code, or -1 |
Throws | |
---|---|
IOException |
if an error occurred connecting to the server. |
getResponseMessage
public String 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
Returns | |
---|---|
String |
the HTTP response message, or null |
Throws | |
---|---|
IOException |
if an error occurred connecting to the server. |
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 |
int : 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. |
See also:
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 |
int : 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. |
See also:
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 |
long : 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. |
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 |
boolean : 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. |
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 |
boolean : a boolean indicating
whether or not to follow HTTP redirects. |
setRequestMethod
public void setRequestMethod (String method)
Set the method for the URL request, one of:
- GET
- POST
- HEAD
- OPTIONS
- PUT
- DELETE
- TRACE
Parameters | |
---|---|
method |
String : 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:
usingProxy
public abstract boolean usingProxy ()
Indicates if the connection is going through a proxy.
Returns | |
---|---|
boolean |
a boolean indicating if the connection is using a proxy. |