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Copyright © 2006 Sun Microsystems, Inc. and Motorola, Inc. All rights reserved.

javax.microedition.io
Interface HttpConnection

All Superinterfaces:

Connection, ContentConnection, InputConnection, OutputConnection, StreamConnection

All Known Subinterfaces:

HttpsConnection

public interface HttpConnection

extends ContentConnection

This interface defines the necessary methods and constants for an HTTP connection.

HTTP is a request-response protocol in which the parameters of request must be set before the request is sent. The connection exists in one of three states:

• Setup, in which the request parameters can be set
• Connected, in which request parameters have been sent and the response is expected
• Closed, the final state, in which the HTTP connection as been terminated

The following methods may be invoked only in the Setup state:

• setRequestMethod
• setRequestProperty

The transition from Setup to Connected is caused by any method that requires data to be sent to or received from the server.

The following methods cause the transition to the Connected state when the connection is in Setup state.

• openInputStream
• openDataInputStream
• getLength
• getType
• getEncoding
• getHeaderField
• getResponseCode
• getResponseMessage
• getHeaderFieldInt
• getHeaderFieldDate
• getExpiration
• getDate
• getLastModified
• getHeaderField
• getHeaderFieldKey

The following methods may be invoked while the connection is in Setup or Connected state.

• close
• getRequestMethod
• getRequestProperty
• getURL
• getProtocol
• getHost
• getFile
• getRef
• getPort
• getQuery

After an output stream has been opened by the openOutputStream or openDataOutputStream methods, attempts to change the request parameters via setRequestMethod or the setRequestProperty are ignored. Once the request parameters have been sent, these methods will throw an IOException. When an output stream is closed via the OutputStream.close or DataOutputStream.close methods, the connection enters the Connected state. When the output stream is flushed via the OutputStream.flush or DataOutputStream.flush methods, the request parameters MUST be sent along with any data written to the stream.

The transition to Closed state from any other state is caused by the close method and the closing all of the streams that were opened from the connection.

Example using StreamConnection

Simple read of a URL using StreamConnection. No HTTP specific behavior is needed or used. (Note: this example ignores all HTTP response headers and the HTTP response code. Since a proxy or server may have sent an error response page, an application can not distinquish which data is retreived in the InputStream.)

Connector.open is used to open URL and a StreamConnection is returned. From the StreamConnection the InputStream is opened. It is used to read every character until end of file (-1). If an exception is thrown the connection and stream are closed.

     void getViaStreamConnection(String url) throws IOException {
         StreamConnection c = null;
         InputStream s = null;
         try {
             c = (StreamConnection)Connector.open(url);
             s = c.openInputStream();
             int ch;
             while ((ch = s.read()) != -1) {
                 ...
             }
         } finally {
             if (s != null)
                 s.close();
             if (c != null)
                 c.close();
         }
     }
 

Example using ContentConnection

Simple read of a URL using ContentConnection. No HTTP specific behavior is needed or used.

Connector.open is used to open url and a ContentConnection is returned. The ContentConnection may be able to provide the length. If the length is available, it is used to read the data in bulk. From the ContentConnection the InputStream is opened. It is used to read every character until end of file (-1). If an exception is thrown the connection and stream are closed.

     void getViaContentConnection(String url) throws IOException {
         ContentConnection c = null;
         DataInputStream is = null;
         try {
             c = (ContentConnection)Connector.open(url);
             int len = (int)c.getLength();
             dis = c.openDataInputStream();
             if (len > 0) {
                 byte[] data = new byte[len];
                 dis.readFully(data);
             } else {
                 int ch;
                 while ((ch = dis.read()) != -1) {
                     ...
                 }
             }
         } finally {
             if (dis != null)
                 dis.close();
             if (c != null)
                 c.close();
         }
     }
 

Example using HttpConnection

Read the HTTP headers and the data using HttpConnection.

Connector.open is used to open url and a HttpConnection is returned. The HTTP headers are read and processed. If the length is available, it is used to read the data in bulk. From the HttpConnection the InputStream is opened. It is used to read every character until end of file (-1). If an exception is thrown the connection and stream are closed.

     void getViaHttpConnection(String url) throws IOException {
         HttpConnection c = null;
         InputStream is = null;
         int rc;

         try {
             c = (HttpConnection)Connector.open(url);

             // Getting the response code will open the connection,
             // send the request, and read the HTTP response headers.
             // The headers are stored until requested.
             rc = c.getResponseCode();
             if (rc != HttpConnection.HTTP_OK) {
                 throw new IOException("HTTP response code: " + rc);
             }

             is = c.openInputStream();

             // Get the ContentType
             String type = c.getType();

             // Get the length and process the data
             int len = (int)c.getLength();
             if (len > 0) {
                 int actual = 0;
                 int bytesread = 0 ;
                 byte[] data = new byte[len];
                 while ((bytesread != len) && (actual != -1)) {
                    actual = is.read(data, bytesread, len - bytesread);
                    bytesread += actual;
                 }
             } else {
                 int ch;
                 while ((ch = is.read()) != -1) {
                     ...
                 }
             }
         } catch (ClassCastException e) {
             throw new IllegalArgumentException("Not an HTTP URL");
         } finally {
             if (is != null)
                 is.close();
             if (c != null)
                 c.close();
         }
     }
 

Example using POST with HttpConnection

Post a request with some headers and content to the server and process the headers and content.

Connector.open is used to open url and a HttpConnection is returned. The request method is set to POST and request headers set. A simple command is written and flushed. The HTTP headers are read and processed. If the length is available, it is used to read the data in bulk. From the HttpConnection the InputStream is opened. It is used to read every character until end of file (-1). If an exception is thrown the connection and stream is closed.

    void postViaHttpConnection(String url) throws IOException {
        HttpConnection c = null;
        InputStream is = null;
        OutputStream os = null;
        int rc;

        try {
            c = (HttpConnection)Connector.open(url);

            // Set the request method and headers
            c.setRequestMethod(HttpConnection.POST);
            c.setRequestProperty("If-Modified-Since",
                "29 Oct 1999 19:43:31 GMT");
            c.setRequestProperty("User-Agent",
                "Profile/MIDP-2.0 Configuration/CLDC-1.0");
            c.setRequestProperty("Content-Language", "en-US");

            // Getting the output stream may flush the headers
            os = c.openOutputStream();
            os.write("LIST games\n".getBytes());
            os.flush();           // Optional, getResponseCode will flush

            // Getting the response code will open the connection,
            // send the request, and read the HTTP response headers.
            // The headers are stored until requested.
            rc = c.getResponseCode();
            if (rc != HttpConnection.HTTP_OK) {
                throw new IOException("HTTP response code: " + rc);
            }

            is = c.openInputStream();

            // Get the ContentType
            String type = c.getType();
            processType(type);

            // Get the length and process the data
            int len = (int)c.getLength();
            if (len > 0) {
                 int actual = 0;
                 int bytesread = 0 ;
                 byte[] data = new byte[len];
                 while ((bytesread != len) && (actual != -1)) {
                    actual = is.read(data, bytesread, len - bytesread);
                    bytesread += actual;
                 }
                process(data);
            } else {
                int ch;
                while ((ch = is.read()) != -1) {
                    process((byte)ch);
                }
            }
        } catch (ClassCastException e) {
            throw new IllegalArgumentException("Not an HTTP URL");
        } finally {
            if (is != null)
                is.close();
            if (os != null)
                os.close();
            if (c != null)
                c.close();
        }
    }
 

Simplified Stream Methods on Connector

Please note the following: The Connector class defines the following convenience methods for retrieving an input or output stream directly for a specified URL:

• InputStream openInputStream(String url)
• DataInputStream openDataInputStream(String url)
• OutputStream openOutputStream(String url)
• DataOutputStream openDataOutputStream(String url)

Please be aware that using these methods implies certain restrictions. You will not get a reference to the actual connection, but rather just references to the input or output stream of the connection. Not having a reference to the connection means that you will not be able to manipulate or query the connection directly. This in turn means that you will not be able to call any of the following methods:

• getRequestMethod()
• setRequestMethod()
• getRequestProperty()
• setRequestProperty()
• getLength()
• getType()
• getEncoding()
• getHeaderField()
• getResponseCode()
• getResponseMessage()
• getHeaderFieldInt
• getHeaderFieldDate
• getExpiration
• getDate
• getLastModified
• getHeaderField
• getHeaderFieldKey

Since:

MIDP 1.0

Field Summary

static String	GET HTTP Get method.
static String	HEAD HTTP Head method.
static int	HTTP_ACCEPTED 202: The request has been accepted for processing, but the processing has not been completed.
static int	HTTP_BAD_GATEWAY 502: The server, while acting as a gateway or proxy, received an invalid response from the upstream server it accessed in attempting to fulfill the request.
static int	HTTP_BAD_METHOD 405: The method specified in the Request-Line is not allowed for the resource identified by the Request-URI.
static int	HTTP_BAD_REQUEST 400: The request could not be understood by the server due to malformed syntax.
static int	HTTP_CLIENT_TIMEOUT 408: The client did not produce a request within the time that the server was prepared to wait.
static int	HTTP_CONFLICT 409: The request could not be completed due to a conflict with the current state of the resource.
static int	HTTP_CREATED 201: The request has been fulfilled and resulted in a new resource being created.
static int	HTTP_ENTITY_TOO_LARGE 413: The server is refusing to process a request because the request entity is larger than the server is willing or able to process.
static int	HTTP_EXPECT_FAILED 417: The expectation given in an Expect request-header field could not be met by this server, or, if the server is a proxy, the server has unambiguous evidence that the request could not be met by the next-hop server.
static int	HTTP_FORBIDDEN 403: The server understood the request, but is refusing to fulfill it.
static int	HTTP_GATEWAY_TIMEOUT 504: The server, while acting as a gateway or proxy, did not receive a timely response from the upstream server specified by the URI or some other auxiliary server it needed to access in attempting to complete the request.
static int	HTTP_GONE 410: The requested resource is no longer available at the server and no forwarding address is known.
static int	HTTP_INTERNAL_ERROR 500: The server encountered an unexpected condition which prevented it from fulfilling the request.
static int	HTTP_LENGTH_REQUIRED 411: The server refuses to accept the request without a defined Content- Length.
static int	HTTP_MOVED_PERM 301: The requested resource has been assigned a new permanent URI and any future references to this resource SHOULD use one of the returned URIs.
static int	HTTP_MOVED_TEMP 302: The requested resource resides temporarily under a different URI.
static int	HTTP_MULT_CHOICE 300: The requested resource corresponds to any one of a set of representations, each with its own specific location, and agent- driven negotiation information is being provided so that the user (or user agent) can select a preferred representation and redirect its request to that location.
static int	HTTP_NO_CONTENT 204: The server has fulfilled the request but does not need to return an entity-body, and might want to return updated meta-information.
static int	HTTP_NOT_ACCEPTABLE 406: The resource identified by the request is only capable of generating response entities which have content characteristics not acceptable according to the accept headers sent in the request.
static int	HTTP_NOT_AUTHORITATIVE 203: The returned meta-information in the entity-header is not the definitive set as available from the origin server.
static int	HTTP_NOT_FOUND 404: The server has not found anything matching the Request-URI.
static int	HTTP_NOT_IMPLEMENTED 501: The server does not support the functionality required to fulfill the request.
static int	HTTP_NOT_MODIFIED 304: If the client has performed a conditional GET request and access is allowed, but the document has not been modified, the server SHOULD respond with this status code.
static int	HTTP_OK 200: The request has succeeded.
static int	HTTP_PARTIAL 206: The server has fulfilled the partial GET request for the resource.
static int	HTTP_PAYMENT_REQUIRED 402: This code is reserved for future use.
static int	HTTP_PRECON_FAILED 412: The precondition given in one or more of the request-header fields evaluated to false when it was tested on the server.
static int	HTTP_PROXY_AUTH 407: This code is similar to 401 (Unauthorized), but indicates that the client must first authenticate itself with the proxy.
static int	HTTP_REQ_TOO_LONG 414: The server is refusing to service the request because the Request-URI is longer than the server is willing to interpret.
static int	HTTP_RESET 205: The server has fulfilled the request and the user agent SHOULD reset the document view which caused the request to be sent.
static int	HTTP_SEE_OTHER 303: The response to the request can be found under a different URI and SHOULD be retrieved using a GET method on that resource.
static int	HTTP_TEMP_REDIRECT 307: The requested resource resides temporarily under a different URI.
static int	HTTP_UNAUTHORIZED 401: The request requires user authentication.
static int	HTTP_UNAVAILABLE 503: The server is currently unable to handle the request due to a temporary overloading or maintenance of the server.
static int	HTTP_UNSUPPORTED_RANGE 416: A server SHOULD return a response with this status code if a request included a Range request-header field , and none of the range-specifier values in this field overlap the current extent of the selected resource, and the request did not include an If-Range request-header field.
static int	HTTP_UNSUPPORTED_TYPE 415: The server is refusing to service the request because the entity of the request is in a format not supported by the requested resource for the requested method.
static int	HTTP_USE_PROXY 305: The requested resource MUST be accessed through the proxy given by the Location field.
static int	HTTP_VERSION 505: The server does not support, or refuses to support, the HTTP protocol version that was used in the request message.
static String	POST HTTP Post method.

Method Summary

long	getDate() Returns the value of the date header field.
long	getExpiration() Returns the value of the expires header field.
String	getFile() Returns the file portion of the URL of this HttpConnection.
String	getHeaderField(int n) Gets a header field value by index.
String	getHeaderField(String name) Returns the value of the named header field.
long	getHeaderFieldDate(String name, long def) Returns the value of the named field parsed as date.
int	getHeaderFieldInt(String name, int def) Returns the value of the named field parsed as a number.
String	getHeaderFieldKey(int n) Gets a header field key by index.
String	getHost() Returns the host information of the URL of this HttpConnection.
long	getLastModified() Returns the value of the last-modified header field.
int	getPort() Returns the network port number of the URL for this HttpConnection.
String	getProtocol() Returns the protocol name of the URL of this HttpConnection.
String	getQuery() Returns the query portion of the URL of this HttpConnection.
String	getRef() Returns the ref portion of the URL of this HttpConnection.
String	getRequestMethod() Get the current request method.
String	getRequestProperty(String key) Returns the value of the named general request property for this connection.
int	getResponseCode() Returns the HTTP response status code.
String	getResponseMessage() Gets the HTTP response message, if any, returned along with the response code from a server.
String	getURL() Return a string representation of the URL for this connection.
void	setRequestMethod(String method) Set the method for the URL request, one of: GET POST HEAD are legal, subject to protocol restrictions.
void	setRequestProperty(String key, String value) Sets the general request property.

Methods inherited from interface javax.microedition.io.ContentConnection

getEncoding, getLength, getType

Methods inherited from interface javax.microedition.io.InputConnection

openDataInputStream, openInputStream

Methods inherited from interface javax.microedition.io.Connection

close

Methods inherited from interface javax.microedition.io.OutputConnection

openDataOutputStream, openOutputStream

Field Detail

HEAD

public static final String HEAD

HTTP Head method.

See Also:

Constant Field Values

GET

public static final String GET

HTTP Get method.

See Also:

Constant Field Values

POST

public static final String POST

HTTP Post method.

See Also:

Constant Field Values

HTTP_OK

public static final int HTTP_OK

200: The request has succeeded.

See Also:

Constant Field Values

HTTP_CREATED

public static final int HTTP_CREATED

201: The request has been fulfilled and resulted in a new resource being created.

See Also:

Constant Field Values

HTTP_ACCEPTED

public static final int HTTP_ACCEPTED

202: The request has been accepted for processing, but the processing has not been completed.

See Also:

Constant Field Values

HTTP_NOT_AUTHORITATIVE

public static final int HTTP_NOT_AUTHORITATIVE

203: The returned meta-information in the entity-header is not the definitive set as available from the origin server.

See Also:

Constant Field Values

HTTP_NO_CONTENT

public static final int HTTP_NO_CONTENT

204: The server has fulfilled the request but does not need to return an entity-body, and might want to return updated meta-information.

See Also:

Constant Field Values

HTTP_RESET

public static final int HTTP_RESET

205: The server has fulfilled the request and the user agent SHOULD reset the document view which caused the request to be sent.

See Also:

Constant Field Values

HTTP_PARTIAL

public static final int HTTP_PARTIAL

206: The server has fulfilled the partial GET request for the resource.

See Also:

Constant Field Values

HTTP_MULT_CHOICE

public static final int HTTP_MULT_CHOICE

300: The requested resource corresponds to any one of a set of representations, each with its own specific location, and agent- driven negotiation information is being provided so that the user (or user agent) can select a preferred representation and redirect its request to that location.

See Also:

Constant Field Values

HTTP_MOVED_PERM

public static final int HTTP_MOVED_PERM

301: The requested resource has been assigned a new permanent URI and any future references to this resource SHOULD use one of the returned URIs.

See Also:

Constant Field Values

HTTP_MOVED_TEMP

public static final int HTTP_MOVED_TEMP

302: The requested resource resides temporarily under a different URI. (Note: the name of this status code reflects the earlier publication of RFC2068, which was changed in RFC2616 from "moved temporalily" to "found". The semantics were not changed. The Location header indicates where the application should resend the request.)

See Also:

Constant Field Values

HTTP_SEE_OTHER

public static final int HTTP_SEE_OTHER

303: The response to the request can be found under a different URI and SHOULD be retrieved using a GET method on that resource.

See Also:

Constant Field Values

HTTP_NOT_MODIFIED

public static final int HTTP_NOT_MODIFIED

304: If the client has performed a conditional GET request and access is allowed, but the document has not been modified, the server SHOULD respond with this status code.

See Also:

Constant Field Values

HTTP_USE_PROXY

public static final int HTTP_USE_PROXY

305: The requested resource MUST be accessed through the proxy given by the Location field.

See Also:

Constant Field Values

HTTP_TEMP_REDIRECT

public static final int HTTP_TEMP_REDIRECT

307: The requested resource resides temporarily under a different URI.

See Also:

Constant Field Values

HTTP_BAD_REQUEST

public static final int HTTP_BAD_REQUEST

400: The request could not be understood by the server due to malformed syntax.

See Also:

Constant Field Values

HTTP_UNAUTHORIZED

public static final int HTTP_UNAUTHORIZED

401: The request requires user authentication. The response MUST include a WWW-Authenticate header field containing a challenge applicable to the requested resource.

See Also:

Constant Field Values

HTTP_PAYMENT_REQUIRED

public static final int HTTP_PAYMENT_REQUIRED

402: This code is reserved for future use.

See Also:

Constant Field Values

HTTP_FORBIDDEN

public static final int HTTP_FORBIDDEN

403: The server understood the request, but is refusing to fulfill it. Authorization will not help and the request SHOULD NOT be repeated.

See Also:

Constant Field Values

HTTP_NOT_FOUND

public static final int HTTP_NOT_FOUND

404: The server has not found anything matching the Request-URI. No indication is given of whether the condition is temporary or permanent.

See Also:

Constant Field Values

HTTP_BAD_METHOD

public static final int HTTP_BAD_METHOD

405: The method specified in the Request-Line is not allowed for the resource identified by the Request-URI.

See Also:

Constant Field Values

HTTP_NOT_ACCEPTABLE

public static final int HTTP_NOT_ACCEPTABLE

406: The resource identified by the request is only capable of generating response entities which have content characteristics not acceptable according to the accept headers sent in the request.

See Also:

Constant Field Values

HTTP_PROXY_AUTH

public static final int HTTP_PROXY_AUTH

407: This code is similar to 401 (Unauthorized), but indicates that the client must first authenticate itself with the proxy.

See Also:

Constant Field Values

HTTP_CLIENT_TIMEOUT

public static final int HTTP_CLIENT_TIMEOUT

408: The client did not produce a request within the time that the server was prepared to wait. The client MAY repeat the request without modifications at any later time.

See Also:

Constant Field Values

HTTP_CONFLICT

public static final int HTTP_CONFLICT

409: The request could not be completed due to a conflict with the current state of the resource.

See Also:

Constant Field Values

HTTP_GONE

public static final int HTTP_GONE

410: The requested resource is no longer available at the server and no forwarding address is known.

See Also:

Constant Field Values

HTTP_LENGTH_REQUIRED

public static final int HTTP_LENGTH_REQUIRED

411: The server refuses to accept the request without a defined Content- Length.

See Also:

Constant Field Values

HTTP_PRECON_FAILED

public static final int HTTP_PRECON_FAILED

412: The precondition given in one or more of the request-header fields evaluated to false when it was tested on the server.

See Also:

Constant Field Values

HTTP_ENTITY_TOO_LARGE

public static final int HTTP_ENTITY_TOO_LARGE

413: The server is refusing to process a request because the request entity is larger than the server is willing or able to process.

See Also:

Constant Field Values

HTTP_REQ_TOO_LONG

public static final int HTTP_REQ_TOO_LONG

414: The server is refusing to service the request because the Request-URI is longer than the server is willing to interpret.

See Also:

Constant Field Values

HTTP_UNSUPPORTED_TYPE

public static final int HTTP_UNSUPPORTED_TYPE

415: The server is refusing to service the request because the entity of the request is in a format not supported by the requested resource for the requested method.

See Also:

Constant Field Values

HTTP_UNSUPPORTED_RANGE

public static final int HTTP_UNSUPPORTED_RANGE

416: A server SHOULD return a response with this status code if a request included a Range request-header field , and none of the range-specifier values in this field overlap the current extent of the selected resource, and the request did not include an If-Range request-header field.

See Also:

Constant Field Values

HTTP_EXPECT_FAILED

public static final int HTTP_EXPECT_FAILED

417: The expectation given in an Expect request-header field could not be met by this server, or, if the server is a proxy, the server has unambiguous evidence that the request could not be met by the next-hop server.

See Also:

Constant Field Values

HTTP_INTERNAL_ERROR

public static final int HTTP_INTERNAL_ERROR

500: The server encountered an unexpected condition which prevented it from fulfilling the request.

See Also:

Constant Field Values

HTTP_NOT_IMPLEMENTED

public static final int HTTP_NOT_IMPLEMENTED

501: The server does not support the functionality required to fulfill the request.

See Also:

Constant Field Values

HTTP_BAD_GATEWAY

public static final int HTTP_BAD_GATEWAY

502: The server, while acting as a gateway or proxy, received an invalid response from the upstream server it accessed in attempting to fulfill the request.

See Also:

Constant Field Values

HTTP_UNAVAILABLE

public static final int HTTP_UNAVAILABLE

503: The server is currently unable to handle the request due to a temporary overloading or maintenance of the server.

See Also:

Constant Field Values

HTTP_GATEWAY_TIMEOUT

public static final int HTTP_GATEWAY_TIMEOUT

504: The server, while acting as a gateway or proxy, did not receive a timely response from the upstream server specified by the URI or some other auxiliary server it needed to access in attempting to complete the request.

See Also:

Constant Field Values

HTTP_VERSION

public static final int HTTP_VERSION

505: The server does not support, or refuses to support, the HTTP protocol version that was used in the request message.

See Also:

Constant Field Values

Method Detail

getURL

public String getURL()

Return a string representation of the URL for this connection.

Returns:

the string representation of the URL for this connection.

getProtocol

public String getProtocol()

Returns the protocol name of the URL of this HttpConnection. e.g., http or https

Returns:

the protocol of the URL of this HttpConnection.

getHost

public String getHost()

Returns the host information of the URL of this HttpConnection. e.g. host name or IPv4 address

Returns:

the host information of the URL of this HttpConnection.

getFile

public String getFile()

Returns the file portion of the URL of this HttpConnection.

Returns:

the file portion of the URL of this HttpConnection. null is returned if there is no file.

getRef

public String getRef()

Returns the ref portion of the URL of this HttpConnection. RFC2396 specifies the optional fragment identifier as the the text after the crosshatch (#) character in the URL. This information may be used by the user agent as additional reference information after the resource is successfully retrieved. The format and interpretation of the fragment identifier is dependent on the media type[RFC2046] of the retrieved information.

Returns:

the ref portion of the URL of this HttpConnection. null is returned if there is no value.

getQuery

public String getQuery()

Returns the query portion of the URL of this HttpConnection. RFC2396 defines the query component as the text after the first question-mark (?) character in the URL.

Returns:

the query portion of the URL of this HttpConnection. null is returned if there is no value.

getPort

public int getPort()

Returns the network port number of the URL for this HttpConnection.

Returns:

the network port number of the URL for this HttpConnection. The default HTTP port number (80) is returned if there was no port number in the string passed to Connector.open.

getRequestMethod

public String getRequestMethod()

Get the current request method. e.g. HEAD, GET, POST The default value is GET.

Returns:

the HTTP request method

See Also:

setRequestMethod(java.lang.String)

setRequestMethod

public void setRequestMethod(String method)
                      throws IOException

Set the method for the URL request, one of:

• GET
• POST
• HEAD

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

Parameters:

method - the HTTP method

Throws:

IOException - if the method cannot be reset or if the requested method isn't valid for HTTP.

See Also:

getRequestMethod()

getRequestProperty

public String getRequestProperty(String key)

Returns the value of the named general request property for this connection.

Parameters:

key - the keyword by which the request property is known (e.g., "accept").

Returns:

the value of the named general request property for this connection. If there is no key with the specified name then null is returned.

See Also:

setRequestProperty(java.lang.String, java.lang.String)

setRequestProperty

public void setRequestProperty(String key,
                               String value)
                        throws IOException

Sets the general request property. If a property with the key already exists, overwrite its value with the new value.

Note: HTTP requires all request properties which can legally have multiple instances with the same key to use a comma-separated list syntax which enables multiple properties to be appended into a single property.

Parameters:

key - the keyword by which the request is known (e.g., "accept").

value - the value associated with it.

Throws:

IOException - is thrown if the connection is in the connected state.

See Also:

getRequestProperty(java.lang.String)

getResponseCode

public int getResponseCode()
                    throws IOException

Returns the HTTP response status code. It parses responses like:

 HTTP/1.0 200 OK
 HTTP/1.0 401 Unauthorized
 

and extracts the ints 200 and 401 respectively. from the response (i.e., the response is not valid HTTP).

Returns:

the HTTP Status-Code or -1 if no status code can be discerned.

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.

getExpiration

public long getExpiration()
                   throws IOException

Returns the value of the expires header field.

Returns:

the expiration date of the resource that this URL references, or 0 if not known. The value is the number of milliseconds since January 1, 1970 GMT.

Throws:

IOException - if an error occurred connecting to the server.

getDate

public long getDate()
             throws IOException

Returns the value of the date header field.

Returns:

the sending date of the resource that the URL references, or 0 if not known. The value returned is the number of milliseconds since January 1, 1970 GMT.

Throws:

IOException - if an error occurred connecting to the server.

getLastModified

public long getLastModified()
                     throws IOException

Returns the value of the last-modified header field. The result is the number of milliseconds since January 1, 1970 GMT.

Returns:

the date the resource referenced by this HttpConnection was last modified, or 0 if not known.

Throws:

IOException - if an error occurred connecting to the server.

getHeaderField

public String getHeaderField(String name)
                      throws IOException

Returns the value of the named header field.

Parameters:

name - of a header field.

Returns:

the value of the named header field, or null if there is no such field in the header.

Throws:

IOException - if an error occurred connecting to the server.

getHeaderFieldInt

public int getHeaderFieldInt(String name,
                             int def)
                      throws IOException

Returns the value of the named field parsed as a number.

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 - the name of the header field.

def - the default value.

Returns:

the value of the named field, parsed as an integer. The def value is returned if the field is missing or malformed.

Throws:

IOException - if an error occurred connecting to the server.

getHeaderFieldDate

public long getHeaderFieldDate(String name,
                               long def)
                        throws IOException

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 - the name of the header field.

def - a default value.

Returns:

the value of the field, parsed as a date. The value of the def argument is returned if the field is missing or malformed.

Throws:

IOException - if an error occurred connecting to the server.

getHeaderField

public String getHeaderField(int n)
                      throws IOException

Gets a header field value by index.

Parameters:

n - the index of the header field

Returns:

the value of the nth header field or null if the array index is out of range. An empty String is returned if the field does not have a value.

Throws:

IOException - if an error occurred connecting to the server.

getHeaderFieldKey

public String getHeaderFieldKey(int n)
                         throws IOException

Gets a header field key by index.

Parameters:

n - the index of the header field

Returns:

the key of the nth header field or null if the array index is out of range.

Throws:

IOException - if an error occurred connecting to the server.