Class HTTPClient.HTTPConnection

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Class HTTPClient.HTTPConnection

java.lang.Object
   |
   +----HTTPClient.HTTPConnection

public class HTTPConnection
extends Object

This class implements http protocol requests; it contains most of HTTP/1.1 and ought to be unconditionally compliant. Redirections are automatically handled, and authorizations requests are recognized and dealt with via an authorization handler. Only full HTTP/1.0 and HTTP/1.1 requests are generated. HTTP/1.1, HTTP/1.0 and HTTP/0.9 responses are recognized.

Using the HTTPClient should be quite simple. First add the import statement 'import HTTPClient.*;' to your file(s). Request can then be sent using one of the methods Head(), Get(), Post(), etc in HTTPConnection. These methods all return an instance of HTTPResponse which has methods for accessing the response headers (getHeader(), getHeaderAsInt(), etc), various response info (getStatusCode(), getReasonLine(), etc) and the reponse data (getData() and getInputStream()). Following are some examples.

If this is in an applet you can retrieve files from your server as follows:

    HTTPConnection con = new HTTPConnection(this);
    HTTPResponse   rsp = con.Get("/my_file");
    if (rsp.getStatusCode() >= 300)
    {
	System.err.println("Received Error: "+rsp.getReasonLine());
	System.err.println(new String(rsp.getData(),0));
    }
    else
	data = rsp.getData();
    rsp = con.Get("/another_file");
    if (rsp.getStatusCode() >= 300)
    {
	System.err.println("Received Error: "+rsp.getReasonLine());
	System.err.println(new String(rsp.getData(),0));
    }
    else
	other_data = rsp.getData();

This will get the files "/my_file" and "/another_file" and put their contents into byte[]'s accessible via getData(). Note that you need to only create a new HTTPConnection when sending a request to a new server (different host or port); although you may create a new HTTPConnection for every request to the same server this not recommended, as various information about the server is cached after the first request (to optimize subsequent requests) and persistent connections are used whenever possible.

To POST form data you would use something like this (assuming you have two fields called name and e-mail, whose contents are stored in the variables name and email):

    NVPair form_data[] = new NVPair[2];
    form_data[0] = new NVPair("name", name);
    form_data[1] = new NVPair("e-mail", email);
    HTTPConnection con = new HTTPConnection(this);
    HTTPResponse   rsp = con.Post("/cgi-bin/my_script", form_data);
    if (rsp.getStatusCode() >= 300)
    {
	System.err.println("Received Error: "+rsp.getReasonLine());
	System.err.println(new String(rsp.getData(),0));
    }
    else
        stream = rsp.getInputStream();

Here the response data is read at leasure via an InputStream instead of all at once into a byte[].

As another example, if you have a URL you're trying to send a request to you would do something like the following:

    URL url = new URL("http://www.mydomain.us/test/my_file");
    HTTPConnection con = new HTTPConnection(url);
    HTTPResponse   rsp = con.Put(url.getFile(), "Hello World");
    if (rsp.getStatusCode() >= 300)
    {
	System.err.println("Received Error: "+rsp.getReasonLine());
	System.err.println(new String(rsp.getData(),0));
    }
    else
        data = rsp.getData();

There are a whole number of methods for each request type; however the general form's are:

Head ( file [, form-data [, headers ] ] )
Head ( file [, query [, headers ] ] )
Get ( file [, form-data [, headers ] ] )
Get ( file [, query [, headers ] ] )
Post ( file [, data [, headers ] ] )
Put ( file [, data [, headers ] ] )
Delete ( file [, headers ] )
Options ( file [, headers ] )
Trace ( file [, headers ] )

Version:: 0.2 (bug fix 2) 23/03/1997
Author:: Ronald Tschalär

version: Current version

HTTPConnection(Applet): Constructs a connection to the host from where the applet was loaded.
HTTPConnection(String): Constructs a connection to the specified host on port 80
HTTPConnection(String, int): Constructs a connection to the specified host on the specified port
HTTPConnection(String, String, int): Constructs a connection to the specified host on the specified port, using the specified protocol (currently only "http" is supported).
HTTPConnection(URL): Constructs a connection to the host (port) as given in the url.

addAuthorization(String, String, String, NVPair[]): Add's an authorization entry to the list.
addBasicAuthorization(String, String, String): Add's an authorization entry for the "basic" authorization scheme to the list.
Delete(String): Requests that file be DELETEd from the server.
Delete(String, NVPair[]): Requests that file be DELETEd from the server.
ExtensionMethod(String, String, byte[], NVPair[]): This is here to allow an arbitrary, non-standard request to be sent.
Get(String): GET's the file.
Get(String, NVPair[]): GET's the file with a query consisting of the specified form-data.
Get(String, NVPair[], NVPair[]): GET's the file with a query consisting of the specified form-data.
Get(String, String): GET's the file using the specified query string.
Get(String, String, NVPair[]): GET's the file using the specified query string.
getDefaultHeaders(): Gets the current list of default http headers.
Head(String): Sends the HEAD request.
Head(String, NVPair[]): Sends the HEAD request.
Head(String, NVPair[], NVPair[]): Sends the HEAD request.
Head(String, String): Sends the HEAD request.
Head(String, String, NVPair[]): Sends the HEAD request.
Options(String): Request OPTIONS from the server.
Options(String, NVPair[]): Request OPTIONS from the server.
Post(String): POST's to the specified file.
Post(String, byte[]): POST's the raw data to the specified file.
Post(String, byte[], NVPair[]): POST's the raw data to the specified file using the specified headers.
Post(String, NVPair[]): POST's form-data to the specified file.
Post(String, String): POST's the data to the specified file.
Post(String, String, NVPair[]): POST's the data to the specified file using the specified headers.
Put(String, byte[]): PUT's the raw data into the specified file.
Put(String, byte[], NVPair[]): PUT's the raw data into the specified file using the additional headers.
Put(String, String): PUT's the data into the specified file.
Put(String, String, NVPair[]): PUT's the data into the specified file using the additional headers for the request.
setDefaultHeaders(NVPair[]): Sets the default http headers to be sent with each request.
setProxyServer(String, int): Set's the default proxy server to use.
setRawMode(boolean): Sets/Resets raw mode.
setSocksServer(String): Set's the SOCKS server to use.
setSocksServer(String, int): Set's the SOCKS server to use.
setSocksServer(String, int, int): Set's the SOCKS server to use.
Trace(String): Requests a TRACE.
Trace(String, NVPair[]): Requests a TRACE.

version

  public final static String version

Current version

HTTPConnection

  public HTTPConnection(Applet applet) throws ProtocolNotSupportedException

Constructs a connection to the host from where the applet was loaded. Note that current security policies only let applets connect home.

Parameters:: applet - the current applet

HTTPConnection

  public HTTPConnection(String host)

Constructs a connection to the specified host on port 80

Parameters:: host - the host

HTTPConnection

  public HTTPConnection(String host,
                        int port)

Constructs a connection to the specified host on the specified port

Parameters:: host - the host; port - the port

HTTPConnection

  public HTTPConnection(String prot,
                        String host,
                        int port) throws ProtocolNotSupportedException

Constructs a connection to the specified host on the specified port, using the specified protocol (currently only "http" is supported).

Parameters:: prot - the protocol; host - the host; port - the port
Throws: MalformedURLException: if the protocol is not HTTP

HTTPConnection

  public HTTPConnection(URL url) throws ProtocolNotSupportedException

Constructs a connection to the host (port) as given in the url.

Parameters:: url - the url
Throws: ProtocolNotSupportedException: if the protocol is not HTTP