post.java

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package com.mindprod.http;

import java.io.IOException;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URL;
import java.net.URLEncoder;

/**
 * simulates a browser posting a form to CGI via POST. See com.mindprod.submitter for sample code to use this class.
 *
 * @author Roedy Green, Canadian Mind Products may be copied and used freely for any purpose but military.
 * @version 1.9 2008-08-22 support accept-charset, accept-encoding and accept-language.  Fix bugs in gzip support.
 */
public final class Post extends Http
    {
    // -------------------------- PUBLIC INSTANCE  METHODS --------------------------
    /**
     * Constructor
     */
    public Post()
        {
        }

    /**
     * Send a form full of data to the CGI host using POST
     *
     * @param url      URL of the website, including host, path but not the parms.
     *                 only http:
     * @param parms    alternating parm value without = or ? not urlEncoded.
     * @param encoding encoding of the byte stream result, usually UTF-8 or or ISO-8859-1.
     * @return CGI host's response with headers and embedded length fields stripped
     */
    @SuppressWarnings( { "UnusedAssignment", "MethodNamesDifferingOnlyByCase", "WeakerAccess" } )
    public String post( URL url,
                        String encoding,
                        String... parms )
        {
        try
            {
            // defaults
            responseCode = DEFAULT_RESPONSE_CODE;
            responseMessage = DEFAULT_RESPONSE_MESSAGE;

            // prepare parms
            final StringBuilder sb = new StringBuilder( 200 );
            for ( int i = 0; i < parms.length - 1; i += 2 )
                {
                if ( i != 0 )
                    {
                    sb.append( "&" );
                    }
                sb.append( URLEncoder.encode( parms[ i ], "UTF-8"
                        /* encoding */ ) );
                sb.append( '=' );
                sb.append( URLEncoder.encode( parms[ i + 1 ], "UTF-8"
                        /* encoding */ ) );
                }

            final byte[] encodedParms =
                    sb.toString().getBytes( "UTF-8"/* encoding */ );

            final HttpURLConnection urlc = ( HttpURLConnection ) url.openConnection();
            urlc.setAllowUserInteraction( false );
            urlc.setDoInput( true );
            urlc.setDoOutput( true );// parms at the tail of this
            urlc.setUseCaches( false );
            urlc.setRequestMethod( "POST" );
            setStandardProperties( urlc );

            // could set Referrer: here
            urlc.setRequestProperty( "Content-Length",
                    Integer.toString( encodedParms.length )
                    /* in bytes */ );
            urlc.setRequestProperty( "Content-Type",
                    "application/x-www-form-urlencoded" );

            urlc.connect();

            final OutputStream os = urlc.getOutputStream();
            // parms are the data content.
            os.write( encodedParms );
            os.close();

            return processResponse( encoding, urlc );
            }
        catch ( ClassCastException e )
            {
            // was not an http: url
            return null;
            }
        catch ( IOException e )
            {
            return null;
            }
        }

    /**
     * Send a form full of data to the CGI host using POST
     *
     * @param host     domain of the website. no lead http:
     * @param action   action of form, page on website. Usually has a lead /.
     * @param parms    alternating parm value without = or ? not urlEncoded.
     * @param port     -1 if default, 8081 for local echoserver.
     * @param encoding encoding of the byte stream result, usually UTF-8 or or ISO-8859-1.
     * @return CGI host's response with headers and embedded length fields stripped
     */
    @SuppressWarnings( { "UnusedAssignment", "MethodNamesDifferingOnlyByCase" } )
    public String post( String host,
                        int port,
                        String encoding,
                        String action,
                        String... parms )
        {
        try
            {
            // defaults
            responseCode = 404;
            responseMessage = "not HTTP";
            // URL will encode target and parms.
            URL url = new URI( "http",
                    null,
                    host,
                    port,
                    action,
                    null,
                    null ).toURL();

            return post( url, encoding, parms );
            }
        catch ( URISyntaxException e )
            {
            return null;
            }
        catch ( IOException e )
            {
            return null;
            }
        }// end post
    }