Metacat

/**

 *  '$RCSfile$'

 *    Purpose: A Class that implements a URL for use in identifying metacat

 *             files. It also handles http urls

 *  Copyright: 2000 Regents of the University of California and the

 *             National Center for Ecological Analysis and Synthesis

 *    Authors: Chad Berkley

 *    Release: @release@

 *

 *   '$Author: jones $'

 *     '$Date: 2000-11-27 13:55:08 -0800 (Mon, 27 Nov 2000) $'

 * '$Revision: 566 $'

 */

package edu.ucsb.nceas.metacat;

import java.net.MalformedURLException;

import java.util.Hashtable;

import java.util.Enumeration;

public class MetacatURL

{

  private String[][] params = new String[200][2];

  private Hashtable paramsHash = new Hashtable();

  private String protocol = null;

  private String host = null;

  private String url;

  /**

   * This constructor takes a string url and parses it according to the  

   * following rules.  

   * 1) The protocol of the url is the text before the "://" symbol.

   * 2) Parameter names are written first and are terminated with the = symbol

   * 3) Parameter values come 2nd and are terminated with an & except for the

   *    last value

   * The form of the url looks like: 

   * protocol://server.domain.com/servlet/?name1=val1&name2=val2&nameN=valN

   * notice there is no & after the last param.  If one is there it is ignored.

   *

   * @param url the string to parse

   */

  public MetacatURL(String url) throws MalformedURLException

  {

    this.url = url;

    parseURL(url);

  }

  /**

   * This method takes a string url and parses it according to the following 

   * rules.  

   * 1) The protocol of the url is the text before the "://" symbol.

   * 2) Parameter names are written first and are terminated with the = symbol

   * 3) Parameter values come 2nd and are terminated with an & except for the

   *    last value

   * The form of the url looks like: 

   * protocol://server.domain.com/servlet/?name1=val1&name2=val2&nameN=valN

   * notice there is no & after the last param.  If one is there it is ignored.

   */

  private void parseURL(String url) throws MalformedURLException

  {

    String pname = null;

    String param = null;

    String temp = "";

    boolean ampflag = true;

    boolean poundflag = false;

    int arrcount = 0;

    //anything before this is the protocol

    int protocolIndex = url.indexOf("://"); 

    if (protocolIndex == -1) {

      // URL badly formed, no protocol

      throw new MalformedURLException("Invalid URL format: " +

                                      "no protocol provided.");

    }

    this.protocol = url.substring(0, protocolIndex);

    paramsHash.put("protocol", this.protocol);

    if(this.protocol.equals("http"))

    {//if this is an http url

      params[0][0] = "httpurl";

      params[0][1] = url.substring(0, url.length());

      paramsHash.put(params[0][0], params[0][1]);

      for(int i=url.length()-1; i>0; i--)

      {

        if(url.charAt(i) == '/')

        {

          i=0;

        }

        else

        {

          String exchange = temp;

          temp = "";

          temp += url.charAt(i);

          temp += exchange;

        }

      }

      params[1][0] = "filename";

      params[1][1] = temp;

      paramsHash.put(params[1][0], params[1][1]);

    }

    else

    {//other urls that meet the metacat type url structure.

      int hostIndex = url.indexOf("?");

      this.host = url.substring(protocolIndex + 3, hostIndex);

      paramsHash.put("host", this.host);

      for(int i=hostIndex + 1; i<url.length(); i++)

      { //go throught the remainder of the url one character at a time.

        if(url.charAt(i) == '=')

        { //if the current char is a # then the preceding should be a parametet

          //name

          if(!poundflag && ampflag)

          {

            params[arrcount][0] = temp.trim();

            temp = "";

          }

          else

          { //if there are two #s or &s in a row throw an exception.

            throw new MalformedURLException("metacatURL: Two parameter names " +

                                            "not allowed in sequence");

          }

          poundflag = true;

          ampflag = false;

        }

        else if(url.charAt(i) == '&' || i == url.length()-1)

        { //the text preceding the & should be the param value.

          if(i == url.length() - 1)

          { //if we are at the end of the string grab the last value and append it.

            if(url.charAt(i) != '=')

            { //ignore an extra & on the end of the string

              temp += url.charAt(i);

            }

          }

          if(!ampflag && poundflag)

          {

            params[arrcount][1] = temp.trim();

            paramsHash.put(params[arrcount][0], params[arrcount][1]);

            temp = "";

            arrcount++; //increment the array to the next row.

          }

          else

          { //if there are two =s or &s in a row through an exception

            throw new MalformedURLException("metacatURL: Two parameter values " +

                                            "not allowed in sequence");

          }

          poundflag = false;

          ampflag = true;

        }

        else

        { //get the next character in the string

          temp += url.charAt(i); 

        }

      }

    }

  }

  /**

   * Returns the type of the url. This is defined by the text before the "://" 

   * symbol in the url.

   */

  public String getProtocol()

  {

    return this.protocol; 

  }

  /**

   * Returns the parameters as a 2D string array.

   */

  public String[][] getParams()

  {

    return this.params;

  }

  /** 

   * Returns the parameters in a hashtable.

   */

  public Hashtable getHashParams()

  {

    return this.paramsHash;

  }

  /**

   * returns a single parameter from the hash by name

   * @param paramname the name of the parameter to return.

   */

  public Object getHashParam(String paramname)

  {

    return this.paramsHash.get(paramname);

  }

  /**

   * returns a string representation of this metacatURL

   */

  public String toString()

  {

    return this.url;

  }

  public void printHashParams()

  {

    Enumeration e = this.paramsHash.keys();

    System.out.println("name          value");

    System.out.println("-------------------");

    while(e.hasMoreElements())

    {

      String key = (String)e.nextElement();

      System.out.print(key);

      System.out.print("          ");

      System.out.println((String)this.paramsHash.get(key));

    }

  }

  /**

   * Prints the parameters neatly to system.out

   */

  public void printParams()

  {

    String[][] p = null;

    System.out.println("protocol: " + this.getProtocol());

    System.out.println("parameters: ");

    p = this.getParams();

    System.out.println("name          value");

    System.out.println("-------------------");

    for(int i=0; i<p.length; i++)

    {

      if(p[i][0] != null)

      {

        System.out.print(p[i][0]);

        System.out.print("          ");

        System.out.print(p[i][1]);

        System.out.println();

      }

    }

  }

  /**

   * Returns a single parameter and value as a 1D string array.

   *

   * @param index the index of the parameter, value array that you want.

   */

  public String[] getParam(int index)

  {

    String[] s = new String[2];

    s[0] = this.params[index][0].trim();

    s[1] = this.params[index][1].trim();

    //System.out.println("0: " + s[0]);

    //System.out.println("1: " + s[1]);

    return s;

  }

  /**

   * Test method for this class.

   */

  public static void main(String args[])

  {

    String testurl =  "metacat://dev.nceas.ucsb.edu?docid=NCEAS:10&username=chad&pasword=xyz";

    String testurl2 = "http://dev.nceas.ucsb.edu/berkley/testdata.dat";

    String testurl3 = "NCEAS.1287873498.32";

    try

    {

      System.out.println("*********************************************");

      MetacatURL murl = new MetacatURL(testurl);

      //String[][] p = null;

      System.out.println("protocol: " + murl.getProtocol());

      System.out.println("parameters: ");

      //p = murl.getParams();

      //Hashtable h = murl.getHashParams();

      murl.printParams();

      murl.printHashParams();

      System.out.println("*********************************************");

      MetacatURL murl2 = new MetacatURL(testurl2);

      System.out.println("protocol: " + murl2.getProtocol());

      System.out.println("parameters: ");

      murl2.printParams();

      murl2.printHashParams();

      System.out.println("*********************************************");

      MetacatURL murl3 = new MetacatURL(testurl3);

      System.out.println("protocol: " + murl3.getProtocol());

      System.out.println("parameters: ");

      murl3.printParams();

      System.out.println("*********************************************");

    }

    catch(MalformedURLException murle)

    {

      System.out.println("bad url " + murle.getMessage()); 

    }

  }

}