[Sommaire] [Imprimer]

   1  /**
   2   * Javascript library for working with XmlHttpRequest objects and
   3   * Horde.
   4   *
   5   * $Horde: horde/js/httpclient.js,v 1.2.10.3 2005/10/18 11:33:38 jan Exp $
   6   *
   7   * See the enclosed file COPYING for license information (LGPL). If you did not
   8   * receive this file, see http://www.fsf.org/copyleft/lgpl.html.
   9   */
  10  
  11  // Constructor for generic HTTP client.
  12  function HTTPClient() {};
  13  
  14  // Add methods and properties as array.
  15  HTTPClient.prototype = {
  16      url: null,
  17  
  18      // Instance of XMLHttpRequest.
  19      request: null,
  20  
  21      // Used to make sure multiple calls are not placed with the same
  22      // client object while another in progress.
  23      callInProgress: false,
  24  
  25      // The user defined handler - see MyHandler below.
  26      userhandler: null,
  27  
  28      init: function(url)
  29      {
  30          this.url = url;
  31  
  32          try {
  33              // Mozilla, Safari.
  34              this.request = new XMLHttpRequest();
  35          } catch (e) {
  36              // IE.
  37              var MSXML_XMLHTTP_PROGIDS = new Array(
  38                  "MSXML2.XMLHTTP.4.0",
  39                  "MSXML2.XMLHTTP.3.0",
  40                  "MSXML2.XMLHTTP",
  41                  "Microsoft.XMLHTTP"
  42                  );
  43              var success = false;
  44              for (var i = 0; i < MSXML_XMLHTTP_PROGIDS.length && !success; i++) {
  45                  try {
  46                      this.request = new ActiveXObject(MSXML_XMLHTTP_PROGIDS[i]);
  47                      success = true;
  48                  } catch (e) {}
  49              }
  50              if (!success) {
  51                  throw "Unable to create XMLHttpRequest.";
  52              }
  53          }
  54      },
  55  
  56      // Handler argument is a user defined object to be called.
  57      asyncGET: function(handler)
  58      {
  59          // Degrade or some such.
  60          if (!this.request) {
  61              return false;
  62          };
  63  
  64          // Prevent multiple calls
  65          if (this.callInProgress) {
  66              throw "Call in progress";
  67          };
  68  
  69          this.callInProgress = true;
  70  
  71          this.userhandler = handler;
  72  
  73          // Open an async request - third argument makes it
  74          // asynchronous.
  75          this.request.open('GET', this.url, true);
  76  
  77          // Have to assign "this" to a variable.
  78          var self = this;
  79  
  80          // Assign a closure to the onreadystatechange callback.
  81          this.request.onreadystatechange = function()
  82          {
  83              self.stateChangeCallback(self);
  84          }
  85  
  86          this.request.send(null);
  87      },
  88  
  89      stateChangeCallback: function(client)
  90      {
  91          switch (client.request.readyState) {
  92              // Request not yet made.
  93              case 1:
  94              try {
  95                  client.userhandler.onInit();
  96              } catch (e) { /* Handler method not defined. */ }
  97              break;
  98  
  99              // Contact established with server but nothing downloaded
 100              // yet.
 101              case 2:
 102              try {
 103                  status = client.request.status;
 104                  // Check for HTTP status 200.
 105                  if (status != 200) {
 106                      client.userhandler.onError(
 107                          status,
 108                          client.request.statusText
 109                          );
 110  
 111                      // Abort the request.
 112                      client.request.abort();
 113  
 114                      // Call no longer in progress.
 115                      client.callInProgress = false;
 116                  }
 117              } catch (e) {
 118                  /* MSXMLHTTP 3.x+ doesn't populate status until
 119                   * readyState 4. */
 120              }
 121              break;
 122  
 123              // Called multiple times while download is in progress.
 124              case 3:
 125              // Notify user handler of download progress.
 126              try {
 127                  // Get the total content length (useful to work
 128                  // out how much has been downloaded).
 129                  try {
 130                      var contentLength =
 131                          client.request.getResponseHeader("Content-Length");
 132                  } catch (e) {
 133                      var contentLength = NaN;
 134                  }
 135  
 136                  // Call the progress handler with what we've got.
 137                  client.userhandler.onProgress(
 138                      client.request.responseText,
 139                      contentLength
 140                      );
 141  
 142              } catch (e) { /* Handler method not defined. */ }
 143              break;
 144  
 145              // Download complete.
 146              case 4:
 147              try {
 148                  client.userhandler.onLoad(client.request.responseText);
 149              } catch (e) {
 150                  /* Handler method not defined. */
 151              } finally {
 152                  // Call no longer in progress.
 153                  client.callInProgress = false;
 154              }
 155              break;
 156          }
 157      }
 158  
 159  }