engine.js

基于ajax的dwr框架开发详细实例

  DWREngine._removeSerializeFunctions();

  // Now we have finished remembering the call, we incr the call count
  DWREngine._batch.map.callCount++;
  if (singleShot) {
    DWREngine.endBatch();
  }
};

/**
 * @private Actually send the block of data in the batch object.
 */
DWREngine._sendData = function(batch) {
  // If the batch is empty, don't send anything
  if (batch.map.callCount == 0) return;
  // Call any pre-hooks
  for (var i = 0; i < batch.preHooks.length; i++) {
    batch.preHooks[i]();
  }
  batch.preHooks = null;
  // Set a timeout
  if (batch.timeout && batch.timeout != 0) {
    batch.interval = setInterval(function() {
      clearInterval(batch.interval);
      DWREngine._abortRequest(batch);
    }, batch.timeout);
  }
  // A quick string to help people that use web log analysers
  var statsInfo;
  if (batch.map.callCount == 1) {
    statsInfo = batch.map["c0-scriptName"] + "." + batch.map["c0-methodName"] + ".dwr";
  }
  else {
    statsInfo = "Multiple." + batch.map.callCount + ".dwr";
  }

  // Get setup for XMLHttpRequest if possible
  if (batch.method == DWREngine.XMLHttpRequest) {
    if (window.XMLHttpRequest) {
      batch.req = new XMLHttpRequest();
    }
    // IE5 for the mac claims to support window.ActiveXObject, but throws an error when it's used
    else if (window.ActiveXObject && !(navigator.userAgent.indexOf('Mac') >= 0 && navigator.userAgent.indexOf("MSIE") >= 0)) {
      batch.req = DWREngine._newActiveXObject(DWREngine._XMLHTTP);
    }
  }

  var query = "";
  var prop;
  if (batch.req) {
    batch.map.xml = "true";
    // Proceed using XMLHttpRequest
    if (batch.async) {
      batch.req.onreadystatechange = function() {
        DWREngine._stateChange(batch);
      };
    }
    // Workaround for Safari 1.x POST bug
    var indexSafari = navigator.userAgent.indexOf('Safari/');
    if (indexSafari >= 0) {
      // So this is Safari, are we on 1.x? POST is broken
      var version = navigator.userAgent.substring(indexSafari + 7);
      var verNum = parseInt(version, 10);
      if (verNum < 400) {
        batch.verb == "GET";
      }
      // else if (verNum <= 417) {
      //   batch.map.isBrokenSafari2 = "true";
      // }
    }
    if (batch.verb == "GET") {
      // Some browsers (Opera/Safari2) seem to fail to convert the value
      // of batch.map.callCount to a string in the loop below so we do it
      // manually here.
      batch.map.callCount = "" + batch.map.callCount;

      for (prop in batch.map) {
        var qkey = encodeURIComponent(prop);
        var qval = encodeURIComponent(batch.map[prop]);
        if (qval == "") {
          if (DWREngine._warningHandler) {
            DWREngine._warningHandler("Found empty qval for qkey=" + qkey);
          }
        }
        query += qkey + "=" + qval + "&";
      }
      query = query.substring(0, query.length - 1);

      try {
        batch.req.open("GET", batch.path + "/exec/" + statsInfo + "?" + query, batch.async);
        batch.req.send(null);
        if (!batch.async) {
          DWREngine._stateChange(batch);
        }
      }
      catch (ex) {
        DWREngine._handleMetaDataError(null, ex);
      }
    }
    else {
      for (prop in batch.map) {
        if (typeof batch.map[prop] != "function") {
          query += prop + "=" + batch.map[prop] + "\n";
        }
      }

      try {
        // This might include Safari too, but it shouldn't do any harm
        //   if (navigator.userAgent.indexOf('Gecko') >= 0) {
        //     batch.req.setRequestHeader('Connection', 'close');
        //   }
        batch.req.open("POST", batch.path + "/exec/" + statsInfo, batch.async);
        batch.req.setRequestHeader('Content-Type', 'text/plain');
        batch.req.send(query);
        if (!batch.async) {
          DWREngine._stateChange(batch);
        }
      }
      catch (ex) {
        DWREngine._handleMetaDataError(null, ex);
      }
    }
  }
  else {
    batch.map.xml = "false";
    var idname = "dwr-if-" + batch.map["c0-id"];
    // Proceed using iframe
    batch.div = document.createElement('div');
    batch.div.innerHTML = "<iframe src='javascript:void(0)' frameborder='0' width='0' height='0' id='" + idname + "' name='" + idname + "'></iframe>";
    document.body.appendChild(batch.div);
    batch.iframe = document.getElementById(idname);
    batch.iframe.setAttribute('style', 'width:0px; height:0px; border:0px;');

    if (batch.verb == "GET") {
      for (prop in batch.map) {
        if (typeof batch.map[prop] != "function") {
          query += encodeURIComponent(prop) + "=" + encodeURIComponent(batch.map[prop]) + "&";
        }
      }
      query = query.substring(0, query.length - 1);

      batch.iframe.setAttribute('src', batch.path + "/exec/" + statsInfo + "?" + query);
      document.body.appendChild(batch.iframe);
    }
    else {
      batch.form = document.createElement('form');
      batch.form.setAttribute('id', 'dwr-form');
      batch.form.setAttribute('action', batch.path + "/exec" + statsInfo);
      batch.form.setAttribute('target', idname);
      batch.form.target = idname;
      batch.form.setAttribute('method', 'post');
      for (prop in batch.map) {
        var formInput = document.createElement('input');
        formInput.setAttribute('type', 'hidden');
        formInput.setAttribute('name', prop);
        formInput.setAttribute('value', batch.map[prop]);
        batch.form.appendChild(formInput);
      }

      document.body.appendChild(batch.form);
      batch.form.submit();
    }
  }
};

/**
 * @private Called by XMLHttpRequest to indicate that something has happened
 */
DWREngine._stateChange = function(batch) {
  if (!batch.completed && batch.req.readyState == 4) {
    try {
      var reply = batch.req.responseText;
      var status = batch.req.status;

      if (reply == null || reply == "") {
        DWREngine._handleMetaDataError(null, "No data received from server");
        return;
      }

      // This should get us out of 404s etc.
      if (reply.search("DWREngine._handle") == -1) {
        DWREngine._handleMetaDataError(null, "Invalid reply from server");
        return;
      }

      if (status != 200) {
        if (reply == null) reply = "Unknown error occured";
        DWREngine._handleMetaDataError(null, reply);
        return;
      }

      eval(reply);

      // We're done. Clear up
      DWREngine._clearUp(batch);
    }
    catch (ex) {
      if (ex == null) ex = "Unknown error occured";
      DWREngine._handleMetaDataError(null, ex);
    }
    finally {
      // If there is anything on the queue waiting to go out, then send it.
      // We don't need to check for ordered mode, here because when ordered mode
      // gets turned off, we still process *waiting* batches in an ordered way.
      if (DWREngine._batchQueue.length != 0) {
        var sendbatch = DWREngine._batchQueue.shift();
        DWREngine._sendData(sendbatch);
        DWREngine._batches[DWREngine._batches.length] = sendbatch;
      }
    }
  }
};

/**
 * @private Called by reply scripts generated as a result of remote requests
 * @param id The identifier of the call that we are handling a response for
 * @param reply The data to pass to the callback function
 */
DWREngine._handleResponse = function(id, reply) {
  // Clear this callback out of the list - we don't need it any more
  var handlers = DWREngine._handlersMap[id];
  DWREngine._handlersMap[id] = null;
  // TODO: How can we do this - delete DWREngine._handlersMap.id
  if (handlers) {
    // Error handlers inside here indicate an error that is nothing to do
    // with DWR so we handle them differently.
    try {
      if (handlers.callback) handlers.callback(reply);
    }
    catch (ex) {
      DWREngine._handleMetaDataError(handlers, ex);
    }
  }

  // Finalize the call for IFrame transport 
  if (DWREngine._method == DWREngine.IFrame) {
    var responseBatch = DWREngine._batches[DWREngine._batches.length-1];	
    // Only finalize after the last call has been handled
    if (responseBatch.map["c"+(responseBatch.map.callCount-1)+"-id"] == id) {
      DWREngine._clearUp(responseBatch);
    }
  }
};

/**
 * @private This method is called by Javascript that is emitted by server
 */
DWREngine._handleServerError = function(id, error) {
  // Clear this callback out of the list - we don't need it any more
  var handlers = DWREngine._handlersMap[id];
  DWREngine._handlersMap[id] = null;
  if (error.message) {
    DWREngine._handleMetaDataError(handlers, error.message, error);
  }
  else {
    DWREngine._handleMetaDataError(handlers, error);
  }
};

/**
 * @private Called as a result of a request timeout
 */ 
DWREngine._abortRequest = function(batch) {
  if (batch && batch.metadata != null && !batch.completed) {
    DWREngine._clearUp(batch);
    if (batch.req) batch.req.abort();
    // Call all the timeout errorHandlers
    var handlers;
    var id;
    for (var i = 0; i < batch.ids.length; i++) {
      id = batch.ids[i];
      handlers = DWREngine._handlersMap[id];
      DWREngine._handleMetaDataError(handlers, "Timeout");
    }
  }
};

/**
 * @private A call has finished by whatever means and we need to shut it all down.
 */
DWREngine._clearUp = function(batch) {
  if (batch.completed) {
    alert("double complete");
    return;
  }

  // IFrame tidyup
  if (batch.div) batch.div.parentNode.removeChild(batch.div);
  if (batch.iframe) batch.iframe.parentNode.removeChild(batch.iframe);
  if (batch.form) batch.form.parentNode.removeChild(batch.form);

  // XHR tidyup: avoid IE handles increase
  if (batch.req) delete batch.req;

  for (var i = 0; i < batch.postHooks.length; i++) {
    batch.postHooks[i]();
  }
  batch.postHooks = null;

  // TODO: There must be a better way???
  for (var i = 0; i < DWREngine._batches.length; i++) {
    if (DWREngine._batches[i] == batch) {
      DWREngine._batches.splice(i, 1);
      break;
    }
  }

  batch.completed = true;
};

/**
 * @private Generic error handling routing to save having null checks everywhere.
 */
DWREngine._handleError = function(reason, ex) {
  if (DWREngine._errorHandler) {
    DWREngine._errorHandler(reason, ex);
  }
};

/**
 * @private Generic error handling routing to save having null checks everywhere.
 */
DWREngine._handleMetaDataError = function(handlers, reason, ex) {
  if (handlers && typeof handlers.errorHandler == "function") {
    handlers.errorHandler(reason, ex);
  }
  else {
    DWREngine._handleError(reason, ex);
  }
};

/**
 * @private Hack a polymorphic dwrSerialize() function on all basic types. Yeulch
 */
DWREngine._addSerializeFunctions = function() {
  Object.prototype.dwrSerialize = DWREngine._serializeObject;
  Array.prototype.dwrSerialize = DWREngine._serializeArray;
  Boolean.prototype.dwrSerialize = DWREngine._serializeBoolean;
  Number.prototype.dwrSerialize = DWREngine._serializeNumber;
  String.prototype.dwrSerialize = DWREngine._serializeString;
  Date.prototype.dwrSerialize = DWREngine._serializeDate;
};

/**
 * @private Remove the hacked polymorphic dwrSerialize() function on all basic types.
 */
DWREngine._removeSerializeFunctions = function() {
  delete Object.prototype.dwrSerialize;
  delete Array.prototype.dwrSerialize;
  delete Boolean.prototype.dwrSerialize;
  delete Number.prototype.dwrSerialize;
  delete String.prototype.dwrSerialize;
  delete Date.prototype.dwrSerialize;
};

/**
 * @private Marshall a data item