engine.js

里面包含dwr于struts

dwr.engine._nextBatchId = 0;

/** A list of the properties that need merging from calls to a batch */
dwr.engine._propnames = [ "rpcType", "httpMethod", "async", "timeout", "errorHandler", "warningHandler", "textHtmlHandler" ];

/** Do we stream, or can be hacked to do so? */
dwr.engine._partialResponseNo = 0;
dwr.engine._partialResponseYes = 1;
dwr.engine._partialResponseFlush = 2;

/** Is this page in the process of unloading? */
dwr.engine._unloading = false;

/**
 * @private Send a request. Called by the Javascript interface stub
 * @param path part of URL after the host and before the exec bit without leading or trailing /s
 * @param scriptName The class to execute
 * @param methodName The method on said class to execute
 * @param func The callback function to which any returned data should be passed
 *       if this is null, any returned data will be ignored
 * @param vararg_params The parameters to pass to the above class
 */
dwr.engine._execute = function(path, scriptName, methodName, vararg_params) {
  var singleShot = false;
  if (dwr.engine._batch == null) {
    dwr.engine.beginBatch();
    singleShot = true;
  }
  var batch = dwr.engine._batch;
  // To make them easy to manipulate we copy the arguments into an args array
  var args = [];
  for (var i = 0; i < arguments.length - 3; i++) {
    args[i] = arguments[i + 3];
  }
  // All the paths MUST be to the same servlet
  if (batch.path == null) {
    batch.path = path;
  }
  else {
    if (batch.path != path) {
      dwr.engine._handleError(batch, { name:"dwr.engine.multipleServlets", message:"Can't batch requests to multiple DWR Servlets." });
      return;
    }
  }
  // From the other params, work out which is the function (or object with
  // call meta-data) and which is the call parameters
  var callData;
  var lastArg = args[args.length - 1];
  if (typeof lastArg == "function" || lastArg == null) callData = { callback:args.pop() };
  else callData = args.pop();

  // Merge from the callData into the batch
  dwr.engine._mergeBatch(batch, callData);
  batch.handlers[batch.map.callCount] = {
    exceptionHandler:callData.exceptionHandler,
    callback:callData.callback
  };

  // Copy to the map the things that need serializing
  var prefix = "c" + batch.map.callCount + "-";
  batch.map[prefix + "scriptName"] = scriptName;
  batch.map[prefix + "methodName"] = methodName;
  batch.map[prefix + "id"] = batch.map.callCount;
  for (i = 0; i < args.length; i++) {
    dwr.engine._serializeAll(batch, [], args[i], prefix + "param" + i);
  }

  // Now we have finished remembering the call, we incr the call count
  batch.map.callCount++;
  if (singleShot) dwr.engine.endBatch();
};

/** @private Poll the server to see if there is any data waiting */
dwr.engine._poll = function() {
  if (!dwr.engine._activeReverseAjax) return;

  var batch = dwr.engine._createBatch();
  batch.map.id = 0; // TODO: Do we need this??
  batch.map.callCount = 1;
  batch.isPoll = true;
  if (dwr.engine._pollWithXhr == "true") {
    batch.rpcType = dwr.engine.XMLHttpRequest;
    batch.map.partialResponse = dwr.engine._partialResponseNo;
  }
  else {
    if (navigator.userAgent.indexOf("Gecko/") != -1) {
      batch.rpcType = dwr.engine.XMLHttpRequest;
      batch.map.partialResponse = dwr.engine._partialResponseYes;
    }
    else {
      batch.rpcType = dwr.engine.XMLHttpRequest;
      batch.map.partialResponse = dwr.engine._partialResponseNo;
    }
  }
  batch.httpMethod = "POST";
  batch.async = true;
  batch.timeout = 0;
  batch.path = dwr.engine._defaultPath;
  batch.preHooks = [];
  batch.postHooks = [];
  batch.errorHandler = dwr.engine._pollErrorHandler;
  batch.warningHandler = dwr.engine._pollErrorHandler;
  batch.handlers[0] = {
    callback:function(pause) {
      dwr.engine._pollRetries = 0;
      setTimeout(dwr.engine._poll, pause);
    }
  };

  // Send the data
  dwr.engine._sendData(batch);
  if (batch.rpcType == dwr.engine.XMLHttpRequest && batch.map.partialResponse == dwr.engine._partialResponseYes) {
    dwr.engine._checkCometPoll();
  }
};

/** Try to recover from polling errors */
dwr.engine._pollErrorHandler = function(msg, ex) {
  // if anything goes wrong then just silently try again (up to 3x) after 10s
  dwr.engine._pollRetries++;
  dwr.engine._debug("Reverse Ajax poll failed (pollRetries=" + dwr.engine._pollRetries + "): " + ex.name + " : " + ex.message);
  if (dwr.engine._pollRetries < dwr.engine._maxPollRetries) {
    setTimeout(dwr.engine._poll, 10000);
  }
  else {
    dwr.engine._activeReverseAjax = false;
    dwr.engine._debug("Giving up.");
  }
};

/** @private Generate a new standard batch */
dwr.engine._createBatch = function() {
  var batch = {
    map:{
      callCount:0,
      page:window.location.pathname + window.location.search,
      httpSessionId:dwr.engine._getJSessionId(),
      scriptSessionId:dwr.engine._getScriptSessionId()
    },
    charsProcessed:0, paramCount:0,
    parameters:{}, headers:{},
    isPoll:false, handlers:{}, preHooks:[], postHooks:[],
    rpcType:dwr.engine._rpcType,
    httpMethod:dwr.engine._httpMethod,
    async:dwr.engine._async,
    timeout:dwr.engine._timeout,
    errorHandler:dwr.engine._errorHandler,
    warningHandler:dwr.engine._warningHandler,
    textHtmlHandler:dwr.engine._textHtmlHandler
  };
  if (dwr.engine._preHook) batch.preHooks.push(dwr.engine._preHook);
  if (dwr.engine._postHook) batch.postHooks.push(dwr.engine._postHook);
  var propname, data;
  if (dwr.engine._headers) {
    for (propname in dwr.engine._headers) {
      data = dwr.engine._headers[propname];
      if (typeof data != "function") batch.headers[propname] = data;
    }
  }
  if (dwr.engine._parameters) {
    for (propname in dwr.engine._parameters) {
      data = dwr.engine._parameters[propname];
      if (typeof data != "function") batch.parameters[propname] = data;
    }
  }
  return batch;
};

/** @private Take further options and merge them into */
dwr.engine._mergeBatch = function(batch, overrides) {
  var propname, data;
  for (var i = 0; i < dwr.engine._propnames.length; i++) {
    propname = dwr.engine._propnames[i];
    if (overrides[propname] != null) batch[propname] = overrides[propname];
  }
  if (overrides.preHook != null) batch.preHooks.unshift(overrides.preHook);
  if (overrides.postHook != null) batch.postHooks.push(overrides.postHook);
  if (overrides.headers) {
    for (propname in overrides.headers) {
      data = overrides.headers[propname];
      if (typeof data != "function") batch.headers[propname] = data;
    }
  }
  if (overrides.parameters) {
    for (propname in overrides.parameters) {
      data = overrides.parameters[propname];
      if (typeof data != "function") batch.map["p-" + propname] = "" + data;
    }
  }
};

/** @private What is our session id? */
dwr.engine._getJSessionId =  function() {
  var cookies = document.cookie.split(';');
  for (var i = 0; i < cookies.length; i++) {
    var cookie = cookies[i];
    while (cookie.charAt(0) == ' ') cookie = cookie.substring(1, cookie.length);
    if (cookie.indexOf(dwr.engine._sessionCookieName + "=") == 0) {
      return cookie.substring(dwr.engine._sessionCookieName.length + 1, cookie.length);
    }
  }
  return "";
};

/** @private Check for reverse Ajax activity */
dwr.engine._checkCometPoll = function() {
  for (var i = 0; i < dwr.engine._outstandingIFrames.length; i++) {
    var text = "";
    var iframe = dwr.engine._outstandingIFrames[i];
    try {
      text = dwr.engine._getTextFromCometIFrame(iframe);
    }
    catch (ex) {
      dwr.engine._handleWarning(iframe.batch, ex);
    }
    if (text != "") dwr.engine._processCometResponse(text, iframe.batch);
  }
  if (dwr.engine._pollReq) {
    var req = dwr.engine._pollReq;
    var text = req.responseText;
    if (text != null) dwr.engine._processCometResponse(text, req.batch);
  }

  // If the poll resources are still there, come back again
  if (dwr.engine._outstandingIFrames.length > 0 || dwr.engine._pollReq) {
    setTimeout(dwr.engine._checkCometPoll, dwr.engine._pollCometInterval);
  }
};

/** @private Extract the whole (executed an all) text from the current iframe */
dwr.engine._getTextFromCometIFrame = function(frameEle) {
  var body = frameEle.contentWindow.document.body;
  if (body == null) return "";
  var text = body.innerHTML;
  // We need to prevent IE from stripping line feeds
  if (text.indexOf("<PRE>") == 0 || text.indexOf("<pre>") == 0) {
    text = text.substring(5, text.length - 7);
  }
  return text;
};

/** @private Some more text might have come in, test and execute the new stuff */
dwr.engine._processCometResponse = function(response, batch) {
  if (batch.charsProcessed == response.length) return;
  if (response.length == 0) {
    batch.charsProcessed = 0;
    return;
  }

  var firstStartTag = response.indexOf("//#DWR-START#", batch.charsProcessed);
  if (firstStartTag == -1) {
    // dwr.engine._debug("No start tag (search from " + batch.charsProcessed + "). skipping '" + response.substring(batch.charsProcessed) + "'");
    batch.charsProcessed = response.length;
    return;
  }
  // if (firstStartTag > 0) {
  //   dwr.engine._debug("Start tag not at start (search from " + batch.charsProcessed + "). skipping '" + response.substring(batch.charsProcessed, firstStartTag) + "'");
  // }

  var lastEndTag = response.lastIndexOf("//#DWR-END#");
  if (lastEndTag == -1) {
    // dwr.engine._debug("No end tag. unchanged charsProcessed=" + batch.charsProcessed);
    return;
  }

  // Skip the end tag too for next time, remembering CR and LF
  if (response.charCodeAt(lastEndTag + 11) == 13 && response.charCodeAt(lastEndTag + 12) == 10) {
    batch.charsProcessed = lastEndTag + 13;
  }
  else {
    batch.charsProcessed = lastEndTag + 11;
  }

  var exec = response.substring(firstStartTag + 13, lastEndTag);

  dwr.engine._receivedBatch = batch;
  dwr.engine._eval(exec);
  dwr.engine._receivedBatch = null;
};

/** @private Actually send the block of data in the batch object. */
dwr.engine._sendData = function(batch) {
  batch.map.batchId = dwr.engine._nextBatchId;
  dwr.engine._nextBatchId++;
  dwr.engine._batches[batch.map.batchId] = batch;
  dwr.engine._batchesLength++;
  batch.completed = false;

  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.timeoutId = setTimeout(function() { dwr.engine._abortRequest(batch); }, batch.timeout);
  }
  // Get setup for XMLHttpRequest if possible
  if (batch.rpcType == dwr.engine.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 = dwr.engine._newActiveXObject(dwr.engine._XMLHTTP);
    }
  }

  var prop, request;
  if (batch.req) {
    // Proceed using XMLHttpRequest
    if (batch.async) {
      batch.req.onreadystatechange = function() {
        if (typeof dwr != 'undefined') dwr.engine._stateChange(batch);
      };
    }
    // If we're polling, record this for monitoring
    if (batch.isPoll) {
      dwr.engine._pollReq = batch.req;
      // In IE XHR is an ActiveX control so you can't augment it like this
      if (!(document.all && !window.opera)) batch.req.batch = batch;
    }
    // Workaround for Safari 1.x POST bug
    var indexSafari = navigator.userAgent.indexOf("Safari/");
    if (indexSafari >= 0) {
      var version = navigator.userAgent.substring(indexSafari + 7);
      if (parseInt(version, 10) < 400) {
        if (dwr.engine._allowGetForSafariButMakeForgeryEasier == "true") batch.httpMethod = "GET";
        else dwr.engine._handleWarning(batch, { name:"dwr.engine.oldSafari", message:"Safari GET support disabled. See getahead.org/dwr/server/servlet and allowGetForSafariButMakeForgeryEasier." });
      }
    }
    batch.mode = batch.isPoll ? dwr.engine._ModePlainPoll : dwr.engine._ModePlainCall;
    request = dwr.engine._constructRequest(batch);