好吧，你可以启动一个实际的保存。
从您的代码启动保存链接：
在上下文菜单中，命令值为gContextMenu.saveLink();。 saveLink() 定义在：chrome://browser/content/nsContextMenu.js http://dxr.mozilla.org/mozilla-central/source/browser/base/content/nsContextMenu.js#1284。它做一些内务处理然后调用saveHelper() 定义在同一文件中 http://mxr.mozilla.org/mozilla-central/source/browser/base/content/nsContextMenu.js#1150。您可以使用适当的参数调用 saveHelper() 。它包含在面板中chrome://browser/content/web-panels.xul http://dxr.mozilla.org/mozilla-central/source/browser/base/content/web-panels.xul#26 with:
<script type="application/javascript"
src="chrome://browser/content/nsContextMenu.js"/>
然后gContextMenu声明于的变量chrome://browser/content/browser.js http://dxr.mozilla.org/mozilla-central/source/browser/base/content/browser.js#45 as null被安排了：
gContextMenu = new nsContextMenu(this, event.shiftKey); http://dxr.mozilla.org/mozilla-central/source/browser/base/content/web-panels.xul#53
在上下文菜单的 onpopupshowing 事件处理程序中。它返回到：
'gContextMenu = null;' http://dxr.mozilla.org/mozilla-central/source/browser/base/content/web-panels.xul#60
in the onpopuphiding事件处理程序。
如果你想在你自己的代码中使用它，你可以这样做：
let urlToSave = "http://stackoverflow.com/questions/26694442";
let linkText = "Some Link text";
// Add a "/" to un-comment the code appropriate for your add-on type.
/* Overlay and bootstrap:
const Cc = Components.classes;
const Ci = Components.interfaces;
const Cr = Components.results;
//*/
/* Add-on SDK:
var {Cc, Ci, Cr} = require("chrome");
//*/
if (window === null || typeof window !== "object") {
//If you do not already have a window reference, you need to obtain one:
// Add a "/" to un-comment the code appropriate for your add-on type.
/* Add-on SDK:
var window = require('sdk/window/utils').getMostRecentBrowserWindow();
//*/
/* Overlay and bootstrap (from almost any context/scope):
var window=Components.classes["@mozilla.org/appshell/window-mediator;1"]
.getService(Components.interfaces.nsIWindowMediator)
.getMostRecentWindow("navigator:browser");
//*/
}
//Create an object in which we attach nsContextMenu.js.
// It needs some support properties/functions which
// nsContextMenu.js assumes are part of its context.
let contextMenuObj = {
makeURI: function (aURL, aOriginCharset, aBaseURI) {
var ioService = Cc["@mozilla.org/network/io-service;1"]
.getService(Ci.nsIIOService);
return ioService.newURI(aURL, aOriginCharset, aBaseURI);
},
gPrefService: Cc["@mozilla.org/preferences-service;1"]
.getService(Ci.nsIPrefService)
.QueryInterface(Ci.nsIPrefBranch),
Cc: Cc,
Ci: Ci,
Cr: Cr
};
Cc["@mozilla.org/moz/jssubscript-loader;1"]
.getService(Ci.mozIJSSubScriptLoader)
.loadSubScript("chrome://browser/content/nsContextMenu.js"
,contextMenuObj);
//Re-define the initMenu function, as there is not a desire to actually
// initialize a menu.
contextMenuObj.nsContextMenu.prototype.initMenu = function() { };
let myContextMenu = new contextMenuObj.nsContextMenu();
//Save the specified URL
myContextMenu.saveHelper(urlToSave,linkText,null,true,window.content.document);
使用 loadSubScript 加载的替代方法nsContextMenu.js:
我的偏好是使用 loadSubScript 加载 saveHelper 代码nsContextMenu.js。这可以使代码与未来 Firefox 版本中所做的任何更改保持同步。但是，它引入了您正在使用来自非官方 API 的函数的依赖性。因此，在未来的 Firefox 版本中，它可能会以某种方式发生变化，并且需要对您的附加组件进行更改。另一种方法是复制saveHelper()您的扩展中的代码。它的定义如下：
// Helper function to wait for appropriate MIME-type headers and
// then prompt the user with a file picker
saveHelper: function(linkURL, linkText, dialogTitle, bypassCache, doc) {
// canonical def in nsURILoader.h
const NS_ERROR_SAVE_LINK_AS_TIMEOUT = 0x805d0020;
// an object to proxy the data through to
// nsIExternalHelperAppService.doContent, which will wait for the
// appropriate MIME-type headers and then prompt the user with a
// file picker
function saveAsListener() {}
saveAsListener.prototype = {
extListener: null,
onStartRequest: function saveLinkAs_onStartRequest(aRequest, aContext) {
// if the timer fired, the error status will have been caused by that,
// and we'll be restarting in onStopRequest, so no reason to notify
// the user
if (aRequest.status == NS_ERROR_SAVE_LINK_AS_TIMEOUT)
return;
timer.cancel();
// some other error occured; notify the user...
if (!Components.isSuccessCode(aRequest.status)) {
try {
const sbs = Cc["@mozilla.org/intl/stringbundle;1"].
getService(Ci.nsIStringBundleService);
const bundle = sbs.createBundle(
"chrome://mozapps/locale/downloads/downloads.properties");
const title = bundle.GetStringFromName("downloadErrorAlertTitle");
const msg = bundle.GetStringFromName("downloadErrorGeneric");
const promptSvc = Cc["@mozilla.org/embedcomp/prompt-service;1"].
getService(Ci.nsIPromptService);
promptSvc.alert(doc.defaultView, title, msg);
} catch (ex) {}
return;
}
var extHelperAppSvc =
Cc["@mozilla.org/uriloader/external-helper-app-service;1"].
getService(Ci.nsIExternalHelperAppService);
var channel = aRequest.QueryInterface(Ci.nsIChannel);
this.extListener =
extHelperAppSvc.doContent(channel.contentType, aRequest,
doc.defaultView, true);
this.extListener.onStartRequest(aRequest, aContext);
},
onStopRequest: function saveLinkAs_onStopRequest(aRequest, aContext,
aStatusCode) {
if (aStatusCode == NS_ERROR_SAVE_LINK_AS_TIMEOUT) {
// do it the old fashioned way, which will pick the best filename
// it can without waiting.
saveURL(linkURL, linkText, dialogTitle, bypassCache, false,
doc.documentURIObject, doc);
}
if (this.extListener)
this.extListener.onStopRequest(aRequest, aContext, aStatusCode);
},
onDataAvailable: function saveLinkAs_onDataAvailable(aRequest, aContext,
aInputStream,
aOffset, aCount) {
this.extListener.onDataAvailable(aRequest, aContext, aInputStream,
aOffset, aCount);
}
}
function callbacks() {}
callbacks.prototype = {
getInterface: function sLA_callbacks_getInterface(aIID) {
if (aIID.equals(Ci.nsIAuthPrompt) || aIID.equals(Ci.nsIAuthPrompt2)) {
// If the channel demands authentication prompt, we must cancel it
// because the save-as-timer would expire and cancel the channel
// before we get credentials from user. Both authentication dialog
// and save as dialog would appear on the screen as we fall back to
// the old fashioned way after the timeout.
timer.cancel();
channel.cancel(NS_ERROR_SAVE_LINK_AS_TIMEOUT);
}
throw Cr.NS_ERROR_NO_INTERFACE;
}
}
// if it we don't have the headers after a short time, the user
// won't have received any feedback from their click. that's bad. so
// we give up waiting for the filename.
function timerCallback() {}
timerCallback.prototype = {
notify: function sLA_timer_notify(aTimer) {
channel.cancel(NS_ERROR_SAVE_LINK_AS_TIMEOUT);
return;
}
}
// set up a channel to do the saving
var ioService = Cc["@mozilla.org/network/io-service;1"].
getService(Ci.nsIIOService);
var channel = ioService.newChannelFromURI(makeURI(linkURL));
if (channel instanceof Ci.nsIPrivateBrowsingChannel) {
let docIsPrivate = PrivateBrowsingUtils.isWindowPrivate(doc.defaultView);
channel.setPrivate(docIsPrivate);
}
channel.notificationCallbacks = new callbacks();
let flags = Ci.nsIChannel.LOAD_CALL_CONTENT_SNIFFERS;
if (bypassCache)
flags |= Ci.nsIRequest.LOAD_BYPASS_CACHE;
if (channel instanceof Ci.nsICachingChannel)
flags |= Ci.nsICachingChannel.LOAD_BYPASS_LOCAL_CACHE_IF_BUSY;
channel.loadFlags |= flags;
if (channel instanceof Ci.nsIHttpChannel) {
channel.referrer = doc.documentURIObject;
if (channel instanceof Ci.nsIHttpChannelInternal)
channel.forceAllowThirdPartyCookie = true;
}
// fallback to the old way if we don't see the headers quickly
var timeToWait =
gPrefService.getIntPref("browser.download.saveLinkAsFilenameTimeout");
var timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
timer.initWithCallback(new timerCallback(), timeToWait,
timer.TYPE_ONE_SHOT);
// kick off the channel with our proxy object as the listener
channel.asyncOpen(new saveAsListener(), null);
}
