如何从Firefox附加SDK扩展程序启动正常下载 [英] How to launch a normal download from a Firefox Add-on SDK extension
本文介绍了如何从Firefox附加SDK扩展程序启动正常下载的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我正在为Firefox开发附加SDK扩展.我发现我需要能够像用户请求的那样启动下载，即显示正常的文件保存对话框或将文件保存到用户喜欢的任何地方，因为可以在首选项>内容下对其进行配置. /p>
关于下载的每个帖子或文档似乎都只考虑了我知道从哪里下载文件的情况，但是在这种情况下，这不是我所需要的.在这种情况下，必须就像用户开始下载一样.
如何才能做到这一点，最好通过SDK的方法完成?
解决方案
好吧，您可以直接进行实际保存.
从您的代码中启动保存链接:
在上下文菜单中，oncommand值为gContextMenu.saveLink();. saveLink()在以下位置定义: chrome://browser/content/nsContextMenu.js .它会做一些内务处理，然后调用 saveHelper()，在同一文件中定义.您可以只使用适当的参数调用saveHelper().它包含在 chrome://browser/content/web-panels.xul的面板中与:
<script type="application/javascript"
src="chrome://browser/content/nsContextMenu.js"/>
然后在中声明的gContextMenu变量chrome://browser/content/browser.js 作为null被分配:
gContextMenu = new nsContextMenu(this, event.shiftKey);
在上下文菜单的onpopupshowing事件处理程序中.它返回到:
'gContextMenu = null;'
在onpopuphiding事件处理程序中.
如果要在自己的代码中使用它，可以执行以下操作:
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);
替代使用loadSubScript加载nsContextMenu.js:
我的偏好是使用loadSubScript从nsContextMenu.js加载saveHelper代码.这样可以使代码保持最新，并在将来的Firefox版本中进行任何更改.但是，它引入了您正在使用非官方API中的函数的依赖关系.因此，它可能会在将来的Firefox版本中以某种方式更改，并且需要更改您的加载项.另一种方法是在扩展名中复制saveHelper()代码.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);
}
I'm developing an Add-on SDK extension for Firefox. I find that I need to be able to launch a download as if the user requested it, that is, either showing the normal file save dialog or saving the file to wherever the user prefers, as it could be configured under preferences > content.
Every single post or documentation regarding downloads seem to only take in consideration the scenario where I know where to download the file, but that is not what I need in this case. In this case, it needs to be as if the user started the download.
How can this be accomplished, preferably via the methods of the SDK?
解决方案
Well, you could just initiate an actual save.
Initiating a save link from your code:
In the context menu the oncommand value is gContextMenu.saveLink();. saveLink() is defined in: chrome://browser/content/nsContextMenu.js. It does some housekeeping and then calls saveHelper() which is defined in the same file. You could just call saveHelper() with appropriate arguments. It is included in panels from chrome://browser/content/web-panels.xul with:
<script type="application/javascript"
src="chrome://browser/content/nsContextMenu.js"/>
Then the gContextMenu variable declared in chrome://browser/content/browser.js as null is assigned:
gContextMenu = new nsContextMenu(this, event.shiftKey);
in the onpopupshowing event handler for context menus. It is returned to:
'gContextMenu = null;'
in the onpopuphiding event handler.
If you want to use it in your own code you can do:
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);
Alternative to using loadSubScript to load nsContextMenu.js:
My preference is to use loadSubScript to load the saveHelper code from nsContextMenu.js. This keeps the code up to date with any changes which are made in future Firefox releases. However, it introduces the dependency that you are using a function from a non-official API. Thus, it might change in some way in future Firefox release and require changes in your add-on. The alternative is to duplicate the saveHelper() code in your extension. It is defined as the following:
// 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);
}
这篇关于如何从Firefox附加SDK扩展程序启动正常下载的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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