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如何在Firefox擴展中更改HTTP響應正文？我使用下面的代碼設置了一個http-on-examine-response觀察者和一個nsIStreamListener對象。獲取數據，解析並修改數據後，如何將更改的響應返回給Firefox瀏覽器？例如，假設我在啓用了我的擴展程序的情況下訪問Google.com，擴展程序應攔截響應並將每次發生的「谷歌」更改爲「護目鏡」。所以當頁面加載時，用戶會在任何地方看到「護目鏡」。在Firefox擴展中更改HTTP響應
function TmSteroidsObserver()
{
this.register();
}
TmSteroidsObserver.prototype = {
observe: function(subject, topic, data) {
if (topic == "http-on-examine-response") {
}
else if (topic == "http-on-modify-request") {
var channel = subject.QueryInterface(Components.interfaces.nsIChannel);
var listener = new StreamListener(channel);
}
},
register: function() {
var observerService = Components.classes["@mozilla.org/observer-service;1"]
.getService(Components.interfaces.nsIObserverService);
observerService.addObserver(listener, "http-on-modify-request", false);
observerService.addObserver(listener, "http-on-examine-response", false);
},
unregister: function() {
var observerService = Components.classes["@mozilla.org/observer-service;1"]
.getService(Components.interfaces.nsIObserverService);
observerService.removeObserver(this, "http-on-modify-request");
observerService.removeObserver(this, "http-on-examine-response");
},
QueryInterface : function(aIID) {
if (aIID.equals(Components.interfaces.nsISupports) ||
aIID.equals(Components.interfaces.nsIObserver))
return this;
throw Components.results.NS_NOINTERFACE;
}
}
function StreamListener(channel) {
channel.notificationCallbacks = listener;
channel.asyncOpen(listener, null);
}
StreamListener.prototype = {
mData: "",
mChannel: null,
// nsIStreamListener
onStartRequest: function (aRequest, aContext) {
this.mData = "";
},
onDataAvailable: function (aRequest, aContext, aStream, aSourceOffset, aLength) {
var scriptableInputStream =
Components.classes["@mozilla.org/scriptableinputstream;1"]
.createInstance(Components.interfaces.nsIScriptableInputStream);
scriptableInputStream.init(aStream);
this.mData += scriptableInputStream.read(aLength);
},
onStopRequest: function (aRequest, aContext, aStatus) {
if (Components.isSuccessCode(aStatus)) {
// request was successfull
this.mCallbackFunc(this.mData);
} else {
// request failed
this.mCallbackFunc(null);
}
this.mChannel = null;
},
// nsIChannelEventSink
onChannelRedirect: function (aOldChannel, aNewChannel, aFlags) {
// if redirecting, store the new channel
this.mChannel = aNewChannel;
},
// nsIInterfaceRequestor
getInterface: function (aIID) {
try {
return this.QueryInterface(aIID);
} catch (e) {
throw Components.results.NS_NOINTERFACE;
}
},
// nsIProgressEventSink (not implementing will cause annoying exceptions)
onProgress : function (aRequest, aContext, aProgress, aProgressMax) { },
onStatus : function (aRequest, aContext, aStatus, aStatusArg) { },
// nsIHttpEventSink (not implementing will cause annoying exceptions)
onRedirect : function (aOldChannel, aNewChannel) { },
// we are faking an XPCOM interface, so we need to implement QI
QueryInterface : function(aIID) {
if (aIID.equals(Components.interfaces.nsISupports) ||
aIID.equals(Components.interfaces.nsIInterfaceRequestor) ||
aIID.equals(Components.interfaces.nsIChannelEventSink) ||
aIID.equals(Components.interfaces.nsIProgressEventSink) ||
aIID.equals(Components.interfaces.nsIHttpEventSink) ||
aIID.equals(Components.interfaces.nsIStreamListener))
return this;
throw Components.results.NS_NOINTERFACE;
}
};