nsITraceableChannel確實是去這裏的路。 Jan Odvarko（softwareishard.com）和我自己（ashita.org）的博客文章展示瞭如何做到這一點。您可能也想看到http://www.ashita.org/implementing-an-xpcom-firefox-interface-and-creating-observers/，但是在XPCOM組件中執行此操作並不是必須的。
的步驟是基本上是：
- 創建對象原型實施nsITraceableChannel;創造觀察者監聽HTTP-ON-修改請求和HTTP-上審視響應
- 寄存器觀察者
- 觀察員聽兩個請求類型增加了我們的nsITraceableChannel對象到聽衆的鏈，並確保我們的nsITC知道誰是鏈
- nsITC對象提供三個回調和各會在適當的階段被稱爲下一個：onStartRequest，onDataAvailable和onStopRequest
- 在上述各回調，我們nsITC對象必須在數據傳遞到鏈中的下一個項目
下面是我寫的一個特定於站點的插件的實際代碼，其行爲與我所知道的非常類似。
function TracingListener() {
//this.receivedData = [];
}
TracingListener.prototype =
{
originalListener: null,
receivedData: null, // array for incoming data.
onDataAvailable: function(request, context, inputStream, offset, count)
{
var binaryInputStream = CCIN("@mozilla.org/binaryinputstream;1", "nsIBinaryInputStream");
var storageStream = CCIN("@mozilla.org/storagestream;1", "nsIStorageStream");
binaryInputStream.setInputStream(inputStream);
storageStream.init(8192, count, null);
var binaryOutputStream = CCIN("@mozilla.org/binaryoutputstream;1",
"nsIBinaryOutputStream");
binaryOutputStream.setOutputStream(storageStream.getOutputStream(0));
// Copy received data as they come.
var data = binaryInputStream.readBytes(count);
//var data = inputStream.readBytes(count);
this.receivedData.push(data);
binaryOutputStream.writeBytes(data, count);
this.originalListener.onDataAvailable(request, context,storageStream.newInputStream(0), offset, count);
},
onStartRequest: function(request, context) {
this.receivedData = [];
this.originalListener.onStartRequest(request, context);
},
onStopRequest: function(request, context, statusCode)
{
try
{
request.QueryInterface(Ci.nsIHttpChannel);
if (request.originalURI && piratequesting.baseURL == request.originalURI.prePath && request.originalURI.path.indexOf("/index.php?ajax=") == 0)
{
var data = null;
if (request.requestMethod.toLowerCase() == "post")
{
var postText = this.readPostTextFromRequest(request, context);
if (postText)
data = ((String)(postText)).parseQuery();
}
var date = Date.parse(request.getResponseHeader("Date"));
var responseSource = this.receivedData.join('');
//fix leading spaces bug
responseSource = responseSource.replace(/^\s+(\S[\s\S]+)/, "$1");
piratequesting.ProcessRawResponse(request.originalURI.spec, responseSource, date, data);
}
}
catch (e)
{
dumpError(e);
}
this.originalListener.onStopRequest(request, context, statusCode);
},
QueryInterface: function (aIID) {
if (aIID.equals(Ci.nsIStreamListener) ||
aIID.equals(Ci.nsISupports)) {
return this;
}
throw Components.results.NS_NOINTERFACE;
},
readPostTextFromRequest : function(request, context) {
try
{
var is = request.QueryInterface(Ci.nsIUploadChannel).uploadStream;
if (is)
{
var ss = is.QueryInterface(Ci.nsISeekableStream);
var prevOffset;
if (ss)
{
prevOffset = ss.tell();
ss.seek(Ci.nsISeekableStream.NS_SEEK_SET, 0);
}
// Read data from the stream..
var charset = "UTF-8";
var text = this.readFromStream(is, charset, true);
// Seek locks the file so, seek to the beginning only if necko hasn't read it yet,
// since necko doesn't seek to 0 before reading (at lest not till 459384 is fixed).
if (ss && prevOffset == 0)
ss.seek(Ci.nsISeekableStream.NS_SEEK_SET, 0);
return text;
}
else {
dump("Failed to Query Interface for upload stream.\n");
}
}
catch(exc)
{
dumpError(exc);
}
return null;
},
readFromStream : function(stream, charset, noClose) {
var sis = CCSV("@mozilla.org/binaryinputstream;1", "nsIBinaryInputStream");
sis.setInputStream(stream);
var segments = [];
for (var count = stream.available(); count; count = stream.available())
segments.push(sis.readBytes(count));
if (!noClose)
sis.close();
var text = segments.join("");
return text;
}
}
hRO = {
observe: function(request, aTopic, aData){
try {
if (typeof Cc == "undefined") {
var Cc = Components.classes;
}
if (typeof Ci == "undefined") {
var Ci = Components.interfaces;
}
if (aTopic == "http-on-examine-response") {
request.QueryInterface(Ci.nsIHttpChannel);
if (request.originalURI && piratequesting.baseURL == request.originalURI.prePath && request.originalURI.path.indexOf("/index.php?ajax=") == 0) {
var newListener = new TracingListener();
request.QueryInterface(Ci.nsITraceableChannel);
newListener.originalListener = request.setNewListener(newListener);
}
}
} catch (e) {
dump("\nhRO error: \n\tMessage: " + e.message + "\n\tFile: " + e.fileName + " line: " + e.lineNumber + "\n");
}
},
QueryInterface: function(aIID){
if (typeof Cc == "undefined") {
var Cc = Components.classes;
}
if (typeof Ci == "undefined") {
var Ci = Components.interfaces;
}
if (aIID.equals(Ci.nsIObserver) ||
aIID.equals(Ci.nsISupports)) {
return this;
}
throw Components.results.NS_NOINTERFACE;
},
};
var observerService = Cc["@mozilla.org/observer-service;1"]
.getService(Ci.nsIObserverService);
observerService.addObserver(hRO,
"http-on-examine-response", false);
在上面的代碼中，originalListener是我們在鏈中插入的偵聽器。在創建跟蹤監聽器並在所有三個回調中傳遞數據時保持該信息至關重要。否則什麼都不會起作用（頁面甚至不會加載，Firefox本身是鏈中的最後一個）。
注：有一些函數調用上面代碼中的哪些是piratequesting附加的部分，例如：parseQuery()和dumpError()
主題給你一個錯誤的想法，也許。我不在尋找現有的解決方案。請閱讀完整的問題。謝謝:) – Jumper 2010-01-26 18:33:21
@跳線，篡改數據可能是一個很好的基礎，開始建立你的附加。您必須撕掉大部分UI代碼，但您需要監控和更改XHR請求的代碼將位於該代碼中。 – 2010-01-26 19:15:20
是的，在過去有一個粗略的看。它似乎使用觀察者服務。問題中的鏈接（即關於nsITraceableChannel的討論）也使用Observer。 今天再看看tamperData代碼。 – Jumper 2010-01-27 07:13:17