用 Progress Listener下载二进制文件

用自定义progress listener下载二进制文件:

var persist = Components.classes["@mozilla.org/embedding/browser/nsWebBrowserPersist;1"]
.createInstance(Components.interfaces.nsIWebBrowserPersist);
var file = Components.classes["@mozilla.org/file/local;1"]
.createInstance(Components.interfaces.nsILocalFile);
file.initWithPath("C:\\a\\path\\file.bin"); // 下载目的地
var obj_URI = Components.classes["@mozilla.org/network/io-service;1"]
.getService(Components.interfaces.nsIIOService)
.newURI(aURLToDownload, null, null);
persist.progressListener = {
onProgressChange: function(aWebProgress, aRequest, aCurSelfProgress, aMaxSelfProgress, aCurTotalProgress, aMaxTotalProgress) {
var percentComplete = (aCurTotalProgress/aMaxTotalProgress)*100;
var ele = document.getElementById("progress_element");
ele.innerHTML = percentComplete +"%";
},
onStateChange: function(aWebProgress, aRequest, aStatus, aMessage) {
// do something
}
}
persist.saveURI(obj_URI, null, null, null, "", file);

下载需要认证的文件

在调用nsIWebBrowserPersist.saveURI()前, 你需要设置 nsIWebBrowserPersist 实例的progressListener属性为 nsIAuthPrompt对象 。通常, nsIAuthPrompt 会期待显示一个提示框让用户输入认证信息, 但你可以直接返回用户名和密码而不提示用户. 如果你想打开一个登陆提示框，你能调用window watcher的 getNewAuthPrompter()方法。

TODO: 此代码需要测试

var persist = Components.classes["@mozilla.org/embedding/browser/nsWebBrowserPersist;1"].
createInstance(Components.interfaces.nsIWebBrowserPersist);
var hardCodedUserName = "ericjung";
var hardCodedPassword = "foobar";
persist.progressListener = {
// implements nsIAuthPrompt
prompt: function(dialogTitle, text, passwordRealm, savePassword, defaultText, result) {
result.value = hardCodedPassword;
return true;
},
promptPassword: function(dialogTitle, text, passwordRealm, savePassword, pwd) {
pwd.value = hardCodedPassword;
return true;
},
promptUsernameAndPassword: function(dialogTitle, text, passwordRealm, savePassword, user, pwd) {
user.value = hardCodedUserName;
pwd.value = hardCodedPassword;
return true;
}
};
persist.saveURI(urlToFile, null, null, null, "", nsFileInstance);

下载图片

从一个URL下载图片的简单函数。

// 接受一个URL，返回文件
// 如果文件没找到（404错误）返回empty.
//试试 .jpg, .ico, .gif (甚至 .html).

function GetImageFromURL(url) {
var ioserv = Components.classes["@mozilla.org/network/io-service;1"]
.getService(Components.interfaces.nsIIOService);
var channel = ioserv.newChannel(url, 0, null);
var stream = channel.open();

if (channel instanceof Components.interfaces.nsIHttpChannel && channel.responseStatus != 200) {
return "";
}

var bstream = Components.classes["@mozilla.org/binaryinputstream;1"]
.createInstance(Components.interfaces.nsIBinaryInputStream);
bstream.setInputStream(stream);

var size = 0;
var file_data = "";
while(size = bstream.available()) {
file_data += bstream.readBytes(size);
}

return file_data;
}

下载观测器

Sample download observer for Firefox 2 Download manager.

// ******************************
// DownloadObserver
// ******************************
function sampleDownload_init(){
//**** Add download observer
var observerService = Components.classes["@mozilla.org/observer-service;1"]
.getService(Components.interfaces.nsIObserverService);
observerService.addObserver(sampleDownloadObserver, "dl-start", false);
observerService.addObserver(sampleDownloadObserver, "dl-done", false);
observerService.addObserver(sampleDownloadObserver, "dl-cancel", false);
observerService.addObserver(sampleDownloadObserver, "dl-failed", false);

window.addEventListener("unload", function() {
observerService.removeObserver(sampleDownloadObserver, "dl-start");
observerService.removeObserver(sampleDownloadObserver, "dl-done");
observerService.removeObserver(sampleDownloadObserver, "dl-cancel");
observerService.removeObserver(sampleDownloadObserver, "dl-failed");
}, false);
}
var sampleDownloadObserver = {
observe: function (subject, topic, state) {
var oDownload = subject.QueryInterface(Components.interfaces.nsIDownload);
//**** Get Download file object
var oFile = null;
try{
oFile = oDownload.targetFile; // New firefox 0.9+
} catch (e){
oFile = oDownload.target; // Old firefox 0.8
}
//**** Download Start
if (topic == "dl-start"){
alert('Start download to - '+oFile.path);
}
//**** Download Cancel
if(topic == "dl-cancel"){
alert('Canceled download to - '+oFile.path);
}
//**** Download Failed
else if(topic == "dl-failed"){
alert('Failed download to - '+oFile.path);
}
//**** Download Successs
else if(topic == "dl-done"){
alert('Done download to - '+oFile.path);
}
}
}
window.addEventListener("load", sampleDownload_init, false);

得到特别的文件

// 得到profile目录
var file = Components.classes["@mozilla.org/file/directory_service;1"].
getService(Components.interfaces.nsIProperties).
get("ProfD", Components.interfaces.nsIFile);

// NOTE: "file" nsIFile的实例对象. 如果要得到文件系统路径,用file.path
可以放在 "ProfD" 位置的字符串:

其它可用的字符串去查源代码: xpcom/io/nsAppDirectoryServiceDefs.h , xpcom/io/nsDirectoryServiceDefs.h .

创建文件夹

创建一个文件夹,用 nsIFile.create():

var file = Components.classes["@mozilla.org/file/directory_service;1"].
getService(Components.interfaces.nsIProperties).
get("ProfD", Components.interfaces.nsIFile);
file.append("DIR");
if( !file.exists() || !file.isDirectory() ) { // if it doesn't exist, create
file.create(Components.interfaces.nsIFile.DIRECTORY_TYPE, 0777);
}
在Profile文件夹创建目录"DIR". 更多信息参见 nsIFile.create reference.

创建临时文件

用nsIFile.createUnique():

var file = Components.classes["@mozilla.org/file/directory_service;1"].
getService(Components.interfaces.nsIProperties).
get("TmpD", Components.interfaces.nsIFile);
file.append("suggestedName.tmp");
file.createUnique(Components.interfaces.nsIFile.NORMAL_FILE_TYPE, 0666);
// do whatever you need to the created file
alert(file.path);

用户由nsIFilePicker输入

The file picker component (nsIFilePicker) 可以用来打开标准的打开/保存对话框. 返回用户指定的文件 nsIFile.

nsIFile和路径字符串

你能用nsIFile.path得到特定平台的路径字符串, e.g. "C:\Windows\System32" or "/usr/share".

得到一个文件的URL，用 nsIIOService#newFileURI():

// file is nsIFile
var ios = Components.classes["@mozilla.org/network/io-service;1"].
getService(Components.interfaces.nsIIOService);
var URL = ios.newFileURI(file);
// URL是nsIURI;得到字符串, "file://...", 用URL.spec

从 'file://' URL得到nsIFile,用 nsIFileURL:

var file = URL.QueryInterface(Components.interfaces.nsIFileURL).file;
// file is now a nsIFile

从file://, http://, chrome://, resource:// 和其它 URLs直接载入, 用 XMLHttpRequest 或 nsIChannel (example).

Also note that generally you don't need to use nsIFile::path. Use nsIFile directly wherever possible. An example below shows how you should save a path in user prefs.

存储nsILocalFile到preferences

下面2个片段展示了存储文件路径到用户preferences的正确方式 (more about preferences in Mozilla):

用nsIFile浏览

读一个文件

写文件

// file is nsIFile, data is a string
var foStream = Components.classes["@mozilla.org/network/file-output-stream;1"].
createInstance(Components.interfaces.nsIFileOutputStream);

// use 0x02 | 0x10 to open file for appending.
foStream.init(file, 0x02 | 0x08 | 0x20, 0666, 0);
// write, create, truncate
// In a c file operation, we have no need to set file mode with or operation,
// directly using "r" or "w" usually.

// 如果你确信数据中永远不会有非ASCII数据，你也可以直接执行foStream.writeData
var converter = Components.classes["@mozilla.org/intl/converter-output-stream;1"].
createInstance(Components.interfaces.nsIConverterOutputStream);
converter.init(foStream, "UTF-8", 0, 0);
converter.writeString(data);
converter.close(); // this closes foStream