如何使用OS.File将图像下载到桌面 [英] How to download image to desktop with OS.File

问题描述

我有一个位于网络上的图像。例如： https://www.gravatar.com/avatar/eb9895ade1bd6627e054429d1e1​​8b576?s=24&d=identicon&r=PG&f=1

我想下载这个文件到我的硬盘上。

我尝试了这个，但它没有工作：在这里我XHR它并请求数据类型arraybuffer，然后当我尝试写入OS.File我得到这个错误： TypeError：Value [对象ArrayBuffer]不能转换为一个指针osfile_shared_allthreads.jsm：443

  var {Cu：utils，Cc：classes，Ci：instances} =组件; 
 Cu.import（'resource：//gre/modules/Services.jsm'）; 
函数xhr（url，cb）{
 let xhr = Cc [@ mozilla.org/xmlextras/xmlhttprequest;1\"].createInstance(Ci.nsIXMLHttpRequest）; 
 
 let handler = ev => {
 evf（m => xhr.removeEventListener（m，handler，！1））; 
 switch（ev.type）{
 case'load'：
 if（xhr.status == 200）{
 cb（xhr.response）; 
 break; 
 
默认：
 Services.prompt.alert（null，'XHR Error'，'Error Fetching Package：'+ xhr.statusText +'['+ ev.type +'：' + xhr.status +']'）; 
 break; 
} 
}; 
 
 let evf = f => ['load'，'error'，'abort']。forEach（f）; 
 evf（m => xhr.addEventListener（m，handler，false））; 
 
 xhr.mozBackgroundRequest = true; 
 xhr.open（'GET'，url，true）; 
 xhr.channel.loadFlags | = Ci.nsIRequest.LOAD_ANONYMOUS | Ci.nsIRequest.LOAD_BYPASS_CACHE | Ci.nsIRequest.INHIBIT_PERSISTENT_CACHING; 
 xhr.responseType =arraybuffer; //不设置它，所以它返回字符串，你不想要arraybuffer。你只需要这个，如果你的网址是一个zip文件或者一些你想下载的文件，并且把一个nsIArrayBufferInputStream从它或者某个地方取出来的话
 xhr.send（null）; 
} 
 
 xhr（'https://www.gravatar.com/avatar/eb9895ade1bd6627e054429d1e1​​8b576?s=24&d=identicon&r=PG&f=1'，data => ; {
 Services.prompt.alert（null，'XHR Success'，data）; 
 var file = OS.Path.join（OS.Constants.Path.desktopDir，test.png）; 
 var promised = OS.File.writeAtomic（file，data）; 
 promised.then（
 function（）{
 alert（'成功保存的图像到桌面'）
 $ b（$）
 alert（'将图像保存到桌面失败'）
} 
）; 
}）; 
  

解决方案

href =https://stackoverflow.com/a/25112976/3791822> https://stackoverflow.com/a/25112976/3791822

而另一半来自@ nmaier的解决方案在这里： https://stackoverflow.com/a/25148685/3791822

非常好;）

哈哈无论如何，你真的很接近。你得到了 ArrayBuffer ，但是把它作为 Uint8Array 传递给它：

< （$ file $ new $ U $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $不知道这是下载它的最好方法。但它看起来几乎是100％异步。也许这是最好的方法。真正的酷男！

I have an image located on the web. For example: https://www.gravatar.com/avatar/eb9895ade1bd6627e054429d1e18b576?s=24&d=identicon&r=PG&f=1

I would like to download this to a folder on my hd.

I tried this but it didnt work: Here I XHR it and request datatype arraybuffer, then when i try to write it with OS.File I get this error: TypeError: Value [object ArrayBuffer] cannot be converted to a pointer osfile_shared_allthreads.jsm:443

var {Cu: utils, Cc: classes, Ci: instances} = Components;
Cu.import('resource://gre/modules/Services.jsm');
function xhr(url, cb) {
    let xhr = Cc["@mozilla.org/xmlextras/xmlhttprequest;1"].createInstance(Ci.nsIXMLHttpRequest);

    let handler = ev => {
        evf(m => xhr.removeEventListener(m, handler, !1));
        switch (ev.type) {
            case 'load':
                if (xhr.status == 200) {
                    cb(xhr.response);
                    break;
                }
            default:
                Services.prompt.alert(null, 'XHR Error', 'Error Fetching Package: ' + xhr.statusText + ' [' + ev.type + ':' + xhr.status + ']');
                break;
        }
    };

    let evf = f => ['load', 'error', 'abort'].forEach(f);
    evf(m => xhr.addEventListener(m, handler, false));

    xhr.mozBackgroundRequest = true;
    xhr.open('GET', url, true);
    xhr.channel.loadFlags |= Ci.nsIRequest.LOAD_ANONYMOUS | Ci.nsIRequest.LOAD_BYPASS_CACHE | Ci.nsIRequest.INHIBIT_PERSISTENT_CACHING;
    xhr.responseType = "arraybuffer"; //dont set it, so it returns string, you dont want arraybuffer. you only want this if your url is to a zip file or some file you want to download and make a nsIArrayBufferInputStream out of it or something
    xhr.send(null);
}

xhr('https://www.gravatar.com/avatar/eb9895ade1bd6627e054429d1e18b576?s=24&d=identicon&r=PG&f=1', data => {
    Services.prompt.alert(null, 'XHR Success', data);
    var file = OS.Path.join(OS.Constants.Path.desktopDir, "test.png");
    var promised = OS.File.writeAtomic(file, data);
    promised.then(
        function() {
            alert('succesfully saved image to desktop')
        },
        function(ex) {
             alert('FAILED in saving image to desktop')
        }
    );
});

解决方案

You stole half that from my solution here: https://stackoverflow.com/a/25112976/3791822

And the other half from @nmaier's solution here: https://stackoverflow.com/a/25148685/3791822

Very nice ;)

Haha anyways you are real close. You got the ArrayBuffer but pass it as Uint8Array so:

var promised = OS.File.writeAtomic(file, new Uint8Array(data));

I don't know if this is the best way to download it. But it looks almost 100% async. Maybe it is the best way. Real cool man!

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