How do I enable UniversalXPConnect for a particular web page?_问答_开发者

I need to test various web services which are posts that take an uploaded file as the content of the body. To do this I'd like to do quick tests using ajax call. I found the following page which describes how to do this: http://www.captain.at/ajax-file-upload.php However, it requires that the page have "UniversalXPConnect" privileges in firefox.

How do I enable that privilege? I tried editing prefs.js and adding:

user_pref("capability.principal.foo.id", "http://localhost:8080/access/index.html");
user_pref("capability.principal.foo.granted", "UniversalXPConnect");

which should give access to the page开发者_高级运维 http://localhost:8080/access/index.html. But, it doesn't seem to work.

Improving on panzi's answer, you can use the FormData object to send files with Ajax in a very simple manner:

<html>
<head>
<title>HTML5 File API</title>
</head>
<script type="text/javascript">
// <!--
// See: https://developer.mozilla.org/En/XMLHttpRequest/Using_XMLHttpRequest#Using_FormData_objects
function upload() {
    var uploadRequest = new XMLHttpRequest,
        uploadForm = document.getElementById('file_upload');

    function transferProgress(progressEvent) {
    /*Executes For each update of the progress of the Ajax transfer.*/
        // show progress bar or something....
    }
    function transferComplete() {
    /*Executes when the transfer is complete.*/
        //Do something like show a nice message...
    }
    function transferFailed() {
    /*Executes when the transfer fails.*/
        alert('Upload failed!');
    }
    function transferCanceled() {
    /*Executes when the transfer is canceled.*/
        alert('Upload canceled!');
    }

    uploadRequest.upload.addEventListener('progress', transferProgress, false);
    //uploadRequest.upload.addEventListener('load', transferComplete, false); // transfer complete, but this doesn't mean a response from the server has been received.
    uploadRequest.addEventListener('load', transferComplete, false); // ajax request complete, response from the server has been received and all has been processed.
    uploadRequest.upload.addEventListener('error', transferFailed, false);
    uploadRequest.upload.addEventListener('abort', transferCanceled, false);

    uploadRequest.open('POST', action, true);
    uploadRequest.send(new FormData(uploadForm));
}
// -->
</script>
<body>
<form id="file_upload" enctype="multipart/form-data">
    <input type="text" id="text" value="blah blah blah"/>
    <input type="file" onchange="upload();"/>
</form>
</body>
</html>

If the user specifies the file you don't need UniversalXPConnect. The HTML5 File API is enough:

<html>
<head>
<title>HTML5 File API</title>
</head>
<script type="text/javascript">
// <!--
// See: http://dev.w3.org/2006/webapi/FileAPI/

function upload (input) {
    for (var i = 0; i < input.files.length; ++ i) {
        // makes multiple uploads
        uploadFile(input.files[i]);
    }
}

function uploadFile (file) {
    var reader = new FileReader();
    reader.onprogress = function (event) {
        var percent = 100 * event.loaded / event.total;
        // TODO: display progress
    };

    reader.onerror = function (event) {
        // display error
        alert(errorMessage(reader.error)+': '+file.name);
    };

    reader.onload = function (event) {
        if (reader.error) {
            // display error
            alert(errorMessage(reader.error)+': '+file.name);
        }
        else {
            // You could also use reader.readAsBinaryString(file)
            // and the mozilla specific function call btoa(reader.result).
            // For more mozilla specific stuff (e.g. sending data as binary)
            // see: https://developer.mozilla.org/en/using_xmlhttprequest
            var data = reader.result.substring(reader.result.search(',')+1);
            var text = document.getElementById('text').value;
            var request = new XMLHttpRequest();
            var boundaryString = guid();
            var boundary = '--' + boundaryString;

            while (text.search(boundary) != -1) {
                boundaryString = guid();
                boundary = '--' + boundaryString;
            }

            var requestbody = boundary + '\n' +
                'Content-Disposition: form-data; name="mytext"\n' +
                '\n' +
                text +
                '\n' +
                boundary + '\n' +
                'Content-Disposition: form-data; name="myfile"; filename="' +
                file.name.replace(/"/g, '') + '"\n' +
                'Content-Type: application/octet-stream\n' +
                'Content-Transfer-Encoding: base64\n' +
                '\n' +
                data + '\n' +
                boundary;

            request.onreadystatechange = function () {
                if (request.readyState == 4) {
                    if (request.status == 200) {
                        alert('Result: ' + request.responseText);
                    }
                    else {
                        alert(
                            'Error "' + request.statusText + '" occured while uploading: ' +
                            file.name);
                    }
                }
            };

            /* a non-standard variant (still supported by many browsers) would be:
            request.onuploadprogress = function () {
                // possibly only mozilla, but awesome! upload progress!
                var percent = 100 * event.loaded / event.total;
                // TODO: display progress
            };

            request.onload = function () {
                if (request.status == 200) {
                    alert('Result: ' + request.responseText);
                }
                else {
                    alert(
                        'Error "' + request.statusText + '" occured while uploading: ' +
                        file.name);
                }
            };

            request.onerror = function () {
                alert(
                    'There was a problem with the request when uploading file: ' +
                    file.name);
            };
            */

            request.open('POST', 'post.php', true);
            request.setRequestHeader('Content-type', 'multipart/form-data; boundary="' +
                boundaryString + '"');
            request.setRequestHeader('Connection', 'close');
            request.setRequestHeader('Content-Length', requestbody.length);
            request.send(requestbody);

        }
    };

    reader.readAsDataURL(file);

    // there would also be:
    // reader.readAsBinaryString(file);
    // reader.readAsText(file, 'UTF-8');
    // reader.readAsArrayBuffer(file);
}

function errorMessage (error) {
    switch (error.code) {
        case FileError.ABORT_ERR:
            return 'Aborted';

        case FileError.ENCODING_ERR:
            return 'Encoding Error';

        case FileError.NOT_FOUND_ERR:
            return 'File not found';

        case FileError.NOT_READABLE_ERR:
            return 'File is not readable';

        case FileError.NO_MODIFICATION_ALLOWED_ERR:
            return 'File is not writeable';

        case FileError.SECURITY_ERR:
            return 'Security Error';

        default:
            return 'Unknown error code: ' + error.code;
    }
}

// from: https://stackoverflow.com/questions/105034/how-to-create-a-guid-uuid-in-javascript
function S4() {
    return (((1+Math.random())*0x10000)|0).toString(16).substring(1);
}

function guid() {
    return (S4()+S4()+"-"+S4()+"-"+S4()+"-"+S4()+"-"+S4()+S4()+S4());
}

// -->
</script>
<body>
<input type="text" id="text" value="My text.."/>
<input type="file" onchange="upload(this);"/>
</body>
</html>

Still, I would recommend to use an iframe, because it is best supported by all browsers: Is it possible to use Ajax to do file upload?