这是读取文件选择器选取的文件内容的正确方法吗?我需要读取图像数据,以便将其发送到我的 Windows Metro Javascript 应用程序中的 Web 服务。我使用带有回调的 readFile 函数,该回调返回 evt 参数,然后使用encodeURIComponent(evt.target.result):
document.getElementById("btnUpload").onclick = function () {
var input = document.getElementById("file_input");
readFile(input.files[0], function(file, evt)
{
WinJS.xhr({
type: "post",
url: "http://servlett.domain.com:8080/Servlet/addImage",
headers: { "Content-type": "application/x-www-form-urlencoded" },
data: "fk_floor_id=" + currentFloorId + "&map=" + encodeURIComponent(evt.target.result)
}).then(
function (xhr) {
var success = xhr.response;
}, function (xhr) {
var error = xhr.response;
}
);
});
参数evt.target.result通过以下方法获取:
function readFile(file, callback) {
var reader = new FileReader();
reader.onload = function (evt) {
if (typeof callback == "function")
callback(file, evt);
};
reader.readAsText(file);
}
其中 file_input 是以下表单内的输入组件:
<form action="" method="post">
<input type="file" id="file_input" />
<button type="button" id="btnUpload">Upload</button>
</form>
提前致谢。
最佳答案
更好的解决方案是:
var picker = new Windows.Storage.Pickers.FileOpenPicker();
picker.fileTypeFilter.replaceAll([".jpg", ".bmp", ".gif", ".png"]);
picker.pickSingleFileAsync().then(progressResults, displayError);
function progressResults(file) {
file.openAsync(Windows.Storage.FileAccessMode.read).done(function (stream) {
var inputStream = stream.getInputStreamAt(0);
var reader = new Windows.Storage.Streams.DataReader(inputStream);
var size = stream.size;
if (size > 0) {
reader.loadAsync(size).then(function () {
var b = reader.readBuffer(size);
var s = Windows.Security.Cryptography.CryptographicBuffer.encodeToBase64String(b);
var xhrOptions = {
type: 'post',
url: "http://servlet.domain.com:8080/Servlet/addImage",
headers: { "Content-type": "application/x-www-form-urlencoded" },
data: "fk_floor_id=" + currentFloorId + "&map=" + s
}
WinJS.xhr(xhrOptions);
});
});
关于javascript - 在 Windows Metro javascript 应用程序中读取文件,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/20225629/