phonegap (2.8.1) 上 FileWriter 的奇怪问题。每当我尝试使用 filewriter 写入文件时,都会创建一个文件,但文件中唯一的内容是一行显示 {"type":"application/pdf","size":235577}。任何文件都一样 - 类型和大小不同,但这是写入文件的唯一内容。
我使用 Chrome 版本 28 运行相同的代码,它工作得很好,但使用 Blob 而不是 WebKitBlobBuilder。所以我下载了一个旧版本的 Chromium(版本 20),它使用了 WebKitBlobBuilder 并且运行良好。
为了检查我是否在做一些奇怪的事情,我在尝试写入文件之前使用 FileReader 转储文件的内容(使用 readAsDataURL) - 内容看起来不错。
所以...?
代码如下:
function convert2blob(bin, type){
// takes a BINARY or a BLOB input and returns a blob
var blob;
if (bin.size? true: false) {
console.log("its a blob already"); // do nothing?? Line 3494
blob = bin;
} else {
var arr = new Uint8Array(bin.length);
for (var i = 0; i < length; i++) {
arr[i] = bin.charCodeAt(i) & 0xff;
}
var bl = new window.BlobBuilder();
bl.append(arr.buffer);
blob = bl.getBlob(type);
}
return blob;
}
blob = convert2blob(resx, attinfo.contenttype);
console.log(blob.size); // Line 3543
// just to verify the contents of the blob
// tested with fileReader - contents are valid
/* // just to check the file contents
var rdr = new FileReader();
rdr.onloadend = function(evt){
console.log(evt.target.result.slice(0,128));
};
rdr.readAsDataURL(blob);
*/
// its a blob - that's what we decided
global.tmpFilesystem.root.getFile(attinfo.name, { create: true }, function (fileEntry) {
console.log(fileEntry);
fileEntry.createWriter(function (fileWriter) {
console.log(fileWriter);
fileWriter.onwriteend = function (e) {
console.log(e.error); // Line 3582
console.log("finished writing"); // Line 3583
console.log(e.target.length); // Line 3584
runpopup(selectorid, fileEntry.toURL());
};
fileWriter.onerror = function(e) {
console.log(e);
};
fileWriter.write(blob);
}, function(e) {
console.log(e);
});
}, function(e) {
console.log(JSON.stringify(e));
});
Logcat 输出如下所示:
I/Web Console(19696): {"encoding":null,"name":"005.jpg","fullPath":"005.jpg","contenttype":"image/jpeg"}:3521
I/Web Console(19696): /9j/4AAQSkZJRgABAQEAYABgAAD/2wBDAAEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQH/2wBDAQEB:5236
I/Web Console(19696): 516857:5240
I/Web Console(19696): using WebKitBlobBuilder:5246
I/Web Console(19696): 516857:5250
// above few lines are after fetching from Websql DB
I/Web Console(19696): [object Blob]:3541
I/Web Console(19696): its a blob already:3494
I/Web Console(19696): 516857:3543
I/Web Console(19696): [object Object]:3560
I/Web Console(19696): [object Object]:3580
I/Web Console(19696): undefined:3582
I/Web Console(19696): finished writing:3583
I/Web Console(19696): 36:3584
使用浏览器输出更新 ============= Chromium 20 的可比输出:
{"encoding":null,"fullPath":"closed-padlock.png","name":"closed-padlock.png","doc_id":"FE261266-B04C-48F3-8557-7FCF160E7F9F","contenttype":"image/png"} - :3521
iVBORw0KGgoAAAANSUhEUgAAAS4AAAHXCAYAAAAC3beSAAAABmJLR0QA/wD/AP+gvaeTAAAXWElEQVR4nO3debDVdf3H8de9XJZAsACX1CwNwWVSGhfck2LMTEzDpazB - :5236
6051 - :5240
using WebKitBlobBuilder - :5246
6051 - :5250
Blob - :3541
its a blob already - :3494
6051 - :3543
FileEntry - :3560
FileWriter - :3580
undefined - :3582
finished writing - :3583
6051 - :3584
filesystem:file:///temporary/closed-padlock.png