Cordova fileReader适用于文本，但对于jpgs返回null

Question

I'm using an emulation of an android nexus 9 for testing.

I run this code for text, and it works:

var filePath = cordova.file.dataDirectory + "files/newFile.txt";
window.resolveLocalFileSystemURL(filePath, gotFileEntry, fail);

function gotFileEntry(fileEntry) {
    console.log("gotFileEntry: "+fileEntry.name); //"newFile.txt"
    console.log("fileEntry fullpath: "+fileEntry.fullPath); //"/newFile.txt" - cause for concern?
    fileEntry.file(gotFile, fail);
}

function gotFile(file){
    console.log("Got the File");
    console.log("Type: " + file.type); //text/plain
    console.log("Path: " + file.fullPath); //undefined
    //path wasn't defined, manually set it
    file.fullPath = fullPath = cordova.file.dataDirectory + 'files/' + file.name;
    console.log("Path: " + file.fullPath); //"file:///data/data/com.ionicframework.myproject123456/files/files/newFile.txt"
    console.log("Bytes: " + file.size); //~14 bytes

    var reader = new FileReader();
    reader.onloadend = function(evt) {
        console.log('Reader status "onloadend": '+reader.readyState); //2 (a.k.a loaded)
        console.log('Result: '+evt.target.result); //"data:text/plain;base64,c26tZSBmaWx1IGrhdGE=" (success)
        console.log('Result: '+reader.result); //"data:text/plain;base64,c26tZSBmaWx1IGrhdGE=" (success)
    };
    reader.onerror = function(e) {
        console.log('Error.code: '+reader.error.code) //unused
        console.log('Error.message: '+reader.error.message) //unused
    }
    console.log("Reader status before: "+reader.readyState); //0
    reader.readAsDataURL(file);
    console.log("Reader status after: "+reader.readyState); //1
}

So I switch it to try and use the picture. Same code, switching "newFile.txt" for "mypicture.jpg":

var filePath = cordova.file.dataDirectory + "files/mypicture.jpg";
window.resolveLocalFileSystemURL(filePath, gotFileEntry, fail);

function gotFileEntry(fileEntry) {
    console.log("gotFileEntry: "+fileEntry.name); //"mypicture.jpg"
    console.log("fileEntry fullpath: "+fileEntry.fullPath); //"/mypicture.jpg" - cause for concern?
    fileEntry.file(gotFile, fail);
}

function gotFile(file){
    console.log("Got the File");
    console.log("Type: " + file.type); //image/jpeg
    console.log("Path: " + file.fullPath); //undefined
    //path wasn't defined, manually set it
    file.fullPath = fullPath = cordova.file.dataDirectory + 'files/' + file.name;
    console.log("Path: " + file.fullPath); //"file:///data/data/com.ionicframework.myproject123456/files/files/mypicture.jpg"
    console.log("Bytes: " + file.size); //~3 mega bytes

    var reader = new FileReader();
    reader.onloadend = function(evt) {
        console.log('Reader status "onloadend": '+reader.readyState); //2 (a.k.a loaded)
        console.log('Result: '+evt.target.result); //"null" (FAILURE)
        console.log('Result: '+reader.result); //"null" (FAILURE)
    };
    reader.onerror = function(e) {
        console.log('Error.code: '+reader.error.code) //1 (NOT_FOUND_ERR?)
        console.log('Error.message: '+reader.error.message) //undefined
    }
    console.log("Reader status before: "+reader.readyState); //0
    reader.readAsDataURL(file);
    console.log("Reader status after: "+reader.readyState); //1
}

Using "adb shell" I'm able to show the directory where the files are located. Both files are there. The permissions and owner of both files are the same.

My end goal is to read in a file as a base64 datastream and add it as an attachment to an email using katzer's emailComposer plugin. I'm hoping that I can use this method on an iOS deployment also.

How am I reading this image file incorrectly -- why is reader.readyState returning null?

Thanks in advance.

Answer 1

弄清楚了..这是一个笨拙的错误-在调试其他内容时改写文件时更改了图像的权限。