Cordova fileReader 适用于文本，但对于 jpgs 返回 null

Question

我正在使用 android nexus 9 的仿真进行测试。

我为文本运行此代码，它可以工作：

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
}

所以我切换它来尝试使用图片。相同的代码，为“mypicture.jpg”切换“newFile.txt”：

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
}

使用“adb shell”我可以显示文件所在的目录。两个文件都在那里。两个文件的权限和所有者相同。

我的最终目标是读取文件作为 base64 数据流，并使用 katzer 的 emailComposer 插件将其作为附件添加到电子邮件中。我希望我也可以在 iOS 部署中使用这种方法。

我怎么读错了这个图像文件——为什么 reader.readyState 返回 null？

提前致谢。

Answer 1

想通了..这是一个愚蠢的错误-当我在调试其他东西时覆盖了文件时，图像的权限被更改了。