ionic cordova file download and load

1.先添加插件

cordova plugin add org.apache.cordova.file
cordova plugin add org.apache.cordova.file-transfer 

　　2. 在index.html 中添加

<img width="80px" height="80px" id="smallImage" />

　　3.在index.js中添加

document.addEventListener("deviceready", downloadstart, false);
/**
 * 用一個文件夾download，存儲下載的圖片/文件 ;
 * @return {[type]} [description]
 */
function downloadstart() {
    try {
        window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, function(fileSystem) {
            fileSystem.root.getDirectory("download", {
                create: true,
                exclusive: false
            }, function(entry) {
                var storepath = entry.toURL();
                alert(storepath.toString() + '文件夾已經存在');
                downloadFile(storepath, "http://www.baidu.com/img/bdlogo.png");//開始下載文件
            }, function() {
                console.log('建立文件夾失敗');
            });
        }, function() {
            console.log('建立文件夾失敗');
        });
    } catch (e) {
        alert(e.name + ":" + e.message);
    }
}
/**
 * 下載文件，
 *
 * @param  {[string]} storefilepath   [下載的文件存儲的路徑]
 * @param  {[string]} downloadfileurl [須要下載文件的URL 或者名稱]
 * @return {[type]}                 [description]
 */
function downloadFile(storefilepath, downloadfileurl) {
    try {
        var ft = new FileTransfer();
        var uri = encodeURI(downloadfileurl);
        var fileURL = storefilepath + downloadfileurl.substr(downloadfileurl.lastIndexOf('/') + 1);
        ft.download(
            uri,
            fileURL,
            function(entry) {
                var smallImage = document.getElementById('smallImage');
                smallImage.style.display = 'block';
                smallImage.src = entry.toURL();
                alert("download complete: " + entry.toURL());
            },
            function(error) {
                alert("download error source " + error.source);
                alert("download error target " + error.target);
                console.log("download error source " + error.source);
                console.log("download error target " + error.target);
                console.log("upload error code" + error.code);
            },
            false, {
                headers: {
                    "Authorization": "Basic dGVzdHVzZXJuYW1lOnRlc3RwYXNzd29yZA=="
                }
            }
        );
    } catch (e) {
        alert(e.name + ":" + e.message);
    }
}