http://stackoverflow.com/questions/22574645/phonegap-android-create-file-if-not-exists-and-write-to-it

var savedFS;

function gotFS(fileSystem) {
    savedFS = fileSystem;
    fileSystem.root.getFile("test.txt", null, gotFileEntry, fail);
}

function gotFS2(fileSystem) {
    alert('trying again');
    fileSystem.root.getFile("test.txt", {create:true}, gotFileEntry, fail);
}

function fail(error) {
    if(error.code == 1) {
        alert('not found');
        gotFS2(savedFS);
    }
    alert(error.code);
}

http://stackoverflow.com/questions/11077303/how-to-create-a-directory-and-file-in-that-directory-using-phonegap-file-api

document.addEventListener("deviceready", onDeviceReady, false);

function onDeviceReady() {
    window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, gotFS, fail);
}

function gotFS(fileSystem) {
   fileSystem.root.getDirectory("data", {create: true}, gotDir);
}

function gotDir(dirEntry) {
    dirEntry.getFile("lockfile.txt", {create: true, exclusive: true}, gotFile);
}

function gotFile(fileEntry) {
    // Do something with fileEntry here
}

Worklight Create Folder Write File

http://stackoverflow.com/questions/15545112/combining-native-app-with-worklight-project

Here's a quick example of the File I/O API for Writing a file:

// Wait for Cordova to load
//
document.addEventListener("deviceready", onDeviceReady, false);

// Cordova is ready
//
function onDeviceReady() {
    window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, gotFS, fail);
}

function gotFS(fileSystem) {
    fileSystem.root.getFile("readme.txt", {create: true, exclusive: false}, gotFileEntry, fail);
}

function gotFileEntry(fileEntry) {
    fileEntry.createWriter(gotFileWriter, fail);
}

function gotFileWriter(writer) {
    writer.onwriteend = function(evt) {
        console.log("contents of file now 'some sample text'");
        writer.truncate(11);  
        writer.onwriteend = function(evt) {
            console.log("contents of file now 'some sample'");
            writer.seek(4);
            writer.write(" different text");
            writer.onwriteend = function(evt){
                console.log("contents of file now 'some different text'");
            }
        };
    };
    writer.write("some sample text");
}

function fail(error) {
    console.log(error.code);
}

Here's an example of Reading a file:

// Wait for Cordova to load
//
function onLoad() {
    document.addEventListener("deviceready", onDeviceReady, false);
}

// Cordova is ready
//
function onDeviceReady() {
    window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, gotFS, fail);
}

function gotFS(fileSystem) {
    fileSystem.root.getFile("readme.txt", null, gotFileEntry, fail);
}

function gotFileEntry(fileEntry) {
    fileEntry.file(gotFile, fail);
}

function gotFile(file){
    readDataUrl(file);
    readAsText(file);
}

function readDataUrl(file) {
    var reader = new FileReader();
    reader.onloadend = function(evt) {
        console.log("Read as data URL");
        console.log(evt.target.result);
    };
    reader.readAsDataURL(file);
}

function readAsText(file) {
    var reader = new FileReader();
    reader.onloadend = function(evt) {
        console.log("Read as text");
        console.log(evt.target.result);
    };
    reader.readAsText(file);
}

function fail(evt) {
    console.log(evt.target.error.code);
}