windows 8 metro app 读取本地json的方法

metro app  读取本地json的方法

// read the file you want
function ReadAllDataFile(fileNameInLocalTree) {

var package = Windows.ApplicationModel.Package.current;
var installedLocation = package.installedLocation;

installedLocation.createFileAsync(fileNameInLocalTree, Windows.Storage.CreationCollisionOption.openIfExists).then(function (dataFile) {
dataFile.openAsync(Windows.Storage.FileAccessMode.read).then(function (stream) {
var size = stream.size;
if (size == 0) {
// Data not found
}
else {
var inputStream = stream.getInputStreamAt(0);
var reader = new Windows.Storage.Streams.DataReader(inputStream);

reader.loadAsync(size).then(function () {

//var contents = reader.readString(size); // fails with multibyte error if bad data (see legislators.getList.json)

// allocate the full array so readBytes can insert it in full
var array = new Array(size);
reader.readBytes(array);

var newString = "";
for (var i = 0; i < array.length; i++) {
// only printable characters (include spaces because could be part of names) (very rough here)
// http://www.csgnetwork.com/asciiset.html if (array[i] >= 32 && array[i] <= 126) {
var c = String.fromCharCode(array[i]);
newString += c;
}
}

var result = JSON.parse(newString);
var newYorkPopulation = result.NY.P001001;

// output to the screen
document.getElementById('outputhere').innerHTML = "New York Population: " + newYorkPopulation;

//outputhere.winControl.dataSource = postItems;

});
}
})
});
}

用法：
1.在js文件中调用函数：

(function () {
'use strict';
// Uncomment the following line to enable first chance exceptions.
Debug.enableFirstChanceException(true);

WinJS.Application.onmainwindowactivated = function (e) {
if (e.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) {

// start of my insert code
ReadAllDataFile("\data\\states_data.json");
// end of my insert code
}
}

WinJS.Application.start();
})();

2.在html文件中
<h1>
<div id="outputhere" >
</div>
</h1>