making a vector layer with geoJson in openlayer

I used to mak开发者_C百科e GML vector like this:

layer = new OpenLayers.Layer.GML("based",
        "./parser2.php",
        {
            isBaseLayer: true,
            format: OpenLayers.Format.GeoJSON,
            styleMap: new OpenLayers.StyleMap(mystyle),
            units:"m",
            maxResolution: 0.2,
            minResolution: 0.01
        })

map.addLayer(layer);

but is now depreciated an for multiple raison i need to use OpenLayers.Layer.Vector but i can't succed to read a geoJon file. I tried like this:

   var test = new OpenLayers.Layer.Vector("test", {
    strategies: [new OpenLayers.Strategy.Fixed()],
    protocol: new OpenLayers.Protocol.HTTP({
        isBaseLayer: true,
        url: "data.json",
        styleMap: myStyles,
        format: new OpenLayers.Format.JSON()
        })
    });
map.addLayer(test);

but unfortunately it's not working.

do you have any clue?

Thanks

---

I use the steps described in the following web page to add GeoJSON format data to a layer: http://thinkwhere.wordpress.com/2011/06/26/geocommons-geojson-in-openlayers/ As your GeoJSON is already correct format do not add {"type": "FeatureCollection", "features": ...} around the GeoJSON string, as shown in this example.

In plain English, the steps are:

1. Create a new OpenLayers.Layer.Vector layer without options to read data.
2. You read the URL yourself.
3. In the callback function called when reading is complete you create a OpenLayers.Format.GeoJSON() object, use it to read features from the GeoJSON string, then add the features to the layer.