关于angularjs中ajax请求php接口参数个是转换的问题

mainApp.config(function($httpProvider){
    $httpProvider.defaults.transformRequest = function(obj){
        var str = [];
        for(var p in obj){
            str.push(encodeURIComponent(p) + "=" + encodeURIComponent(obj[p]));
        }
        return str.join("&");
    }
    $httpProvider.defaults.headers.post = {
        'Content-Type': 'application/x-www-form-urlencoded'
    }
});