Jquery的Ajax中contentType和dataType的区别

$.ajax({
    type: httpMethod,
    cache:false,
    async:false,
    contentType: "application/json; charset=utf-8",
    dataType: "json",//返回值类型
    url: path+url,
    data:jsonData,
    success: function(data){
        var resultData = ‘返回码=‘+data.status+‘,响应结果=‘+data.message+‘,耗时=‘+data.tcost;
        layer.msg(resultData,{icon: 1});
    },
    error : function(xhr, ts, et) {
        layer.msg(‘服务调用失败!‘, {icon: 2});
    }
});