脚本异步时切记声明数据格式

function test(){
$.ajax({
   type: "POST",
   url: "json.txt",
   data: '000',
   dataType:'json',//此项十分重要，切记！
   success: function(msg){
	var data_text="";
	$.each(msg.logistics_companies_get_response.logistics_companies.logistics_company, function(i,item){
	data_text+="code:"+item.code+",　id:"+item.id+",　name:"+item.name+"<br/>";})
	$("div").html(data_text);
	$("p").html('总共个数：'+msg.logistics_companies_get_response.logistics_companies.logistics_company.length);}
　　});
}
test();