ajax接收不到后端传的数据

Question

$.ajax({url:"csadd.do",
type:"post",
dataType:"json",
traditional: true,
data:{cs_date:cs_date,cs_name:cs_name,cs_df:cs_df,cs_kpxx:cs_kpxx,cs_sm:cs_sm},
success: function(msg) {
alert(msg);
if(msg=="Y"){
alert("添加成功");
}
}
});

PrintWriter pw = response.getWriter();
    pw.print("Y");
    pw.flush();
    pw.close();     

Answer 1

什么情况啊这是，后端也必须传json格式的吗？