c#后台将数据转换为json字符串，前台ajax解析json字符串

 <pre name="code" class="csharp">public partial class ShowMsg
{
public string FromUserImg { get; set; }
public string Message { get; set; }
public string MessageType { get; set; }
}

[WebMethod]
//得到缓冲的消息

public static string GetBufferText(string Touser, string Fromuser)
{
OCEntities oc = new OCEntities();
List<ShowMsg> msgList = new List<ShowMsg>();//PrivateMsg是一个类，转到定义可显示其成员
SqlConnection Con = SQLhelper.CreateConnection();
SqlCommand CmdObj;
SqlDataReader reader;
int FromUid = int.Parse(Fromuser);
var ToUid = oc.Users.Where(p => p.Uusername == Touser).FirstOrDefault().Uid;
string sql = "select FromUid,ToUid,Message,MessageType from  PrivateMsg  where (FromUid=" + FromUid + " and ToUid=" + ToUid + ") or (FromUid=" + ToUid + " and ToUid=" + FromUid + ") and DateDiff(day,MessageTime,getdate())<=3 order by MessageTime";
CmdObj = new SqlCommand(sql, Con);
Con.Open();
reader = CmdObj.ExecuteReader(CommandBehavior.CloseConnection);
while (reader.Read())
{
var FromUserImg = oc.Users.Where(p => p.Uid == FromUid).FirstOrDefault().Uphoto;
// var ToUserImg = oc.Users.Where(p => p.Uid == int.Parse(reader["ToUid"].ToString())).FirstOrDefault().Uphoto;
ShowMsg msg = new ShowMsg { FromUserImg = FromUserImg, Message = reader["Message"].ToString(), MessageType = reader["MessageType"].ToString() };
msgList.Add(msg);
}
reader.Close();
return  JsonConvert.SerializeObject(msgList);//将PrivateMsg转换为json字符串
}

先定义类ShowMessage,其中有三个成员变量，在GetBufferText方法中新建List<ShowMessage> msgList,将数据库中查出的数据添加到msgList,用JsonConvert将其转化为

json字符串，注意是json字符串，传到前台是还需要转化为json对象。

[WebMethod]是前台ajax调用的方法，即GetBufferText,参数为ToUser与FromUser.

前台代码

$.ajax({
type: "Post",
url: "WebChat.aspx/GetBufferText",
contentType: "application/json; charset=utf-8",
data: "{'Touser':'" + Touser + "','Fromuser':"+uid+"}",
dataType: "json",
success: function (data) {
//alert(data.d)
var json = $.parseJSON(data.d);
var show = "";
$.each(json, function (index, item) { //循环获取数据
var FromUserImg = json[index].FromUserImg;
// alert(FromUserImg)
//  var ToUserImg = json[index].ToUserImg;
var Message = json[index].Message;
var MessageType = json[index].MessageType;//消息类型是"0",代表用户发出的消息。"1"代表用户收到的消息
show += "<div style='width:640px;min-height:50px;height:auto;float:left'><div class='userImgWrap1' style='background:url(" + FromUserImg + ") no-repeat no-repeat; background-size:contain;'></div><div class='usermsgContent1' >" + Message + "</div></div>";
});
$("#chatbuffer").html(show);
},
error: function (err) {
alert("错误信息");
}
});

data.d为后台传来的json字符串，用$.parseJSON将其转换为json对象，然后访问其中的数据。