在我能说的一切之前，您选择的不是最简单的方法。ScriptMethods易于与ASP.NET
ScriptManager一起使用，而不与jQuery一起使用。我建议您最好使用启用JSON的WCF
HTTP服务（最好是RESTfull服务），而不要使用现在尝试使用的ASMX
Web服务。但是，可以使您的代码工作而无需在客户端使用任何Microsoft技术。

首先验证服务器端。

1. 将webmethods.aspx重命名为webmethods.asmx。

2. 确认您放置在\里面，并且配置中还存在一个用于asmx扩展的httpHandlers（ScriptHandlerFactory）：

   <configuration>
   

   
   
   
   
   
   
   
   
   
   
   

3. 验证是否为从System.Web.Services.WebService继承的类设置了[ScriptService]属性（如果喜欢全名，则为[System.Web.Script.Services.ScriptService]）。

现在您可以测试服务了。在您的Web浏览器URL中打开，例如http：//localhost/webmethods.asmx/AjaxGet？id =
li1234 如果收到类似
<?xml version="1.0" encoding="utf-8" ?>
<string xmlns="http://tempuri.org/">li1234</string>

您可以确定您维修的零件工作正常。

备注： 如果“ Content-Type：application / json;”，则独立于“ ResponseFormat =
System.Web.Script.Services.ResponseFormat.Json”为服务应答赋予XML响应 未在请求中设置。

现在，我们将修复客户端代码。我希望我在以下代码中添加的注释能够全部解释。

再说一句。在代码的最后一部分，我调用了另一个“复杂”的web方法：

[WebMethod]
[ScriptMethod (UseHttpGet = true, ResponseFormat = ResponseFormat.Json)]
public OutputData AjaxGetMore (InputData input) {
    return new OutputData () {
        id = input.id,
        message = "it's work!",
        myInt = input.myInt+1
    };
}

哪里

public class OutputData {
    public string id { get; set; }
    public string message { get; set; }
    public int myInt { get; set; }
}
public class InputData {
    public string id { get; set; }
    public int myInt { get; set; }
}

现在只有在某些地方使用JSON插件的JavaScript代码，如果有人喜欢的话，可以用Crockford的json2.js替换。

var id = "li1234";
// version 1 - works
var idAsJson = '"' + id + '"';  // string serializes in JSON format
$.ajax({
    type: "GET",
    url: "/webmethods.asmx/AjaxGet?id=" + idAsJson,
    contentType: "application/json; charset=utf-8",
    success: function(msg) {
        alert(msg.d);   // var msg = {d: "li1234"} 
    },
    error: function(res, status) {
        if (status ==="error") {
            // errorMessage can be an object with 3 string properties: ExceptionType, Message and StackTrace
            var errorMessage = $.parseJSON(res.responseText);
            alert(errorMessage.Message);
        }
    }
});

// version 2 with respect of JSON plugin
$.ajax({
    type: "GET",
    url: "/webmethods.asmx/AjaxGet?id=" + $.toJSON(id),
    contentType: "application/json; charset=utf-8",
    success: function(msg) {
        alert(msg.d);   // var msg = {d: "li1234"} 
    },
    error: function(res, status) {
        if (status ==="error") {
            // errorMessage can be an object with 3 string properties: ExceptionType, Message and StackTrace
            var errorMessage = $.parseJSON(res.responseText);
            alert(errorMessage.Message);
        }
    }
});
// version 3 where jQuery will construct URL for us
$.ajax({
    type: "GET",
    url: "/webmethods.asmx/AjaxGet",
    data: {id: $.toJSON(id)},
    dataType: "json",
    contentType: "application/json; charset=utf-8",
    success: function(msg) {
        alert(msg.d);   // var msg = {d: "li1234"} 
    },
    error: function(res, status) {
        if (status ==="error") {
            // errorMessage can be an object with 3 string properties: ExceptionType, Message and StackTrace
            var errorMessage = $.parseJSON(res.responseText);
            alert(errorMessage.Message);
        }
    }
});
// version 4. We set "Content-Type: application/json" about our data, but we use no 
//            not 'dataType: "json"' parameter. Then we have "Accept: */*" in the request
//            instead of "Accept: application/json, text/javascript, */*" before.
//            Everithing work OK like before.
$.ajax({
    type: "GET",
    url: "/webmethods.asmx/AjaxGet",
    data: {id: $.toJSON(id)},
    contentType: "application/json; charset=utf-8",
    success: function(msg) {
        alert(msg.d);   // var msg = {d: "li1234"} 
    },
    error: function(res, status) {
        if (status ==="error") {
            // errorMessage can be an object with 3 string properties: ExceptionType, Message and StackTrace
            var errorMessage = $.parseJSON(res.responseText);
            alert(errorMessage.Message);
        }
    }
});
// version 5. If we don't place "Content-Type: application/json" in our reqest we
//            receive back XML (!!!) response with "HTTP/1.1 200 OK" header and 
//            "Content-Type: text/xml; charset=utf-8" which will be placed.
//            How one can read in
// http://weblogs.asp.net/scottgu/archive/2007/04/04/json-hijacking-and-how-asp-net-ajax-1-0-mitigates-these-attacks.aspx),
//             ASP.NET AJAX will not make JSON serialized of response data for
//             security reasons.
$.ajax({
    type: "GET",
    url: "/webmethods.asmx/AjaxGet",
    data: {id: $.toJSON(id)},
    dataType: "json",
    //contentType: "application/json; charset=utf-8",
    success: function(msg) {
        alert(msg.d);   // var msg = {d: "li1234"} 
    },
    error: function (res, status, ex) {
        // the code here will be works because of error in parsing server response
        if (res.status !== 200) {   // if not OK
            // we receive exception in the next line, be
            var errorMessage = $.parseJSON(res.responseText);
            alert(errorMessage.Message);
        } else {
            alert("status=" + status + "\nex=" + ex + "\nres.status=" + res.status + "\nres.statusText=" + res.statusText +
                    "\nres.responseText=" + res.responseText);
        }
    }
});
// version 6. Send more komplex data to/from the service
var myData = { id: "li1234", myInt: 100}
$.ajax({
    type: "GET",
    url: "/webmethods.asmx/AjaxGetMore",
    data: {input:$.toJSON(myData)},
    dataType: "json",
    contentType: "application/json; charset=utf-8",
    success: function(msg) {
        // var msg = {__type: "Testportal.OutputData", id: "li1234", message: "it's work!", myInt:101}
        alert("message=" + msg.d.message + ", id=" + msg.d.id + ", myInt=" + msg.d.myInt); 
    },
    error: function(res, status) {
        if (status ==="error") {
            // errorMessage can be an object with 3 string properties: ExceptionType, Message and StackTrace
            var errorMessage = $.parseJSON(res.responseText);
            alert(errorMessage.Message);
        }
    }
});