System.InvalidOperationException: 生成 XML 文档时出错。 ---> System.ArgumentException: WriteStartDocument 已编写 XML 声明。
at System.Xml.XmlTextWriter.WriteProcessingInstruction(String name, String text)
at System.Xml.XmlDeclaration.WriteTo(XmlWriter w)
at System.Xml.XmlDocument.WriteContentTo(XmlWriter xw)
at System.Xml.XmlDocument.WriteTo(XmlWriter w)
at System.Xml.Serialization.XmlSerializationWriter.WriteElement(XmlNode node, String name, String ns, Boolean any)
at System.Xml.Serialization.XmlSerializationWriter.WriteElementLiteral(XmlNode node, String name, String ns, Boolean isNullable, Boolean any)
at Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationWriter1.Write1_Item(Object o)
--- 内部异常堆栈跟踪的结尾 ---
at System.Xml.Serialization.XmlSerializer.Serialize(XmlWriter xmlWriter, Object o, XmlSerializerNamespaces namespaces)
at System.Xml.Serialization.XmlSerializer.Serialize(TextWriter textWriter, Object o)
at System.Web.Services.Protocols.XmlReturnWriter.Write(HttpResponse response, Stream outputStream, Object returnValue)
at System.Web.Services.Protocols.HttpServerProtocol.WriteReturns(Object[] returnValues, Stream outputStream)
at System.Web.Services.Protocols.WebServiceHandler.WriteReturns(Object[] returnValues)
at System.Web.Services.Protocols.WebServiceHandler.Invoke()
at System.Web.Services.Protocols.WebServiceHandler.CoreProcessRequest()
这是错误提示
你们帮我看看,这有什么错误!
using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Web;
using System.Web.Services;
using System.Xml;
//using System.Xml.XPath;
using System.Web.Services.Protocols;
namespace WebServiceCallXml
{
/// <summary>
/// ServiceCallXml 的摘要说明。
/// </summary>
[WebService(Namespace = "China.XiAn.DongGaoXin")]
public class ServiceCallXml : System.Web.Services.WebService
{
public ServiceCallXml()
{
//CODEGEN:该调用是 ASP.NET Web 服务设计器所必需的
InitializeComponent();