利用正则表达式将html网页数据变成Web Service

这次的题目很简单，中国银行有一个查当天汇率的网页(http://www.bank-of-china.com/info/qpindex.shtml)，不过是传统的Html格式，而其又没有提供Xml格式或者WebService查询。现在如果希望其他的信息系统能够随时读取其中的数据，那么方便的莫过于中行提供一个WebService接口供大家调用，这也是典型的安全的WebService应用。可惜中行没有做，那么我们能不能自己来做呢？当然可以，只要用程序分析其html网页，那么就可以很容易的读取其中的数据。文本分析，当然要看我们的"Regular Expression"(呵呵，其实这才是写这个程序的真实目的 -- 应用正则表达式。)

中行的页面类似于：

日期:2004/09/30 有效期至2004/10/07

货币名称	现汇买入价	现钞买入价	卖出价	基准价
英镑	1488.1700	1453.1500	1492.6400
港币	105.9700	105.3300	106.2900	106.1100
美元	826.4200	821.4500	828.9000	827.6600
瑞士法郎	655.9300	641.1400	659.2200
新加坡元	488.7600	477.2600	490.2300
瑞典克朗	112.4900	109.8400	112.8300
丹麦克朗	136.5900	133.3700	137.0000
挪威克朗	121.9500	119.0800	122.3100
日元	7.4344	7.3785	7.4717	7.4519
加拿大元	650.8000	635.4800	652.7600
澳大利亚元	591.9900	578.6400	594.9600
欧元	1019.6400	1010.9600	1022.7000	1019.7000
澳门元	103.2200	102.6000	103.5300
菲律宾比索	14.6700	14.3300	14.7200
泰国铢	19.9000	19.4300	19.9600
新西兰元	553.7000		555.3600

对其代码分析后，给出了一个正则表达式，当然这个表达式还不完善，但是针对目前比较固定的中行的汇率页面来说，暂时还没有问题。

                @"<tr bgcolor='#\w+' ><td height='20'>(?<currency>.*)</td>\s*" +
                @"<td height='20'><p align='right'>(?<bankbuytt>\d*.?\d*)(&nbsp)+.?</td>\s*" +
                @"<td height='20'><p align='right'>(?<buynotes>\d*.?\d*)(&nbsp)+.?</td>\s*" +
                @"<td height='20'><p align='right'>(?<sell>\d*.?\d*)(&nbsp)+.?</td>\s*" +
                @"<td height='20'><p align='right'>(?<base>\d*.?\d*)(&nbsp)+.?</td>\s*"

然后过滤就非常简单了。我一直以为代码是最好的说明，特别是对于优雅的语言来说，因为我就不多说了，代码伺候。

这是所建WebService页面ForeignExchange.asmx的代码：

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Web;
using System.Net;
using System.Web.Services;
using System.Xml;
using System.Text;
using System.Text.RegularExpressions;
using System.IO;

namespace ChinaBank
{
    /// <summary>
    /// Summary description for ForeignExchange.
    /// </summary>
    [WebService(Namespace="http://dancefires.com/ChinaBank/")]        
    public class ForeignExchange : System.Web.Services.WebService
    {
        public ForeignExchange()
        {
            //CODEGEN: This call is required by the ASP.NET Web Services Designer
            InitializeComponent();
        }

        #region Component Designer generated code
        
        //Required by the Web Services Designer
        private IContainer components = null;
                
        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
        }

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        protected override void Dispose( bool disposing )
        {
            if(disposing && components != null)
            {
                components.Dispose();
            }
            base.Dispose(disposing);        
        }
        
        #endregion

        [WebMethod]
        public XmlDataDocument GetForeignExchangeRates()
        {
            return getXmlDoc();
        }
        [WebMethod]
        public DataSet GetForeignExchangeRatesDataSet()
        {
            return getXmlDoc().DataSet;
        }
        [WebMethod]
        public string GetBankPage()
        {
            return getWebContent( "http://www.bank-of-china.com/info/whjrpj.html" );
        }
        //    private methods
        private string getWebContent( string url )
        {
            using( WebClient client = new WebClient() )
            {
                byte[] buffer = client.DownloadData( url );
                string str = Encoding.GetEncoding("GB2312").GetString( buffer, 0, buffer.Length );
                return str;
            }
        }
        private XmlDataDocument getXmlDoc()
        {
            string webcontent = getWebContent("http://www.bank-of-china.com/info/whjrpj.html");

            //    Prepair for DataSet
            DataSet ds = new DataSet("Exchange");
            DataTable dt = new DataTable("ForeignExchange");
            ds.Tables.Add( dt );
            dt.Columns.Add( "Currency", typeof(string) );
            dt.Columns.Add( "BankBuyTT", typeof(double) );
            dt.Columns.Add( "BankBuyNotes", typeof(double) );
            dt.Columns.Add( "BankSell", typeof(double) );
            dt.Columns.Add( "Baseline", typeof(double) );
            XmlDataDocument xmldoc = new XmlDataDocument( ds );

            Regex expr = new Regex(
                @"<tr bgcolor='#\w+' ><td height='20'>(?<currency>.*)</td>\s*" +
                @"<td height='20'><p align='right'>(?<bankbuytt>\d*.?\d*)(&nbsp)+.?</td>\s*" +
                @"<td height='20'><p align='right'>(?<buynotes>\d*.?\d*)(&nbsp)+.?</td>\s*" +
                @"<td height='20'><p align='right'>(?<sell>\d*.?\d*)(&nbsp)+.?</td>\s*" +
                @"<td height='20'><p align='right'>(?<base>\d*.?\d*)(&nbsp)+.?</td>\s*"
                , RegexOptions.Compiled);
            for( Match m = expr.Match(webcontent) ; m.Success ; m=m.NextMatch() )
            {
                string key;
                DataRow row = dt.NewRow();
                row["Currency"] = m.Groups["currency"];
                key = m.Groups["bankbuytt"].ToString();
                row["BankBuyTT"] = key.Length > 0 ? Convert.ToDouble( key )/100 : 0;
                key = m.Groups["buynotes"].ToString();
                row["BankBuyNotes"] = key.Length > 0 ? Convert.ToDouble( key )/100 : 0;
                key = m.Groups["sell"].ToString();
                row["BankSell"] = key.Length > 0 ? Convert.ToDouble( key )/100 : 0;
                key = m.Groups["base"].ToString();
                row["Baseline"] = key.Length > 0 ? Convert.ToDouble( key )/100 : 0;
                dt.Rows.Add( row );
            }
            return xmldoc;
        }
    }
}

客户端也很容易，只要用wsdl生成了相应的WebService Proxy后，直接调用就行了，由于我让Server端返回了DataSet，因此客户端直接用DataGrid来显示DataSet即可，非常Easy，在这个问题上客户端没有什么技术关键点。

using System;
using System.Threading;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;

namespace BankDataClient
{
    /// <summary>
    /// Summary description for frmMainBankRates.
    /// </summary>
    public class frmMainBankRates : System.Windows.Forms.Form
    {
        private System.Windows.Forms.DataGrid dataGrid1;
        private System.Windows.Forms.Button btnConnect;
        private System.Data.DataSet ds;
        private BankDataClient.com.dancefires.[url]www.ForeignExchange[/url] proxy = new BankDataClient.com.dancefires.www.ForeignExchange();
        private System.Windows.Forms.TextBox txtUrl;
        /// <summary>
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.Container components = null;

        public frmMainBankRates()
        {
            //
            // Required for Windows Form Designer support
            //
            InitializeComponent();
            try
            {
                txtUrl.Text = System.Configuration.ConfigurationSettings.AppSettings["url"];
                proxy.Url = txtUrl.Text;
            }
            catch(Exception)
            {
                proxy.Url = "http://www.dancefires.com/ChinaBank/ForeignExchange.asmx";
                txtUrl.Text = proxy.Url;
            }
        }

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        protected override void Dispose( bool disposing )
        {
            if( disposing )
            {
                if(components != null)
                {
                    components.Dispose();
                }
            }
            base.Dispose( disposing );
        }

        #region Windows Form Designer generated code
        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            this.dataGrid1 = new System.Windows.Forms.DataGrid();
            this.ds = new System.Data.DataSet();
            this.btnConnect = new System.Windows.Forms.Button();
            this.txtUrl = new System.Windows.Forms.TextBox();
            ((System.ComponentModel.ISupportInitialize)(this.dataGrid1)).BeginInit();
            ((System.ComponentModel.ISupportInitialize)(this.ds)).BeginInit();
            this.SuspendLayout();
            //
            // dataGrid1
            //
            this.dataGrid1.DataMember = "";
            this.dataGrid1.DataSource = this.ds;
            this.dataGrid1.HeaderForeColor = System.Drawing.SystemColors.ControlText;
            this.dataGrid1.Location = new System.Drawing.Point(32, 48);
            this.dataGrid1.Name = "dataGrid1";
            this.dataGrid1.Size = new System.Drawing.Size(480, 256);
            this.dataGrid1.TabIndex = 0;
            //
            // ds
            //
            this.ds.DataSetName = "Exchange";
            this.ds.Locale = new System.Globalization.CultureInfo("zh-CN");
            //
            // btnConnect
            //
            this.btnConnect.Location = new System.Drawing.Point(432, 16);
            this.btnConnect.Name = "btnConnect";
            this.btnConnect.TabIndex = 1;
            this.btnConnect.Text = "连接";
            this.btnConnect.Click += new System.EventHandler(this.btnConnect_Click);
            //
            // txtUrl
            //
            this.txtUrl.Location = new System.Drawing.Point(32, 16);
            this.txtUrl.Name = "txtUrl";
            this.txtUrl.Size = new System.Drawing.Size(384, 20);
            this.txtUrl.TabIndex = 2;
            this.txtUrl.Text = "";
            //
            // frmMainBankRates
            //
            this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
            this.ClientSize = new System.Drawing.Size(544, 318);
            this.Controls.Add(this.txtUrl);
            this.Controls.Add(this.btnConnect);
            this.Controls.Add(this.dataGrid1);
            this.Name = "frmMainBankRates";
            this.Text = "Foreign Exchange Rates of Bank of China";
            ((System.ComponentModel.ISupportInitialize)(this.dataGrid1)).EndInit();
            ((System.ComponentModel.ISupportInitialize)(this.ds)).EndInit();
            this.ResumeLayout(false);

        }
        #endregion

        private void btnConnect_Click(object sender, System.EventArgs e)
        {
            UpdateDataGrid();
        }
        private void UpdateDataGrid()
        {
            try
            {
                btnConnect.Enabled = false;
                txtUrl.ReadOnly = true;
                proxy.Url = txtUrl.Text;
                ds = proxy.GetForeignExchangeRatesDataSet();
                dataGrid1.SetDataBinding( ds, "ForeignExchange" );
                dataGrid1.Update();
            }
            catch( Exception err )
            {
                MessageBox.Show( err.Message );
            }
            finally
            {
                txtUrl.ReadOnly = false;
                btnConnect.Enabled = true;
            }
        }
        [STAThread]
        static void Main( string[] args )
        {
            Application.Run( new frmMainBankRates() );
        }
    }
}

有了这个例子，应该可以从中了解最基本的XML, WebService, Regular Expression, DataSet, DataGrid的知识。

软件所有代码，及相关截屏可以从下面的连接中获得：

http://www.dancefires.com/ChinaBank/