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。
@ "
1<tr bgcolor="#\w+"><td height="20">(?<currency>.*)</currency></td>\s*" \+
2@ "<td height="20"><p align="right">(?<bankbuytt>\d*.?\d*)( )+.?</bankbuytt></p></td>\s*" \+
3@ "<td height="20"><p align="right">(?<buynotes>\d*.?\d*)( )+.?</buynotes></p></td>\s*" \+
4@ "<td height="20"><p align="right">(?<sell>\d*.?\d*)( )+.?</sell></p></td>\s*" \+
5@ "<td height="20"><p align="right">(?<base/>\d*.?\d*)( )+.?</p></td>\s*"
6
7
8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。
9
10这是所建WebService页面ForeignExchange.asmx的代码：
11
12using System ;
13using System . Collections ;
14using System . ComponentModel ;
15using System . Data ;
16using System . Diagnostics ;
17using System . Web ;
18using System . Net ;
19using System . Web . Services ;
20using System . Xml ;
21using System . Text ;
22using System . Text . RegularExpressions ;
23using System . IO ;
24
25namespace ChinaBank
26{
27/// <summary>
28/// Summary description for ForeignExchange.
29/// </summary>
30[ WebService ( Namespace = "http://dancefires.com/ChinaBank/" )]
31public class ForeignExchange : System . Web . Services . WebService
32{
33public ForeignExchange ()
34{
35//CODEGEN: This call is required by the ASP.NET Web Services Designer
36InitializeComponent ();
37}
38
39#region Component Designer generated code
40
41//Required by the Web Services Designer
42private IContainer components = null ;
43
44/// <summary>
45/// Required method for Designer support - do not modify
46/// the contents of this method with the code editor.
47/// </summary>
48private void InitializeComponent ()
49{
50}
51
52/// <summary>
53/// Clean up any resources being used.
54/// </summary>
55protected override void Dispose ( bool disposing )
56{
57if( disposing && components != null )
58{
59components . Dispose ();
60}
61base . Dispose ( disposing );
62}
63
64#endregion
65
66[ WebMethod ]
67public XmlDataDocument GetForeignExchangeRates ()
68{
69return getXmlDoc ();
70}
71[ WebMethod ]
72public DataSet GetForeignExchangeRatesDataSet ()
73{
74return getXmlDoc (). DataSet ;
75}
76[ WebMethod ]
77public string GetBankPage ()
78{
79return getWebContent ( "http://www.bank-of-china.com/info/whjrpj.html" );
80}
81// private methods
82private string getWebContent ( string url )
83{
84using ( WebClient client = new WebClient () )
85{
86byte [] buffer = client . DownloadData ( url );
87string str = Encoding . GetEncoding ( "GB2312" ). GetString ( buffer , 0 , buffer . Length );
88return str ;
89}
90}
91private XmlDataDocument getXmlDoc ()
92{
93string webcontent = getWebContent ( "http://www.bank-of-china.com/info/whjrpj.html" );
94
95// Prepair for DataSet
96DataSet ds = new DataSet ( "Exchange" );
97DataTable dt = new DataTable ( "ForeignExchange" );
98ds . Tables . Add ( dt );
99dt . Columns . Add ( "Currency" , typeof (string) );
100dt . Columns . Add ( "BankBuyTT" , typeof (double) );
101dt . Columns . Add ( "BankBuyNotes" , typeof (double) );
102dt . Columns . Add ( "BankSell" , typeof (double) );
103dt . Columns . Add ( "Baseline" , typeof (double) );
104XmlDataDocument xmldoc = new XmlDataDocument ( ds );
105
106Regex expr = new Regex (
107@ "<tr bgcolor="#\w+"><td height="20">(?<currency>.*)</currency></td>\s*" \+
108@ "<td height="20"><p align="right">(?<bankbuytt>\d*.?\d*)( )+.?</bankbuytt></p></td>\s*" \+
109@ "<td height="20"><p align="right">(?<buynotes>\d*.?\d*)( )+.?</buynotes></p></td>\s*" \+
110@ "<td height="20"><p align="right">(?<sell>\d*.?\d*)( )+.?</sell></p></td>\s*" \+
111@ "<td height="20"><p align="right">(?<base/>\d*.?\d*)( )+.?</p></td>\s*"
112, RegexOptions . Compiled );
113for( Match m = expr . Match ( webcontent ) ; m . Success ; m = m . NextMatch () )
114{
115string key ;
116DataRow row = dt . NewRow ();
117row [ "Currency" ] = m . Groups [ "currency" ];
118key = m . Groups [ "bankbuytt" ]. ToString ();
119row [ "BankBuyTT" ] = key . Length > 0 ? Convert . ToDouble ( key )/ 100 : 0 ;
120key = m . Groups [ "buynotes" ]. ToString ();
121row [ "BankBuyNotes" ] = key . Length > 0 ? Convert . ToDouble ( key )/ 100 : 0 ;
122key = m . Groups [ "sell" ]. ToString ();
123row [ "BankSell" ] = key . Length > 0 ? Convert . ToDouble ( key )/ 100 : 0 ;
124key = m . Groups [ "base" ]. ToString ();
125row [ "Baseline" ] = key . Length > 0 ? Convert . ToDouble ( key )/ 100 : 0 ;
126dt . Rows . Add ( row );
127}
128return xmldoc ;
129}
130}
131}
132
133
134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。
135
136using System ;
137using System . Threading ;
138using System . Drawing ;
139using System . Collections ;
140using System . ComponentModel ;
141using System . Windows . Forms ;
142
143namespace BankDataClient
144{
145/// <summary>
146/// Summary description for frmMainBankRates.
147/// </summary>
148public class frmMainBankRates : System . Windows . Forms . Form
149{
150private System . Windows . Forms . DataGrid dataGrid1 ;
151private System . Windows . Forms . Button btnConnect ;
152private System . Data . DataSet ds ;
153private BankDataClient . com . dancefires .[ url ] www . ForeignExchange [/ url ] proxy = new BankDataClient . com . dancefires . www . ForeignExchange ();
154private System . Windows . Forms . TextBox txtUrl ;
155/// <summary>
156/// Required designer variable.
157/// </summary>
158private System . ComponentModel . Container components = null ;
159
160public frmMainBankRates ()
161{
162//
163// Required for Windows Form Designer support
164//
165InitializeComponent ();
166try
167{
168txtUrl . Text = System . Configuration . ConfigurationSettings . AppSettings [ "url" ];
169proxy . Url = txtUrl . Text ;
170}
171catch ( Exception )
172{
173proxy . Url = "http://www.dancefires.com/ChinaBank/ForeignExchange.asmx" ;
174txtUrl . Text = proxy . Url ;
175}
176}
177
178/// <summary>
179/// Clean up any resources being used.
180/// </summary>
181protected override void Dispose ( bool disposing )
182{
183if( disposing )
184{
185if( components != null )
186{
187components . Dispose ();
188}
189}
190base . Dispose ( disposing );
191}
192
193#region Windows Form Designer generated code
194/// <summary>
195/// Required method for Designer support - do not modify
196/// the contents of this method with the code editor.
197/// </summary>
198private void InitializeComponent ()
199{
200this . dataGrid1 = new System . Windows . Forms . DataGrid ();
201this . ds = new System . Data . DataSet ();
202this . btnConnect = new System . Windows . Forms . Button ();
203this . txtUrl = new System . Windows . Forms . TextBox ();
204(( System . ComponentModel . ISupportInitialize )( this . dataGrid1 )). BeginInit ();
205(( System . ComponentModel . ISupportInitialize )( this . ds )). BeginInit ();
206this . SuspendLayout ();
207//
208// dataGrid1
209//
210this . dataGrid1 . DataMember = "" ;
211this . dataGrid1 . DataSource = this . ds ;
212this . dataGrid1 . HeaderForeColor = System . Drawing . SystemColors . ControlText ;
213this . dataGrid1 . Location = new System . Drawing . Point ( 32 , 48 );
214this . dataGrid1 . Name = "dataGrid1" ;
215this . dataGrid1 . Size = new System . Drawing . Size ( 480 , 256 );
216this . dataGrid1 . TabIndex = 0 ;
217//
218// ds
219//
220this . ds . DataSetName = "Exchange" ;
221this . ds . Locale = new System . Globalization . CultureInfo ( "zh-CN" );
222//
223// btnConnect
224//
225this . btnConnect . Location = new System . Drawing . Point ( 432 , 16 );
226this . btnConnect . Name = "btnConnect" ;
227this . btnConnect . TabIndex = 1 ;
228this . btnConnect . Text = "连接" ;
229this . btnConnect . Click += new System . EventHandler ( this . btnConnect_Click );
230//
231// txtUrl
232//
233this . txtUrl . Location = new System . Drawing . Point ( 32 , 16 );
234this . txtUrl . Name = "txtUrl" ;
235this . txtUrl . Size = new System . Drawing . Size ( 384 , 20 );
236this . txtUrl . TabIndex = 2 ;
237this . txtUrl . Text = "" ;
238//
239// frmMainBankRates
240//
241this . AutoScaleBaseSize = new System . Drawing . Size ( 5 , 13 );
242this . ClientSize = new System . Drawing . Size ( 544 , 318 );
243this . Controls . Add ( this . txtUrl );
244this . Controls . Add ( this . btnConnect );
245this . Controls . Add ( this . dataGrid1 );
246this . Name = "frmMainBankRates" ;
247this . Text = "Foreign Exchange Rates of Bank of China" ;
248(( System . ComponentModel . ISupportInitialize )( this . dataGrid1 )). EndInit ();
249(( System . ComponentModel . ISupportInitialize )( this . ds )). EndInit ();
250this . ResumeLayout ( false );
251
252}
253#endregion
254
255private void btnConnect_Click ( object sender , System . EventArgs e )
256{
257UpdateDataGrid ();
258}
259private void UpdateDataGrid ()
260{
261try
262{
263btnConnect . Enabled = false ;
264txtUrl . ReadOnly = true ;
265proxy . Url = txtUrl . Text ;
266ds = proxy . GetForeignExchangeRatesDataSet ();
267dataGrid1 . SetDataBinding ( ds , "ForeignExchange" );
268dataGrid1 . Update ();
269}
270catch ( Exception err )
271{
272MessageBox . Show ( err . Message );
273}
274finally
275{
276txtUrl . ReadOnly = false ;
277btnConnect . Enabled = true ;
278}
279}
280[ STAThread ]
281static void Main ( string [] args )
282{
283Application . Run ( new frmMainBankRates () );
284}
285}
286}
287
288
289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。
290
291软件所有代码，及相关截屏可以从下面的连接中获得：
292
293http://www.dancefires.com/ChinaBank/
294
295**</tr></tr>