Asp.net2.0中ObjectDataSource在三层（N层）架构中的应用
不知道大家看没看过《ASP.NET2.0开发指南》这本书。不管这本书怎么样（看到网上骂声不断），对于我这种菜鸟来说还是有些帮助的。既然花了钱买了书，肯定得学点东西才行。下面我就把个人学习ObjectDataSource的一些心得跟大家分享一下。
这里说是使用ObjectDataSource，其实更多的，是要了解三层（N层）架构方面的知识。首先我们可以根据下面的图例，建立三个项目：
1、WEB站点 用户界面层
2、AuthorDB 数据访问层
3、LogicLibrary 业务逻辑层
接下来，我们分别实现这三层。
数据访问层的实现：
这里用了一个组件AuthorDB.cs来完成对数据库的操作，具体代码如下
1
using System;
2using System.Collections.Generic;
3using System.Text;
4using System.Data;
5using System.Data.OleDb;
6using System.Xml;
7
8namespace AuthorDB
9
{
10
public class AuthorDB
11
{
12 //数据库连接字符串
13 static string str = System.Configuration.ConfigurationSettings.AppSettings["ConnStrings"].ToString().Trim();
14 //构造函数
15 public AuthorDB()
16 { }
17 //获取地址
18 public static DataSet GetStates()
19 {
20 string strCmd = "select distinct state from authors";
21 return DataAdapterFill(strCmd,"state");
22
}
23 //通过地址获取信息
24 public static DataSet GetAuthorsByState(string state)
25 {
26 string strCmd = "select * from authors where state='"+state.ToString().Trim()+"'";
27 return DataAdapterFill(strCmd,"authors");
28
29 }
30 //修改信息
31 public static int UpdateAuthor(string au_id,string au_fname,string au_lname,string state)
32 {
33 string strCmd = "update authors set firstname='"+au_fname+"',lastname='"+au_lname+"',state='"+state+"' where id='"+au_id+"'";
34 return DataCommand(strCmd);
35 }
36 /// <summary>
37 /// DataAdapterFill
38 /// </summary>
39 /// <param name="strCmd">SQL语句</param>
40 /// <param name="tablename">表名</param>
41 /// <returns>数据集</returns>
42 private static DataSet DataAdapterFill(string strCmd, string tablename)
43 {
44 OleDbConnection conn = new OleDbConnection(str);
45 OleDbDataAdapter da = new OleDbDataAdapter(strCmd, conn);
46 DataSet ds = new DataSet();
47 conn.Open();
48 da.Fill(ds, tablename);
49 conn.Close();
50 return ds;
51 }
52 /// <summary>
53 /// DataCommand方法
54 /// </summary>
55 /// <param name="strCmd">SQL语句</param>
56 /// <returns>影响行数</returns>
57 private static int DataCommand(string strCmd)
58 {
59 OleDbConnection conn = new OleDbConnection(str);
60 OleDbCommand cmd = new OleDbCommand(strCmd, conn);
61 int rowsAffected = 0;
62 conn.Open();
63 try
64 {
65 rowsAffected = cmd.ExecuteNonQuery();
66 }
67 catch
68 { }
69 finally
70 {
71 conn.Close();
72 }
73 return rowsAffected;
74 }
75 }
76
}
77
using System;2
using System.Collections.Generic;3
using System.Text;4
using System.Data;5
using System.Data.OleDb;6
using System.Xml;7
8
namespace AuthorDB9
{
10
public class AuthorDB11
{
12
//数据库连接字符串13
static string str = System.Configuration.ConfigurationSettings.AppSettings["ConnStrings"].ToString().Trim();14
//构造函数15
public AuthorDB()16
{ }17
//获取地址18
public static DataSet GetStates()19
{20
string strCmd = "select distinct state from authors";21
return DataAdapterFill(strCmd,"state");22
}23
//通过地址获取信息24
public static DataSet GetAuthorsByState(string state)25
{26
string strCmd = "select * from authors where state='"+state.ToString().Trim()+"'";27
return DataAdapterFill(strCmd,"authors");28
29
}30
//修改信息31
public static int UpdateAuthor(string au_id,string au_fname,string au_lname,string state)32
{33
string strCmd = "update authors set firstname='"+au_fname+"',lastname='"+au_lname+"',state='"+state+"' where id='"+au_id+"'";34
return DataCommand(strCmd);35
}36
/// <summary>37
/// DataAdapterFill38
/// </summary>39
/// <param name="strCmd">SQL语句</param>40
/// <param name="tablename">表名</param>41
/// <returns>数据集</returns>42
private static DataSet DataAdapterFill(string strCmd, string tablename)43
{44
OleDbConnection conn = new OleDbConnection(str);45
OleDbDataAdapter da = new OleDbDataAdapter(strCmd, conn);46
DataSet ds = new DataSet();47
conn.Open();48
da.Fill(ds, tablename);49
conn.Close();50
return ds;51
}52
/// <summary>53
/// DataCommand方法54
/// </summary>55
/// <param name="strCmd">SQL语句</param>56
/// <returns>影响行数</returns>57
private static int DataCommand(string strCmd)58
{59
OleDbConnection conn = new OleDbConnection(str);60
OleDbCommand cmd = new OleDbCommand(strCmd, conn);61
int rowsAffected = 0;62
conn.Open();63
try64
{65
rowsAffected = cmd.ExecuteNonQuery();66
}67
catch68
{ }69
finally70
{71
conn.Close();72
}73
return rowsAffected;74
}75
}76
}77
业务逻辑层的实现：[注：逻辑层要引用AuthorDB.dll]
业务逻辑层主要由业务实体Author.cs和逻辑组件AuthorsComponent.cs组成[为什么要使用业务实体/怎么使用业务实体这里暂时不做介绍，请不择手段自己搜索]
业务实体实现代码
1using System;
2using System.Collections.Generic;
3using System.Text;
4
5namespace LogicLibrary
6{
7 public class Author
8 {
9 private string _id;
10 private string _firstname;
11 private string _lastname;
12 private string _state;
13
14 public Author()
15 { }
16 public Author(string id,string firstname,string lastname,string state)
17 {
18 this.ID = id;
19 this.FirstName = firstname;
20 this.LastName = lastname;
21 this.State = state;
22 }
23 public string ID
24 {
25 get
26 {
27 return _id;
28 }
29 set
30 {
31 _id = value;
32 }
33 }
34 public string FirstName
35 {
36 get
37 {
38 return _firstname;
39 }
40 set
41 {
42 _firstname = value;
43 }
44 }
45 public string LastName
46 {
47 get
48 {
49 return _lastname;
50 }
51 set
52 {
53 _lastname = value;
54 }
55 }
56 public string State
57 {
58 get
59 {
60 return _state;
61 }
62 set
63 {
64 _state = value;
65 }
66 }
67
68 }
69}
70
using System;2
using System.Collections.Generic;3
using System.Text;4
5
namespace LogicLibrary6
{7
public class Author8
{9
private string _id;10
private string _firstname;11
private string _lastname;12
private string _state;13
14
public Author()15
{ }16
public Author(string id,string firstname,string lastname,string state)17
{18
this.ID = id;19
this.FirstName = firstname;20
this.LastName = lastname;21
this.State = state;22
}23
public string ID24
{25
get26
{27
return _id;28
}29
set30
{31
_id = value;32
}33
}34
public string FirstName35
{36
get37
{38
return _firstname;39
}40
set41
{42
_firstname = value;43
}44
}45
public string LastName46
{47
get48
{49
return _lastname;50
}51
set52
{53
_lastname = value;54
}55
}56
public string State57
{58
get59
{60
return _state;61
}62
set63
{64
_state = value;65
}66
}67
68
}69
}70
逻辑组件实现代码
1using System;
2using System.Collections.Generic;
3using System.Text;
4using System.Data;
5
6namespace LogicLibrary
7{
8 public class AuthorsComponent
9 {
10 //构造函数
11 public AuthorsComponent()
12 { }
13 //通过地址获取信息
14 public List<Author> GetAuthorsByState(string state, string sortExpression)
15 {
16 List<Author> authors = new List<Author>();
17 DataSet ds = AuthorDB.AuthorDB.GetAuthorsByState(state);
18 foreach (DataRow row in ds.Tables["authors"].Rows)
19 {
20 authors.Add(new Author((string)row["id"],(string)row["firstname"],(string)row["lastname"],(string)row["state"]));
21 }
22 authors.Sort(new AuthorComparer(sortExpression));
23 return authors;
24 }
25 //获取地址
26 public List<string> GetStates()
27 {
28 List<string> states = new List<string>();
29 DataSet ds = AuthorDB.AuthorDB.GetStates();
30 foreach (DataRow row in ds.Tables["state"].Rows)
31 states.Add((string)row["state"]);
32 return states;
33 }
34 //修改信息
35 public int UpdateAuthor(Author a)
36 {
37 return AuthorDB.AuthorDB.UpdateAuthor(a.ID,a.LastName,a.FirstName,a.State);
38 }
39 //修改信息
40 public int UpdateAuthor(string ID,string FirstName,string LastName,string State)
41 {
42 return AuthorDB.AuthorDB.UpdateAuthor(ID,FirstName,LastName,State);
43 }
44 }
45 //自定义排序 实现IComparer接口
46 public class AuthorComparer : IComparer<Author>
47 {
48 private string _sortColumn;
49 private bool _reverse;
50 //构造函数
51 public AuthorComparer(string sortExpression)
52 {
53 _reverse = sortExpression.ToLowerInvariant().EndsWith(" desc");
54 if (_reverse)
55 {
56 _sortColumn = sortExpression.Substring(0, sortExpression.Length - 5);
57 }
58 else
59 {
60 _sortColumn = sortExpression;
61 }
62 }
63 //实现接口的Compare方法 比较两个Author对象实例
64 public int Compare(Author a,Author b)
65 {
66 int retVal = 0;
67 switch (_sortColumn)
68 {
69 case "ID":
70 retVal = String.Compare(a.ID, b.ID, StringComparison.InvariantCultureIgnoreCase);
71 break;
72 case "FirstName":
73 retVal = String.Compare(a.FirstName, b.FirstName, StringComparison.InvariantCultureIgnoreCase);
74 break;
75 case "LastName":
76 retVal = String.Compare(a.LastName, b.LastName, StringComparison.InvariantCultureIgnoreCase);
77 break;
78 case "State":
79 retVal = String.Compare(a.State, b.State, StringComparison.InvariantCultureIgnoreCase);
80 break;
81 }
82 return (retVal*(_reverse?-1:1));
83 }
84 }
85}
86
using System;2
using System.Collections.Generic;3
using System.Text;4
using System.Data;5
6
namespace LogicLibrary7
{8
public class AuthorsComponent9
{10
//构造函数11
public AuthorsComponent()12
{ }13
//通过地址获取信息14
public List<Author> GetAuthorsByState(string state, string sortExpression)15
{16
List<Author> authors = new List<Author>();17
DataSet ds = AuthorDB.AuthorDB.GetAuthorsByState(state);18
foreach (DataRow row in ds.Tables["authors"].Rows)19
{20
authors.Add(new Author((string)row["id"],(string)row["firstname"],(string)row["lastname"],(string)row["state"]));21
}22
authors.Sort(new AuthorComparer(sortExpression));23
return authors;24
}25
//获取地址26
public List<string> GetStates()27
{28
List<string> states = new List<string>();29
DataSet ds = AuthorDB.AuthorDB.GetStates();30
foreach (DataRow row in ds.Tables["state"].Rows)31
states.Add((string)row["state"]);32
return states;33
} 34
//修改信息35
public int UpdateAuthor(Author a)36
{37
return AuthorDB.AuthorDB.UpdateAuthor(a.ID,a.LastName,a.FirstName,a.State);38
}39
//修改信息40
public int UpdateAuthor(string ID,string FirstName,string LastName,string State)41
{42
return AuthorDB.AuthorDB.UpdateAuthor(ID,FirstName,LastName,State);43
}44
}45
//自定义排序 实现IComparer接口46
public class AuthorComparer : IComparer<Author>47
{48
private string _sortColumn;49
private bool _reverse;50
//构造函数51
public AuthorComparer(string sortExpression)52
{53
_reverse = sortExpression.ToLowerInvariant().EndsWith(" desc");54
if (_reverse)55
{56
_sortColumn = sortExpression.Substring(0, sortExpression.Length - 5);57
}58
else59
{60
_sortColumn = sortExpression;61
}62
}63
//实现接口的Compare方法 比较两个Author对象实例64
public int Compare(Author a,Author b)65
{66
int retVal = 0;67
switch (_sortColumn)68
{69
case "ID":70
retVal = String.Compare(a.ID, b.ID, StringComparison.InvariantCultureIgnoreCase);71
break;72
case "FirstName":73
retVal = String.Compare(a.FirstName, b.FirstName, StringComparison.InvariantCultureIgnoreCase);74
break;75
case "LastName":76
retVal = String.Compare(a.LastName, b.LastName, StringComparison.InvariantCultureIgnoreCase);77
break;78
case "State":79
retVal = String.Compare(a.State, b.State, StringComparison.InvariantCultureIgnoreCase);80
break;81
}82
return (retVal*(_reverse?-1:1));83
}84
} 85
}86
接下来我们要实现的是用户界面层：[注：界面层要引用LogicLibrary项目生成的dll文件]
用户界面层实现比较简单，这要归功于asp.net2.0中为我们提供的两个用户控件GridView和ObjectDataSource.[具体使用方法自己搜索]
我们先在页面上拖放1个DropDownList,2个ObjectDataSource,1个GridView控件。
具体设置请参见如下页面代码[注：加粗部分要特别注意]
1<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
2
3<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
4<html xmlns="http://www.w3.org/1999/xhtml">
5<head runat="server">
6 <title>Untitled Page</title>
7</head>
8<body>
9 <form id="form1" runat="server">
10 <div>
11 State:
12 <asp:DropDownList ID="DropDownList1" runat="server" DataSourceID="obj1" AutoPostBack="True"
13 Width="255px">
14 </asp:DropDownList>
15 <asp:ObjectDataSource ID="obj1" runat="server" TypeName="LogicLibrary.AuthorsComponent"
16 SelectMethod="GetStates"></asp:ObjectDataSource>
17 <asp:GridView ID="gridview1" runat="server" DataSourceID="objectdatasource2" AllowPaging="True"
18 AllowSorting="True" AutoGenerateColumns="False" EnableTheming="True" BackColor="White"
19 BorderColor="#CCCCCC" BorderStyle="None" BorderWidth="1px" CellPadding="3" Width="308px">
20 <Columns>
21 <asp:CommandField ShowEditButton="True" CancelText="Cancle" />
22 <asp:BoundField DataField="id" HeaderText="id" SortExpression="ID" />
23 <asp:BoundField DataField="firstname" HeaderText="firstname" SortExpression="FristName" />
24 <asp:BoundField DataField="lastname" HeaderText="lastname" SortExpression="LastName" />
25 <asp:BoundField DataField="state" HeaderText="state" SortExpression="State" />
26 </Columns>
27 <FooterStyle BackColor="White" ForeColor="#000066" />
28 <RowStyle ForeColor="#000066" />
29 <SelectedRowStyle BackColor="#669999" Font-Bold="True" ForeColor="White" />
30 <PagerStyle BackColor="White" ForeColor="#000066" HorizontalAlign="Left" />
31 <HeaderStyle BackColor="#006699" Font-Bold="True" ForeColor="White" />
32 </asp:GridView>
33 <asp:ObjectDataSource ID="objectdatasource2" runat="server" TypeName="LogicLibrary.AuthorsComponent"
34 DataObjectTypeName="LogicLibrary.Author" SelectMethod="GetAuthorsByState" UpdateMethod="UpdateAuthor"
35 SortParameterName="sortExpression">
36 <SelectParameters>
37 <asp:ControlParameter ControlID="DropDownList1" Name="state" PropertyName="SelectedValue" />
38 </SelectParameters>
39 </asp:ObjectDataSource>
40 </div>
41 </form>
42</body>
43</html>
44
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>2
3
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">4
<html xmlns="http://www.w3.org/1999/xhtml">5
<head runat="server">6
<title>Untitled Page</title>7
</head>8
<body>9
<form id="form1" runat="server">10
<div>11
State:12
<asp:DropDownList ID="DropDownList1" runat="server" DataSourceID="obj1" AutoPostBack="True"13
Width="255px">14
</asp:DropDownList>15
<asp:ObjectDataSource ID="obj1" runat="server" TypeName="LogicLibrary.AuthorsComponent"16
SelectMethod="GetStates"></asp:ObjectDataSource>17
<asp:GridView ID="gridview1" runat="server" DataSourceID="objectdatasource2" AllowPaging="True"18
AllowSorting="True" AutoGenerateColumns="False" EnableTheming="True" BackColor="White"19
BorderColor="#CCCCCC" BorderStyle="None" BorderWidth="1px" CellPadding="3" Width="308px">20
<Columns>21
<asp:CommandField ShowEditButton="True" CancelText="Cancle" />22
<asp:BoundField DataField="id" HeaderText="id" SortExpression="ID" />23
<asp:BoundField DataField="firstname" HeaderText="firstname" SortExpression="FristName" />24
<asp:BoundField DataField="lastname" HeaderText="lastname" SortExpression="LastName" />25
<asp:BoundField DataField="state" HeaderText="state" SortExpression="State" />26
</Columns>27
<FooterStyle BackColor="White" ForeColor="#000066" />28
<RowStyle ForeColor="#000066" />29
<SelectedRowStyle BackColor="#669999" Font-Bold="True" ForeColor="White" />30
<PagerStyle BackColor="White" ForeColor="#000066" HorizontalAlign="Left" />31
<HeaderStyle BackColor="#006699" Font-Bold="True" ForeColor="White" />32
</asp:GridView>33
<asp:ObjectDataSource ID="objectdatasource2" runat="server" TypeName="LogicLibrary.AuthorsComponent"34
DataObjectTypeName="LogicLibrary.Author" SelectMethod="GetAuthorsByState" UpdateMethod="UpdateAuthor"35
SortParameterName="sortExpression">36
<SelectParameters>37
<asp:ControlParameter ControlID="DropDownList1" Name="state" PropertyName="SelectedValue" />38
</SelectParameters>39
</asp:ObjectDataSource>40
</div>41
</form>42
</body>43
</html>44
OK,一切都搞定了。以上代码已经在winxp+vs.net2005上测试通过。它可以实现数据的显示、筛选、排序功能。我们来看看运行结果：
附：Access数据库的XML文件
1<?xml version="1.0" encoding="UTF-8"?>
2<root xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:od="urn:schemas-microsoft-com:officedata">
3 <xsd:schema>
4 <xsd:element name="dataroot">
5 <xsd:complexType>
6 <xsd:sequence>
7 <xsd:element ref="authors" minOccurs="0" maxOccurs="unbounded"/>
8 </xsd:sequence>
9 <xsd:attribute name="generated" type="xsd:dateTime"/>
10 </xsd:complexType>
11 </xsd:element>
12 <xsd:element name="authors">
13 <xsd:annotation>
14 <xsd:appinfo>
15 <od:index index-name="id" index-key="id " primary="no" unique="no" clustered="no"/>
16 </xsd:appinfo>
17 </xsd:annotation>
18 <xsd:complexType>
19 <xsd:sequence>
20 <xsd:element name="id" minOccurs="0" od:jetType="text" od:sqlSType="nvarchar">
21 <xsd:simpleType>
22 <xsd:restriction base="xsd:string">
23 <xsd:maxLength value="50"/>
24 </xsd:restriction>
25 </xsd:simpleType>
26 </xsd:element>
27 <xsd:element name="firstname" minOccurs="0" od:jetType="text" od:sqlSType="nvarchar">
28 <xsd:simpleType>
29 <xsd:restriction base="xsd:string">
30 <xsd:maxLength value="50"/>
31 </xsd:restriction>
32 </xsd:simpleType>
33 </xsd:element>
34 <xsd:element name="lastname" minOccurs="0" od:jetType="text" od:sqlSType="nvarchar">
35 <xsd:simpleType>
36 <xsd:restriction base="xsd:string">
37 <xsd:maxLength value="50"/>
38 </xsd:restriction>
39 </xsd:simpleType>
40 </xsd:element>
41 <xsd:element name="state" minOccurs="0" od:jetType="text" od:sqlSType="nvarchar">
42 <xsd:simpleType>
43 <xsd:restriction base="xsd:string">
44 <xsd:maxLength value="50"/>
45 </xsd:restriction>
46 </xsd:simpleType>
47 </xsd:element>
48 </xsd:sequence>
49 </xsd:complexType>
50 </xsd:element>
51 </xsd:schema>
52 <dataroot xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" generated="2007-04-16T15:32:00">
53 <authors>
54 <id>1</id>
55 <firstname>Wang</firstname>
56 <lastname>First</lastname>
57 <state>usa</state>
58 </authors>
59 <authors>
60 <id>2</id>
61 <firstname>Second</firstname>
62 <lastname>Li</lastname>
63 <state>Japan</state>
64 </authors>
65 <authors>
66 <id>3</id>
67 <firstname>Third</firstname>
68 <lastname>Zhao</lastname>
69 <state>USA</state>
70 </authors>
71 <authors>
72 <id>5</id>
73 <firstname>Four</firstname>
74 <lastname>Guo</lastname>
75 <state>China</state>
76 </authors>
77 <authors>
78 <id>4</id>
79 <firstname>Five</firstname>
80 <lastname>Qi</lastname>
81 <state>China</state>
82 </authors>
83 </dataroot>
84</root>
85
<?xml version="1.0" encoding="UTF-8"?>2
<root xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:od="urn:schemas-microsoft-com:officedata">3
<xsd:schema>4
<xsd:element name="dataroot">5
<xsd:complexType>6
<xsd:sequence>7
<xsd:element ref="authors" minOccurs="0" maxOccurs="unbounded"/>8
</xsd:sequence>9
<xsd:attribute name="generated" type="xsd:dateTime"/>10
</xsd:complexType>11
</xsd:element>12
<xsd:element name="authors">13
<xsd:annotation>14
<xsd:appinfo>15
<od:index index-name="id" index-key="id " primary="no" unique="no" clustered="no"/>16
</xsd:appinfo>17
</xsd:annotation>18
<xsd:complexType>19
<xsd:sequence>20
<xsd:element name="id" minOccurs="0" od:jetType="text" od:sqlSType="nvarchar">21
<xsd:simpleType>22
<xsd:restriction base="xsd:string">23
<xsd:maxLength value="50"/>24
</xsd:restriction>25
</xsd:simpleType>26
</xsd:element>27
<xsd:element name="firstname" minOccurs="0" od:jetType="text" od:sqlSType="nvarchar">28
<xsd:simpleType>29
<xsd:restriction base="xsd:string">30
<xsd:maxLength value="50"/>31
</xsd:restriction>32
</xsd:simpleType>33
</xsd:element>34
<xsd:element name="lastname" minOccurs="0" od:jetType="text" od:sqlSType="nvarchar">35
<xsd:simpleType>36
<xsd:restriction base="xsd:string">37
<xsd:maxLength value="50"/>38
</xsd:restriction>39
</xsd:simpleType>40
</xsd:element>41
<xsd:element name="state" minOccurs="0" od:jetType="text" od:sqlSType="nvarchar">42
<xsd:simpleType>43
<xsd:restriction base="xsd:string">44
<xsd:maxLength value="50"/>45
</xsd:restriction>46
</xsd:simpleType>47
</xsd:element>48
</xsd:sequence>49
</xsd:complexType>50
</xsd:element>51
</xsd:schema>52
<dataroot xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" generated="2007-04-16T15:32:00">53
<authors>54
<id>1</id>55
<firstname>Wang</firstname>56
<lastname>First</lastname>57
<state>usa</state>58
</authors>59
<authors>60
<id>2</id>61
<firstname>Second</firstname>62
<lastname>Li</lastname>63
<state>Japan</state>64
</authors>65
<authors>66
<id>3</id>67
<firstname>Third</firstname>68
<lastname>Zhao</lastname>69
<state>USA</state>70
</authors>71
<authors>72
<id>5</id>73
<firstname>Four</firstname>74
<lastname>Guo</lastname>75
<state>China</state>76
</authors>77
<authors>78
<id>4</id>79
<firstname>Five</firstname>80
<lastname>Qi</lastname>81
<state>China</state>82
</authors>83
</dataroot>84
</root>85
