Specific algorithms for implementing the tree structure of JSP forums

1. Structure of the demo table in the JSP Forum:

 
 

  
  
Table Name: mybbslist
  
  
Field data type description
  
  
Automatic BBSID ID
  
  
RootID Int root post ID, which is the root postRootID= ID
  
  
FID Int parent post ID, the ID of the previous post, if it is the root postFID=0 
  
  
DEPTHInt root postLevel=0, Others increase based on the depth of the reply
  
  
BBSSubject Char topic
  
  
 
 
 

2. Create a table in the JSP Forum:

 
 

  
  
create table mybbslist (  
  
  
　forumID int(20) not null,  
  
  
　bbsID int auto_increment primary key,  
  
  
　rootid int(20) not null,  
  
  
　fid int(20) not null,  
  
  
　depth int(20) not null,  
  
  
　userID int(20) not null,  
  
  
　bbsUser varchar(24) not null,  
  
  
　bbsSubject varchar(100) not null,  
  
  
　bbsContent text,  
  
  
　bbsTime varchar(30),  
  
  
　bbsRead int(20),  
  
  
　bbsReply int(20),  
  
  
INDEX forumID (forumID))  
  
  
 
 
 

3. JSP Forum Implementation of BEAN for connecting to MYSQL database

 
 

  
  
package netzero;  
  
  
import java.sql.*;  
  
  
public class mydb  
  
  
{  
  
  
String driverName = "org.gjt.mm.mysql.Driver";  
  
  
Connection conn = null;  
  
  
Statement stmt = null;  
  
  
ResultSet rs = null;  
  
  
String connURL= "jdbc:mysql://localhost/mybbs?user=root&password=how&useUnicode=true&characterEncode=8859_1";  
  
  
//String connURL= "jdbc:mysql://localhost/netzerobbs?user=root&password=how";  
  
  
public mydb()  
  
  
{  
  
  
try  
  
  
{  
  
  
Class.forName(driverName);  
  
  
}  
  
  
catch (java.lang.ClassNotFoundException e)  
  
  
{  
  
  
System.err.println("netzero(String): " + e.getMessage());  
  
  
}  
  
  
}  
  
  
 
  
  
public ResultSet executeQuery(String sql) throws SQLException  
  
  
{  
  
  
conn = DriverManager.getConnection(connURL);  
  
  
stmt = conn.createStatement();  
  
  
rs = stmt.executeQuery(sql);  
  
  
return rs;  
  
  
}  
  
  
 
  
  
public boolean closeConn()  
  
  
{  
  
  
try  
  
  
{  
  
  
if (rs!=null) rs.close();  
  
  
if (stmt!=null) stmt.close();  
  
  
if (conn!=null) conn.close();  
  
  
return true;  
  
  
}  
  
  
catch ( SQLException ex )  
  
  
{  
  
  
System.err.println("closeConn: " + ex.getMessage());  
  
  
return false;  
  
  
}  
  
  
}  
  
  
 
  
  
}  
  
  
 
 
 

4. display the JavaScript/"target =" _ blank "> JSP program of the JSP Forum

 
 

  
  
<Jsp: useBeanId="Mybbs" Scope="Session" Class="Netzero. mydb"/>
  
  
<%@ PageContentType="Text/html; charset = gb2312"%>
  
  
<%@ PageImport="Java. io .*"%>
  
  
<%@ PageImport="Java. SQL .*"%>
  
  
<%
  
  
Int intRowCount;
  
  
Out. print ("display Forum tree structure ");
  
  
Out. print ("<br> ");
  
  
Try {
  
  
StringSQL="Select * from mybbslist order by rootid desc, depth, fid, bbsid";
  
  
ResultSetRs=Mybbs. ExecuteQuery (SQL );
  
  
If (rs. next ())
  
  
{
  
  
Rs. last ();
  
  
IntRowCount=Rs. GetRow ();
  
  
Out. print ("in the Forum Tree ");
  
  
Out. print (intRowCount );
  
  
Out. print ("leaf nodes ");
  
  
Rs. first ();
  
  
IntJ=0;
  
  
IntDepth=0;
  
  
Out. print ("<ul> ");
  
  
While (j <intRowCount)
  
  
{
  
  
IntRsRsDepth= Rs. getInt ("Depth ");
  
  
If (rsDepth <Depth)
  
  
{
  
  
For (intI=1; I <Depth + 1;II= I + 1)
  
  
{
  
  
Out. print ("</ul> ");
  
  
}
  
  
}
  
  
RsRsDepth= Rs. getInt ("Depth ");
  
  
If (rsDepth> Depth)
  
  
{
  
  
Out. print ("<ul> ");
  
  
}
  
  
Out. print ("<li> ");
  
  
 
  
  
StringBbssubject=Rs. GetString ("bbssubject ");
  
  
Out. print (bbssubject );
  
  
Out. print ("</li> ");
  
  
Depth=Rs. GetInt ("Depth ");
  
  
JJ= J + 1;
  
  
Rs. next ();
  
  
}
  
  
Out. print ("</ul> ");
  
  
}
  
  
Else
  
  
{
  
  
Out. print ("no record in Database ");
  
  
}
  
  
} Catch (SQLException E ){
  
  
Out. println ("SQLException:" + E. getMessage ());
  
  
Out. println ("SQLState:" + E. getSQLState ());
  
  
Out. println ("VendorError:" + E. getErrorCode ());
  
  
}
  
  
%>
  
  
<%// Close the mysql connection
  
  
Try {
  
  
If (! Mybbs. closeConn ());
  
  
} Catch (Exception ex ){
  
  
System. err. println ("closeConn:" + ex. getMessage ());
  
  
}
  
  
%>
 
 

The preceding figure shows the specific algorithm and tree structure of the JSP forum. We hope this will help you.

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