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JSP完成论坛树型结构的具体算法

网站教程2024-06-04 阅读
[摘要]1、演示表的结构:    表名:mybbslist    字段     数据类型  说明    BBSID    自动编号      RootID    Int     根帖ID,本身为根帖则RootID = ID    FID     Int     父帖ID,上一层帖子的ID,如是根帖则FID...

  1、演示表的结构:

   表名:mybbslist
   字段     数据类型  说明
   BBSID    自动编号  
   RootID    Int     根帖ID,本身为根帖则RootID = ID
   FID     Int     父帖ID,上一层帖子的ID,如是根帖则FID = 0
   DEPTH    Int     根帖Level=0,其他依据回复的深度递增
   BBSSubject  Char    主题

  2。创建表:

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、连接MYSQL数据库的BEAN

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、显示论坛的JavaScript/" target="_blank">JSP程序

<jsp:useBean id="mybbs" scope="session" class="netzero.mydb" />
<%@ page contentType="text/html;charset=gb2312" %>
<%@ page import="java.io.*" %>
<%@ page import="java.sql.*" %>
<%
int intRowCount;
out.print("显示论坛树形结构");
out.print("<br><br>");
try {
String sql="select * from mybbslist order by rootid desc,depth,fid,bbsid";
ResultSet rs = mybbs.executeQuery(sql);
if (rs.next())
{
rs.last();
intRowCount=rs.getRow();
out.print("论坛树中有");
out.print(intRowCount);
out.print("个叶子节点");
rs.first();
int j=0;
int Depth = 0;
out.print("<ul>");
while(j<intRowCount)
{
int rsDepth=rs.getInt("Depth");
if (rsDepth<Depth)
{
for(int i=1;i<Depth+1;i=i+1)
{
out.print("</ul>");
}
}
rsDepth=rs.getInt("Depth");
if (rsDepth>Depth)
{
out.print("<ul>");
}
out.print("<li>");

String bbssubject=rs.getString("bbssubject");
out.print(bbssubject);
out.print("</li>");
Depth = rs.getInt("Depth");
j=j+1;
rs.next();
}
out.print("</ul>");
}
else
{
out.print("数据库中无记录");
}
}catch (SQLException E) {
out.println("SQLException: " + E.getMessage());
out.println("SQLState: " + E.getSQLState());
out.println("VendorError: " + E.getErrorCode());
}
%>
<% //关闭mysql连接
try {
if(!mybbs.closeConn());
} catch (Exception ex) {
System.err.println("closeConn: " + ex.getMessage());
}
%>


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