實現論壇樹型結構的算法很多，這里是一個不用遞歸實現樹型結構的算法
1.演示表的結構：
表名：mybbslist
字段 數據類型 說明
BBSID 自動編號
RootID Int 根帖ID，本身為根帖則RootID = BBSID
FID Int 父帖ID，上一層帖子的ID，如是根帖則FID = 0
DEPTH Int 根帖Level=0，其他依據回復的深度遞增
BBSSubject Char 主題 |
2.創建表（可根據此表的結構在ACCESS中創建表）：
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.演示論壇樹型結構的JSP程序，注意此程序只對一個根貼進行了演示（數據庫用ACCESS）
<%@ page contentType="text/html;charset=gb2312" %>
<%@ page import="java.io.*" %>
<%@ page import="java.sql.*" %>
<%
String driverName = "sun.jdbc.odbc.JdbcOdbcDriver";
String connURL= "jdbc:odbc:cwb";
Connection conn = null;
Statement stmt = null;
int intRowCount;
out.print("顯示論壇樹形結構");
out.print("<br><br>");
try {
Class.forName(driverName);
conn = DriverManager.getConnection(connURL);
stmt = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY);
String sql="select * from mybbslist order by rootid desc,depth,fid,bbsid";
ResultSet rs = stmt.executeQuery(sql);
if (rs.next()){
rs.last();
intRowCount=rs.getRow();
out.print("論壇樹中有");
out.print(intRowCount);
out.print("個葉子節點");
rs.first();
int j=0;
int Depth = 0;
out.print("<ul>");
while(j<intRowCount){
int 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=rsDepth;
j=j+1;
rs.next();
}
for(int i=0;i<Depth+1;i=i+1) {
out.print("</ul>");
}
}else{
out.print("數據庫中無記錄");
}
}catch (SQLException E) {
out.println("SQLException: " + E.getMessage());
out.println("SQLState: " + E.getSQLState());
out.println("VendorError: " + E.getErrorCode());
}
%>
<% //關閉mysql連接
try {
if(conn!=null) conn.close();
} catch (Exception ex) {
System.err.println("closeConn: " + ex.getMessage());
}
%>
|