产品目录/论坛 树形结构的实现

本例采用Access做为实例，所有还有很多要改进的地方。
请读者自已改进

package product;
import Java.sql.*;
public class ConnectDB{
String strDBDriver="sun.JDBC.odbc.JdbcOdbcDriver";
String strConnstr="jdbc:odbc:product";
Connection conn=null;
ResultSet rs=null;
Statement stmt=null;
// Statement stmt=null;
//构造函数
public ConnectDB(){
try{
Class.forName(strDBDriver); conn=DriverManager.getConnection(strConnstr);
stmt=conn.createStatement();
}
catch(Exception e){
System.out.println(e);
}
}

public ResultSet execute(String sql){
rs=null;
try{

rs=stmt.executeQuery(sql);
}
catch(SQLException e){
System.out.println(e.getMessage());
}
return rs;
}

public Connection getConnection(){
return conn;
}

public boolean close(){
try{
if(this.rs!=null){
this.rs.close();
}
if(stmt!=null){
this.stmt.close();
}
if(conn!=null){
this.conn.close();
}
return true;
}catch(Exception err){
return false;
}
}

}
//=======================================
package product;
import java.sql.*;
public class catalog
{
ConnectDB conn=new ConnectDB();
String str=null;
String sql=null;
ResultSet rs=null;
String AncestorID,LinkStr;

public String getCatalog(){

str="<select name=\"FatherID\" class=\"p9\">\n"
"<option value=\"-1\" selected>请选择父类</option>\n";
String sql=null;
sql="select * from catalog order by AncestorID,Linkstr";
ResultSet rs=conn.execute(sql);
try{
while (rs.next()) {
str=str "<option value=" rs.getString("Productid") ">";
int nbspCount=rs.getString("LinkStr").length()-1;
for(int i=0;i<nbspCount;i ){
str=str " ";
}
if(nbspCount>0)
str=str "┠" rs.getString("title") "</option>\n";
else
str=str rs.getString("title") "</option>\n";

}
str=str "</select>";
rs.close();
}
catch(SQLException e){
System.out.println(e.getMessage());
}
return str;
}
public void setCatalog(String CatalogName,String FatherID){
int ChildNum=0;
if(FatherID.compareTo("-1")!=0){
sql="select AncestorID,ChildNum,linkstr from catalog where productid=" FatherID;
//out.println(sql);
try{
rs=conn.execute(sql);
if(rs.next()){
AncestorID=rs.getString("AncestorID");
ChildNum=rs.getInt("ChildNum");
LinkStr=rs.getString("linkstr");
}
else{
AncestorID="";
LinkStr="1";
ChildNum=0;
}
LinkStr=LinkStr (ChildNum 1);
//out.println(AncestorID ":" LinkStr ":" ChildNum);
sql="insert into catalog(title,fatherID,AncestorID,LinkStr) values(''" CatalogName "'',''" FatherID "'',''" AncestorID "'',''" LinkStr "'')";
//out.println(sql);
conn.execute(sql);
sql="update catalog set childNum=" (ChildNum 1) " where productID=" FatherID;
//out.println("<br>" sql);
conn.execute(sql);
}catch(Exception e){
System.out.println(e);
}

}else{
sql="insert into catalog(title,fatherID,LinkStr) values(''" CatalogName "'',''" FatherID "'',''1'')";
//out.println(sql);
try{
conn.execute(sql);
sql="select top 1 productID from catalog order by productID desc ";
rs=conn.execute(sql);
if(rs.next()){
AncestorID=rs.getString("productID");
}
else{
AncestorID="";
}
rs.close();
sql="update catalog set AncestorID=''" AncestorID "'' where productID=" AncestorID;
//out.println(sql);
conn.execute(sql);
}catch(Exception e){
System.out.println(e);

}

}//end if

if(rs!=null){
try{
rs.close();
}catch(Exception e){
System.out.println(e);
}
}

}

public void deleteCatalog(String FatherID){
int tempData=0;
sql="select fatherID,linkstr,AncestorID from catalog where >rs=conn.execute(sql);
try{
if(rs.next()){
tempData=rs.getInt("fatherID");
LinkStr=rs.getString("linkstr");
AncestorID=rs.getString("AncestorID");
}

try{rs.close();}
catch(Exception e){
System.out.println(e);
}
sql="delete from catalog where ProductID=" FatherID;
// out.println(sql);
try{
conn.execute(sql);
}catch(Exception e){
System.out.println(e);
}
sql="delete from catalog where linkstr like ''" LinkStr "%'' and AncestorID=" AncestorID;
//out.println(sql);
try{
conn.execute(sql);
}catch(Exception e){
System.out.println(e);
}
sql="update catalog set ChildNum=ChildNum-1 where productID=" tempData;
//out.println(sql);
try{
conn.execute(sql);
}catch(Exception e){
System.out.println(e);
}
}catch(Exception e){
System.out.println(e);
}
} //end public

public void updateCatalog(int id){

}

public String getCatalog(int id){

str="<select name=\"FatherID\" class=\"p9\">\n"
"<option value=\"-1\" >请选择父类</option>\n";

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