Recursive implementation of tree-type directory database +jsp+javabean

js| Recursion | data | database

Recursive implementation of tree-type directory (i) database +jsp+javabean

<%@ page contenttype= "text/html; charset=gb2312 "language=" java "import=" java.sql.* "errorpage=" "%>"
<!--
Database structure:
Library Name: Test
Table Name: Tree
CREATE TABLE [dbo]. [Tree] (
[ID] [int] IDENTITY (1, 1) not NULL,
[ParentID] [INT] Not NULL,
[Message] [varchar] (m) COLLATE chinese_prc_ci_as NULL
)
In order to achieve better results, there are five small pictures prepared
Plus: http://www.webjx.com/htmldata/2005-09-27/plus.gif
Minus sign: http://www.webjx.com/htmldata/2005-09-27/minus.gif
Open folder: Http://www.webjx.com/htmldata/2005-09-27/openfold.gif
Closed folder: Http://www.webjx.com/htmldata/2005-09-27/closedfold.gif
Whiteboard: Http://www.webjx.com/htmldata/2005-09-27/white.gif
-->
<%!//, it's not written javabean here.
Class CN {//Connection database, take Ms-sql for example
String jdbcdriver= "Com.microsoft.jdbc.sqlserver.SQLServerDriver";//jdbc Drive
String connectionstring= "jdbc:microsoft:sqlserver://localhost:1433;databasename=test";//Database connection string
String user= "sa";//Database user name
String pass= "";//Database Password
Connection Conn=null;
ResultSet Rs=null;

Public cn () {
try {
Class.forName (Jdbcdriver);
catch (ClassNotFoundException e) {
System.err.println (E.tostring ());
}
}

Public ResultSet executequery (String sql) {
Rs=null;
try {
Conn=drivermanager.getconnection (Connectionstring,user,pass);
Statement stmt=conn.createstatement (resultset.type_scroll_sensitive,resultset.concur_updatable);
Rs=stmt.executequery (SQL);
}
catch (SQLException e) {
System.err.println (E.tostring ());
}
Return RS;
}

public void executeupdate (String sql) {
try {
Conn=drivermanager.getconnection (Connectionstring,user,pass);
Statement stmt=conn.createstatement (resultset.type_scroll_sensitive,resultset.concur_updatable);
Stmt.executeupdate (SQL);
}
catch (SQLException e) {
System.err.println (E.tostring ());
}
}
}

Class Tree {
CN conn=new cn ();
public void init (Javax.servlet.jsp.JspWriter out,javax.servlet.http.httpservletrequest request) throws Exception {
Out.println ("<title> jsp seed Tree </title>");
Dowith (Request);
Buildtree (out,0,0);//Initial call
}

private void Dowith (Javax.servlet.http.HttpServletRequest request) {
if (Request.getparameter ("ParentID") ==null| | Request.getparameter ("ParentID"). Equals ("")) return;
String action=request.getparameter ("action");
if (Action.equals ("add")
Conn.executeupdate ("INSERT INTO Tree" (parentid,message) VALUES (' "+request.getparameter (" ParentID ") +" ', ' "+ Request.getparameter ("message") + "')";
else if (action.equals ("delete"))
Conn.executeupdate ("Delete from tree where id=" +request.getparameter ("ParentID") + "or parentid=" + Request.getparameter ("ParentID"));
}

public void Buildtree (Javax.servlet.jsp.JspWriter out,int parentid,int level) throws Exception {
level++;
ResultSet rs=conn.executequery ("select * from tree where parentid=" +parentid+ "ORDER by id");
while (Rs.next ()) {
Out.println ("<div>");
for (int i=0;i<level-1;i++)
Out.print ("if (Has_child rs.getint ("id")) {
Out.print (" Out.print ("<span +rs.getint (" id ") +" ");" style= "Cursor:default;" id= "span +rs.getint (" id ") +" > "+rs.getstring ("message") + "id=" +rs.getint ("id") + "</span>");
Out.println ("<div style=" display:none; "id=" div "+rs.getint (" id ") +" > ");
Buildtree (Out,rs.getint ("id"), level);//Recursive call
Out.println ("</div>");
} else
Out.print (" <span +rs.getint (" id ") +" '); "style=" Cursor:default; "id=" span "+rs.getint ("id") + ">" +rs.getstring ("message") + "id=" +rs.getint ("id") + "</span>");
Out.println ("</div>");
}
Rs.close ();
Rs=null;
}

Private Boolean has_child (int parentid) throws Exception {
ResultSet rs=conn.executequery ("select * from tree where parentid=" +parentid+ "ORDER by id");
return Rs.next ();
}

Public String getOption () throws Exception {
String option= "";
ResultSet rs=conn.executequery ("SELECT * from tree order by id");
while (Rs.next ())
option+= "<option value=" "+rs.getint (" id ") +" > "+rs.getint (" id ") +" </option> ";
return option;
}
}
%>
<!--above code can be written as javabean-->
<script language= "JavaScript" ><!--this JS in order to realize the effect of the tree's expansion and shutdown-->
<!--
function Myclick (ID) {
Eval ("var div=div" +id);
Eval ("var img=img" +id);
Eval ("var im=im" +id);
Div.style.display=div.style.display!= "None"? " None ": Block";
Img.src=div.style.display!= "None"? " Http://www.webjx.com/htmldata/2005-09-27/minus.gif ":" Http://www.webjx.com/htmldata/2005-09-27/plus.gif ";
Im.src=div.style.display!= "None"? " Http://www.webjx.com/htmldata/2005-09-27/openfold.gif ":" Http://www.webjx.com/htmldata/2005-09-27/closedfold.gif ";
Img.alt=div.style.display!= "None"? " Close ": unfold";
}
function MyClick1 (ID) {
Document.form1.parentid.value=id;
}
-->
</script>
<table>
&LT;TR&GT;&LT;TD height= "valign=" "Top" >
<%
Tree Mytree=new ();
Mytree.init (out,request);
%>
</td></tr>
&LT;TR&GT;&LT;TD valign= "Top" >
<%
if (Mytree.getoption (). Equals ("")) {
%>
<form name= "Form1" action= "method=" Get ">
parentid:0-represents the root node
Message:<input type= "text" name= "message" >
<input type= "hidden" name= "ParentID" value= "0" >
<input type= "Submit" name= "action" value= "Add" >
</form>
<%} else {%>
<form name= "Form1" action= "method=" Get ">
Parentid:<select name= "ParentID" ><%=mytree.getoption ()%></select>
Message:<input type= "text" name= "message" >
<input type= "Submit" name= "action" value= "Add" > <input type= "Submit" name= "action" value= "delete" >
</form>
<%}%>
</td></tr></table>