Hi all. Let me introduce you my case. I'm developing a workers control system
with pure java servlets. I'm using Visual Age for java, IBM Http server and IBM
Websphere application server. I'm curretly working in the administration
module. The idea is to provide a service indenpendent of the database model.
What i'm trying to do is a servlet that query the DB structure and render in a
web page the neccesary fields for input a new record, and at the same time
displays all availables records in the table with options to deleto or modify
the record. Here is the code i wrote:
package com.ibm.pss.servlets;
import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class TableMgrServlet extends ServletConnection {
public TableMgrServlet() {
super();
setDbName("MODELO");
setDriverName("COM.ibm.db2.jdbc.app.DB2Driver");
setPoolName("MyConnectionPool");
}
public void doGet(javax.servlet.http.HttpServletRequest req,
javax.servlet.http.HttpServletResponse res) throws
javax.servlet.ServletException, java.io.IOException {
res.setContentType("text/html");
PrintWriter out = res.getWriter();
out.println("<HTML><HEAD><TITLE>AJFDIASJDKASJD</TITLE></HEAD><BODY
BGCOLOR=\"#003333\" LINK=\"#FF3300\" VLINK=\"#FF6600\" TEXT=\"#FFFFFF\"
TOPMARGIN=0 LEFTMARGIN=0 MARGINWIDTH=0 MARGINHEIGHT=0><CENTER>");
HttpSession session = req.getSession(false);
setUserName((String)session.getValue("com.ibm.pss.servlets.LoginServlet.UserName"));
setUserPassword((String)session.getValue("com.ibm.pss.servlets.LoginServlet.UserPassword"));
connect();
try{
TableMetaDataMgr TMetaData = new
TableMetaDataMgr(getConnection(),getParameter(req,"tabla"),out);
releaseConnection();
}catch(Exception e){ out.println(e); }
out.println("</CENTER></BODY></HTML>");
out.close();
}
package com.ibm.pss.servlets;
import java.io.*;
import java.sql.*;
import java.util.*;
public class TableMetaDataMgr {
private Connection conn = null;
private String TableName = null;
private PrintWriter out;
private DatabaseMetaData MyMetaData = null;
public TableMetaDataMgr(Connection con, String TableName,PrintWriter out) {
super();
this.conn = con;
this.TableName = TableName;
this.out= out;
try{
MyMetaData = conn.getMetaData();
this.columnsExtract();
}catch(Exception e) { out.println(e);}
}
private synchronized void columnsExtract() {
ResultSet rs2 = null;
Statement stmt = null;
ResultSetMetaData rsMetaData = null;
try{
stmt = conn.createStatement();
rs2= stmt.executeQuery("SELECT * FROM DB2ADMIN."+TableName);
rsMetaData = rs2.getMetaData();
out.println("<CENTER><FORM
ACTION=\"http://seniat1/servlet/AddRecordServlet\" METHOD=\"GET\">");
out.println("<TABLE BORDER=\"0\">");
int i;
for(i=0;i<rsMetaData.getColumnCount();i++){
out.println("<TR>");
out.println("<TD>"+rsMetaData.getColumnName(i+1)+"</TD>");
out.println("<TD><INPUT TYPE=\"TEXT\"
NAME=\""+rsMetaData.getColumnName(i+1)+"\"></td>");
}
out.println("</TABLE>");
out.println("<INPUT TYPE=\"SUBMIT\" VALUE=\"AGREGAR\">");
out.println("<INPUT TYPE=\"RESET\"
VALUE=\"CANCELAR\"></FORM></CENTER>");
out.println("<br><br>");
out.println("<CENTER><FORM
ACTION=\"http://seniat1/servlet/UpdateDeleteRecordServlet\" METHOD=\"GET\">");
out.println("<TABLE BORDER=\"1\" cellpadding=\"1\"
cellspacing=\"1\">");
out.println("<THEAD><H1><CENTER>"+TableName+"</CENTER></H1></THEAD>");
out.println("<TR>");
for(i=0;i<rsMetaData.getColumnCount();i++){
out.println("<TH>"+rsMetaData.getColumnName(i+1)+"</TH>");
}
out.println("</TR>");
while(rs2.next()){
out.println("<TR>");
for(i=0;i<rsMetaData.getColumnCount();i++){
out.println("<TD>"+rs2.getString(i+1)+"</TD>");
}
out.println("<TD><INPUT TYPE=\"SUBMIT\"
VALUE=\"MODIFICAR\"><BR><INPUT TYPE=\"SUBMIT\" VALUE=\"ELIMINAR \"></TD>");
out.println("</TR>");
}
out.println("</TABLE></FORM></CENTER>");
}catch(Exception e){ out.println(e); }
}
}
The super class ServletConnection is for the Connection pool managment, so it
doesn't care. The problem occurs when the table contents more than 100 records.
When this happend the web page render wrong!. I don't konw much about html but
i guess it must be a HTML or browser problem.
The only solution that i thought was to divide the ResultSet in short pieces of
about 15 records and provide a "next" link, but the ResultSet interface doesn't
provide methods to set the cursor. I'd need this for record count and for allow
the user to go foward and backward as needed. Any idea?
Esteban Felipe
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