Problem to connect to mysql from servlet using a javabean

Question

Hi,
I'm new here and beginner on java to.
I have problem to connect to MySql database, by a connection javabean.
It's the following: a HTML page calls a servlet and this servlet imports the package connection javabean.
It has no problem when I establish the connection inside the servlet, with all its methods (public and private). But i want to separate the code connection from servlet.
Detail: there is no problem, using the javabean to connect to MS Access database.
I put "mysql-connector-java-3.1.12-bin.jar" file inside WEB-INF/lib application and common/lib directories.
I set the classpath:
SET CLASSPATH=%CATALINA_HOME%\COMMON\LIB\mysql-connector-java-3.1.12-bin.jar;%CLASSPATH%
I think that the servlet cannot create an instance of javabean, because passed by catch exception of the servlet init method.
But I don't know why.
Please Why?
Below there are the fragment of errors, servlet code e javabean code.
Thank you.
Zovao.
HTTP Status 500 -
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
java.lang.NullPointerException
at CadServletFileBeanConexArq.doPost(CadServletFileBeanConexArq.java:47)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:716)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:809)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:200)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:146)
Note: The line 47 is calling insertIntoDB javabean method.
========///////////////===============
// Here is the servlet CadServletFileBeanConexArq.java
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
import java.sql.*;
import conJdbc.*;
public class CadServletFileBeanConexArq extends HttpServlet {
public ConexPed connect = null;
private String driver = "com.mysql.jdbc.Driver";
private String URL = "jdbc:mysql://localhost:3306/cadastro";
public void init( ServletConfig config )
throws ServletException
super.init( config );
try
connect = new ConexPed(driver, URL, "monty", "some_pass");
catch ( Exception e )
e.printStackTrace();
connect = null;
public void doPost( HttpServletRequest req,
HttpServletResponse res )
throws ServletException
boolean success = true;
String email, nome, sobrenome, produto, valor;
email = req.getParameter( "Email" );
nome = req.getParameter( "Nome" );
sobrenome = req.getParameter( "Sobrenome" );
produto = req.getParameter( "Produto" );
valor = req.getParameter( "Valor" );
res.setContentType( "text/html" );
if ( email.length() > 0 && nome.length() > 0 && sobrenome.length() > 0 && valor.length() > 0 )
/* inserting data */
success = connect.insertIntoDB(
"'" + email + "','" + nome + "','" + sobrenome + "','" + produto + "'", Double.parseDouble(valor) );
//closing connection
public void destroy()
connect.fecharConexao();
=============///////////////============
Here is the JavaBean.
package conJdbc;
import java.sql.*;
public class ConexPed
public Connection connection;
public Statement statement;
public ConexPed (String driver, String urlServidor, String user, String password)
try
Class.forName(driver);
connection = DriverManager.getConnection(urlServidor,user,password);
catch (ClassNotFoundException ex)
System.out.println("N�o foi poss�vel encontrar a classe do Driver: " + driver);
catch (SQLException ex)
System.out.println("N�o foi poss�vel conectar ao servidor");
try
statement = connection.createStatement();
catch (SQLException ex)
System.out.println("N�o foi poss�vel criar a statement");
*Inserting data to database
public synchronized boolean insertIntoDB( String stringtoinsert, double valor)
try
statement.executeUpdate( "INSERT INTO pedido values (" + stringtoinsert + " , " + valor + ");" );
catch ( Exception e ) {
System.err.println(
"ERROR: Problemas ao adicionar nova entrada" );
e.printStackTrace();
return false;
return true;
* Close statement.
public void fecharStatement()
try
statement.close();
catch (SQLException ex)
ex.printStackTrace();
* close database
public void fecharConexao()
try
connection.close();
catch (SQLException ex)
ex.printStackTrace();
}

Answer 1

Hi,
I'm new here and beginner on java to.
I have problem to connect to MySql database, by a connection javabean.
It's the following: a HTML page calls a servlet and this servlet imports the package connection javabean.
It has no problem when I establish the connection inside the servlet, with all its methods (public and private). But i want to separate the code connection from servlet.
Detail: there is no problem, using the javabean to connect to MS Access database.
I put "mysql-connector-java-3.1.12-bin.jar" file inside WEB-INF/lib application and common/lib directories.
I set the classpath:
SET CLASSPATH=%CATALINA_HOME%\COMMON\LIB\mysql-connector-java-3.1.12-bin.jar;%CLASSPATH%
I think that the servlet cannot create an instance of javabean, because passed by catch exception of the servlet init method.
But I don't know why.
Please Why?
Below there are the fragment of errors, servlet code e javabean code.
Thank you.
Zovao.
HTTP Status 500 -
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
java.lang.NullPointerException
at CadServletFileBeanConexArq.doPost(CadServletFileBeanConexArq.java:47)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:716)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:809)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:200)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:146)
Note: The line 47 is calling insertIntoDB javabean method.
========///////////////===============
// Here is the servlet CadServletFileBeanConexArq.java
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
import java.sql.*;
import conJdbc.*;
public class CadServletFileBeanConexArq extends HttpServlet {
public ConexPed connect = null;
private String driver = "com.mysql.jdbc.Driver";
private String URL = "jdbc:mysql://localhost:3306/cadastro";
public void init( ServletConfig config )
throws ServletException
super.init( config );
try
connect = new ConexPed(driver, URL, "monty", "some_pass");
catch ( Exception e )
e.printStackTrace();
connect = null;
public void doPost( HttpServletRequest req,
HttpServletResponse res )
throws ServletException
boolean success = true;
String email, nome, sobrenome, produto, valor;
email = req.getParameter( "Email" );
nome = req.getParameter( "Nome" );
sobrenome = req.getParameter( "Sobrenome" );
produto = req.getParameter( "Produto" );
valor = req.getParameter( "Valor" );
res.setContentType( "text/html" );
if ( email.length() > 0 && nome.length() > 0 && sobrenome.length() > 0 && valor.length() > 0 )
/* inserting data */
success = connect.insertIntoDB(
"'" + email + "','" + nome + "','" + sobrenome + "','" + produto + "'", Double.parseDouble(valor) );
//closing connection
public void destroy()
connect.fecharConexao();
=============///////////////============
Here is the JavaBean.
package conJdbc;
import java.sql.*;
public class ConexPed
public Connection connection;
public Statement statement;
public ConexPed (String driver, String urlServidor, String user, String password)
try
Class.forName(driver);
connection = DriverManager.getConnection(urlServidor,user,password);
catch (ClassNotFoundException ex)
System.out.println("N�o foi poss�vel encontrar a classe do Driver: " + driver);
catch (SQLException ex)
System.out.println("N�o foi poss�vel conectar ao servidor");
try
statement = connection.createStatement();
catch (SQLException ex)
System.out.println("N�o foi poss�vel criar a statement");
*Inserting data to database
public synchronized boolean insertIntoDB( String stringtoinsert, double valor)
try
statement.executeUpdate( "INSERT INTO pedido values (" + stringtoinsert + " , " + valor + ");" );
catch ( Exception e ) {
System.err.println(
"ERROR: Problemas ao adicionar nova entrada" );
e.printStackTrace();
return false;
return true;
* Close statement.
public void fecharStatement()
try
statement.close();
catch (SQLException ex)
ex.printStackTrace();
* close database
public void fecharConexao()
try
connection.close();
catch (SQLException ex)
ex.printStackTrace();
}