How To Create A New Java Class For Database Connection
Jan 15, 2015
I have a shop and I use visual studio.net to create an Inventory application to manage my shop. So I am familiar with vb.net codes.
Now, I'm trying to built another Inventory application for my shop using java, 'coz now I'm using Linux Ubuntu for my OS desktop and there's no visual studio.net in linux.
So in vb.net, there's a module that I use for database connection that I can call from any form that I needed.
I searched google for the equivalent module for java and there is none. But, there's an example that use a new java class.
Here's the code in MySQLConnect.java :
Java Code:
public class MySQLConnect {
static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
static final String DB_URL = "jdbc:mysql://localhost/dbInventory";
static final String USER = "root";
static final String PASS = "root";
public static Connection ConnectDb() {
[Code] ....
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Oct 7, 2014
i have a problem in connecting my jsp program in MSsql 2005 i want to create a connection in my jsp program to MSsql database but theres an error of my work here is my code
Code:
PHP Code:
<%@ page import="java.util.*" %>
<%@ page import="javax.sql.*;" %>
<%@ page import="java.sql.*;" %>
<%@ page import="java.util.Enumeration;" %>
<html>
<head><title>Sample MS connection</title></head>
[Code]...
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Jan 15, 2015
I was wondering if I could take the following code and somehow put the connection to database in it's own class without the "public static void main(String[] args)" method. That way I could call it anytime i want to open a connection to the database.
Java Code:
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class Sample {
public static void main(String[] args) throws ClassNotFoundException
[Code] ....
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Oct 27, 2014
I'm using oracle 10g Database and Java 'jdk1.7.0_45' version.I have to a create program to insert data into a table.
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May 25, 2012
I am trying to use a custom listener to initialize database connection pool (C3P0) on start up and then destroy on context shut down. The reason for that is that I whenever context is shutdown I have a memory leak because initialized connection pool is not being destroyed.
I have a static class called C3P0Utils that deals with connection pool. In my listener in contextInitialized method I have tried at first to init the pool like this :
+public void contextInitialized(ServletContextEvent sce) {+
+try {+
C3P0Utils.newInstance().init();
+} catch (PropertyVetoException ex) {+
Logger.getLogger(DatabaseInit.class.getName()).log(Level.SEVERE, null, ex);
+}+
+}+
I know that object is created. I checked it using jconsole. However it is not accessible with in the application. My second attempt was to regester the pool and then add it to the context and then when I need it read from there.
+public void contextInitialized(ServletContextEvent sce) {+
+try {+
ServletContext ctx=sce.getServletContext();
C3P0Utils.newInstance().init();
ctx.setAttribute("myDataSource", C3P0Utils.newInstance().getDataSource());
+} catch (PropertyVetoException ex) {+
Logger.getLogger(DatabaseInit.class.getName()).log(Level.SEVERE, null, ex);
+}+
+}+
However when I try to red from the context I get nothing. I try to read like this.
+(ComboPooledDataSource)ctx.getAttribute("myDataSource")+
When I print names of all of the attributes in the context I get these attributes.
Context Name
org.apache.tomcat.InstanceManager
org.apache.catalina.jsp_classpath
javax.servlet.context.tempdir
org.apache.catalina.resources
+org.apache.tomcat.JarScanner
+org.apache.jasper.compiler.TldLocationsCache
+org.springframework.web.context.WebApplicationContext.ROOT
Why I can not use anything initialized in the listener.
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Sep 16, 2014
I'm using JSF framework. I can let Netbeans to create the persistence unit and hardcodes connection parameters into the persistence.xml file or i can use resource tag in context.xml file or using another file like property file or class for holding connection parameters like username and password; what is the most secure way or expert way to use connection properties in my app or there is no difference?
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Mar 15, 2015
I am trying to make a simple login using netbeans, derby database included in netbeans and tomcat server. I made everything nice and separated: I have a model package with a class called DbConnector that has the following method:
public Connection connect() {
try {
return DriverManager.getConnection(url, user, pass);
} catch (SQLException ex) {
return null;
}
}
Then i have another class, an userDAODB that has a password check method:
public boolean checkPassword(String user, String password) {
try (Connection con = new DbConnector().connect(); Statement stmt = con.createStatement()) {
//checks the password in the database
In the main method of this class i tested everything, it works very nice, logs me in, other methods work too, no problem what so ever.But then i go to my servlet:
public class LoginTest extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
String username = request.getParameter("username");
String pass = request.getParameter("pass");
UserDAODB userDAO = new UserDAODB();
boolean authe = userDAO.checkPassword(username, pass);
[code]....
So when i start the webpage and i try to click on the login button I get a NullPointerException com.model. UserDAODB. check Password (User DAODB. java:14) - so line 2 here
I have been googling a bit, i placed the derby.jar and the derbyclient.jar in the lib directory of tomcat, i tried to modify the context.xml of my application, but then it wouldn't even start anymore.
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May 21, 2014
I am trying to make connection with oracle database but when i run java file it's raise an error
"classnotfoundexception oracle.jdbc.driver.oracledriver"
DriverManager.getConnection(
"jdbc:oracle:thin:@erp:1521:ORCL", "apps",
"apps");
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Jul 10, 2015
I have small Java code, which execute every day and checks for data in database using Cronj Schedular and everything works fine, but recently I have observed that, it is failing due to
java.sql.SQLException: No suitable driver found for jdbc:oracle:thin:@160.110.xx.xxx:1521/test
At the same time, when I run my test code to check Database connectivity that works fine without above exception. I'm unable to figure it out. Although, there was just slight code change, but that was nowhere related to Database or Database connection.
dbconf.java
public class dbconf {
private Connection connect;
private String connstr;
public Connection getConnection() throws SQLException {
connstr = "jdbc:oracle:thin:@160.110.xx.xxx:1521/test";
[Code] ....
Application Log file
Wed Jul 01 09:25:17 IST 2015:------- Initializing -------------------
Wed Jul 01 09:25:17 IST 2015:------- Scheduling Jobs ----------------
Wed Jul 01 09:25:17 IST 2015:------- Job Started Running ----------------
Thu Jul 02 06:00:00 IST 2015 : Job Executed..!! Bschedularv2.2
java.sql.SQLException: No suitable driver found for jdbc:oracle:thin:@160.xxx.67.xxx:1521/test
Sat Jul 04 06:00:00 IST 2015 : Job Executed..!! Bschedularv2.2
Sun Jul 05 06:00:00 IST 2015 : Job Executed..!! Bschedularv2.2
java.sql.SQLException: No suitable driver found for jdbc:oracle:thin:@160.xxx.67.xxx:1521/test
So, you can see, It failed on 3rd of July and 5th July as well. But, in between it ran fine.
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Jun 19, 2014
We have a J2EE business web application that runs in WebLogic. We noticed in application log files errors messages that seems like "No resource available in db pool", it means all the connection objects (to Oracle database) are used. Then the application is unstable and unseable.
I think the maximum number of connections configured in Weblogic pool has been reached due to an increase of users and activity. But when the workload decreases the application is still out of service. It seems connections objects are not relased to the pool. What can be the explanation for this issue ? Normally it is managed by the container (EJB3 for the business tier).
Once the limit of the pool is reached it is necessary to restart the server to solve this kind of error ?
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Sep 1, 2014
I have created a JSP page, on click of a particular button, the control moves to the servlet "TestServlet".
This is the code under TestServlet:
import java.io.IOException;
import java.io.PrintWriter;
import java.security.Principal;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;
[Code]...
Now, I have got a comment saying I should get the database connection from connection pool. And one more issue is that I have used the function System.getProperty("user.name") to get the username which i have logged in. But this code will be run on Unix which will not support this function. Any function where I can get the windows username. There is a function getUserPrincipal(), but this function returns a NULL. How to resolve this.
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Jan 11, 2015
I configured a connection pool in tomcat 7. For every database activity I get a connection from the pool. Do I have to close the connection like other regular connection after the database operation is done? If I close the connection will it have any effect on the connection pool?
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Feb 1, 2014
In the class below I'm trying to create a class that will accept dates in various formats and create a range. The first constructor is easy because I send it the begin date and end date as Date objects. Now I want to send a month(and year) in a constructor and derive the begin and end dates from it. In my constructor that accepts the month/year I need to put the this(startDate, endDate) at the top to be allowed, but the parameters are not built yet.
package com.scg.athrowaway;
import java.util.Calendar;
import java.util.Date;
public class DateRange {
private Date startDate;
private Date endDate;
[code].....
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Jan 30, 2015
We are asked to create a JDialog showing our database. I am able to show the database but i can't seem to position the heading panel, table and back button. My back button is also not showing up. Here is part of my code...
import java.awt.Color;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.sql.*;
import javax.swing.*;
[Code] ....
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Oct 14, 2014
I have created a sample java web service client using Apache Axis. It works well with basicHTTPbinding (without security and Basic authentication).I am not able to make a secured communication. How to make it work in a secured way using NTLM or any other security.
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Dec 30, 2014
I am trying to connect to an oracle rac using jdbc thin . when i use the scan as the host, like this
String url = "jdbc:oracle:thin:@//<scan>:port/servicename;
I get error 1153, connection refused
but when i use the ip of the rac instead of the scan
String url = "jdbc:oracle:thin:@//<ip>:port/servicename;
The connection is successful
Is the issue at the application level? or is the problem with the server ....
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Jan 23, 2013
I am working on netbeans IDE , but I understand how the application know the parametres for the connections. I understand what is a Context , specifically i understand this code about the init method
Context initCtx = new InitialContext();
Context envCtx = (Context) initCtx.lookup("java:comp/env");
servicioConexiones = (DataSource) envCtx.lookup("jdbc/bd_tutorias");
I want to know how the application knows to use these connection parameters, on the Context.xml
<?xml version="1.0" encoding="UTF-8"?>
<Context antiJARLocking="true" path="/tutorias_pag480">
<Resource auth="Container" driverClassName="com.mysql.jdbc.Driver"
maxActive="8" maxIdle="4" name="jdbc/bd_tutorias" password="mysqladmin"
type="javax.sql.DataSource" removeAbandoned="true"
url="jdbc:mysql://localhost:3306/bd_tutorias" username="root"/>
</Context>
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Apr 15, 2015
I'm working in project, my theme is to develop an application management system for fingerprint and RFID card attendance machine in java programming language.
My problem i didn't find documentation in java for connecting with this device.
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Jul 18, 2014
I am very new to multithreading thus the code below reeks of ignorance,but i guess thats a place to start from.I am trying to obtain values that are already in my db and send them to a database by creating a new thread as follows:
//ADDED JUL 15 2014 12:07, LISTITEMS SO
public void getList() throws SQLException {
String sql = "select * from PRODUCTS";
out.print(m_Stmt);
ResultSet rs = m_Stmt.executeQuery(sql);
ExecutorService es=Executors.newCachedThreadPool();
es.execute(new Runnable(){
@Override
[code]...
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Apr 19, 2014
I am creating an application in core java where i am using database. I need to create a database configuration file & include it all other files. So, how can i do that ?
Java Code:
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Connection con = DriverManager.getConnection("jdbc:odbc:MYDSN","system","tiger"); mh_sh_highlight_all('java');
I cannot do this in an interface since only abstract methods exist there. I tried to create an another class file to extend it but my program is already extending other class i.e. javax.swing.JFrame..How can i implement this ? just by creating the object of that class in main method ?
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Apr 22, 2015
How to create object for "class B" and call the "function_B" from other different class D where class D has no connection with class A? Here is my program.
public class A(){
void print(){}
}
class B{
void function_B(){}
}
class C{
void function_C(){}
}
Here, A, B, C are in the same package. But class D is in different package.
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Jan 19, 2015
I want lo list all the devices connected to my network, I done like this
InetAddress i = InetAddress.getLocalHost();
byte[] ip1 = i.getAddress();
InetAddress address = InetAddress.getByAddress(ip1);
for (int b = 0; b <255;b++) {
ip1[3] = (byte)b;
[Code] ....
It prints all the connected devices, its k.. my doubt is, how to list the wired connections and wireless connections from them...
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Mar 9, 2013
I am using EJB (Stateless) without any web service. I simply need to send a String from Client to Server
I can connect any Java SE Client with this EJB. But how I can connect an Android Client with this EJB (i.e. Using EJBRemote Interface) directly? I am using :
Glassfish Application Server
Netbeans IDE
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Jun 10, 2014
Design a class named Person and its two subclasses named Student and Employee. Make Faculty and Staff subclasses of Employee. There is also a MyDate class as explained below. A person has a name, address, phone number, and email address. A student has a status (freshman, sophomore, junior, or senior). Define the status as an integer which can have the value 0 (for "Freshman"),
1 (for "Sophomore"),
2 (for "Junior"), and
3 (for "Senior"),
but don't allow the status to be set to any other values. An employee has an office, salary, and dateHired. The dateHired is a MyDate field, which contains the fields: year, month, and day. The MyDate class does not explicitly inherit from any class, and it should have a no-arg constructor that sets the year, month, and day to the current year, month, and day. The MyDate class should also have a three-argument constructor that gets three int arguments for the year, month and day to set the year, month and day.
A faculty member has office hours and a rank. Define the rank as a String (for values like "Professor" or "Instructor"). A staff member has a title, which is also a String. Use data types for the fields as specified, or where one is not specified, use a data type that is appropriate for the particular field. Write a test program called TestEveryone.java that creates a Person, Student, Employee, Faculty, and Staff object, and invoke their toString() method (you don't need to call the objects' toString() method explicitly).
Note: Your MyDate.java class is the object class that your dateHired field is created from in the Employee.java class.
Do not use the Person, Employee or Faculty classes defined on pages 383 and 384 of the book. Create new ones.Here is the code I have so far concerning the employee and MyDate.
public class Employee extends Person {
private String office;
private double salary;
//private MyDate dateHired;
//7 argument constructor for employee
public Employee(String name, String phoneNumber, String email, String address, String office, double salary /*MyDate dateHired*/) {
super(name, phoneNumber, email, address);
[code]....
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Jun 3, 2014
The assignment is to create a SmartString class that implements a SmartStringInterface class (created by professor) and implements a few methods. We are basically taking a string and then taking various substrings and inserting, deleting them and undoing changes as well. Here are the methods in the interface to use along with the parameters.
public interface SmartStringInterface {
public void insert(int pos, String sstring);
public void delete(int pos, int count);
public void undo();
public String toString();
The Undo is supposed to be able to be called multiple times (to be tested using a driver program that we must create) but the part that's got me is that the changes are only supposed to be stored. Currently, I am storing the "new" string after each change onto a stack, so that undo can just pop off the stack and it will revert to the previous string. Professor said that was wrong, so I don't know how to do it. Here is what I have so far (some of the code we have is using default StackADT stuff from our book, so if you need that I can post as well. You can see in the undo method where I currently save the string. We can use multiple stacks if needed, but the less the better. Must use at least 1. The exception code is already coded for us in another file also. I am only having to code these methods and the driver to test.
import java.util.Arrays;
public class ArrayStack<T> implements StackADT<T>
private final static int DEFAULT_CAPACITY = 100
private int top;
private T[] stack;
[code]...
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Jun 6, 2014
So I'm trying to create a simple user database that I could eventually turn into a login system. I created a simple table on MySQL with a name and address for the sake of simplicity. I tried to create simple statement inside my main method that would connect to my MySQL server and when I run my program I get a ClassNotFoundException from "org.gjt.mm.mysql.Driver"..Here is what I have in my main method thus far:
public static void main(String args[]) {
try {
Class.forName("org.gjt.mm.mysql.Driver"); //Load the driver
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/data", "root", ""); //Connect
/*
conn.createStatement().execute("CREATE TABLE people (" + "id int(64) NOT NULL AUTO_INCREMENT," + "name varchar(255) NOT NULL," + "address varchar(255) NOT NULL," + "UNIQUE (id)," + "FULLTEXT(name, address))");
[code]....
I downloaded Connector/J in the the binary .zip form and extracted it to my C: drive and put the .jar file into my java directories lib folder. I also added the directory of the .jar file into my CLASSPATH and I still get the exception.
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