I'm doing an app for my high school and I have the following situation:
I will use an embedded HSQL database for storing my application data. When I open the connection, I try to connect to the database only if exists, so it will not be created if it doesn't exist. Basically, if an HsqlException is thrown, functions to create the database, tables and constraints will be called.
The point is that this line:
Connection c = DriverManager.getConnection(url, user, pwd);
Throws an SQLException AND an HsqlException. But if I try to catch and control them, the output keeps being like this:
run:
2014-11-19T20:15:25.142+0100 SEVERE could not reopen database
Catched an Hsql or SQL Exception. //This is my 'control' over the Exceptions.
org.hsqldb.HsqlException: La base de datos no existe: C:/Databases/DB
at org.hsqldb.error.Error.error(Unknown Source)
at org.hsqldb.error.Error.error(Unknown Source)
at org.hsqldb.persist.Logger.open(Unknown Source)
at org.hsqldb.Database.reopen(Unknown Source)
at org.hsqldb.Database.open(Unknown Source)
at org.hsqldb.DatabaseManager.getDatabase(Unknown Source)
at org.hsqldb.DatabaseManager.newSession(Unknown Source)
at org.hsqldb.jdbc.JDBCConnection.<init>(Unknown Source)
at org.hsqldb.jdbc.JDBCDriver.getConnection(Unknown Source)
at org.hsqldb.jdbc.JDBCDriver.connect(Unknown Source)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:247)
at DBManager.DBManager.main(DBManager.java:20)
BUILD SUCCESSFUL (total time: 0 seconds)
And finally this is my code. I hope someone call tell me why is this happening.
package DBManager;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
public class DBManager {
static Connection c;
static Statement stm;
public static void main(String[] args){
try {
Class.forName("org.hsqldb.jdbc.JDBCDriver");
c = DriverManager.getConnection("jdbc:hsqldb:file:C:/Databases/DB;create=false", "SA", "");
} catch (ClassNotFoundException ex) {
System.out.println("ClassNotFoundException has been catched.");
} catch (SQLException | org.hsqldb.HsqlException ex) {
System.out.println("Catched an Hsql or SQL Exception.");
//TODO call connection where the database is created.
//TODO create schema CreateSchema.run(c);
//TODO create constraints
} finally {
//TODO
}
}
private static class CreateSchema{
public static void run(Connection con){
//TODO: Create table queries.
}
}
}
Assuming you do not already have a HSQLDB database in C:/Databases/DB then this is behaving how I would expect. Your connection string tells it not to create the database if it does not exist, so it can't return an exception so it throws an exception which you are catching and logging.
Because the exception has been caught the run is considered successful because the main method did not throw an exception or call System.exit() with a non-zero value.
The exception you are catching is actually the SQLException and not the HsqlException (which is a RuntimeException) - the SQLException has a nested HsqlException. If you print the stack trace of the exception (ex.printStackTrace()) you can see this. So you should just catch SQLException.
The extra output you see is from within the HSQLDB driver class - if you look at the source for org.hsqldb.Database#reopen() you can see it calls logger.logSevereEvent("could not reopen database", e); and that's what responsible for the extra output you see. It tries to use a logging framework if one is available and defaults to the one in the JDK, which if not configured will print to System.err.
Related
I try to insert data into MySQL using Java and I have error all the time.
I use this video to understand how to do to the connection.
This is my Java code:
import java.sql.*;
public class Main {
public static void main(String[] args) {
// TODO Auto-generated method stub
Connection conn = null;
//DriverManager.registerDriver(new com.mysql.jdbc.Driver ());
try {
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/try1-progrem", "root", "123456");
Statement st = conn.createStatement();
String username = "kola";
String password = "24688642";
String insert = "INSERT INTO login VALUES ('"+username+"','"+password+"')";
st.executeUpdate(insert);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
Get the error:
java.sql.SQLException: No suitable driver found for
jdbc:mysql://localhost:3306/try1-progrem
at java.sql.DriverManager.getConnection(Unknown Source)
at java.sql.DriverManager.getConnection(Unknown Source)
at Main.main(Main.java:11)
And here to SQL image: sql data:
** I learned from YouTube how to make the connection, if there is a good guild, I will glad to take him.
*EDIT1:
build
To fix this you should follow the steps below:
You need to download the correct ConnectorJ from the link below.
After downloading the correct installer for your machine you will need to run the installer to install only the correct jdbc connector for you. (A series of prompts will lead you to selecting the connector and not all the MySQL downloads)
Then you can put the .jar file (connectorJDBC file) into your classpath appropriately and this should fix your problem as I encountered a similar problem while trying to connect to a SQL server with java.
Hopefully this fixes your problem, comment if it doesn't. :)
ConnectorJ Download
Environment: Eclipse(luna)
I am not able to retrive data from the oracle database 11g (11.2.0.2) used jdbe 6
I am getting the following two exception
java.sql.SQLRecoverableException
oracle.net.ns.NetException
Here is the code
import java.sql.*;
public class JavaConnection {
public static void main(String[] args) throws ClassNotFoundException, SQLException {
Class.forName("oracle.jdbc.driver.OracleDriver");
Connection con=DriverManager.getConnection("jdbc:oracle:thin:#localhost:1521:xe","******","*******");
Statement st=con.createStatement();
String sql="select * from emp";
ResultSet rs=st.executeQuery(sql);
while(rs.next())
System.out.println(rs.getInt(1)+" "+rs.getString(2));
con.close();
}
}
the exception thrown is
Exception in thread "main" java.sql.SQLRecoverableException: IO Error: Got minus one from a read call
at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:489)
at oracle.jdbc.driver.PhysicalConnection.(PhysicalConnection.java:553)
at oracle.jdbc.driver.T4CConnection.(T4CConnection.java:254)
at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:32)
at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:528)
at java.sql.DriverManager.getConnection(Unknown Source)
at java.sql.DriverManager.getConnection(Unknown Source)
at emodatabase.JavaConnection.main(JavaConnection.java:9)
Caused by: oracle.net.ns.NetException: Got minus one from a read call
at oracle.net.ns.Packet.receive(Packet.java:311)
at oracle.net.ns.NSProtocol.connect(NSProtocol.java:300)
at oracle.jdbc.driver.T4CConnection.connect(T4CConnection.java:1140)
at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:340)
... 7 more
What is cause that is causing it and how to resolve it?
Additional Information about listner
I am getting the following exception :-
java.sql.SQLException: [DataDirect][OpenEdge JDBC Driver][OpenEdge] Access denied(Authorisation failed)
at com.ddtek.jdbc.openedge.client.ddd.aw(Unknown Source)
at com.ddtek.jdbc.openedge.client.ddd.j(Unknown Source)
at com.ddtek.jdbc.openedge.OpenEdgeImplConnection.j(Unknown Source)
at com.ddtek.jdbc.openedgebase.BaseConnection.b(Unknown Source)
at com.ddtek.jdbc.openedgebase.BaseConnection.k(Unknown Source)
at com.ddtek.jdbc.openedgebase.BaseConnection.b(Unknown Source)
at com.ddtek.jdbc.openedgebase.BaseConnection.a(Unknown Source)
at com.ddtek.jdbc.openedgebase.BaseDriver.connect(Unknown Source)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:247)
at com.ncr.sj250216.JdbcTest.main(JdbcTest.java:18)
There is no compile time error in my code, i am using the right jars as referenced libraries.
package com.ncr.sj250216;
import java.sql.*;
public class JdbcTest
{
public static String
URL="jdbc:datadirect:openedge://sun3899.daytonoh.ncr.com:28409;DatabaseName=dispatch";
public static String username="CSMSRUP";
public static String password=null;
public static void main(String [] args)
{
try
{
Class.forName ("com.ddtek.jdbc.openedge.OpenEdgeDriver");
System.out.println("Driver loaded");
Connection conn = DriverManager.getConnection(URL,username,password);
System.out.println("Connected");
Statement stmt = conn.createStatement();
System.out.println("Statement created");
ResultSet rs = stmt.executeQuery("select remark from pub.dupdate_remarks");
System.out.println("ResultSet : \n");
while (rs.next())
{
System.out.println(rs.getString(1));
}
System.out.println("AFTER CRUISING THROUGH THE RESULT SET");
rs.close();
stmt.close();
conn.close();
}
catch (Exception x)
{
x.printStackTrace();
}
}
}
Access denied and Authorization failed mean that you either have the wrong userid & password or you are attempting to connect to the wrong db.
If you have access to the server that the db runs on you can test your credentials using Progress' sqlexp command line tool:
sqlexp -user userName -password passWord -db dnName -S servicePort
Or you could use any popular Windows based SQL querying tool to try the connection...
This question already has answers here:
Connect Java to a MySQL database
(14 answers)
Closed 7 years ago.
I have searched the internet trying to find solutions on using java and JDBC to connect to MySQL. Unfortunately I have found multiple answers and none that solved my problem.
I downloaded the JDBC from MySQL, and unzipped the file to find the .jar. I placed the .jar in my C:/Program Files (X86)/Java/JDK.../JRE/lib/ext folder. I set my environmental variable classpath (maybe CLASSPATH, ClassPath ??) to the following:
%CLASSPATH%;.;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext
I use the script I composed based on all the different solutions I have seen to get this:
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class MySql {
public static void main(String[] args)
{
Connection con = getConnection();
if (con != null) {
System.out.println("Connection Made");
}
else {
System.out.println("Connection not made");
}
}
private static Connection getConnection() {
Connection con = null;
try {
Class.forName("com.mysql.jdbc");
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/sakila", "java", "java");
System.out.println("Connection Made");
conn.close();
}
catch (SQLException e)
{
System.out.println(e.getMessage());
System.exit(0);
}
catch (ClassNotFoundException e)
{
System.out.println(e.getMessage());
System.exit(0);
}
return con;
}
}
It compiles with javac MySql.java. Then when it runs (java MySql) I get com.mysql.jdbc. I have read that I don't need to register the driver, but when I remove Class.forName all I get is 'cannot find JDBC driver' error.
I can't narrow down my problem to either:
1). Classpath not setup correctly.
2). Improper java connection code.
3). Unable to locate MySQL server.
Any help would be appreciated.
Edit -
I placed the .jar file onto Desktop for testing purposes. Changed system classpath variable:
%CLASSPATH%;.;C:\User\User\Desktop\mysql-connector-java-5.1.38-bin.jar
Then when I add the trace for the error statement I get:
java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
at java.net.URLClassLoader.findClass<Unkown Source>
at java.lang.ClassLoader.loadclass (Unknown source)
at sun.misc.Launcher$AppClassLoader.loadclass(Unkown Source)
etc.
etc.
edit 2 - I have spent two days using Connect Java to a MySQL database as a resource and none of the instructions I have followed have solved my problem.
Instead of
System.out.println(e.getMessage());
Do this
e.printStackTrace();
You will see that the exception is:
java.lang.ClassNotFoundException: com.mysql.jdbc
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:264)
at MySql.getConnection(MySql.java:24)
at MySql.main(MySql.java:10)
Remove the Class.forName. You might get an access denied or some other error but it will solve the ClassNotFoundException. Here is the final edited version that should work:
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class MySql {
public static void main(String[] args)
{
Connection con = getConnection();
if (con != null) {
System.out.println("Connection Made");
}
else {
System.out.println("Connection not made");
}
}
private static Connection getConnection() {
Connection con = null;
try {
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/sakila", "java", "java");
System.out.println("Connection Made");
conn.close();
}
catch (SQLException e)
{
e.printStackTrace();
System.exit(0);
}
return con;
}
}
If you need Class.forName() you have to use correct class:
Class.forName("com.mysql.jdbc.Driver");
But with JDBC 4 that has become no longer needed.
Create full Exception stack traces and use the result to search here - most common errors have been solved here before.
NoSuitableDriverFound is a very strong indication your mysql-connector.jar (not the .zip....) is missing from your classpath when you run your code.
You could try like this:
Run java -cp .;C:\User\User\Desktop\mysql-connector-java-5.1.38-bin.jar MySql
I think you must add the path including the jar file name of the driver in your classpath. Like so:
%CLASSPATH%;.;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\mysql-connector-java-xxx.jar
If your Java is version 6 or above you doesn't need Class.formName(...) code.
And for ensure that everything works, compile and execute your code in the follow way.
To compile:
java -cp PATH_TO_DRIVER; YOUR_CLASS.java
To execute:
java -cp PATH_TO_DRIVER; YOUR_CLASS
Change YOUR_CLASS to the name of your class and PATH_TO_DRIVER to the path where you download the MySQL driver.
Hope it helps!
Try this code!
public static void main(String[] argv) {
try {
Class.forName("com.mysql.jdbc.Driver");
} catch (ClassNotFoundException e) {
System.out.println("Where is your MySQL JDBC Driver?");
e.printStackTrace();
return;
}
System.out.println("MySQL JDBC Driver Registered!");
Connection connection = null;
try {
connection = DriverManager
.getConnection("jdbc:mysql://localhost:3306/yourSCHEMAname,"login", "password");
} catch (SQLException e) {
System.out.println("Connection Failed! Check output console");
e.printStackTrace();
return;
}
if (connection != null) {
System.out.println("You made it, take control your database now!");
} else {
System.out.println("Failed to make connection!");
}
}
}
I am working on a GWT project in which I need to make some MySQL queries. I have handled RPC properly and in the server-side I am trying to make a mysql connection but am running into an exception:
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.google.appengine.tools.development.agent.runtime.Runtime.newInstance_(Runtime.java:112)
at com.google.appengine.tools.development.agent.runtime.Runtime.newInstance(Runtime.java:120)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.Util.getInstance(Util.java:386)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1013)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:987)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:982)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:927)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2412)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2154)
at com.mysql.jdbc.ConnectionImpl.(ConnectionImpl.java:792)
at com.mysql.jdbc.JDBC4Connection.(JDBC4Connection.java:47)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.google.appengine.tools.development.agent.runtime.Runtime.newInstance_(Runtime.java:112)
at com.google.appengine.tools.development.agent.runtime.Runtime.newInstance(Runtime.java:120)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:381)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:305)
at java.sql.DriverManager.getConnection(Unknown Source)
at java.sql.DriverManager.getConnection(Unknown Source)
.
.
.
more
.
.
.
I created a very simple java class to test out my code to confirm that my connection syntax and use is proper, and have confirmed that syntax is not a problem because with the very same code in a simple only main method java app I can create a connection and query the database properly. I have made sure to have mysql-connector-java-5.1.16-bin.jar in the classpath as well as the /lib folder in the WEB-INF folder.
Here is the class that I am using in order to create a connection:
public class DB_Connection {
protected Connection getConnection() {
Connection conn = null;
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
conn = DriverManager.getConnection("jdbc:mysql:///",
"",
"");
}
catch (Exception ex)
{
ex.printStackTrace();
}
return conn;
}
}
public class Login extends DB_Connection {
public User getUser(String email) {
User user = new User();
user.setUserEmail(email);
String query = "";
try {
Connection conn = getConnection();
Statement statement = conn.createStatement();
ResultSet result = statement.executeQuery(query);
while(result.next()) {
user.setUserId(result.getInt("rvuser_id"));
System.out.println(user.getUserId());
}
}
catch (Exception ex)
{
ex.printStackTrace();
}
return user;
}
It seems my problem happens all the way at the beginning in DB_Connection. Does anyone know what is making this happen? It is strange to me, because as a standalone the code works fine.
Another thing I just realized that I am at home now and don't even have access to that database server as it is on a local network and I am not connected through VPN. So it must be failing somehow before it even attempts to make the connection.
Thanks!
com.google.appengine ..
Does it means you are deploying on Google App Engine?
If so, MySQL,JDBC and many other things are restricted.