I am trying to have an OSGI bundle access a MYSQL DB, using Eclipse as my IDE (Windows 7 x64). I am able to load the jdbc connector. The actual .jar is placed in all \bin folders in the java install directories, along with the \bin folder of the bundle. I have set the environment classpath variable to this folder also. I have an error stating that the driver is not suitable. I know OSGI has some issues with drivers etc. Can someone recommend a way to circumvent this?
ClassLoader DBHCL = ClassLoader.getSystemClassLoader();
DBHCL.loadClass("com.mysql.jdbc.Driver");
Class.forName("com.mysql.jdbc.Driver", true, DBHCL).newInstance();
System.out.println("Class Loaded");
//DriverManager.getDriver("jdbc:mysql://localhost/timedb");
//System.out.println("Driver Gotten");
conn = DriverManager.getConnection(URL + DBName,username,password);
System.out.println("Connection Created");
stmt = conn.createStatement();
System.out.println("Statement Created");
connFlag = true;
Console Output, Error: osgi> start 7 Data Base Service (MYSQL) Starting Class Loaded No suitable driver found for jdbc:mysql://localhost/timedb Exception in thread "Thread-1" INSERT INTO appliance1...
Does anybody have any insight into this problem?
I have tried making a separate bundle solely for the jdbc driver and exporting/importing this to the appropriate bundle, but no luck.
Thanks
In your code snippet, you get the SystemClassLoader, and you ask it for the "com.mysql.jdbc.Driver". Given that that call doesn't give you a ClassNotFoundException, we can conclude the system classloader can find the class for you; the driver will then register itself to the DriverManager.
However, you don't see the same DriverManager that the MySQL driver does! The MySQL driver sees the one from the system classloader, but your code (conn = DriverManager. ...) uses the one from the bundle's own classloader. These are two different classes, hence, no suitable driver is found.
My solution would be to not use the SystemClassLoader (which you shouldn't do in OSGi anyway, unless you know exactly what you're doing), but use the bundle's classloader. So, I would
not put the MySQL jar on the system classpath, but let OSGi do the hard work. You can put the jar in a bundle, and put the jar on the Bundle-ClassPath. You can then choose either to keep it private to your bundle (if you're the only one using it), or export the packages.
In stead of using the system classloader, use the bundle's classloader. This can be as simple as using Class.forName("com.mysql.jdbc.Driver"); this will do the right thing.
Related
I have created a program that works perfectly in the IDE on NetBeans, but anytime I build the .jar file, the database connection stops working. I've already added the CLASSPATH to the MySQL Connector, as well as defined Class.forName("com.mysql.jdbc.Driver"); Still nothing..
try {
Class.forName("com.mysql.jdbc.Driver");
String url = "jdbc:mysql://localhost:3306/gearheads";
Connection conn = DriverManager.getConnection(url,"root","HellOnEarth202021");
Statement stmt = conn.createStatement();
ResultSet rs;
String pid = txt_staffID.getText();
rs = stmt.executeQuery("SELECT name,timeraccess FROM staff WHERE staffid = '"+pid+"'");
while ( rs.next() ) {
String timeraccess = rs.getString("timeraccess");
String staffName = rs.getString("name");
getLogin = staffName;
System.out.println(staffName);
System.out.println("Users Admin Level: " + timeraccess);
if ( timeraccess.equals("1")) {
this.dispose();
new menu().setVisible(true);
System.out.println("Access Granted");
}else
System.out.println("Access Restricted.");
}
conn.close();
} catch (Exception e) {
System.err.println("Got an exception! ");
txt_staffID.setText(e.toString());
System.err.println(e.getMessage());
}
This, as it stands, outputs:
java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
Where taking out the Class.forName outputs:
java.sql.SQLException: No suitable driver found for jdbc:mysql://localhost:3306/gearheads
Please help me. This link is a screenshot of my libraries.
My Libraries:
If its runnning correctly inside Netbeans, then the MySQL driver is correct.
You have to search for Manifest file (MANIFEST.MF) and probably will have to unjar the contents of the driver inside your own JAR file.
I'll leave this answer by now, but will try to gather the details to bring it back here.
I also use NetBeans and when I generate the JAR file, its already copying the dependant libraries and generating the correct MANIFEST.MF.
I ended up with the following structure
MyProject\dist\lib\JdbcDriver.jar
and
MyProject\dist\MyProject.jar
Inside MyProject.jar, I have the following MANIFEST.MF:
Manifest-Version: 1.0
Ant-Version: Apache Ant 1.9.7
Created-By: 1.8.0_201-b09 (Oracle Corporation)
Class-Path: lib/JdbcDriver.jar
X-COMMENT: Main-Class will be added automatically by build
Main-Class: myproject.MyMainClass
Please, verify with you are copying the lib folder altogether with your JAR file.
Just to leave here the final solution (#Nick Media final comment): you have to check "Copy Dependent Libraries" in Build>Packaging Project Properties.
It is not clear exactly what you are doing wrong, but you are clearly doing something incorrectly:
It is often better to use DriverManager.getConnection rather than Class.forName and a specific driver class name. This is the approach recommended by the Oracle Java Tutorial; see https://docs.oracle.com/javase/tutorial/jdbc/basics/connecting.html
If you are loading the driver via its classname, use com.mysql.jdbc.Driver with MySQL Connector/J 5.x and com.mysql.cj.jdbc.Driver with MySQL Connector/J 8.x.
If this is a webapp, make sure that the relevant driver JAR file is actually in your WAR file, and/or that it is being deployed correctly.
If this is a command line app, make sure that you include the driver JAR on the runtime classpath. (Especially if you are trying to run it outside of your IDE.) Alternatively, consider creating a shaded JAR that included all of the apps dependencies. (It is a bit hard to advise since you haven't told us if you are using a build tool like Ant, Maven, Gradle, etc.)
The driver doesn't actually need to be a compile time dependency, though there is little harm in doing that. (The harm is that you might accidentally add imports to the MySQL implementation classes to your app ... and run into problems.)
I am having some difficulty in making connectivity with Java and PostgreSQL Database.I have download the JDBC4 Postgresql Driver, Version 9.2-1002 driver and properly set the application ClassPath. My code is as under
import java.sql.*;
public class JavaPostGreSQLConnectivity
{
public static void main(String[] args)
{
DB db = new DB();
db.dbConnect("jdbc:postgresql://127.0.0.1:5432/TestDB", "postgres","pwd");
}
}
class DB
{
public DB() {}
public void dbConnect(String db_connect_string, String db_userid, String db_password)
{
try
{
Class.forName("org.postgresql.Driver");
Connection conn = DriverManager.getConnection(db_connect_string, db_userid, db_password);
System.out.println("connected");
}
catch (Exception e)
{
e.printStackTrace();
}
}
};
Upon running I am getting the below error
Is it complaining about
Class.forName("org.postgresql.Driver");
If so then what will be the driver name? However, I followed this for my learning purpose.
However, If I do
C:\Program Files (x86)\Java\jdk1.7.0\bin>java -cp C:\Users\pos
tgresql-9.2-1002.jdbc4.jar; JavaPostGreSQLConnectivity
connected
It works.Why I need to explicitly mention the driver again when I have already placed it in the classpath properly? Is there any alternative way (I just want to put the JAR file in Classpath and the program should read from there)?
Thanks in advance
The driver name is OK. It is the same as mentioned in the official docs of the driver. Therefore the driver is just not in the classpath.
You say:
I [...] properly set the application ClassPath
On the other hand you start the program by just calling:
java JavaPostGreSQLConnectivity
In that case no PG driver is on the classpath. You have to add it by hand using someting like
java -cp postgresql-jdbc4.jar JavaPostGreSQLConnectivity
EDIT The question has been changed while typing, hence the duplication.
You added the jar only in you IDE. This helps the IDE to compile your code. If you start the program using you IDE then the IDE will also set the classpath for you. But if you don't start via the IDE then nobody knows the correct classpath and it has to be set by hand.
Your options are:
start always via IDE
make some batch script which hides the setting of the classpath (common solution)
set the CLASSPATH environment variable (does not scale with other Java applications)
make an "Executable Jar" and set the classpath there. (Search this site using that term).
put the jar into a place where the JVM picks it up automatically (e.g. in the lib/ext directory of the JRE). But polluting the JRE/JDK libs is the worst option.
Note: This is all basic Java knowledge and has nothing to do with PostgreSQL.
There is a VERY similar question to mine but in my case I don't have any duplicate jars in my build path, so the solution does not work for me. I've searched google for a couple of hours now, but none of the solutions I've found there actually resolve my issue. I'm creating a web site with some database connectivity for a homework. I'm using a MySQL database, developing in Eclipse and running on Windows.
I keep getting java.lang.ClassNotFoundException: com.mysql.jdbc.Driver with the following code:
import java.sql.*;
//...
public void someMethodInMyServlet(PrintWriter out)
{
Connection connection = null;
PreparedStatement query = null;
try {
out.println("Create the driver instance.<br>");
Class.forName("com.mysql.jdbc.Driver").newInstance();
out.println("Get the connection.<br>");
connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", "secret");
query = connection.prepareStatement( "SELECT * FROM customers");
//...
} catch (Exception e)
{
out.println(e.toString()+"<br>");
}
}
//...
When I run the above code I get the following output:
Create the driver instance.
java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
It doesn't get past the Class.forName... line and I can't figure out why! Here is what I did:
Download mysql-connector.
Put it in my MySQL folder C:\Program Files\MySQL\mysql-connector-java-5.1.12\mysql-connector-java-5.1.12-bin.jar.
Opened the project properties in Eclipse.
Add External Jar to my Build Path and I selected mysql-connector-java-5.1.12-bin.jar.
Every time I attempt to use the servlet I get the same error regardless if I have the jar in there or if I don't. Could you help me figure this out?
As for every "3rd-party" library in flavor of a JAR file which is to be used by the webapp, just copy/drop the physical JAR file in webapp's /WEB-INF/lib. It will then be available in webapp's default classpath. Also, Eclipse is smart enough to notice that. No need to hassle with buildpath. However, make sure to remove all unnecessary references you added before, else it might collide.
An alternative is to install it in the server itself by dropping the physical JAR file in server's own /lib folder. This is required when you're using server-provided JDBC connection pool data source which in turn needs the MySQL JDBC driver.
See also:
How to add JAR libraries to WAR project without facing java.lang.ClassNotFoundException? Classpath vs Build Path vs /WEB-INF/lib
How should I connect to JDBC database / datasource in a servlet based application?
Where do I have to place the JDBC driver for Tomcat's connection pool?
JDBC CLASSPATH Not Working
Since you are running it in servlet, you need to have the jar accessible by the servlet container. You either include the connector as part of your application war or put it as part of the servlet container's extended library and datasource management stuff, if it has one. The second part is totally depend on the container that you have.
The others are right about making the driver JAR available to your servlet container. My comment was meant to suggest that you verify from the command line whether the driver itself is intact.
Rather than an empty main(), try something like this, adapted from the included documentation:
public class LoadDriver {
public static void main(String[] args) throws Exception {
Class.forName("com.mysql.jdbc.Driver");
}
}
On my platform, I'd do this:
$ ls mysql-connector-java-5.1.12-bin.jar
mysql-connector-java-5.1.12-bin.jar
$ javac LoadDriver.java
$ java -cp mysql-connector-java-5.1.12-bin.jar:. LoadDriver
On your platform, you need to use ; as the path separator, as discussed here and here.
Place mysql-connector-java-5.1.6-bin.jar to the \Apache Tomcat 6.0.18\lib folder. Your problem will be solved.
What you should not do do (especially when working on a shared project)
Ok, after had the same issue and after reading some answers here and other places. it seems that putting external lib into WEB-INF/lib is not that good idea as it pollute webapp/JRE libs with server-specific libraries - for more information check this answer"
Another solution that i do NOT recommend is: to copy it into tomcat/lib folder. although this may work, it will be hard to manage dependency for a shared(git for example) project.
Good solution 1
Create vendor folder. put there all your external lib. then, map this folder as dependency to your project. in eclipse you need to
add your folder to the build path
Project Properties -> Java build path
Libraries -> add external lib or any other solution to add your files/folder
add your build path to deployment Assembly (reference)
Project Properties -> Deployment Assembly
Add -> Java Build Path Entries
You should now see the list of libraries on your build path that you can specify for inclusion into your finished WAR.
Select the ones you want and hit Finish.
Good solution 2
Use maven (or any alternative) to manage project dependency
Just follow these steps:
1) Install eclipse
2) Import Apache to eclipse
3) Install mysql
4) Download mysqlconnector/J
5) Unzip the zipped file navigate through it until you get the bin file in it. Then place all files that are present in the folder containing bin to C:\Program Files\mysql\mysql server5.1/
then give the same path as the address while defining the driver in eclipse.
That's all very easy guys.
If the problem still persists,
Put the-
mysql-connector-java-5.0.8-bin jar in a place inside your Tomcat->lib->folder (No matter where you've installed your Tomcat). And change your environmental variable (Done by clicking Properties of Mycomputer -Advanced system settings- Environmental variables-And set a new variable name & variable values as the place where your lib file resides.Dont forget to enter a ; at the end of the path)
If still problem persists
Try downloading commons-collections-2.0.jar (http://www.docjar.com/jar_detail/commons-collections-2.0.jar.html) and paste the jar in the same place where your mysql jar resides (ie) inside Tomcat-lib.
Clean your project-Stop your server- Finally try to run.
Many times I have been facing this problem, I have experienced ClassNotFoundException.
if jar is not at physical location.
So make sure .jar file(mysql connector) in the physical location of WEB-INF lib folder. and
make sure restarting Tomcat by using shutdown command in cmd.
it should work.
The only solution worked for me is putting the .jar file under WEB-INF/lib . Hope this will help.
assuming your project is maven based, add it to your POM:
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.26</version>
</dependency>
Save > Build > and test connection again. It works! Your actual mysql java connector version may vary.
Put mysql-connector-java-5.1.38-bin.jar to the C:\Program Files\Apache Software Foundation\Tomcat 7.0\lib folder.by doing this program with execute
My issue was a little different. Instead of jdbc:oracle:thin:#server:port/service i had it as server:port/service.
Missing was jdbc:oracle:thin:# in url attribute in GlobalNamingResources.Resource. But I overlooked tomcat exception's
java.sql.SQLException: Cannot create JDBC driver of class 'oracle.jdbc.driver.OracleDriver' for connect URL 'server:port/service'
for this error:
java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
you need to:
Import java.sql.*;
Import com.mysql.jdbc.Driver;
even if its not used till app running.
I have a terrible problem with Tomcat, well terrible because of this problem I've thrown away the project for more than a month now... Yet I'll still need to solve it and to go on with the project...
So it's throwing me this error:
java.sql.SQLException: No suitable driver found for jdbc:sqlserver://isd.ktu.lt:1433;DatabaseName=LN2012_bakDB2
java.lang.NullPointerException
The thing is that the same application is working in the desktop version perfectlz, however when it comes to the version which is supposed to be running on the server (Tomcat 7.0.22.0 inside NetBeans 7.1.2) it just throws the Error. It seems it doesn't load the pooling driver or I don't even know...
Well here's the part responsible for that:
public DatabaseConnection(Parameters params) {
// parameters and the output
this.gui = params.getGui();
// activate database pool
connectionPool = new GenericObjectPool(null);
connectionFactory = new DriverManagerConnectionFactory(params.getDbAdr(), params.getDbUser(), params.getDbPass());
poolableConnectionFactory = new PoolableConnectionFactory(connectionFactory, connectionPool, null, null, false, true);
driver = new PoolingDriver();
driver.registerPool("GenTreeDatabase", connectionPool);
//driver.registerPool("jdbc:apache:commons:dbcp:GenTreeDatabase", connectionPool);
}
public void openConn() {
if (allowOutput) gui.print("Getting connection to database");
try {
con = DriverManager.getConnection("jdbc:apache:commons:dbcp:GenTreeDatabase");
if (con != null) {
if (allowOutput) gui.print("Connection to database was successful");
}
} catch (SQLException ex) {
gui.err(specificError + "Error getting connection to database - " + ex);
}
}
It happens at the point where it tries to get the connection, then it gets a null pointer exception, since the connection is not retrieved successfuly.
I'm not familiar with Tomcat and up until this moment, Netbeans handled tomcat fine...
The thing is I hate errors like this... If you don't solve it in three days, you get so frustrated and don't wanna get back to that, you feel like hitting a wall...
Now I tried googling a lot about it, but still it wasn't much of a help...
So I'd be really glad if somebody could help me with this. Thanks. :)
You have to copy the JDBC Driver's jar into $CATALINA_HOME/lib.
This is probably too late to answer this question but in order to help with similar issues, Here's how I got around it.
Quick Solution:
Copy the JDBC-driver JAR file (mine was ojdbc6) into $JAVA_HOME/jre/lib/ext (for me it was C:\Program Files\Java\jdk1.7.0_80\jre\lib\ext).
Details:
According to Apache Tomcat 7 documentations When Tomcat is started, it creates a set of class-loaders that are organized into the following parent-child relationships:
Bootstrap
|
System
|
Common
/ \
Webapp1 Webapp2 ...
Each class loader, searches for JAR files inside a certain directory. The classes and resources that they make visible are explained below:
Bootstrap : This class loader contains the basic runtime classes provided by the JVM, plus any classes from JAR files present in the System Extensions directory $JAVA_HOME/jre/lib/ext.
System : This class loader is normally initialized from the contents of the CLASSPATH environment variable. All such classes are visible to both Tomcat internal classes, and to web applications. However, There are some exceptions for Tomcat.
Common : This class loader contains additional classes that are made visible to both Tomcat internal classes and to all web applications. This class loader looks (by default) in $CATALINA_BASE/lib and $CATALINA_Home/lib for jar files.
Webapps : A class loader is created for each web application that is deployed in a single Tomcat instance. All unpacked classes and resources in the /WEB-INF/classes directory of your web application, plus classes and resources in JAR files under the /WEB-INF/lib directory of your web application, are made visible to this web application, but not to other ones.
In conclusion, buy putting the ojdbc JAR file inside $JAVA_HOME/jre/lib/ext the JDBC driver, will get visible at the Bootstrap level.
I too encountered the same issue. It is because your tomcat server does not have the jar file of your JDBC. I fixed the problem by copying the JAR file to lib folder in tomcat server.
it helped me copying the mssql-jdbc-9.2.1.jre8.jar file to the C: \ Java \ jdk1.8.0_291 \ jre \ lib \ ext folder
I have written a code to check whether connection is successful or not.
But its giving error.
I have a oracle 10g express edition instsalled on my computer.
try{
String url="jdbc:oracle:thin:#//localhost:1521:XE";
String driver= "oracle.jdbc.driver.OracleDriver";
Class.forName(driver);
System.out.println(" Driver loaded ");
Connection con = DriverManager.getConnection(url,"system:,"manager");
System.out.println("Connection Successful");
} //catch block
The error given is:
java.lang.ClassNotFoundException: oracle.jdbc.driver.OracleDriver
Thanks for help.
you need to add oracle jdbc driver (jar) to your class path.
Looks like the JAR file containing the oracle.jdbc.driver.OracleDriver class is simply not on your classpath. Find it and fix that problem by adding the location (e.g., via the -cp option to java; the details of how to fix it will vary by the kind of application you're building).
Add ojdbc.jar in classpath.
Check this for How to Add JARs to Project Build Paths in Eclipse
You have to put the oracle_jdbc.jar file in the same folder of your code, or anywhere else and add that folder to your classpath.