在Linux Java中动态加载类

Question

I'm doing as a school project a multi-platform Distributed Data Base System

I need to extract data from the Data Base in Java so i dynamically load my jdbc connector

Works Perfect in Windows

But in Linux I got the error:

"No suitable driver found for jdbc:mysql://..."

This is the code:

File f = new File("mysql-connector-java-5.1.24-bin.jar");
URLClassLoader urlCl = new URLClassLoader(new URL[] { f.toURL()},System.class.getClassLoader());
Class conector = urlCl.loadClass("com.mysql.jdbc.Driver");
conector.newInstance();


Connection conexion = DriverManager.getConnection("jdbc:mysql://localhost/test","root",""); 
Statement instruccion = conexion.createStatement();
ResultSet tabla = instruccion.executeQuery("select * from prueba where uno=1");
while(tabla.next())
{
     System.out.println(tabla.getString(1));
     System.out.println(tabla.getString(2));
}

 conexion.close();

I don't know what can I do.

This it's made to avoid the installation of the connector on each site

I pass a file with the configuration for each DB, if is postgresql load postgres jdbc conector if is mysql etc...

Suggestions?

Answer 1

Why don't just put the connector into a lib sub-directory and then passed all jar contained in this one to the Java Class-Path ?

Samples folder tree :

• MyApp
  • bin
    • launcher.sh
    • MyApp.jar
  • lib
    • myLib.jar

Here is the launcher.sh script :

#!/bin/sh
#Set basedir
LAUNCHER_DIR=$(cd $(dirname $0); pwd)

#Set Java Class-Path
CLASSPATH="$LAUNCHER_DIR/bin/MyApp.jar"$(find "$LAUNCHER_DIR" -name '*.jar' -printf ":%p")

#Launch application
java -cp "$CLASSPATH" com.company.MyApp $*

EDIT: It is not recommanded to directly use File.toURL as describe in the documentation, you must do File.toURI().toURL().