MySQL with ant: can not find driver class

[Edward Chen]

I am testing a MySQL jdbc program. My project looks like this:

--build
-- mysql-jdbc-connector.jar
--classes
-- ddd.class

so I use
-----------------
<jar dest="dd.jar">
<fileset dir="${classes}"/>
<fileset dir="{build}"/> <!-- add MySQL-jdbc-con.jar into it -->
</jar>

<java classname="ddd" classpath="dd.jar" />
-------------

But still have the error, "can not find class com.mysql.jdbc.Driver". I unzip the dd.jar, I do see the MySql driver inside.

I don't know why. Could you help me?

after this

[Dirk Schreckmann]

To be clear, are you placing a JAR inside of a JAR?

[Edward Chen]

Dear Dirk,

no, I just want to make a single executable jar file.

Actually I solve the part of problem. I add the classpath "ant.java.classpath" to "java" target. It works.

But the problem is, when I go to windows console, to java -jar myjar.jar. It NOT works, still can not find "com.mysql.jdbc.Driver". Actually the mysql driver jar is located in ./jar folder.

How to work out?

Thanks

[Dirk Schreckmann]

If I understand correctly, you need to add the JAR file to your CLASSPATH.

[Edward Chen]

Dear Dirk,

Below is what I have tried to do. I have to place the MySQL driver jar into my jar file. My goal is to make the jar file self-executalbe, say,double click to lanuch it.

Error should be here
<attribute name="Main-Class" value="classes/${project-main-class}"/>
<attribute name="Class-Path" value="lib/mysql-connector***-bin.jar"/>

Thanks.

Edward

--mysql
  --classes  
  --jar
  --lib
    --mysql-connector-java-3.0.14-production-bin.jar
  --src
    --ddd.java
 
------------- Coding -----------------
import java.sql.* ;
public class ddd {   
    public ddd() { }     
    public static void main(String[] args) {
        try{
           String connectionURL = "jdbc:mysql://localhost:3306/mysql?user=root&password=";
           Connection connection = null;
           Statement statement = null;
           ResultSet rs = null;
 
           Class.forName("com.mysql.jdbc.Driver").newInstance();
           connection = DriverManager.getConnection(connectionURL, "", "");
           statement = connection.createStatement();
           rs = statement.executeQuery("SELECT host,db,user FROM db");
           while (rs.next()) {
      System.out.println(rs.getString("db"));
           }
           rs.close();
       }
       catch(Exception e){
           System.out.println("error "+e.getMessage());
           e.printStackTrace();
       }
    }    
}
 
-------- build.xml --------------
<?xml version="1.0" encoding="UTF-8"?>
 
<project name="ant test" default="run" basedir="./mysql">
   <property name="src" value="${basedir}/src"/>
   <property name="classes" value="${basedir}/classes"/>
   <property name="jar" value="${basedir}/jar"/>
   <property name="lib" value="${basedir}/lib"/>
   
   <!-- edit this -->
   <property name="project-name" value="MySQLTest"/>
   <property name="project-main-class" value="ddd"/>   
 
   <target name="clean" description="clean folder">
       <delete dir="${classes}" />
       <mkdir  dir="${classes}" />
       <delete dir="${jar}"/>
       <mkdir  dir="${jar}"/> 
       <delete dir="${basedir}/temp"/>         
   </target>
 
   <target name="init" depends="clean" description="init"> 
       <mkdir  dir="${basedir}/temp" />       
       <mkdir  dir="${basedir}/temp/lib" />
       
       <copy todir="${basedir}/temp/lib">
           <fileset dir="${lib}" />
       </copy>         
   </target>
 
   <target name="build" depends="init" description="compile" >
        <javac srcdir="${src}" destdir="${classes}" debug="true">
             <classpath>
                 <fileset file=""/>  <!-- this is for third party jar file -->
                 <fileset dir=""/>   <!-- this is for extra classes -->
             </classpath>
        </javac>
   </target>
 
   <target name="jar" depends="build" description="jar">
       
       <mkdir  dir="${basedir}/temp/classes" />
       <copy todir="${basedir}/temp/classes">
           <fileset dir="${classes}" />
       </copy>    
 
      <jar destfile="${jar}/${project-name}.jar">
          
          <fileset dir="${basedir}/temp"  />
          <manifest>
              <attribute name="Built-By" value="${user.name}"/>
              <!--
              <section name="${project-main-class}.class">
                  <attribute name="Sealed" value="false"/>
              </section>
              -->
              <attribute name="Main-Class" value="classes/${project-main-class}"/>
              <attribute name="Class-Path" value="lib/mysql-connector-java-3.0.14-production-bin.jar"/>
          </manifest>          
      </jar> 
      <delete dir="${basedir}/temp"/>       
   </target>
 
   <target name="run"  depends="jar" description="run this program">
       <java jar="${jar}/${project-name}.jar"  fork="true">          
       </java>        
   </target>      
</project>
 
******** error message *******************
[java] java.lang.NoClassDefFoundError: classes/ddd (wrong name: ddd)
[java]     at java.lang.ClassLoader.defineClass0(Native Method)
[java]     at java.lang.ClassLoader.defineClass(ClassLoader.java:539)
[java]     at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:
[java]     at java.net.URLClassLoader.defineClass(URLClassLoader.java:251)
[java]     at java.net.URLClassLoader.access$100(URLClassLoader.java:55)
[java]     at java.net.URLClassLoader$1.run(URLClassLoader.java:194)
[java]     at java.security.AccessController.doPrivileged(Native Method)
[java]     at java.net.URLClassLoader.findClass(URLClassLoader.java:187)
[java]     at java.lang.ClassLoader.loadClass(ClassLoader.java:289)
[java]     at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:274)
[java]     at java.lang.ClassLoader.loadClass(ClassLoader.java:235)
[java]     at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:302)
[java] Exception in thread "main"
[java] Java Result: 1

[Lasse Koskela]

That NoClassDefFoundError is due to
<attribute name="Main-Class" value="classes/${project-main-class}"/>
which should be
<attribute name="Main-Class" value="${project-main-class}"/>

[Edward Chen]

Originally posted by Lasse Koskela:
That NoClassDefFoundError is due to
<attribute name="Main-Class" value="classes/${project-main-class}"/>
which should be
<attribute name="Main-Class" value="${project-main-class}"/>

HI, Lasse, thanks for your response. But it still doesn't work.

The main class , ddd.java , doesn't belong to any package. It is plain. Its class file, ddd.class, just is placed into classes directory.

The question is, I should tell the compiler: "classes\ddd" or just "ddd" ? I guess should be the former one.

But it doesn't work.

[Dirk Schreckmann]

If you've a class that is not part of a package, you can add it to your CLASSPATH by specifying the location of the directory where the class resides.

[somkiat puisungnoen]

Set class path in build.xml of ANT

 
    <property name="dist" value="${basedir}/dist"></property>
<!-- Set Classpath of Libraries -->
<path id="lib.class.path">
<fileset dir="${dist}">
<include name="**/*.jar"/>
</fileset>
<fileset dir="${build}">
<include name="**/*.class"/>
</fileset>
    </path>
 

 
<!-- Compile source code -->
<target name="compile" depends="init">
 <javac srcdir="${src}" destdir="${build}">
    <classpath refid="lib.class.path"></classpath>
 </javac> 
</target>