Ant构建版本的应用程序无法找到依赖的jar

Question

尝试构建java应用程序，我能够通过Eclipse成功运行该应用程序，但我无法运行ant构建的jar文件。我怀疑我的build.xml是罪魁祸首，我正在努力使它正确。需要帮助!

mysql driver .jar文件在项目的lib/目录下。

错误:

$ java -jar dist/lib/MyProject.jar 
Loading Mysql JDBC driver...
java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
    at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:186)
    at com.test.bh1.bh.main(Unknown Source)

bh.java

package com.test.bh1;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class bh {
    /**
     * @param args
     */
    public static void main(String[] args) {        
        System.out.println("Loading Mysql JDBC driver...");
        try {
            Class.forName("com.mysql.jdbc.Driver").newInstance();
        } catch (Exception e) {
            msg ("Error instantiating mysql jdbc driver. E=" + e.getMessage());
            // bail. 
            return;
        }
        msg ("Successfully instantiated mysql jdbc driver. ");
        Connection con = null;
        String url = "jdbc:mysql://servername:3306/databasename";
        String user = "username";
        String password = "password";
        try {            
            con = DriverManager.getConnection(url, user, password);
            Statement st = con.createStatement();
            ResultSet result = st.executeQuery("SELECT VERSION()");
            if (result.next()) {
                msg(result.getString(1));
            }
            con.close();
        } catch (SQLException ex) {
            msg(ex.getMessage());
        }
    }
    private static void msg (String m) {
        System.out.println(m);
    }
}

build . xml

<project name="TestProj1" default="dist" basedir=".">
    <description>
        Build File For This Project
    </description>
  <!-- set global properties for this build -->
  <property name="src"      location="src"/>
  <property name="build"    location="build"/>
  <property name="dist"     location="dist"/>
  <property name="user.name"    location="Brad Hein (CQA)"/>
  <property name="lib.dir"  location="lib/"/>
  <property name="mysql.jar"    location="mysql-connector-java-5.0.8-bin.jar"/>
  <property name="appName.jar"  location="${dist}/lib/MyProject.jar"/>
    <path id="classpath">
        <fileset dir="${lib.dir}" includes="**/*.jar"/>
    </path>
  <path id="build.classpath">
    <pathelement location="${mysql.jar}"/>
    <pathelement path="${appName.jar}"/>
  </path>

  <target name="init">
    <!-- Create the time stamp -->
    <tstamp/>
    <!-- Create the build directory structure used by compile -->
    <mkdir dir="${build}"/>
  </target>
  <target name="compile" depends="init"
        description="compile the source " >
    <!-- Compile the java code from ${src} into ${build} -->
    <javac srcdir="${src}" destdir="${build}" includeantruntime="false">
           <classpath refid="build.classpath"/>
    </javac>
    <!-- Copy dependency libraries to the build path so they get packaged up in the distro jar file. -->
    <copy todir="${build}/lib">
         <fileset dir="${lib.dir}">
             <include name="*.jar"/>
     </fileset>
    </copy>
  </target>

  <target name="dist" depends="compile"
        description="generate the distribution" >
    <!-- Create the distribution directory -->
    <mkdir dir="${dist}/lib"/>
    <!-- Put everything in ${build} into the MyProject-${DSTAMP}.jar file -->
    <jar jarfile="${appName.jar}" basedir="${build}">
    <!-- Creates a manifest file in the jar-->
        <manifest>
                <attribute name="Built-By" value="${user.name}" />
                <attribute name="Class-Path" value="./lib/mysql-connector-java-5.0.8-bin.jar"/>
                <attribute name="Main-Class" value="com.test.bh1.bh"/>
        </manifest>
    </jar>
  </target>
  <target name="clean"
        description="clean up" >
    <!-- Delete the ${build} and ${dist} directory trees -->
    <delete dir="${build}"/>
    <delete dir="${dist}"/>
  </target>
</project>

Answer 1

这样做:

<attribute name="Class-Path" value="./lib/mysql-connector-java-5.0.8-bin.jar"/>

表示mysql-connector-java-5.0.8-bin.jar需要在appName.jar旁边的lib文件夹中。不是在里面。试着把你的lib文件夹和mysql jar放在你的appName.jar旁边，运行应用程序应该确认这是问题。

Answer 2

Try

java -cp lib -jar dist/lib/MyProject.jar