我正在使用swf来运行一个创建emr集群的工作流，在这个集群上运行一个pig脚本。我正在尝试用pig 0.12.0和hadoop 2.4.0运行此脚本，当脚本试图使用org.apache.pig.piggybank.storage.dbstorage存储到rds中的mysql数据库时，抛出了一个异常：

2015-05-26 14:36:47,057 [main] ERROR org.apache.pig.piggybank.storage.DBStorage - 
    can't load DB driver:com.mysql.jdbc.Driver
java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
  at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
  at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
  at java.security.AccessController.doPrivileged(Native Method)
  at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
  at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
  at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
  at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
  at java.lang.Class.forName0(Native Method)
  at java.lang.Class.forName(Class.java:191)
  at org.apache.pig.piggybank.storage.DBStorage.<init>(DBStorage.java:66)

这是以前使用pig0.11.1和hadoop1.0.3实现的。swf工作流和活动是用java编写的，使用javaawsdkversion1.9.19。在更广泛的互联网上搜索信息表明pig\u类路径需要修改，以包含mysql连接器jar——目前脚本包括

REGISTER $LIB_PATH/mysql-connector-java-5.1.26.jar;

其中，$lib\u path是一个s3位置，但有人认为这对于pig0.12.0+hadoop2.4.0已经不够了
构建用于启动集群的请求的代码如下所示

public final RunJobFlowRequest constructRequest(final List<String> params) {
    ConductorContext config = ContextHolder.get();

    final JobFlowInstancesConfig instances = new JobFlowInstancesConfig().withInstanceCount(config.getEmrInstanceCount())
            .withMasterInstanceType(config.getEmrMasterType()).withSlaveInstanceType(config.getEmrSlaveType())
            .withKeepJobFlowAliveWhenNoSteps(false).withHadoopVersion(config.getHadoopVersion());

    if (!StringUtils.isBlank(config.getEmrEc2SubnetId())) {
        instances.setEc2SubnetId(config.getEmrEc2SubnetId());
    }

    final BootstrapActionConfig bootStrap = new BootstrapActionConfig().withName("Bootstrap Pig").withScriptBootstrapAction(
            new ScriptBootstrapActionConfig().withPath(config.getEmrBootstrapPath()).withArgs(config.getEmrBootstrapArgs()));

    final StepFactory stepFactory = new StepFactory();
    final List<StepConfig> steps = new LinkedList<>();

    steps.add(new StepConfig().withName("Enable Debugging").withActionOnFailure(ActionOnFailure.TERMINATE_JOB_FLOW)
            .withHadoopJarStep(stepFactory.newEnableDebuggingStep()));

    steps.add(new StepConfig().withName("Install Pig").withActionOnFailure(ActionOnFailure.TERMINATE_JOB_FLOW)
            .withHadoopJarStep(stepFactory.newInstallPigStep(config.getPigVersion())));

    for (final PigScript originalScript : config.getScripts()) {
        ArrayList<String> newParams = new ArrayList<>();

        newParams.addAll(Arrays.asList(originalScript.getScriptParams()));
        newParams.addAll(params);

        final PigScript script = new PigScript(originalScript.getName(), originalScript.getScriptUrl(),
                AWSHelper.burstParameters(newParams.toArray(new String[newParams.size()])));

        steps.add(new StepConfig()
                .withName(script.getName())
                .withActionOnFailure(ActionOnFailure.CONTINUE)
                .withHadoopJarStep(
                        stepFactory.newRunPigScriptStep(script.getScriptUrl(), config.getPigVersion(), script.getScriptParams())));
    }

    final RunJobFlowRequest request = new RunJobFlowRequest().withName(makeRunJobName()).withSteps(steps).withVisibleToAllUsers(true)
            .withBootstrapActions(bootStrap).withLogUri(config.getEmrLogUrl()).withInstances(instances);

    return request;
}