运行maven中的例外情况

Question

I imported Example from how to use storm book

and when i run it i got this

INFO] An exception occured while executing the Java class. null 0

i used this command in Terminal

mvn -f pom.xml compile exec:java -Dstorm.topology=TopologyMain

Code:

import spouts.WordReader;
import backtype.storm.Config; 
import backtype.storm.LocalCluster;
import backtype.storm.topology.TopologyBuilder;
import backtype.storm.tuple.Fields;
import bolts.WordCounter; import bolts.WordNormalizer;
public class TopologyMain {

    public static void main(String[] args) throws InterruptedException {

        //Topology definition
        TopologyBuilder builder = new TopologyBuilder();
        builder.setSpout("word-reader",new WordReader());
        builder.setBolt("word-normalizer", new WordNormalizer()) .shuffleGrouping("word-reader");
        builder.setBolt("word-counter", new WordCounter(),1) .fieldsGrouping("word-normalizer", new Fields("word"));

        //Configuration
        Config conf = new Config(); conf.put("wordsFile", args[0]); conf.setDebug(false);
        //Topology run
        conf.put(Config.TOPOLOGY_MAX_SPOUT_PENDING, 1);
        LocalCluster cluster = new LocalCluster(); cluster.submitTopology("Getting-Started-Toplogie", conf, builder.createTopology());
        Thread.sleep(1000);
        cluster.shutdown();
     }
}

I also tried this:

mvn -f pom.xml clean install

then tried to use this

mvn exec:java -Dexec.mainClass="TopologyMain" -Dexec.args="src/main/resources/words.txt"

error here

[0] Inside the definition for plugin 'exec-maven-plugin' specify the following:

<configuration> ... <mainClass>VALUE</mainClass></configuration>

Answer 1

You're using the -D argument incorrectly. It should be instead:

mvn -f pom.xml compile exec:java -Dexec.mainClass=storm.topology.TopologyMain

This will specify the main class to execute. It should be packaged with package storm.topology , which is not evident in the code you pasted.

---

Also, I don't know why you're explicitly specifying your POM file. You should create a pom.xml file in the project's root directory, and then you won't have to specify it on the command-line. Ideally you should be typing,

mvn clean install

mvn exec:java -Dexec.mainClass="storm.topology.TopologyMain"

This will clean your project, compile it, install any dependencies, and then execute the project with TopologyMain as the entry point.