Heroku, Java, Procfile, Could not find or load main class

问题

I'm using heroku with maven to run a server. My goal is to have heroku run the java class server.class as a web dyno.

How would I write a procfile to execute the java program server.class as web?

My current Procfile

web: java -cp $JAVA_OPTS target/classes/v1/a1/server

My error.(From heroku logs)

Picked up JAVA_TOOL_OPTIONS: -Xmx350m -Xss512k -Dfile.encoding=UTF-8
Error: Could not find or load main class target.classes.v1.a1.server
State changed from starting to crashed

Possibly useful information

The procfile

web: java -cp $JAVA_OPTS target/classes/v1/a1/*

Returns

Error: Could not find or load main class target.classes.v1.a1.myOtherClass

My original Procfile(Also didn't work)

web: java -cp target/classes/:target/dependency/* server

My file structure is a bit different than the example given in the heroku docs so I modified the procfile a bit.
My dependencies are not inside /target/dependencies.
My classes are inside target/classes/v1/a1/.
server.java has a main method and valid constructor method.
All my dependencies seem to be in order.
Maven does builds my .java files into .class files in the target directory.
I'm on unix so quotes and semicolons probably won't work.

回答1:

I think your Procfile should contain:

web: java -cp target/classes/:target/dependency/* v1.a1.server

This assumes the following:

Your server class is in the file target/v1/a1/server.class
The Java code for your server class includes package v1.a1;
Your class name and file name are lowercase.

A few problems I noticed in your earlier attempts included:

You are passing $JAVA_OPTS to the -cp options (incorrect)
You are using / instead of . in the fully qualified class name (incorrect)
You are including the target dir in the fully qualified class name (incorrect)

The files in the target/classes/ and target/dependency/ directory belong on the classpath (i.e. passed to -cp) while the last argument to the java command should be the fully qualified class name (in the form package.Class).

回答2:

The default Procfile for heroku is written for Linux. Where the separator used is ":".

To use the Procfile on Windows machines modify the Procfile as below

web: java -cp target/classes/;target/dependency/* com.yourpackage.MainClassName

回答3:

I forgot a bit of my POM.

<plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-dependency-plugin</artifactId>
            <version>2.4</version>
            <executions>
                <execution>
                    <id>copy-dependencies</id>
                    <phase>package</phase>
                    <goals><goal>copy-dependencies</goal></goals>
                </execution>
            </executions>
        </plugin>

And modified my Procfile a bit

web: java $JAVA_OPTS -cp target/classes/:target/dependency/* v1.a1.server

来源：https://stackoverflow.com/questions/36732703/heroku-java-procfile-could-not-find-or-load-main-class

标签

java

maven

heroku

procfile