docker-j2me

This project create docker images for Oracle Java ME.

As a subset of Java SE for embedded, it is probably the smallest JVM ever made by Oracle.

Supported tags and respective Dockerfile links

• latest (Dockerfile)

Details

What are these?

tl;dr : Busybox + libc 64bit + libc 32 bits + Embedded JRE = Small Java Container

All image are based on Busybox with 32 bits (and 64 bits) libs (see docker-busybox-jvm and docker-busybox-lib32 ).

The overhead on top of a JRE is around 8 MB.

Size matters

The biggest advantage of this image is its size : only 21 MB !!!

It's 24 times smaller than the official java image (not really fair cause it's a full 64 bits JVM and based on a full Debian) !

Here is a list of some java image.

REPOSITORY                  TAG          IMAGE ID        CREATED         VIRTUAL SIZE
ofayau/j2me                 latest       f56c31b1cc20    26 hours ago    21.73 MB
frolvlad/alpine-oraclejdk8  latest       8e87306ea37d    7 weeks ago     170.4 MB
jeanblanchard/busybox-java  8            f9b532dbdd9f    3 months ago    162 MB
java                        8-jre        b0f21df5333b    5 months ago    478.7 MB

Drawback

• rather old truncated JRE : based on a J2SE 1.4, it doesn't contain every java package.

• 32 bits only : you can't run 64 bits code.

• the command is cvm, not java.

• JRE, not JDK : hence there is no compiler (javac) included, only runtime executor (cvm). You have to compile somewhere else (i.e. a standard jdk).

License

• Busybox : see license information.

• Debian libc-i386 : see licence of debian package.

• Oracle and Java : see OTN licence.

Oracle and Java are registered trademarks of Oracle and/or its affiliates.

The Java softwares (including JDK or JRE) belong to Oracle and this redistribution is not for commercial use.

The ojec1.1.1 directory is the unzipped version of ojec-1.1.1-rr-bin-b02-linux-x86-generic-product-22_apr_2013.zip available (with login) on Oracle

Installation & Usage

Download or update image :

docker pull ofayau/j2me

Showing java version (default command) :

docker run --rm -it ofayau/j2me
Product version "Oracle Java Micro Edition Embedded Client 1.1.1"
*Java(TM) ME CDC 1.1.2 Runtime Environment (build 1.1.1-b02)*
Components: CDC JSR218, FP JSR219, JAAS JSR219, JCE JSR219, JSSE JSR219, RMI JSR66, JDBC JSR169, XML JSR280
JVM:        CVM (mixed mode)

Simple runs

# Run a fat jar from current dir with full JRE
docker run --rm -v "$PWD":/tmp/myapp -w /tmp/myapp ofayau/j2me cvm -jar myFatJar.jar

Compile and run for j2me

# Compile with jdk (outside container)
javac -target 1.4 HelloWorld.java
# Run a "HelloWorld" class from current dir
docker run --rm -v "$PWD":/tmp/myapp -w /tmp/myapp ofayau/j2me cvm HelloWorld.class