miniJVM

Develop iOS Android app in java, Cross platform java virtual machine , the minimal jvm .

Features:

• Jvm Build pass: iOS / Android / mingww64 32-64bit / cygwin / MSVC 32-64bit / MacOS / Linux .
• No dependence Library .
• Minimal memory footprint .
• Minimal binary ,300 KB jvm.
• Minimal runtime classlib .
• Support java5+ class file .
• Support embedded java source compiler(janino compiler) .
• Java native method .
• Java garbage collection .
• Java remote debug supported, JDWP Spec .

iOS/Android Platform Extended Features:

• OpenGL ES 3.0 .
• Swing like gui .
• Audio Playback and Capture .
• Take photo from Camera or Album .
• Save and Load file from mobile storage .
• Api compatible with miniJVM desktop platform, can running on pc .

mobile app IM Demo ,Github:

This demo can be download from : http://bb.egls.cn:8080/down/BiBiX.jar , First install AppManager from : /binary/ios/MiniPack.ipa or /binary/android/MiniPack.apk ,or run AppManager in mini_jvm (eg. /binary/win_64) then download demo in AppManager and run the app.

Architecture:

How to develop iOS/Android app in java:

Write java code once , running on all of iOS / Android / MacOSX / Win / Linux platforms.

• Can develop app by Eclipse, Netbeans or Intelli Idea , or any IDE .
• Build maven projects /minijvm/java and /mobile/java/glfm_gui, it world copy generated jar to /mobile/assets/resfiles/minijvm_rt.jar and /mobile/assets/resfiles/glfm_gui.jar
• Open maven project ExApp in IDE ,or create new project same as ExApp
• Write your code like example /mobile/java/ExApp/src/main/java/test/MyApp.java
• Add your resource to /mobile/java/ExApp/src/main/resource/res/ , such as audio or image etc.
• Configure /mobile/java/ExApp/src/main/config.txt for icon ,version, boot class, etc .
• Build ExApp project , it would copy ExApp.jar to /mobile/assets/resfiles/ExApp.jar
• Install /binary/ios/MiniPack.ipa for iPhone device , (Enterprise distrbute version, need Verify app, Setting->General->Device Management->EGLS Technology ltd->Verify App), or /binary/android/MiniPack.apk for Android device , These two binary built from /mobile/iosapp/ and /mobile/java/androidapp, you can build it yourself.
• Touch the app icon to open MiniPack app, you would see the ExApp is running (the left of picture). You can touch "exit to AppManager" in ExApp, AppManager is a App maintaince tool (the middle and right of picture), It can start a in-app webserver for upload app, it can download app from a website also .
  
  

How to Remote debug:

Prepare: Rebuild /minijvm/c ,change /minijvm/c/jvm/jvm.h "#define JDWP_DEBUG 0" as "#define JDWP_DEBUG 1" Desktop Computer : Run mini_jvm with flag: -Xdebug for debug mode .
iOS/Android simulator : nothing to do .
iOS/Android device : check the device ip address from General Setting -> wifi ->(i).
mini_jvm jdwp listen port is 8000.

• Intelli idea : open the java project , menu Run .> Edit Configurations , + remote , Transport : socket , Debugger mode : attach , host is your mini_jvm running at host ip and port ,ex. "localhost:8000" .
• Eclipse : configuration like as idea .
• Netbeans : open java project , menu Debug .> connect to Debugger, Connector : SocketAttach , host is your mini_jvm running at the host and port, ex. "localhost:8000" , Timeout: 10000 .
  Then you can setup breakpoint or pause mini_jvm and watch variable's value .

How to use Embed java compiler in mini_jvm:

Java Compiler : /binary/libex/janino.jar
Usage of compiler can be found in /binary folder
the compile command :

win:
mini_jvm -cp ../lib/minijvm_rt.jar;../libex/janino.jar;../libex/commons-compiler.jar org.codehaus.janino.Compiler  ../res/BpDeepTest.java
posix:
./mini_jvm -cp ../lib/minijvm_rt.jar:../libex/janino.jar:../libex/commons-compiler.jar org.codehaus.janino.Compiler  ../res/BpDeepTest.java

Janino compiler is not the full java compiler, see limitation , like :

List<String> list=new ArrayList(); 
list.add("abc");
String s=(String)list.get(0);//can't ignore (String) cast qualifier.   

Referenced project and technology:

Sun CLDC :reference
Miniz :for read jar files
GLFM :for cross platform (android/ios) GUI
Nanovg :for GUI paint function
Stb :for GUI truetype font and image
Glad :for replace openGL/GLES head file
GLFW :for pc cross platform GUI
Dirent :for linux style on win vc file and directory access
Tinycthread :for cross platform thread
JRegex :for java String regex match
Janino :for compile java source file
MiniAudio :for java audio playback and capture

Development IDE using:

C code: JetBrains CLion ,Xcode ,Virtual studio .
Swift code/Object c: XCode , LLVM .
Java code: Netbeans ,jdk .
android project: Android Studio , Android SDK

Build GUI application, depend on openGL or openGLES

• iOS/Android system build with GLFM (/mobile/iosapp/ , /mobile/androidapp/)
• Window system build with GLFW (/ex_lib/gui_jni/)
• GUI build with Nanovg

Example of mobile application

the example demonstrate how develop java app for iOS and Android

package test;

import org.mini.apploader.AppManager;
import org.mini.gui.*;
import org.mini.gui.event.*;

/**
 *
 * @author gust
 */
public class MyApp extends GApplication {

    GForm form;
    GMenu menu;
    GFrame gframe;

    @Override
    public GForm getForm(GApplication appins) {
        if (form != null) {
            return form;
        }
        GLanguage.setCurLang(GLanguage.ID_CHN);
        form = new GForm();

        form.setFps(30f);
        long vg = form.getNvContext();

        int menuH = 80;
        GImage img = GImage.createImageFromJar("/res/hello.png");
        menu = new GMenu(0, form.getDeviceHeight() - menuH, form.getDeviceWidth(), menuH);
        menu.setFixed(true);
        GMenuItem item = menu.addItem("Hello World", img);
        item.setActionListener(new GActionListener() {
            @Override
            public void action(GObject gobj) {
                if (gframe != null) {
                    gframe.close();
                }
                gframe = getFrame1();
                form.add(gframe);
                gframe.align(GGraphics.HCENTER | GGraphics.VCENTER);
            }
        });

        img = GImage.createImageFromJar("/res/appmgr.png");
        item = menu.addItem("Exit to AppManager", img);
        item.setActionListener(new GActionListener() {
            @Override
            public void action(GObject gobj) {
                AppManager.getInstance().active();
            }
        });

        form.add(menu);
        return form;
    }

    public GFrame getFrame1() {

        GFrame gframe = new GFrame("Hello World", 50, 50, form.getDeviceWidth() * .8f, (form.getDeviceHeight() - menu.getH()) * .7f);
        GViewPort parent = gframe.getView();
        float pad = 8;
        float x = pad, y = 10;
        float btnH = 28;

        String conttxt = "  This app is an example of mini_jvm, Threre are a menu and a frame .\n"
                + "  Touch the 'Exit to AppManager' , you will enter the AppManager, AppManager manage all app, it can upload ,download , delete app.\n"
                + "  1. DOWNLOAD : Put your jar in a website , then input the url of jar in AppManager, Touch 'Download' ,it would download the jar ,then update the app list.\n"
                + "  2. UPLOAD : The first you touch the 'Start' to open the inapp webserver, then open browser in your Desktop Computer, open 'http://phone_ip_addr:8088' , and pickup a jar in the page, upload it.  NOTE: That computer and the phone must be same LAN.\n"
                + "  3. RUN : Touch the App name in the list, Touch 'Run' can start the app.\n "
                + "  4. SET AS BOOT APP : The boot app will startup when MiniPack opend. \n"
                + "  5. UPGRADE : AppManager will download the new jar ,url that get from config.txt in jar.\n"
                + "  6. DELETE : The app would be deleteted.\n";
        GTextBox cont = new GTextBox(conttxt, "Contents", x, y, parent.getW() - x * 2, parent.getH() - pad * 2 - btnH - y);
        cont.setEditable(false);
        parent.add(cont);
        y += cont.getH() + pad;

        GButton bt2 = new GButton("Cancel", x + 170, y, 110, btnH);
        bt2.setBgColor(0, 0, 0, 0);
        bt2.setActionListener(new GActionListener() {
            @Override
            public void action(GObject gobj) {
                gobj.getForm().remove(gframe);
            }
        });
        parent.add(bt2);

        return gframe;
    }

}

Screen shot :

• Windows mini_jvm gui

* Macos mini_jvm gui

* Linux mini_jvm gui

Directories:

/

binary/-------- minijvm binary (win32/win64/mac/linux/android/ios)
minijvm/

c/------------ minijvm c source
java/--------- minijvm runtime class library

desktop/

glfw_gui/------ desktop computer native gui jni module
jni_test/------ jni example
javalib_test/-- test case of /minijvm/java .

mobile/

c/------------- java native lib, glfm framework, gui jni, glfmapp
java/glfm_gui-- mobile platform native gui lib
java/ExApp----- java app entry point
iosapp/-------- iOS launcher
androidapp/---- Android launcher
assets/resfiles/- mobile app resource, font files, jar files ,pic ,audio etc.

test/

jvm_ios/------ ios swift test project .
jvm_macos/---- macosX test project.
jvm_vs/------- windows virtual studio test project.

• /minijvm/c is an independent small and fast jvm interpreter, Need /javalib runtime class library only, it run on Win/Mac/Linux/iOS/Android.
• /minijvm/java is the jvm foundation runtime class library, ex java.lang , java.util ,and extended classes org.mini for file reflect and network etc, this project generate minijvm_rt.jar , copy it into /mobile/assets/resfiles .
• /mobile/iosapp /mobile/androidapp are iOS/Android launcher program, it include minijvm source and native gui function, java call gui library with jni.
• /mobile/java/glfm_gui is a gui library ,it dependent on native gui library ,that include openGLES glad, glfm, nanovg, stb lib etc , this project generate glfm_gui.jar , copy it into /mobile/assets/resfiles .
• /mobile/java/ExApp is an example of mobile app, it run on iOS and Android platform.

License

License: Public domain

Gust , zhangpeng@egls.cn , Technology and production manage in EGLS ltd. EGLS is a game develop company in China .