Kuidas teha Java-platvormiülest mobiilirakendust

Kas teadsite, et saate Java abil platvormidevahelisi mobiilirakendusi teha? Jah, näpista ennast, sa lugesid seda esimest korda õigesti! Õpetan teile 12 lihtsa sammuga põhitõdesid, kuidas kasutada oma olemasolevaid Java-teadmisi Androidi ja iOS-i jaoks toimivate rakenduste loomiseks. Teeme seda kõike, kasutades GUI tööriistakomplektina JavaFX-i.

Kuid kõigepealt veel mõned esiplaanid. Rakenduse loomiseks nii Androidi kui ka iOS-i jaoks peate vastama järgmistele nõuetele . Kui te aga ei soovi iOS-i rakendust ehitada, võite julgelt välja töötada kõikides x64-bitistes masinates, mis toetavad Java SE 8-d. See projekt on gradliga ehitatud Giti hoidla. Kuid te ei pea Giti hoidlat looma.

Nõuded on järgmised :

  • JDK 1.8 nõuetele vastav JVM
  • Androidi käsurea tööriistad (SDK v.27)
  • XCode 9.2
  • Grader 4.2
  • Git Large File Storage (v.2.5.0) (pole vajalik, kui te ei soovi git-hoidlat luua)
  • Eelistatavalt vähemalt 4G RAM

Kannatamatu? Kas soovite näha lõpptulemust? Tutvuge allpool valminud projektiga.

afinlay5 / OnyxFx

Gradle'i lähtekoodihoidla OnyxFx-le, platvormidevaheline (Android / iOS / Linux / macOS / Windows) JavaFX-i rakenduse renderdamine ... github.com

Minu arenduskeskkonnaks saavad Fedora Linux 28 ja macOS High Sierra. Nüüd, kui meil on see viis kadunud, uurime järele.

1) Looge projekti mahutamiseks kaust

Ma korraldasin oma projekti OnyxFx järgmiselt: “ / home / adriandavid / Projektid / OnyxFx”. Loomulikult võite projekti korraldada kõikjal, kus soovite.

2) Initsialiseeri gradle, Git, määra JAVA_HOME

Avage terminal kataloogi projekti kataloogis. Kui gradle on õigesti konfigureeritud, peaksite pärast järgmise käsu käivitamist nägema midagi sellist:

gradle -v

Peate veenduma, et gradle loetleb teie Java Development Kit (JDK) 8 installi jaotise „JVM” kõrval.

Kuigi selleks on mitmeid viise, on kõige otsesem viis tagada, et teie JAVA_HOME keskkonnamuutuja on õigesti seatud.

Sõltuvalt teie keskkonnast on selleks mitmeid viise. Üks võimalus seda teha enamikus * nixi keskkondades on muutuja seadistamine failis /home//.b ash rc või / etc / pro . Vaadake oma opsüsteemi kasutusjuhendist, et veenduda, et teie JAVA_HOME keskkonnamuutuja on õigesti seadistatud.

JAVA_HOME õigesti seadistamiseks võite lisada järgmised read kas .bashrc või profiili lõppu.

JAVA_HOME=/home/adriandavid/java/oracle_jdk1.8.0_181/export JAVA_HOME

Märkus . Siin saate installida Oracle'i JDK 8.

Seejärel veenduge, et kest kajastaks ülaltoodud muudatusi, käivitades ühe järgmistest käskudest:

source ~/.bashrcsource /etc/profile

Muutuja õigesti seadistamiseks sisestage järgmine käsk:

echo $JAVA_HOME

Kui teil on endiselt probleeme või kasutate Microsoft Windowsi, vaadake siit.

Kõigepealt käivitage git initprojekti juurkataloogis Giti hoidla initsialiseerimine. Märkus. Kui te ei soovi hostida git-hoidlat, võite selle sammu vahele jätta.

Teiseks käivitage gradle initprojekti juurkataloogis gradle'i hoidla initsialiseerimine. See samm on vajalik.

Märkus: märkate, et minu näide on veidi erinev. Seda seetõttu, et mul on grader ja Git juba oma kohalikus keskkonnas initsialiseeritud.

3) Saa toredaks! Redigeerige gradle.build ja

Loodetavasti võib Maa, tuul ja tuli aidata teil raskusi saada! Lülitage sisse oma lemmiktekstiredaktor ja muutke oma projekti juurkataloogis asuvat faili build.gradle ning asendage sisu järgmise GitHubi sisuga.

Need build.gradle'i seaded konfigureerivad meie gradle'i projekti kasutama javafxmobile pistikprogrammi, mis on meie projekti tööhobune. Pistikprogrammi kohta saate lisateavet siit ja siit. Muuhulgas automatiseerib javafxmobile pistikprogramm allalaadimise protsessi (Maven Centralist või jcenterist) ning iOS-i ja Androidi SDK-de lisamist teie rakenduse klassirajale.

Kui olete kursis gradli, saviga või sipelgaga, on suurepärane - teil on tõenäoliselt aimu, mis toimub. Kui te pole gradliga tuttav, ärge muretsege selle pärast . Kõik, mida peate mõistma, on see, et gradle on ehitustööriist, mida kasutatakse paljude rakenduste loomisega seotud ülesannete automatiseerimiseks, näiteks: sõltuvuste haaramine, projekti korraldamine ja nii edasi.

Pange tähele, et sihime operatsioonisüsteemi Android 7.1 Nougat (API versioon 25) ja iOS 11 (varsti näeme, kus seda tehakse). Võite neid väärtusi oma äranägemise järgi kohandada. Pange tähele, et Androidi puhul peate tagama, et API versioon ühilduks teie allalaaditud SDK versiooniga (lisateavet selle kohta hiljem).

Lõpuks ei näita ma selles õpetuses allkirjastatud käivitatavate failide tootmist. Sel põhjusel iOSSkipSigning on seatud õige ja me ei kasuta releaseAndroid gradle ülesanne. Allkirjastatud rakenduste tootmiseks võite siiski pakkuda sobivaid majutuskohti.

4) Tehke uus fail nimega gradle.properties ja konfigureerige see

Looge projekti juurkataloogis uus fail gradle.propertiesja lisage failile järgmine sisu.

robovm.device.name=iPhone-7robovm.sdk.version=11.0org.gradle.jvmargs=-Xms4g -Xmx8g

These settings tell the javafxports plugin to use an iPhone-7 as the on-board emulator, to target iOS 11, and to pass the Xms and Xmx flags to the JVM, which specifies both the initial memory pool to 4GB and the maximum heap memory pool to 8GB. This will be necessary for the compilation of the openJDK and the development of the iOS build.

5) Install Homebrew (iOS only)

If you do not have a Mac and are not intending to produce an iOS build, feel free to skip this step.

Open the terminal in macOS and paste the following command.

/usr/bin/ruby -e "$(curl -fsSL //raw.githubusercontent.com/Homebrew/install/master/install)"

6) Install the USB Multiplexing Socket (iOS only)

Only move on to this step if Homebrew has successfully installed. If you do not have a Mac and are not intending to produce an iOS build, feel free to skip this step.

Open the terminal in macOS and paste the following command.

brew install usbmuxd

7) Grab the Android Command Line Tools

Grab Android Command Line Tools for your platform here. After the download has finished, unzip the folder and paste the contents in the directory of your choice. For me, this was /home//Android.

8) Set Android_HOME, Grab necessary Android packages

As with Java, gradle needs to know where to look to find the Android Command Line Tools. There are a few ways to do this. However, in the spirit of simplicity and consistency, we will set the ANDROID_HOME environmental variable in this tutorial. Add the following variable in the same way that we did it for JAVA_HOME. For example:

ANDROID_HOME=/home/adriandavid/Android/ export ANDROID_HOME

Remember to reload the shell by adding source le> as we did for JAVA_HOME.

Now, grab the tools necessary to build the Android build. Execute the following command:

# *.nix./sdkmanager "platform-tools" "build-tools;25.0.3" "platforms;android-25" "extras;android;m2repository" "extras;google;m2repository"
or
#Windowssdkmanager "platform-tools" "build-tools;25.0.3" "platforms;android-25" "extras;android;m2repository" "extras;google;m2repository"

Take careful notice that the SDK and API version we have specified in gradle.build correspond to the version we have specified in this command. Namely, “25”. Should this be misaligned, the build will not succeed.

9) Create the application’s directory structure

To automate the process of creating these directories, execute the following shell script.

Bourne-Again Shell / Korn Shell:

Windows Shell (cmd):

Save the file as mkpdir.bat or mkpdir.sh and execute the file from the project’s root directory as root (or Administrator).

# *.nixchmod +x mkdir.sh-sh ./mkpdir.sh
# Windowsmkpdir

Notice that we created directories for embedded and desktop. We will produce a desktop build, because it takes no additional work to do so. However, we will not produce any builds for embedded devices.

10) Create your JavaFX Application!

Navigate to /src//java and begin developing your JavaFx application! Application resources are stored in /src//resources.

You can start with a simple Hello World application or look at the source code that I have put together here. OnyxFx is an application I made, following these instructions, that makes REST calls over HTTP to the OnyxFxAPI. The API, in turn, is a web scraper that will return the statistical data (points per game, rebounds per game, assists per game) for the NBA® player and season the client specifies. It returns the data as JSON, which is then parsed and displayed to the screen of the mobile app. Feel free to edit it!

Keep in mind that although you can share source code, you should include custom edits in each copy of the source, should you want to make device specific changes.

Also note that the underlying compiler (MobiDevelop’s fork of RoboVM) does not fully support all Java 8 APIs. If you look very closely at my source code, you will notice that in the iOS version of the source code, I have removed unsupported API such as java.util.function.BiConsumer and java.util.Map.replace().

11) Create a RAM disk for iOS builds (iOS only)

The compilation process for iOS is very resource-heavy, as the plugin will compile the entire openJDK and other libraries twice to create a fat JAR that it will use to build your application. Therefore, you should preemptively create a RAM disk to accommodate for the memory requirements.

This step, however, is subject to your judgement of your machine’s capabilities. For context, the macOS machine that I used to compile my iOS app has 4GB of DDR2 RAM. I decided to make an 8GB RAM disk. To do so, execute the following command in the terminal.

SIZE=8192 ; diskutil erasevolume HFS+ ‘RoboVM RAM Disk’ `hdiutil attach -nomount ram://$((SIZE * 8192))`

12) Build and Run your application!

To build your application, execute the gradle wrapper in the root directory from the terminal as follows.

./gradlew clean build

This will produce a desktop application packaged as a JAR with scripts to run the application provided in /build/distributions/ ar> ; and /build/distributions/ Name.zip>. Should you unzip the directories, you will notice the following structure:

Notice that in /bin there are scripts to execute the application. These scripts rely on preserving the current folder structure. Also notice that is not necessary for you to have tree installed. It is used here simply for illustrative purposes.

There is, additionally, a standalone JAR that you can use to execute the application on any desktop environment supporting JavaFX 8. To run the application, execute one of the following:

# Navigate to /build/distributions//
#On *.nixcd bin./
#On Windowscd bin
#Platform agnosticjava -jar OnyxFxMobile.jar (or double click, if jvm is configured to run .jar files)
Note: If the executable providing "java" is not the same vendor and/or version of the Java 8 JDK with which you built this application, the jar may not run. JavaFX 8 builds between the openJDK & Oracle JDK are incompatible.
Otherwise: /location/to/java8/bin/java -jar 

View this project’s gradle tasks

You can view this project’s gradle tasks by running the following in the project’s root directory.

./gradlew tasks

To Compile, Run on Desktop

The following command will run your project in the host environment.

./gradlew jar./gradlew run

You will find a standalone jar in build/libs/ t;.jar .

To Compile, Run on Android

./android #Generates a debug Android apk containing the JavaFX application.
./androidInstall #Launch the application on a connected android device.
./androidRelease #Generates a release Android apk containing the JavaFX application.
Note: You will need to configure a valid signingConfig when releasing an APK (javafxports).

You will find two APKs in build/javafxports/android.

The first will be named t;.apk.

The second will be named -unaligned.apk.

To Compile, Run on iOS

./createIpa - Generates an iOS ipa containing the JavaFX app.
./launchIOSDevice - Launches app on a connected ios device.
./launchIPadSimulator - Launches app on an iPad simulator.
./launchIPhoneSimulator - Launches app on an iPhone simulator.

You will find three executables in build/javafxports/ios.

The first will be named t;.ipa.

The second will be named ame>.dSYM.

The third will be named <AppName>.app.

Some screenshots of my sample app

On Desktop

On Android

On iPhone

On iPad

Splash Screen

My Closing Thoughts

javafxports is a promising project that aims to bring JavaFX and the Java SE platform onto mobile and other devices. In a way, the tool parallels Xamarin in its efforts. However, the project has a lot of work left to be done.

For a start, the plugin currently does not fully support Java 8. On Android, it uses retrolambda to handle Java 8 Lambda Expressions & Method References. It technically is up to Java 6. Additional dependencies make it such that you can use Java 8. However, the process is straightforward, the builds work as expected, and the compilation time is not too long.

On iOS, however, the builds are extremely memory-intensive and the compilation process takes a very long time. The following is a snippet of the log for ./gradlew createIpa task.

:createIpa (Thread[Task worker for ‘:’,5,main]) completed. Took 1 hrs 46 mins 40.198 secs.

In total, the process consumed about over 6GB of RAM on my machine. This is hardly ideal. However, the future is promising. A company called Gluon has developed a high performance, fully modular custom JVM fully supporting Java 9, that you can read more about here.

This article is originally published on the blog section of my homepage, here.

Resources to explore:

  • JavaFxMobile Plugin Git Repo: //github.com/javafxports/javafxmobile-plugin
  • JavaFxPorts Documentation: //docs.gluonhq.com/javafxports/#_how_it_works
  • JavaFxPorts Homepage: //javafxports.org/
  • Gluon Documentation: //gluonhq.com/developers/documentation/
  • Google Groups Page for JavaFxPorts: //groups.google.com/forum/#!forum/javafxports
  • StackOverflow Page for JavaFxPorts: //stackoverflow.com/questions/tagged/javafxports
  • Gluon Mobile Pricing/License Options: //gluonhq.com/products/mobile/buy/