Suresh's Tech Notes 1.0 Help

OpenJDK

Java Commands

1. Create Source Code Structure

$ mkdir -p src/{main,test}/{java,resources}

2. Preview features

$ javac --enable-preview -release 24 Foo.java $ java --enable-preview Foo

3. Java Platform Module Systems (JPMS)

$ java --list-modules $ java --describe-module java.se $ java --show-module-resolution java.base # Replace upgradeable modules in the runtime image $ java --upgrade-module-path $DIR

4. Disassembles a class

$ javap -p -v <classfile> # Show the class version $ javap -p -v build.classes.kotlin.main.App | grep version

5. App CDS

# Before JDK 18 if [ ! -f app.jsa ]; then java -XX:ArchiveClassesAtExit=app.jsa -jar app.jar else java -XX:ShareArchiveFile=app.jsa -jar app.jar fi # Since JDK 19, auto generate the CDS archive $ java -XX:+AutoCreateSharedArchive -XX:SharedArchiveFile=app.jsa -jar app.jar # Create default CDS archive $ jlink-runtime/java -Xshare:dump [-XX:-UseCompressedOops] # Check if it worked, this will fail if it can't map the archive (lib/server/classes.jsa) $ jlink-runtime/java -Xshare:on --version

  • https://ionutbalosin.com/2022/04/application-dynamic-class-data-sharing-in-hotspot-jvm

  • https://dev.java/learn/class-data-sharing-and-application-class-data-sharing-in-hotspot

  • https://mbien.dev/blog/entry/custom-java-runtimes-with-jlink

6. Show Java VMProperty Settings

$ java --version $ java -Xinternalversion # Show Java Version (Useful for shell scripts) $ java -XshowSettings:properties -version 2>&1 | grep "java.specification.version =" | awk '{print $3}' $ jshell --feedback=silent - <<< 'System.out.println(System.getProperty("java.specification.version"))' # Show all settings $ java -XshowSettings:all --version # Show all Javac linter options $ javac --help-lint # Show all system properties $ java -XshowSettings:properties --version # VM extra options $ java -XX:+UnlockExperimentalVMOptions -XX:+UnlockDiagnosticVMOptions -XX:+PrintFlagsFinal --version # Java JIT compiler options $ java -Xcomp forces compilation of methods on first invocation (slow startup) $ java -Xint interpreted mode execution only (fast startup) $ java -Xmixed mixed mode execution (default)

7. Scan deprecated APIs

# Print dependency summary $ jdeps -summary app.jar # Check the dependencies on JDK internal APIs $ jdeps --jdk-internals --classpath libs.jar app.jar # List of module dependences to be used in JLink $ jdeps --ignore-missing-deps --print-module-deps app.jar # List all service providers $ jlink --suggest-providers java.security.Provider # List all jlink plugins $ jlink --list-plugins # Generate module-info $ jdeps --generate-module-info ./ app.jar # List all deprecated APIs for a release $ jdeprscan --for-removal --release 24 --list # Scan deprecated APIs $ jdeprscan --for-removal --release 24 app.jar

8. JPMS

# Start ModuleMainClass $ java -m jdk.httpserver -b 127.0.0.1 # Compile all modules at once (Start from the main module) $ javac --enable-preview \ --release 24 \ -parameters \ // Optional, Generate metadata for reflection on method parameters --add-modules ALL-MODULE-PATH \ // Optional, Root modules to resolve in addition to the initial modules --module-path ... \ // Optional, where to find application modules --module-source-path "src" \ // Source files for multiple modules -d classes \ --module MainApp // Compile only the specified module(s) # Package all modules (Create for all modules) $ jar --create \ --file mods/app.jar \ --main-class dev.suresh.MainKt \ --module-version 1.0 \ // Optional -C app/ classes resources // Or *.class # Launch app $ java --enable-preview \ --show-version \ --show-module-resolution \ --module-path mods \ --module app // OR <module>/<mainclass> # Build native image from modular jars $ native-image \ -p base-module.jar:main-module.jar \ -m dev.suresh.Main # JavaFX 24 using jlink & jpackage $ wget "https://download.java.net/java/early_access/.../openjfx-xxx_macos-aarch64_bin-jmods.tar.gz" $ tar -xvzf openjfx-xxx_macos-aarch64_bin-jmods.tar.gz $ jlink --output javafx-jdk \ --module-path $JAVA_HOME/jmods:javafx-jmods-24 \ --add-modules javafx.controls,java.desktop,java.logging # --add-modules ALL-MODULE-PATH $ javafx-jdk/bin/java --list-modules $ jpackage --main-jar app.jar \ --runtime-image javafx-jdk \ --type app-image \ --name app \ --java-options "-Xmx64m" \ --arguments "arg" \ --icon app.ico \ --input app \ --dest bin

9. JShell

# JShell with preview feature enabled $ jshell --enable-preview $ jshell --show-version --enable-preview --enable-native-access --startup JAVASE --feedback concise # Use custom startup script $ jshell --enable-preview --startup DEFAULT --startup ~/calc.repl # Query system properties/run java code $ fileEncoding="$(echo 'System.out.println(System.getProperty("file.encoding"))' | jshell -s -)"

10. Java TEMP Config

$ echo "-------- TMP PATH for $OSTYPE --------" $ MKTEMP_PATH="$(dirname "$(mktemp -u)")/" $ JAVA_TMP_DIR="$(java -XshowSettings:properties -version 2>&1 | awk 'tolower($0) ~ /java.io.tmpdir/{print $NF}')/" $ JAVA_FILE_ENC="$(echo 'System.out.println(System.getProperty("file.encoding"))' | jshell -s -)" $ echo "MKTEMP_PATH = $MKTEMP_PATH" $ echo "TMP = $TMP" $ echo "TEMP = $TEMP" $ echo "TMPDIR (Mac) = $TMPDIR" $ echo "RUNNER_TEMP = $RUNNER_TEMP" $ echo "JAVA_IO_TMPDIR = $JAVA_TMP_DIR" $ echo "JAVA_FILE_ENC = $JAVA_FILE_ENC" $ echo "/TMP = $(ls -l /tmp)"

IDEs and Tools

  • IntelliJ Selection Modes

    • All Actions - CMD + SHIFT + A

    • Select all occurrences - CMD + CTRL + G

    • Column selection mode - CMD + SHIFT + 8

    • Multiple Cursors - SHIFT + ALT + Left Click

    • Multi Selection - SHIFT + ALT + Select as usual

    • Caret Cloning - SHIFT + ALT + Middle click on end line

    • Move line - SHIFT + ALT + Arrow UP/DOWN

  • Plugin Version Update

    $ PLUGIN_VERSION="1.2.6.2594" $ wget --content-disposition "https://plugins.jetbrains.com/plugin/download?rel=true&updateId=331908" $ unzip github-copilot-intellij-${PLUGIN_VERSION}.zip $ cd github-copilot-intellij/lib $ jar -tvf github-copilot-intellij-${PLUGIN_VERSION}.jar | grep plugin.xml $ unzip github-copilot-intellij-${PLUGIN_VERSION}.jar # Change until-build="223.*" $ vi META-INF/plugin.xml $ zip -r github-copilot-intellij-${PLUGIN_VERSION}.jar META-INF $ rm -rf META-INF $ cd ../../ $ zip -r github-copilot-intellij-${PLUGIN_VERSION}.zip github-copilot-intellij/ $ rm -rf github-copilot-intellij # Now upload github-copilot-intellij-${PLUGIN_VERSION}.zip (Preferences -> Plugins -> ⚙️ -> Install Plugin from Disk)

  • IntelliJ Plugin Channels

    • https://plugins.jetbrains.com/plugins/beta/list

    • https://plugins.jetbrains.com/plugins/snapshots/org.jetbrains.compose.desktop.ide

Networking & Security

🚨Security Developer’s Guide

1. Allow Unsafe Server Cert Change

# This is Unsafe. Don't use in prod. -Djdk.tls.allowUnsafeServerCertChange=true -Dsun.security.ssl.allowUnsafeRenegotiation=true

2. Debugging TLS

  • https://docs.oracle.com/en/java/javase/23/security/java-secure-socket-extension-jsse-reference-guide.html#GUID-4D421910-C36D-40A2-8BA2-7D42CCBED3C6

  • https://docs.oracle.com/en/java/javase/23/security/java-secure-socket-extension-jsse-reference-guide.html

  • https://github.com/sureshg/InstallCerts/blob/master/src/main/kotlin/io/github/sureshg/extn/Certs.kt

    # Turn on all debugging $ java -Djavax.net.debug=all # Override HostsFileNameService $ java -Djdk.net.hosts.file=/etc/host/style/file # Force IPv4 $ java -Djava.net.preferIPv4Stack=true # The entropy gathering device can also be specified with the system property $ java -Djava.security.egd=file:/dev/./urandom

3. Java Networking Properties

  • http://htmlpreview.github.io/?https://github.com/openjdk/jdk/blob/master/src/java.base/share/classes/java/net/doc-files/net-properties.html

  • https://docs.oracle.com/en/java/javase/23/docs/api/java.base/java/net/doc-files/net-properties.html

  • All Java Networking System Properties

  • https://docs.oracle.com/javase/8/docs/technotes/guides/net/proxies.html

Config

Description

http.proxyHost

The host name of the proxy server

http.proxyPort

The port number, the default value being 80

http.nonProxyHosts

  • HTTP

    # Use JAVA_TOOL_OPTIONS $ export JAVA_TOOL_OPTIONS=" ${JAVA_TOOL_OPTIONS} -Dhttp.useProxy=true -Dhttps.useProxy=true -Dhttp.proxyHost=172.10.10.1 -Dhttp.proxyPort=8100 -Dhttps.proxyHost=172.10.10.1 -Dhttps.proxyPort=8100 -Dhttp.nonProxyHosts='localhost|127.0.0.1|cdn.test.org|*-prod.app.com|slack.com'" # OR use system properties $ java -Dhttp.proxyHost=webcache.example.com -Dhttp.proxyPort=8080 -Dhttp.nonProxyHosts=”localhost|host.example.com” <URL>

  • Env vars

    export HTTP_PROXY=http://USERNAME:PASSWORD@10.0.1.1:8080/ export HTTPS_PROXY=https://USERNAME:PASSWORD@10.0.0.1:8080/ export NO_PROXY=master.hostname.example.com

4. HTTP Client Properties

-Djdk.internal.httpclient.disableHostnameVerification -Djdk.httpclient.HttpClient.log=headers -Djdk.internal.httpclient.debug=false -Djdk.tls.client.protocols="TLSv1.2"

Gradle Kotlin DSL

1. Docs

2. Name Abbrevation

$ ./gradlew --console=plain \ --continuous \ --dry-run \ --no-daemon \ -Dauthor=Suresh \ -Pmyprop=myvalue \ cle dU

3. Configure/Create Tasks

  • Eager

    val p: Jar = getByName<Jar>("jar") // Get existing task val q: Jar = create<Jar>("jar") {} // Create new task val r: Jar by getting(Jar::class) // Get task using property delegate val s: Copy by creating(Copy::class) {} // Create task using property delegate

  • Lazy (Configuration Avoidance API)

    val t: TaskProvider<Jar> = named<Jar>("jar"){} // Get existing task val u: TaskProvider<Jar> = register<Jar>("jar"){} // Create new task val v: TaskProvider<Jar> by registering(Jar::class){} // Create task using property delegate val jar: TaskProvider<Task> by existing // Get task using property delegate val foo: FooTask by existing // Take Task type from val (Kotlin 1.4) val bar: BarTask by registering {} // Take Task type from val (Kotlin 1.4)

4. Reproducible builds

withType<AbstractArchiveTask>().configureEach { isPreserveFileTimestamps = false isReproducibleFileOrder = true }

5. Multi Release Jar

// See https://github.com/melix/mrjar-gradle for more on multi release jars val mrVersion = "11" if (JavaVersion.current().isJava11Compatible) { sourceSets { create("java$mrVersion") { java { srcDirs("src/main/java$mrVersion") } } } tasks { // For each source set, Gradle will automatically create a compile task. val mrJavaCompile = named<JavaCompile>("compileJava${mrVersion}Java") { sourceCompatibility = mrVersion targetCompatibility = mrVersion options.compilerArgs = listOf("--release", mrVersion) } named<Jar>("jar") { into("META-INF/versions/$mrVersion") { from(sourceSets.named("java$mrVersion").get().output) } manifest.attributes( "Multi-Release" to "true" ) dependsOn(mrJavaCompile) } } }

6. Dependencies

# Direct dependencies $ ./gradlew -q dependencies --configuration implementation # Transitive dependencies $ ./gradlew -q dependencies --configuration runtimeClasspath # Dependencies insight for a dependency group. $ ./gradlew -q dependencyInsight --configuration runtimeClasspath --dependency kotlin $ ./gradlew -q dependencyInsight --dependency log4j-core # Task Dependencies $ ./gradlew clean build --dry-run # Dependency updates $ ./gradlew clean dependencyUpdates -Drevision=release
# Force Gradle to execute all tasks ignoring up-to-date checks $ ./gradlew clean build --rerun-tasks # Don't reuse outputs from previous builds (org.gradle.caching=false) $ ./gradlew clean build --no-build-cache # To refresh all dependencies in the dependency cache $ ./gradlew clean build --refresh-dependencies

Maven

1. Create a Project

$ mvn archetype:generate -DgroupId=dev.suresh -DartifactId=my-app -DarchetypeArtifactId=maven-archetype-quickstart -DarchetypeVersion=1.4 -DinteractiveMode=false

2. Enabling Java preview feature

<build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.6.2</version> <configuration> <release>15</release> <compilerArg>--enable-preview</compilerArg> </configuration> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <configuration> <argLine>--enable-preview</argLine> </configuration> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-failsafe-plugin</artifactId> <configuration> <argLine>--enable-preview</argLine> </configuration> </plugin> </plugins> </build>

3. Reproducible Builds

<properties> <project.build.outputTimestamp>2020-04-02T08:04:00Z</project.build.outputTimestamp> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties>

4. Maven Wrapper

$ mvn wrapper:wrapper -Dmaven=3.8.5

5. Update Version number

$ ./mvnw versions:set -DnewVersion=1.0.1-SNAPSHOT -DprocessAllModules -DgenerateBackupPoms=false $ ./mvnw versions:revert // Rollback $ ./mvnw versions:commit

6. Dependency Tree

# Show all orginal versions, not the resolved ones. $ ./mvnw dependency:tree $ ./mvnw dependency:tree -Ddetail=true $ ./mvnw dependency:tree -Dverbose -Dincludes=org.jetbrains.kotlin:kotlin-stdlib $ ./mvnw clean verify # Dependency and plugin updates $ ./mvnw clean versions:display-dependency-updates versions:display-plugin-updates # Search Artifacts by class https://search.maven.org/search?q=fc:kotlin.text.Regex

Microservices Starters

1. SpringBoot

$ curl https://start.spring.io/starter.zip \ -d dependencies=devtools,web \ -d type=gradle-project \ -d language=kotlin \ -d javaVersion=11 \ -d packaging=jar \ -d platformVersion=2.2.6.RELEASE \ -d name=helloworld \ -d groupId=dev.suresh \ -d artifactId=helloworld \ -d packageName=dev.suresh \ -d description=Hello%20World%20App \ -d baseDir=helloworld \ -o helloworld.zip

Misc

  • Github Registry

    $ VERSION=$(date +%s) $ docker build . --file Dockerfile --tag docker.pkg.github.com/sureshg/repo/app:${VERSION} $ docker login docker.pkg.github.com --username sureshg --password ${{ secrets.GITHUB_TOKEN }} $ docker push docker.pkg.github.com/sureshg/repo/app:${VERSION}

  • Install Command Line Tools

    $ xcode-select --install

OpenJDK Build

$ sdk install java 24-open $ git clone https://github.com/openjdk/jdk.git $ cd jdk # $ make clean $ bash configure $ make images $ build/*/images/jdk/bin/java --version

Oracle A1 Flex

# Reset the password # https://docs.oracle.com/en-us/iaas/Content/Compute/References/serialconsole.htm#four__opcpasswordreset $ /usr/sbin/load_policy -i $ sudo /bin/mount -o remount, rw / $ sudo passwd opc $ sudo reboot -f # Install softwares $ sudo yum upgrade -y $ sudo yum install curl wget tree docker git zsh -y $ sh -c "$(curl -fsSL https://raw.github.com/ohmyzsh/ohmyzsh/master/tools/install.sh)" $ curl -s "https://get.sdkman.io" | bash $ sdk i java 24.ea-open # For Github self hosted runners on Aarch64 export LD_LIBRARY_PATH=/opt/oracle/oracle-armtoolset-8/root/usr/lib64:/usr/local/lib:/usr/lib:/usr/local/lib64:/usr/lib64 export DOTNET_SYSTEM_GLOBALIZATION_INVARIANT=1 export JAVA_HOME_11_X64=/home/opc/.sdkman/candidates/java/11.0.11.hs-adpt # Install EPEL $ sudo rpm -Uvh https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm

  • Open Ports

    # Networking > Virtual cloud networks > Security List > Add Ingress Rules (open tcp/8080) $ firewall-cmd --permanent --zone=public --add-port=8080/tcp $ firewall-cmd --reload $ http://ip:8080

Awesome Svgs

Illustrations

  • https://undraw.co/illustrations

  • https://www.manypixels.co/gallery/

  • https://www.pixeltrue.com/free-illustrations

Background

  • https://www.svgbackgrounds.com/

Icons

  • https://icons.getbootstrap.com/

  • https://material.io/resources/icons/?style=baseline (not sag)

  • https://fontawesome.com/v4.7.0/icons/ (not sag)

  • https://simpleicons.org/ (Brand Icons - good one)

  • https://github.com/microsoft/fluentui-system-icons

  • https://tablericons.com/

  • https://tabler-icons.io/

  • https://systemuicons.com/

  • https://github.com/c5inco/intellij-icons-compose

  • https://www.visiwig.com/icons/

  • https://standart.io/

  • https://thenounproject.com/

  • https://www.flaticon.com/

  • https://www.iconfinder.com/

  • https://ionicons.com/

  • https://icons8.com/

  • https://github.com/game-icons/icons

Emojis

  • https://emojipedia.org/search/

  • https://github.com/twitter/twemoji/tree/master/assets

Awesome List

  • https://github.com/vkarampinis/awesome-icons

  • https://github.com/notlmn/awesome-icons

  • https://github.com/ikatyang/emoji-cheat-sheet

Tools

  • https://jakearchibald.github.io/svgomg/

  • https://css-tricks.com/tools-for-optimizing-svg/

  • https://imageoptim.com/mac

  • https://xmlgraphics.apache.org/batik/

  • https://github.com/svg/svgo-osx-folder-action

$ pip3 install mkdocs-macros-plugin $ ./gradlew dokka $ cp docs/mkdocs.yml build/dokka $ cp -R docs/images build/dokka/my-app $ cp CHANGELOG.md build/dokka/my-app/CHANGELOG.md $ cp README.md build/dokka/my-app/Overview.md $ Fix the img reference on Overview.md $ cd build/dokka $ mkdocs build
Last modified: 21 September 2024
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