# ---- Ubuntu / Debian ----
# 方式一：apt 安装
sudo apt update
sudo apt install openjdk-21-jdk

# 方式二：SDKMAN!（推荐，管理多版本）
curl -s "https://get.sdkman.io" | bash
source "$HOME/.sdkman/bin/sdkman-init.sh"
sdk list java           # 查看可用版本
sdk install java 21.0.2-tem  # 安装 Eclipse Temurin 21

# 方式三：手动安装
wget https://github.com/adoptium/temurin21-binaries/releases/download/jdk-21.0.2%2B13/OpenJDK21U-jdk_x64_linux_hotspot_21.0.2_13.tar.gz
sudo tar -xzf OpenJDK21U-jdk_x64_linux_hotspot_21.0.2_13.tar.gz -C /usr/local/

# 使用 Homebrew（推荐）
brew install openjdk@21

# 链接到系统路径
sudo ln -sfn $(brew --prefix openjdk@21)/libexec/openjdk.jdk \
     /Library/Java/JavaVirtualMachines/openjdk-21.jdk

# 使用 SDKMAN!
curl -s "https://get.sdkman.io" | bash
sdk install java 21.0.2-tem

# 方式一：winget（推荐）
winget install EclipseAdoptium.Temurin.21.JDK

# 方式二：手动下载安装
# 访问 https://adoptium.net/ 下载 .msi 安装包

# 方式三：Chocolatey
choco install temurin21

# ~/.bashrc 或 ~/.zshrc
export JAVA_HOME=/usr/local/jdk-21
export PATH=$JAVA_HOME/bin:$PATH
export CLASSPATH=.

# 验证安装
java -version
javac -version
echo $JAVA_HOME

# Windows PowerShell
[Environment]::SetEnvironmentVariable("JAVA_HOME", "C:\Program Files\Eclipse Adoptium\jdk-21", "User")
[Environment]::SetEnvironmentVariable("Path", "$env:JAVA_HOME\bin;$env:Path", "User")

# Linux / macOS
sdk install maven        # SDKMAN!
brew install maven       # Homebrew

# Windows
winget install Apache.Maven
choco install maven

<?xml version="1.0" encoding="UTF-8"?>
<settings xmlns="http://maven.apache.org/SETTINGS/1.2.0"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.2.0
          https://maven.apache.org/xsd/settings-1.2.0.xsd">

    <!-- 本地仓库路径 -->
    <localRepository>${user.home}/.m2/repository</localRepository>

    <!-- 阿里云镜像（国内加速） -->
    <mirrors>
        <mirror>
            <id>aliyun</id>
            <name>Aliyun Maven Mirror</name>
            <url>https://maven.aliyun.com/repository/public</url>
            <mirrorOf>central</mirrorOf>
        </mirror>
    </mirrors>

    <!-- 默认 Profile -->
    <profiles>
        <profile>
            <id>default</id>
            <activation>
                <activeByDefault>true</activeByDefault>
            </activation>
            <properties>
                <maven.compiler.source>21</maven.compiler.source>
                <maven.compiler.target>21</maven.compiler.target>
                <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
            </properties>
        </profile>
    </profiles>
</settings>

# 使用 archetype 创建项目
mvn archetype:generate \
    -DgroupId=com.example \
    -DartifactId=my-app \
    -DarchetypeArtifactId=maven-archetype-quickstart \
    -DarchetypeVersion=1.4 \
    -DinteractiveMode=false

# 项目结构
my-app/
├── pom.xml
└── src
    ├── main/java/com/example/App.java
    └── test/java/com/example/AppTest.java

# Linux / macOS
sdk install gradle
brew install gradle

# Windows
winget install Gradle.Gradle

# 在项目中生成 wrapper（团队统一版本）
gradle wrapper --gradle-version 8.7

# 使用 wrapper 构建（无需全局安装 Gradle）
./gradlew build
./gradlew test
./gradlew run

# 交互式创建
gradle init

# 选项:
# 1. Application（可执行应用）
# 2. Library（库）
# 3. Gradle plugin
# 4. Basic（空项目）

plugins {
    id 'java'
    id 'application'
}

group = 'com.example'
version = '1.0.0'

java {
    toolchain {
        languageVersion = JavaLanguageVersion.of(21)
    }
}

repositories {
    mavenCentral()
}

dependencies {
    implementation 'com.google.guava:guava:33.0.0-jre'
    testImplementation 'org.junit.jupiter:junit-jupiter:5.10.2'
    testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
}

application {
    mainClass = 'com.example.App'
}

tasks.named('test') {
    useJUnitPlatform()
}

{
  "recommendations": [
    "vscjava.vscode-java-pack",
    "vscjava.vscode-maven",
    "vscjava.vscode-gradle",
    "vmware.vscode-spring-boot",
    "vscjava.vscode-spring-initializr"
  ]
}

{
  "java.jdt.ls.java.home": "/usr/local/jdk-21",
  "java.configuration.runtimes": [
    {
      "name": "JavaSE-17",
      "path": "/usr/local/jdk-17",
      "default": false
    },
    {
      "name": "JavaSE-21",
      "path": "/usr/local/jdk-21",
      "default": true
    }
  ],
  "java.compile.nullAnalysis.mode": "automatic",
  "maven.executable.path": "/usr/local/bin/mvn"
}

#!/bin/bash
echo "========== Java 环境检查 =========="

# 检查 Java
if command -v java &> /dev/null; then
    echo "✅ Java: $(java -version 2>&1 | head -1)"
    echo "   JAVA_HOME: $JAVA_HOME"
else
    echo "❌ Java 未安装"
fi

# 检查 javac
if command -v javac &> /dev/null; then
    echo "✅ javac: $(javac -version 2>&1)"
else
    echo "❌ javac 未安装"
fi

# 检查 Maven
if command -v mvn &> /dev/null; then
    echo "✅ Maven: $(mvn -version 2>&1 | head -1)"
else
    echo "⚠️  Maven 未安装（可选）"
fi

# 检查 Gradle
if command -v gradle &> /dev/null; then
    echo "✅ Gradle: $(gradle -version 2>&1 | head -3 | tail -1)"
else
    echo "⚠️  Gradle 未安装（可选）"
fi

echo "====================================="