Java Switch

在 macOS 上自动检测、安装并切换指定版本的 Java，配置 JAVA_HOME 和环境变量，支持持久化配置。

Security Scan

The skill's requirements and actions are consistent with its description: it detects/installs Homebrew and OpenJDK, sets JAVA_HOME, and persists changes to ~/.zshrc; it does not request secrets or contact unexpected endpoints.

Purpose & Capability

The skill declares and implements a macOS Java-version switcher. The included script and SKILL.md only perform Homebrew detection/installation, brew install openjdk@<version>, use /usr/libexec/java_home, update ~/.zshrc, and verify java -version — all coherent with the stated purpose.

Instruction Scope

Instructions modify and source the user's ~/.zshrc to persist JAVA_HOME/PATH. Sourcing ~/.zshrc will execute whatever commands are present there, so the agent running these steps will execute user shell startup code; this is expected for a tool that updates shell config but is worth calling out as a potential side-effect.

Install Mechanism

No arbitrary binary downloads are introduced by the skill. Homebrew is installed using the official installer script from raw.githubusercontent.com and OpenJDK is installed via brew — both are standard mechanisms for macOS package installation.

Credentials

The skill requests no environment variables, no credentials, and no config paths beyond the user's ~/.zshrc; this is proportionate to a Java version switcher.

Persistence & Privilege

The skill persists changes by appending entries to ~/.zshrc and creates a backup when replacing existing JAVA_HOME lines. It does not request always:true or system-wide configuration changes beyond the user's shell file.

Assessment

This skill appears to do what it says: it may install Homebrew and an OpenJDK via brew, set JAVA_HOME, and append lines to ~/.zshrc (backing up the file first). Before running, consider: 1) review your current ~/.zshrc (and any existing startup code) because the script will source it which executes its contents; 2) the installer uses the official Homebrew install URL (raw.githubusercontent.com) and requires network access and possibly elevated privileges; 3) if you prefer manual control, run ./scripts/switch-java.sh <version> yourself rather than letting an agent execute it; and 4) keep the created backup (~/.zshrc.backup.TIMESTAMP) until you confirm the changes are correct.

java-switch Skill

Description

在 macOS 上自动切换 Java 版本。使用 Homebrew 安装 OpenJDK，通过 /usr/libexec/java_home 管理多版本，自动配置环境变量。如果指定版本未安装，则自动安装并切换；如果已安装，则直接切换环境变量。

Trigger Phrases

• "切换 Java 版本"
• "切换 java 版本"
• "安装并切换 Java"
• "安装 java 版本"
• "switch java version"
• "change java version"
• "install java"
• "帮我切换到 java"
• "帮我安装 java"
• "配置 JAVA_HOME"

Parameters

• version (required): Java 版本号，如 17, 11, 8, 21 等

Implementation

当用户请求切换 Java 版本时，按以下步骤执行：

步骤 1: 检查 Homebrew 是否已安装

if ! command -v brew &> /dev/null; then
    echo "Homebrew 未安装，正在安装..."
    /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
fi

步骤 2: 检查指定版本的 Java 是否已安装

# 列出所有已安装的 Java 版本
/usr/libexec/java_home -V

# 检查特定版本是否已安装
/usr/libexec/java_home -v <version> 2>/dev/null

步骤 3: 如果未安装，使用 Homebrew 安装

# 安装指定版本的 OpenJDK
brew install openjdk@<version>

# Homebrew 安装后可能需要链接（根据版本提示）
# 通常路径：/opt/homebrew/opt/openjdk@<version>/libexec/openjdk.jdk (Apple Silicon)
# 或：/usr/local/opt/openjdk@<version>/libexec/openjdk.jdk (Intel)

步骤 4: 切换环境变量（当前会话）

# 使用 /usr/libexec/java_home 获取指定版本的 JAVA_HOME
export JAVA_HOME=$(/usr/libexec/java_home -v <version>)
export PATH=$JAVA_HOME/bin:$PATH

步骤 5: 持久化配置

# 添加到 ~/.zshrc
echo '' >> ~/.zshrc
echo '# Java <version> configuration' >> ~/.zshrc
echo 'export JAVA_HOME=$(/usr/libexec/java_home -v <version>)' >> ~/.zshrc
echo 'export PATH=$JAVA_HOME/bin:$PATH' >> ~/.zshrc

# 使配置生效
source ~/.zshrc

步骤 6: 验证

# 验证 Java 版本
java -version

# 验证 JAVA_HOME
echo $JAVA_HOME

Example Conversation

用户: 帮我切换到 Java 17

助手:

1. 🔍 检查 Homebrew 是否已安装... ✅ 已安装
2. 🔍 检查 Java 17 是否已安装... ⚠️ 未安装
3. 📦 使用 Homebrew 安装 OpenJDK 17...

   brew install openjdk@17
   

4. 🔄 配置环境变量...

   export JAVA_HOME=$(/usr/libexec/java_home -v 17)
   export PATH=$JAVA_HOME/bin:$PATH
   

5. 💾 持久化配置到 ~/.zshrc...
6. ✅ 验证安装:

   openjdk version "17.0.2" 2021-10-19
   OpenJDK Runtime Environment (Homebrew) (build 17.0.2+8)
   

7. ✅ 切换成功！JAVA_HOME: /opt/homebrew/opt/openjdk@17/libexec/openjdk.jdk/Contents/Home

用户: 切换到 Java 11

助手:

1. 🔍 检查 Java 11 是否已安装... ✅ 已安装
2. 🔄 切换环境变量...
3. ✅ 切换成功！当前 Java 版本:

   openjdk version "11.0.20" 2023-07-18 LTS
   

Notes

• Homebrew 路径:
  • Apple Silicon (M1/M2): /opt/homebrew/opt/openjdk@<version>/libexec/openjdk.jdk
  • Intel Mac: /usr/local/opt/openjdk@<version>/libexec/openjdk.jdk
• macOS 内置命令: /usr/libexec/java_home 用于动态获取 Java 路径，支持多版本管理
• Shell 配置: macOS 10.15+ 默认使用 zsh，配置文件为 ~/.zshrc
• 版本格式: 支持 8, 11, 17, 21 等主版本号，也支持完整版本号如 17.0.5
• 如果用户没有指定版本号，询问用户需要哪个版本（推荐 17 或 21）

Related Scripts

• scripts/switch-java.sh - 可复用的切换脚本

Troubleshooting

Homebrew 安装失败

• 检查网络连接
• 尝试使用国内镜像：export HOMEBREW_BREW_GIT_REMOTE="https://mirrors.tuna.tsinghua.edu.cn/git/homebrew/brew.git"

Java 版本找不到

• 运行 /usr/libexec/java_home -V 查看所有已安装版本
• 确认版本号格式正确（如 17 而不是 java17）

环境变量不生效

• 确认已运行 source ~/.zshrc
• 重启终端窗口
• 检查 ~/.zshrc 中是否有冲突的配置