各系统下多版本JDK安装与配置步骤

# 检查当前Java版本
java -version

# 检查Javac版本
javac -version

# 检查当前Java版本
java -version

# 检查Javac版本
javac -version

# 解压到 /usr/local/src/jdks 目录
sudo tar -xzf openjdk-8u41-b04-linux-x64-14_jan_2020.tar.gz -C /usr/local/src/jdks/
sudo tar -xzf openjdk-11.0.2_linux-x64_bin.tar.gz -C /usr/local/src/jdks/
sudo tar -xzf openjdk-17.0.2_linux-x64_bin.tar.gz -C /usr/local/src/jdks/
sudo tar -xzf openjdk-21.0.2_linux-x64_bin.tar.gz -C /usr/local/src/jdks/

# 重命名为简洁的名称（可选）
cd /usr/local/src/jdks
sudo mv java-se-8u41-ri jdk-8
sudo mv jdk-11.* jdk-11
sudo mv jdk-17.* jdk-17
sudo mv jdk-21.* jdk-21

# 设置权限
sudo chmod -R 755 /usr/local/src/jdks/jdk-*
sudo chown -R root:root /usr/local/src/jdks/jdk-*

# 检查每个 JDK 版本
/usr/local/src/jdks/jdk-8/bin/java -version
/usr/local/src/jdks/jdk-11/bin/java -version
/usr/local/src/jdks/jdk-17/bin/java -version
/usr/local/src/jdks/jdk-21/bin/java -version

# 1.创建切换脚本目录
mkdir -p ~/bin/jdk_switcher

# 2.创建脚本
cat > ~/bin/jdk_switcher/jdk-switch.sh << 'EOF'
#!/bin/bash

# JDK 切换脚本

JDK_BASE_DIR="/usr/local/src/jdks"
CURRENT_JDK_FILE="$HOME/.current_jdk"

show_usage() {
    echo "使用方法: $0 [版本号]"
    echo "可用版本:"
    ls -1 "$JDK_BASE_DIR" | grep -E "^jdk-|^java-" | sed 's/^/  /'
    echo ""
    echo "示例:"
    echo "  $0 8        # 切换到 JDK 8"
    echo "  $0 11       # 切换到 JDK 11"
    echo "  $0 17       # 切换到 JDK 17"
    echo "  $0 current  # 显示当前版本"
}

get_jdk_path() {
    local version=$1
    local jdk_path
    
    # 尝试匹配 jdk-版本号
    jdk_path=$(ls -d "$JDK_BASE_DIR"/jdk-$version* 2>/dev/null | head -1)
    
    # 如果没找到，尝试匹配 java-版本号
    if [ -z "$jdk_path" ]; then
        jdk_path=$(ls -d "$JDK_BASE_DIR"/java-$version* 2>/dev/null | head -1)
    fi
    
    echo "$jdk_path"
}

set_jdk() {
    local version=$1
    local jdk_path=$(get_jdk_path "$version")
    
    if [ -z "$jdk_path" ]; then
        echo "错误: 未找到 JDK $version"
        return 1
    fi
    
    if [ ! -d "$jdk_path" ]; then
        echo "错误: JDK 路径不存在: $jdk_path"
        return 1
    fi
    
    # 设置环境变量
    export JAVA_HOME="$jdk_path"
    export PATH="$JAVA_HOME/bin:$PATH"
    
    # 保存当前选择
    echo "$jdk_path" > "$CURRENT_JDK_FILE"
    
    echo "已切换到: $jdk_path"
    java -version
}

show_current() {
    if [ -f "$CURRENT_JDK_FILE" ]; then
        current_jdk=$(cat "$CURRENT_JDK_FILE")
        echo "当前 JDK: $current_jdk"
        $current_jdk/bin/java -version
    else
        echo "未设置 JDK"
        java -version 2>/dev/null || echo "Java 未安装或未在 PATH 中"
    fi
}

# 主逻辑
main() {
    if [ $# -eq 0 ]; then
        show_usage
        return 1
    fi
    
    case "$1" in
        "current")
            show_current
            ;;
        "list")
            echo "已安装的 JDK 版本:"
            ls -1 "$JDK_BASE_DIR" | grep -E "^jdk-|^java-" | sed 's/^/  /'
            ;;
        "help"|"-h"|"--help")
            show_usage
            ;;
        *)
            set_jdk "$1"
            ;;
    esac
}

main "$@"
EOF

# 3.设置执行权限
chmod +x ~/bin/jdk_switcher/jdk-switch.sh

# 4.创建符号链接
ln -sf ~/bin/jdk_switcher/jdk-switch.sh ~/bin/jdk-switch

# 5.添加到 .bashrc 或 .zshrc
echo 'alias java-switch="~/bin/jdk-switch"' >> ~/.bashrc
echo 'export PATH="$HOME/bin:$PATH"' >> ~/.bashrc
source ~/.bashrc

# 列出所有 JDK
jdk-switch list

# 切换到 JDK 8
jdk-switch 8

# 切换到 JDK 11
jdk-switch 11

# 查看当前版本
jdk-switch current

# 显示帮助
jdk-switch help