解决Ollama应用下载慢的问题

官方的下载方法是在PowerShell中输入

irm https://ollama.com/install.ps1 | iex

但直接下载的话可能会报错 Invoke-WebRequest 错误: Unable to read data from the transport connection: 远程主机强迫关闭了一个现有的连接。.，或者 install.ps1 的下载速度极其缓慢

查看 https://ollama.com/install.ps1：

# OLLAMA_DOWNLOAD_URL for developer testing only
$DownloadBaseURL = if ($env:OLLAMA_DOWNLOAD_URL) { $env:OLLAMA_DOWNLOAD_URL.TrimEnd('/') } else { "https://ollama.com/download" }
# ...
$installerUrl = "$DownloadBaseURL/OllamaSetup.exe"

注意到，install.ps1 读取环境变量 $env:OLLAMA_DOWNLOAD_URL 代替原下载源，因此可以借用这个 “for developer testing only” 的后门

最终解决方案（PowerShell）：

$env:OLLAMA_DOWNLOAD_URL = "https://gh-proxy.org/https://github.com/ollama/ollama/releases/latest/download"; $env:OLLAMA_INSTALL_DIR = "安装地址，默认为C:\Ollama"; Invoke-RestMethod "https://gh-proxy.org/https://github.com/ollama/ollama/releases/latest/download/install.ps1" | Invoke-Expression

附：其他脚本中根据获取环境变量的变量

$Version      = if ($env:OLLAMA_VERSION) { $env:OLLAMA_VERSION } else { "" } # Target version (default: latest stable)
$InstallDir   = if ($env:OLLAMA_INSTALL_DIR) { $env:OLLAMA_INSTALL_DIR } else { "" } # Custom install directory
$Uninstall    = $env:OLLAMA_UNINSTALL -eq "1" # Set to 1 to uninstall Ollama
$DebugInstall = [bool]$env:OLLAMA_DEBUG # Enable verbose output

# OLLAMA_DOWNLOAD_URL for developer testing only
$DownloadBaseURL = if ($env:OLLAMA_DOWNLOAD_URL) { $env:OLLAMA_DOWNLOAD_URL.TrimEnd('/') } else { "https://ollama.com/download" }