1. 在Unity打包时获取SD权限
2. Android根目录为 "/storage/emulated/0";
代码：
if (Directory.Exists("/storage/emulated/0/xxx"))
{
StartCoroutine(PostRequest("/xxx/TestLoad.txt", "message"));
if (File.Exists("/storage/emulated/0/xxx/TestLoad.txt"))
{
try
{
text.text = File.ReadAllText("/storage/emulated/0/xxx/TestLoad.txt");
}
catch (System.Exception e)
{
text.text = e.Message;
throw;
}
}
}
