String status = Environment.getExternalStorageState();
if (status.equalsIgnoreCase(Environment.MEDIA_MOUNTED)) {
Toast.makeText(TechoLite.this, "SD卡存在", Toast.LENGTH_LONG).show();
// 此時SD是可讀寫的
} else if (status.equalsIgnoreCase(Environment.MEDIA_MOUNTED_READ_ONLY)) {
Toast.makeText(TechoLite.this, "雖然SD存在，但是為隻讀狀态", Toast.LENGTH_LONG).show();
} else if (status.equalsIgnoreCase(Environment.MEDIA_REMOVED)) {
Toast.makeText(TechoLite.this, "SD不存在", Toast.LENGTH_LONG).show();
} else if (status.equalsIgnoreCase(Environment.MEDIA_SHARED)) {
Toast.makeText(TechoLite.this, "雖然SD卡存在，但是正與PC等相連接配接", Toast.LENGTH_LONG).show();
} else if (status.equalsIgnoreCase(Environment.MEDIA_BAD_REMOVAL)) {
Toast.makeText(TechoLite.this, "SD卡在挂載狀态下被錯誤取出", Toast.LENGTH_LONG).show();
} else if (status.equalsIgnoreCase(Environment.MEDIA_CHECKING)) {
Toast.makeText(TechoLite.this, "正在檢查SD卡", Toast.LENGTH_LONG).show();
} else if (status.equalsIgnoreCase(Environment.MEDIA_NOFS)) {
Toast.makeText(TechoLite.this, "雖然SD卡存在，但其檔案系統不被支援", Toast.LENGTH_LONG).show();
} else if (status.equalsIgnoreCase(Environment.MEDIA_UNMOUNTABLE)) {
Toast.makeText(TechoLite.this, "雖然SD卡存在，但是無法被挂載", Toast.LENGTH_LONG).show();
} else if (status.equalsIgnoreCase(Environment.MEDIA_UNMOUNTED)) {
Toast.makeText(TechoLite.this, "雖然SD卡存在，但是未被挂載", Toast.LENGTH_LONG).show();
} else {
Toast.makeText(TechoLite.this, "其他原因", Toast.LENGTH_LONG).show();
}