android判断外存储卡是否安装并新建文件夹

private File voiceDirectory;
//判断是否已经装载存储卡
if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
voiceDirectory = new File(this.getExternalCacheDir(), "voice");  //已经装载
if(!voiceDirectory.exists()){
voiceDirectory.mkdirs();
}
} else {
voiceDirectory = new File(this.getCacheDir(), "voice");
if(!voiceDirectory.exists()) {
voiceDirectory.mkdirs();
}
}