/**
  * 循环录像，当内存卡容量少于300M时，自动删除视频列表里面的第一个文件
  */
 private void xunhuanluxiang() {
  if (Environment.getExternalStorageState().equals(
    Environment.MEDIA_MOUNTED)) {
   File path = Environment.getExternalStorageDirectory();
   // 取得sdcard文件路径
   StatFs statfs = new StatFs(path.getPath());
   // 获取block的SIZE
   long blocSize = statfs.getBlockSize();
   // 获取BLOCK数量
   long totalBlocks = statfs.getBlockCount();
   // 己使用的Block的数量
   long availaBlock = statfs.getAvailableBlocks();
   // 获取当前可用内存容量，单位：MB
   long sd = availaBlock * blocSize / 1024 / 1024;
   if (sd < 300) {
    String filepath = (Environment.getExternalStorageDirectory()
      .getAbsolutePath() + "/video/");
    File file = new File(filepath);
    if (!file.exists()) {
     file.mkdirs();
    }
    File[] files = file.listFiles();
    if (files.length > 0) {
     String childFile[] = file.list();
     String dele = (filepath + childFile[0]);
     File file2 = new File(dele);
     file2.delete();
    }
   }
  } else if (Environment.getExternalStorageState().equals(
    Environment.MEDIA_REMOVED)) {
   Toast.makeText(this, "请插入内存卡", Toast.LENGTH_SHORT).show();
  }
 }