Android安卓中循环录像并检测内存卡容量

/**
	 * 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();
		}
	}