InputStream的mark和reset方法测试

public class InputStreamTest {
	public static void main(String[] args) throws IOException {
		writeToFile();
		readFromFile();
	}

	private static void readFromFile() {
		InputStream inputStream = null;
		
		try {
			inputStream = new BufferedInputStream(new FileInputStream(new File("test.txt")));
			
			// 判断该输入流是否支持mark操作
			if (!inputStream.markSupported()) {
				System.out.println("mark/reset not supported!");
				return;
			}
			
			int ch;
			int count = 0;
			boolean marked = false;
			while ((ch = inputStream.read()) != -1) {
				System.out.print("." + ch);
				
				if ((ch == 4) && !marked) {
					// 在4的地方标记位置
					inputStream.mark(6);
					marked = true;
				}
				
				if (ch == 8 && count < 2) {
					// 重设位置到4
					inputStream.reset();
					count++;
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				inputStream.close();
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
	}

	private static void writeToFile() {
		OutputStream output = null;
		try {
			output = new BufferedOutputStream(new FileOutputStream(new File("test.txt")));
			byte[] b = new byte[20];
			for (int i = 0; i < 20; i++)
				b[i] = (byte) i;
			// 写入从0到19的20个字节到文件中
			output.write(b);
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				output.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
}

输出为：
.0.1.2.3.4.5.6.7.8 .5.6.7.8.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19