以31位无符号值的形式写入数据长度，后跟实际数据。

/** 
来 自 
时 代 J a v a 公 众 号 - nowjava.com
**/

import java.io.IOException;

import java.io.InputStream;

import java.nio.ByteBuffer;

import java.util.Iterator;

import org.apache.log4j.Logger;


public class Main{

    /**

     * writes the length of data as an 31 bit unsigned value, followed by the

     * actual data. does not check that the length of the data-array actually

     * fits in the lengths field.

     * 

     * @param buf

     * @param data

     */

    final static public void writeArray31(