src/org/nutz/lang/Streams.java
public static BufferedInputStream buff(InputStream ins) {
        if (ins == null)
            throw new NullPointerException("ins is null!");
        if (ins instanceof BufferedInputStream)
            return (BufferedInputStream) ins;
        // BufferedInputStream的构造方法,竟然是允许null参数的!! 我&$#^$&%
        return new BufferedInputStream(ins);
    }
public static BufferedInputStream buff(InputStream ins) {
        if (ins == null)
            throw new NullPointerException("ins is null!");
        if (ins instanceof BufferedInputStream)
            return (BufferedInputStream) ins;
        // BufferedInputStream的构造方法,竟然是允许null参数的!! 我&$#^$&%
        return new BufferedInputStream(ins);
    }
为一个输入流包裹一个缓冲流。如果这个输入流本身就是缓冲流，则直接返回

@param ins
输入流。
@return 缓冲输入流