src/org/nutz/lang/Streams.java
public static BufferedWriter buffw(Writer ops) {
        if (ops instanceof BufferedWriter)
            return (BufferedWriter) ops;
        return new BufferedWriter(ops);
    }
public static BufferedWriter buffw(Writer ops) {
        if (ops instanceof BufferedWriter)
            return (BufferedWriter) ops;
        return new BufferedWriter(ops);
    }
为一个文本输出流包裹一个缓冲流。如果这个文本输出流本身就是缓冲流，则直接返回

@param ops
文本输出流。
@return 缓冲文本输出流