src/org/nutz/mvc/upload/util/BufferRing.java
public long load() throws IOException {
        if (item.isStreamEnd)
            return readed;
        RingItem ri = item;
        while (!ri.isLoaded) {
            ri.load(ins);
            if (ri.max > 0)
                readed += ri.max;
            ri = ri.next;
        }
        return readed;
    }
public long load() throws IOException {
        if (item.isStreamEnd)
            return readed;
        RingItem ri = item;
        while (!ri.isLoaded) {
            ri.load(ins);
            if (ri.max > 0)
                readed += ri.max;
            ri = ri.next;
        }
        return readed;
    }
从当前节点的 next 开始，依次将所有可用的节点全部加载满

@return 一共读去的字节数

@throws IOException