清华大学数据结构课上实现的B+树，设计一个4阶B+树，包括： (1) 叶子的每个记录应该包括4字节（long）关键码值和60字节的数据字段(存储文件名等，可以自定)，设每个叶子可以存储5条记录，而内部节点应该是关键码值/指针对。此外，每个节点还应该有指向同层下一个节点的指针、本节点存储的关键码数等； (2) 此4阶B+树应该支持插入、删除以及根据给定关键码值进行精确检索与关键码范围检索； (3) 显示（打印）此4阶B+树的生长(含删除节点)过程实例；-Tsinghua University class data structure to achieve the B-tree, the design of a B-tree four bands, including : (a) the leaves of each record should include 4-byte (long) key code value and 60 gigabytes of data fields (document storage, etc., can be set), set up each leaf store five records, and internal nodes is the key code value / means against. In addition, each node should have the same point under a layer of the target node, the node storage key code number; (2) The B-tree four bands should support the insertion, deletion and with the given key code value accurate retrieval and key codes scope retrieval; (3) Display (Print ) This four bands B-tree growth (including the deletion of nodes) process examples;