用霍夫曼树进行文件的压缩和解压缩。包括计算字符频率，构建霍夫曼树，进行文件压缩，文件解压缩-Compress file or decompress file with huffman tree. The code include frequency counting, huffman tree building, textzip, decompression.

哈夫曼树是又称最优二叉树，将关键词被搜索的次数看成是哈夫曼树的权值，通过构建哈夫曼树，快速归类，并且通过哈夫曼编码方式无歧义的储存各个关键词。为各个关键字设计哈夫曼编码，使得关键字能无歧义的储存。 内含说明文档-Huffman tree is also known as the optimal binary tree, the number of times the keyword is searched as a Huffman tree weights by constructing t

霍夫曼树的构建，可以添加元素，自动排出霍夫曼树的结构-Huffman tree is constructed, you can add elements

采用java语言实现的霍夫曼树的构建，并利用图形用户界面显示结果(Using java language to achieve the construction of the Hoffman tree, and graphical user interface to display the results)