赫夫曼编码译码器：能对指定的文本文件进行各字符出现频度分析，并建立哈夫曼树与哈夫曼编码，将该文本文件编码成目标文件 -Huffman codec: Can the specified text file to the frequency analysis of characters in there, and the establishment of Huffman Tree and Huffman encoding, the encoded text file into the desti