对于任意一个文件进行压缩，压缩后的文件名为原文件名称去掉后缀加上.hz，例如，原来的未压缩文件的名字为a.txt，压缩后为a.h...

package five; import java.io.*; import java.text.DecimalFormat; import java.util.*; /** 可以为这个类添加额外的方法及数据成员. ID就是指学号, 下面的作者一定要写上你的名字和学号 作业中出现的示范数据abdc001需要改成学生的学号数据 @author YOUR NAME and ID @version THE DATE **/ public class TextZip { public static String code; public static boolean flag; public static int count_huffman,count_fileName,count_fileLength,count_Time; public static String huffman_code,fileName_code,time; public static void decompress(BitReader br, TreeNode huffman, FileOutputStream fw) throws Exception { // IMPLEMENT THIS METHOD TreeNode temp_node=huffman; int headLength=count_huffman+count_fileName+count_Time+1; for(int i=0;i<headLength;i++) { br.next(); } while(br.hasNext()) { if(br.next()) { if(temp_node.isLeaf()) { CharFreq cf=(CharFreq) temp_node.getItem(); fw.write(cf.getChar()); //是叶子结点的话，直接写入文件中 temp_node=huffman; } else { temp_node=temp_node.getRight(); //不是叶子结点，则向右子树继续 } } else { if(temp_node.isLeaf()) { CharFreq cf=(CharFreq) temp_node.getItem(); fw.write(cf.getChar()); //是叶子结点的话，直接写入文件中 temp_node=huffman; } else { temp_node=temp_node.getLeft(); //不是叶子结点，则向左子树继续 } } } } public static TreeNode removeMin(ArrayList a) { int minIndex = 0; for (int i = 0; i < a.size(); i++) { TreeNode ti = (TreeNode)a.get(i); TreeNode tmin = (TreeNode)a.get(minIndex); if (((Comparable)(ti.getItem())).compareTo(tmin.getItem()) < 0) minIndex = i; } TreeNode n = (TreeNode)a.remove(minIndex); return n; } public static TreeNode buildTree(ArrayList trees) throws IOException { // IMPLEMENT THIS METHOD ArrayList<TreeNode> trees_copy=trees; TreeNode leftNode=null,rightNode=null,fatherNode; while(!trees_copy.isEmpty()) { leftNode=removeMin(trees_copy); leftNode.flag=false; if(!trees_copy.isEmpty()) { rightNode=removeMin(trees_copy); rightNode.flag=false; CharFreq cl=(CharFreq)leftNode.getItem(); CharFreq cr=(CharFreq)rightNode.getItem(); fatherNode=new TreeNode(new CharFreq('\u0000',cl.getFreq()+cr.getFreq())); fatherNode.setLeft(leftNode); fatherNode.setRight(rightNode); fatherNode.flag=false; trees_copy.add(fatherNode); } else { break; } } return leftNode; } public static void TLV(File file,TreeNode huffman,FileWriter fw) throws IOException { bianliTree(huffman, ""); huffman_code=code; //哈弗曼编码 fileName_code=file.getName(); //文件名称 count_fileLength=(int) file.length(); //文件长度 time=new Date().toString(); //访问时间 } public static void compress(FileInputStream fr, TreeNode huffman, BitWriter bw) throws Exception { // IMPLEMENT THIS METHOD int i=0; byte[] byte_huffman=huffman_code.getBytes(); for(i=0;i<byte_huffman.length;i++) { count_huffman++; writeFile(huffman, byte_huffman[i], bw); } byte[] byte_fileName=fileName_code.getBytes(); for(i=0;i<byte_fileName.length;i++) { count_fileName++; writeFile(huffman, byte_fileName[i], bw); } String fileLength=Integer.toBinaryString(count_fileLength); byte[] byte_length=fileLength.getBytes(); for(i=0;i<byte_length.length;i++) { count_fileLength++; writeFile(huffman, byte_length[i], bw); } byte[] byte_time=time.getBytes(); for(i=0;i<byte_time.length;i++) { count_Time++; writeFile(huffman, byte_time[i], bw); } byte[] read_byte=new byte[1024]; while(fr.available()>0) { fr.read(read_byte); for(int j=0;j<1024;j++) { if(read_byte[j]<0) i=256+read_byte[j]; else { i=read_byte[j]; } writeFile(huffman, i, bw); } } } public static void writeFile(TreeNode huffman,int i,BitWriter bw) throws Exception { char c=(char)i; flag=false; code=""; TreeNode treeNode=huffman; preVisitTree(treeNode, "", c); System.out.println(code); for(int k=0;k<code.length();k++) { if(code.charAt(k)=='0') { bw.writeBit(0); } else { bw.writeBit(1); } } } public static void bianliTree(TreeNode root , String hfmCode){ //如果根不为0 if(root != null){ String lCode = hfmCode + "0"; bianliTree(root.getLeft() , lCode); String rCode = hfmCode+"1"; bianliTree(root.getRight() , rCode); if(root.isLeaf()) { CharFreq cf=(CharFreq) root.getItem(); getHuffmanCode(hfmCode,cf.getChar()); } else { getHuffmanCode(hfmCode,'\u0000'); } } } public static void preVisitTree(TreeNode root , String hfmCode,char c){ //如果根不为0 if(flag==false) { CharFreq cf=null; if(root != null){ if(root.isLeaf()) { cf=(CharFreq) root.getItem(); if(cf.getChar()==c) flag=true; } setHuffmanCode(hfmCode); String lCode = hfmCode + "0"; preVisitTree(root.getLeft() , lCode,c); String rCode = hfmCode+"1"; preVisitTree(root.getRight() , rCode,c); } } } public static void getHuffmanCode(String str,char c) { code+=(String.valueOf(c)+str); } public static void setHuffmanCode(String str) { code=str; } public static TreeNode setFalse(TreeNode treeNode) { ArrayDeque<TreeNode> queue=new ArrayDeque<TreeNode>(); TreeNode treeNode2=treeNode; queue.push(treeNode2); while(!queue.isEmpty()) { treeNode2=queue.pop(); treeNode2.flag=false; if(treeNode2.getLeft()!=null) { queue.push(treeNode2.getLeft()); } if(treeNode2.getRight()!=null) { queue.push(treeNode2.getRight()); } } return treeNode; } public static ArrayList<TreeNode> readFrequencies(File file) throws Exception { // IMPLEMENT THIS METHOD FileInputStream fis=new FileInputStream(file); int i; int[] byte_count=new int[256]; byte[] byte_array=new byte[64]; String str=null; while(fis.available()>0) { fis.read(byte_array); for(int j=0;j<64;j++) { if(byte_array[j]<0) { int index=byte_array[j]+256; //正数存储在0-127，负数存储在128-255 byte_count[index]++; } else { byte_count[byte_array[j]]++; } } } fis.close(); ArrayList<TreeNode> arrayList=new ArrayList<>(); char c; for(i=0;i<256;i++) { c=(char)i; arrayList.add(new TreeNode(new CharFreq(c, byte_count[i]))); } return arrayList; } public static void main(String[] args) throws Exception { TextZip tz=new TextZip(); File file=new File("qqbn_gygg.flv"); File file2=new File("qqbn_gygg.hz"); File file3=new File("qqbn.flv"); FileWriter fw=new FileWriter(file2); ArrayList<TreeNode> arrayList=readFrequencies(file); //读每个字符出现的频率 TreeNode head=buildTree(arrayList); //根据频率构建哈弗曼树 FileInputStream fis=new FileInputStream(file); BitWriter bw=new BitWriter(file2); TLV(file2,head,fw); compress(fis, head, bw); //把file1压缩到file2里面 BitReader br=new BitReader(file2); FileOutputStream fos=new FileOutputStream(file3); decompress(br, head, fos); //把file2解压到file3里面 } }