霍夫曼文件压缩代码示例java

以下是一个Java的霍夫曼文件压缩代码示例：

import java.io.*;
import java.util.*;

class HuffmanNode implements Comparable<HuffmanNode> {
    int frequency;
    char data;
    HuffmanNode left, right;

    public int compareTo(HuffmanNode node) {
        return this.frequency - node.frequency;
    }
}

class HuffmanTree {
    public static void compressFile(String inputFile, String outputFile) {
        try {
            // 读取输入文件
            FileInputStream fis = new FileInputStream(inputFile);
            byte[] inputBytes = new byte[(int) fis.available()];
            fis.read(inputBytes);
            fis.close();

            // 统计字符频率
            Map<Character, Integer> frequencyMap = new HashMap<>();
            for (byte b : inputBytes) {
                char c = (char) b;
                frequencyMap.put(c, frequencyMap.getOrDefault(c, 0) + 1);
            }

            // 构建霍夫曼树
            PriorityQueue<HuffmanNode> pq = new PriorityQueue<>();
            for (Map.Entry<Character, Integer> entry : frequencyMap.entrySet()) {
                HuffmanNode node = new HuffmanNode();
                node.data = entry.getKey();
                node.frequency = entry.getValue();
                pq.add(node);
            }

            while (pq.size() > 1) {
                HuffmanNode left = pq.poll();
                HuffmanNode right = pq.poll();

                HuffmanNode newNode = new HuffmanNode();
                newNode.frequency = left.frequency + right.frequency;
                newNode.left = left;
                newNode.right = right;

                pq.add(newNode);
            }

            HuffmanNode root = pq.poll();

            // 构建霍夫曼编码表
            Map<Character, String> codeMap = new HashMap<>();
            buildCodeMap(root, "", codeMap);

            // 压缩文件
            StringBuilder compressedData = new StringBuilder();
            for (byte b : inputBytes) {
                char c = (char) b;
                compressedData.append(codeMap.get(c));
            }

            // 写入输出文件
            FileOutputStream fos = new FileOutputStream(outputFile);
            fos.write(compressedData.toString().getBytes());
            fos.close();

            System.out.println("文件压缩成功！");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static void buildCodeMap(HuffmanNode node, String code, Map<Character, String> codeMap) {
        if (node == null) {
            return;
        }

        if (node.left == null && node.right == null) {
            codeMap.put(node.data, code);
        }

        buildCodeMap(node.left, code + "0", codeMap);
        buildCodeMap(node.right, code + "1", codeMap);
    }
}

public class HuffmanTreeTest {
    public static void main(String[] args) {
        String inputFile = "text.txt";
        String outputFile = "compressed.txt";

        HuffmanTree.compressFile(inputFile, outputFile);
    }
}