Java实现哈夫曼编码

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Scanner;


class Node{
    char letter;
    int power;
    Node left_son;
    Node right_son;
    public Node() { super();}
    public Node(int power) {
        this.power = power;
    }
}
public class CurrDesign {

    static Map<Character, String> map = new HashMap<Character, String>();
    public static void main(String[] args) {
        List <Node>list = codingTable();//输入
        Node tree_root = creatHFMtree(list);
        creatTable(tree_root,"");
        display();

        String text = inputText();
        encode(text);

        String code = inputCode();
        decode(code,tree_root);
    }

    public static String[] encode(String text) {
        String []s = new String[100];
        char []key = text.toCharArray();
        System.out.println("编码结果为：");
        for(int i=0;i<key.length;i++) {
            s[i]=map.get(key[i]);
            System.out.print(s[i]+" ");
        }
        System.out.println();
        return s;
    }

    public static void decode(String s,Node tree_root) {
        System.out.println("译码结果为：");
        char []num = s.toCharArray();
        Node node = tree_root;
        for(int i=0;i<num.length;i++) {
            node = check(node,num[i]);
            if(node==null) {
                node = check(tree_root,num[i]);
            }
        }
        System.out.println(node.letter);
    }

    public static Node check(Node node,char c) {
        if(node.left_son!=null && c=='0')
            return node.left_son;
        else if(node.right_son!=null && c=='1'){
            return node.right_son;
        }
        System.out.print(node.letter);
        return null;
    }

    public static Object getKey(Object value){
        for(Object key: map.keySet()){
            if(map.get(key).equals(value)){
                return key;
            }
        }
        return null;
    }

    public static String inputText() {
        Scanner in = new Scanner(System.in);
        System.out.println("请输入要编码的文本，只含大写字母：");
        String text = in.next();
        return text;
    }

    public static String inputCode() {
        Scanner in = new Scanner(System.in);
        System.out.println("请输入编码：");
        String code = in.next();
        in.close();
        return code;
    }

    public static  List<Node> codingTable(){
        List <Node>list = new ArrayList<Node>();
        int []num = {186,64,13,22,32,103,21,15,47,57,1,2,32,20,57,63,15,1,48,51,80,23,8,18,1,16};
        Node node = null;
        for(int n=0;n<26;n++) {
            node = new Node();
            node.letter = (char)('A'+n);
            node.power = num[n];
            list.add(node);
        }
        return list;
    }

    public static void display() {
        System.out.println("The huffman coding table are:");
        System.out.println(map.toString());
    }

    public static Node creatHFMtree(List<Node> list){
        Node p = null;
        int n = 0;
        while(!list.isEmpty()) {
            if(n!=0) {
                list.add(p);
            }
            Node min1 = new Node(1000);
            Node min2 = new Node(999);
            for(Node node:list) {
                if(node.power < min1.power) {
                    if(node.power < min2.power) {
                        min1 = min2;
                        min2 = node;
                    }else {
                        min1 = node;
                    }
                }
            }
            p = new Node(min1.power+min2.power);
            p.left_son  = min2;
            p.right_son = min1;
            list.remove(min1);
            list.remove(min2);
            n++;
        }
        return p;
    }

    public static void creatTable(Node node,String coding){
        if(node.left_son!=null) {
            creatTable(node.left_son,coding+"0");
        }
        if(node.right_son!=null) {
            creatTable(node.right_son,coding+"1");
        }
        if(node.left_son==null && node.right_son==null) {
            map.put(node.letter, coding);
        }
    }
}