Huffman编码的Java实现

TNode.java

[cpp]
定义Huffman编码的节点
/**
*

赫夫曼编码的节点定义类

*
* @version 1.0, 2007-01-8
* @author 李赫元
* @since JDK1.6
*/
class TNode
{
/**权值*/
protected int w;
/**左孩子节点*/
TNode lChild = null;
/**右孩子节点*/
TNode rChild = null;

/**(仅对叶子节点有效)赫夫曼编码*/
String huffCode = null;

/**
* 构造一个赫夫曼编码节点的实例。设定左右子树和权值
*
* @param w int 权值
* @param l TNode 左孩子节点
* @param r TNode 右孩子节点
*/
public TNode(int w,TNode l,TNode r)
{
this.w = w;
lChild = l;
rChild = r;
}

/**
* 构造一个赫夫曼编码叶子点的实例。仅仅设定权值
*
* @param w int 权值
*/
public TNode(int w)
{
this.w = w;
}

/**
* 判断本节点是否为叶子节点
*
* @return boolean 为叶子节点则返回true
*/
public boolean isLeaf()
{
return (rChild==null && lChild == null);
}

/**
* 返回本节点的权值
*
* @return int 本节点的权值
*/
public int getWeight()
{
return w;
}

/**
* 返回本节点的左孩子节点
*
* @return TNode 左孩子节点
*/
public TNode leftChild()
{
return lChild;
}

/**
* 返回本节点的右孩子节点
*
* @return TNode 右孩子节点
*/
public TNode rightChild()
{
return rChild;
}

/**
* 设置节点的赫夫曼编码
* @param str String 被设置的赫夫曼编码
*/
public void setHuffCode(String str)
{
huffCode = str;
}

/**
* 得到节点的赫夫曼编码
* @return String 被设置的赫夫曼编码
*/
public String getHuffCode()
{
return huffCode;
}
}
[/cpp]

Tree.java

[cpp]
import java.util.*;

/**
*

最优二叉树类

*
* @version 1.0, 2007-01-8
* @author 李赫元
* @since JDK1.6
*/
class Tree
{
/**最优二叉树的根节点*/
protected TNode root;

/**存储叶子节点的权值*/
protected List<Integer> leafWList = new ArrayList<Integer>();

/**临时队列,用于存放待组合的节点*/
protected List<TNode> tmpList = new LinkedList<TNode>();

/**存放带权节点*/
protected TNode[] leafArr = null;

/**
* 从键盘读取各个权值
*
*/
public void getLeafWeight()
{
Scanner scan = new Scanner(System.in);

System.out.println("请输入各叶子节点的权值,0为结束:");

while(scan.hasNextInt())
{
int i = scan.nextInt();

if(i==0)
break;
leafWList.add(new Integer(i));
}

scan = null;

return ;
}

/**
* 找出临时队列中权值最小的节点从队列中移出并返回
*@return TNode 权值最小的节点
*/
public TNode min()
{
Iterator<TNode> itr = tmpList.iterator();
TNode minNode = itr.next();
int min = minNode.getWeight();

//找到最小的节点
TNode tmpNode;
while(itr.hasNext())
{
tmpNode = itr.next();
if(tmpNode.getWeight()<min)
{
min = tmpNode.getWeight();
minNode = tmpNode;
}
}

//最小的节点移出临时队列
tmpList.remove(minNode);

//处理垃圾
itr = null;
tmpNode = null;

return minNode;

}

/**
* 根据权值创建叶子节点并加入临时队列
*
*/
public void makeLeafNode()
{
leafArr = new TNode[leafWList.size()];

for(int i=0;i<leafWList.size();i++)
{
TNode node = new TNode(leafWList.get(i).intValue());
leafArr[i] = node;
tmpList.add(node);
}
}

/**
* 根据权值构造最优的二叉树
*
*/
public void makeBestTree()
{
//根据权值创建叶子节点并加入临时队列
makeLeafNode();

TNode minNode1 = null,minNode2 = null;
TNode node = null;
//构造最优树
while(tmpList.size()!=1)
{
minNode1 = min();
minNode2 = min();

node = new TNode(minNode1.getWeight()+minNode2.getWeight(),minNode1,minNode2);
tmpList.add(node);
}

root = node;

}
/**
* 先序遍历的递归调用
*
*/
protected void preT(TNode t)
{
if(t.isLeaf())
{
System.out.print(t.getWeight() + " ");
return ;
}
else
{
System.out.print(t.getWeight() + " ");
preT(t.lChild);
preT(t.rChild);
}
}

/**
* 先序遍历最优二叉树
*
*/
public void preOrderTraverse()
{
preT(root);
}

public static void main(String [] args)
{
Tree t = new Tree();
t.getLeafWeight();
t.makeBestTree();
t.preOrderTraverse();
}
}
[/cpp]

HuffmanCode.java

[cpp]
/**
*

赫夫曼编码类

*
* @version 1.0, 2007-01-8
* @author 李赫元
* @since JDK1.6
*/
public class HuffmanCode extends Tree
{

public HuffmanCode()
{
init();
}

/**
* 初始化节点值并构造最优二叉树
*
*/

public void init()
{
super.getLeafWeight();
super.makeBestTree();
}

/**
* 生成赫夫曼编码的递归函数
*
* @param t TNode 当前遍历节点
* @param s String 目前遍历至此的赫夫曼编码
*/
protected void hufT(TNode t,String s)
{
if(t.isLeaf())
{
t.setHuffCode(s);
}
else
{
hufT(t.lChild,s+"0");
hufT(t.rChild,s+"1");
}
}

/**
* 生成赫夫曼编码的外部调用函数
*
*/
public void makeHuffCode()
{
hufT(root,"");

}

/**
* 查看所有的赫夫曼编码值
*
*/
public void viewHuffCode()
{
for(int i=0;i<leafArr.length;i++)
{
System.out.println(leafArr[i].w + ":" +leafArr[i].getHuffCode());
}
}

public static void main(String [] args)
{
HuffmanCode hc = new HuffmanCode();
hc.makeHuffCode();
hc.viewHuffCode();
}
}
[/cpp]

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