Java学习第30天:Huffman 编码 (编码与解码)
作者：互联网
主要任务：今天主要是根据前两天构建的Huffman树来获得Huffman编码。
继续在昨天代码继续添加以下代码：
/**
*********************
* 前序遍历.
*********************
*/
public void preOrderVisit(HuffmanNode paraNode) {
System.out.print("(" + paraNode.character + ", " + paraNode.weight + ") ");
if (paraNode.leftChild != null) {
preOrderVisit(paraNode.leftChild);
} // Of if
if (paraNode.rightChild != null) {
preOrderVisit(paraNode.rightChild);
} // Of if
}// Of preOrderVisit
/**
*********************
* 为每一个字符创建编码.
*********************
*/
public void generateCodes() {
huffmanCodes = new String[alphabetLength];
HuffmanNode tempNode;
for (int i = 0; i < alphabetLength; i++) {
tempNode = nodes[i];
// Use tempCharCode instead of tempCode such that it is unlike
// tempNode.
// This is an advantage of long names.
String tempCharCode = "";
while (tempNode.parent != null) {
if (tempNode == tempNode.parent.leftChild) {
tempCharCode = "0" + tempCharCode;
} else {
tempCharCode = "1" + tempCharCode;
} // Of if
tempNode = tempNode.parent;
} // Of while
huffmanCodes[i] = tempCharCode;
System.out.println("The code of " + alphabet[i] + " is " + tempCharCode);
} // Of for i
}// Of generateCodes
/**
*********************
* 编码.
*
* @param paraString
* The String.
*********************
*/
public String coding(String paraString) {
String resultCodeString = "";
int tempIndex;
for (int i = 0; i < paraString.length(); i++) {
// From the original char to the location in the alphabet.
tempIndex = charMapping[(int) paraString.charAt(i)];
// From the location in the alphabet to the code.
resultCodeString += huffmanCodes[tempIndex];
} // Of for i
return resultCodeString;
}// Of coding
/**
*********************
* 解码.
*
* @param paraString
* The given string.
*********************
*/
public String decoding(String paraString) {
String resultCodeString = "";
HuffmanNode tempNode = getRoot();
for (int i = 0; i < paraString.length(); i++) {
if (paraString.charAt(i) == '0') {
tempNode = tempNode.leftChild;
System.out.println(tempNode);
} else {
tempNode = tempNode.rightChild;
System.out.println(tempNode);
} // Of if
if (tempNode.leftChild == null) {
System.out.println("Decode one:" + tempNode);
// Decode one char.
resultCodeString += tempNode.character;
// Return to the root.
tempNode = getRoot();
} // Of if
} // Of for i
return resultCodeString;
}// Of decoding
/**
*********************
* 主程序.
*
* @param args
* Not used now.
*********************
*/
public static void main(String args[]) {
Huffman tempHuffman = new Huffman("D:\\Java-eclipse\\eclipse/lalala.txt");
tempHuffman.constructAlphabet();
tempHuffman.constructTree();
HuffmanNode tempRoot = tempHuffman.getRoot();
System.out.println("The root is: " + tempRoot);
System.out.println("Preorder visit:");
tempHuffman.preOrderVisit(tempHuffman.getRoot());
tempHuffman.generateCodes();
String tempCoded = tempHuffman.coding("abcdb");
System.out.println("Coded: " + tempCoded);
String tempDecoded = tempHuffman.decoding(tempCoded);
System.out.println("Decoded: " + tempDecoded);
}// Of main
}// Of class Huffman
运行结果：
The text is:
abcdefg
97 98 99 100 101 102 103 The alphabet is: [a, b, c, d, e, f, g]
Their counts are: [1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0]
The char mappings are: [-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1]
Selecting 0 and 1
The children of 7 are 0 and 1
Selecting 2 and 3
The children of 8 are 2 and 3
Selecting 4 and 5
The children of 9 are 4 and 5
Selecting 6 and 7
The children of 10 are 6 and 7
Selecting 8 and 9
The children of 11 are 8 and 9
Selecting 10 and 11
The children of 12 are 10 and 11
The root is: (*, 7)
Preorder visit:
(*, 7) (*, 3) (g, 1) (*, 2) (a, 1) (b, 1) (*, 4) (*, 2) (c, 1) (d, 1) (*, 2) (e, 1) (f, 1) The code of a is 010
The code of b is 011
The code of c is 100
The code of d is 101
The code of e is 110
The code of f is 111
The code of g is 00
Coded: 010011100101011
(*, 3)
(*, 2)
(a, 1)
Decode one:(a, 1)
(*, 3)
(*, 2)
(b, 1)
Decode one:(b, 1)
(*, 4)
(*, 2)
(c, 1)
Decode one:(c, 1)
(*, 4)
(*, 2)
(d, 1)
Decode one:(d, 1)
(*, 3)
(*, 2)
(b, 1)
Decode one:(b, 1)
Decoded: abcdb注：从根节点到目标叶节点的路径，路径中沿左孩子为0，沿右孩子为1，即到达叶节点这个过程所产生的一串编码即为Huffman编码。同理解码就根据Huffman编码从根节点依次往下遍历到叶节点便会自动停止，然后又从根节点开始往下遍历，直到遍历完所有编码，最终即可得到解码。
标签：编码,code,Java,String,30,System,tempNode,tempHuffman,out 来源： https://blog.csdn.net/xiaowuPHD/article/details/118059570