java 两字符串相似度计算算法

http://itindex.net/detail/46929-java-%E5%AD%97%E7%AC%A6%E4%B8%B2-%E7%9B%B8%E4%BC%BC
Levenshtein distance最先是由俄国科学家Vladimir Levenshtein在1965年发明，用他的名字命名。不会拼读，可以叫它edit distance（编辑距离）。 

原理很简单，就是返回将第一个字符串转换(删除、插入、替换)成第二个字符串的编辑次数。次数越少，意味着字符串相似度越高 

    Levenshtein distance可以用来： 

Spell checking(拼写检查) 
Speech recognition(语句识别) 
DNA analysis(DNA分析) 
Plagiarism detection(抄袭检测) 
LD用m*n的矩阵存储距离值。算法大概过程： 
Demo1:

/**  
* 编辑距离的两字符串相似度  
*  
* @author jianpo.mo  
*/  
public class SimilarityUtil {  

    private static int min(int one, int two, int three) {  
        int min = one;  
        if(two < min) {  
            min = two;  
        }  
        if(three < min) {  
            min = three;  
        }  
        return min;  
    }  
     
    public static int ld(String str1, String str2) {  
        int d[][];    //矩阵  
        int n = str1.length();  
        int m = str2.length();  
        int i;    //遍历str1的  
        int j;    //遍历str2的  
        char ch1;    //str1的  
        char ch2;    //str2的  
        int temp;    //记录相同字符,在某个矩阵位置值的增量,不是0就是1  
        if(n == 0) {  
            return m;  
        }  
        if(m == 0) {  
            return n;  
        }  
        d = new int[n+1][m+1];  
        for(i=0; i<=n; i++) {    //初始化第一列  
            d[i][0] = i;  
        }  
        for(j=0; j<=m; j++) {    //初始化第一行  
            d[0][j] = j;  
        }  
        for(i=1; i<=n; i++) {    //遍历str1  
            ch1 = str1.charAt(i-1);  
            //去匹配str2  
            for(j=1; j<=m; j++) {  
                ch2 = str2.charAt(j-1);  
                if(ch1 == ch2) {  
                    temp = 0;  
                } else {  
                    temp = 1;  
                }  
                //左边+1,上边+1, 左上角+temp取最小  
                d[i][j] = min(d[i-1][j]+1, d[i][j-1]+1, d[i-1][j-1]+temp);  
            }  
        }  
        return d[n][m];  
    }  
     
    public static double sim(String str1, String str2) {  
        int ld = ld(str1, str2);  
        return 1 - (double) ld / Math.max(str1.length(), str2.length());  
    }  
     
    public static void main(String[] args) {  
        
        String str1 = "chenlb.blogjava.net";  
        String str2 = "chenlb.javaeye.com";  
        System.out.println("ld="+ld(str1, str2));  
        System.out.println("sim="+sim(str1, str2));  
    }  
}

Demo2:

public class LevenshteinDistance {
	public static void main(String[] args){
		String str1 = "i5rrrvan1";
        String str2 = "ittvan2";
        System.out.println("字符串1 {0}:"+str1);
 
        System.out.println("字符串2 {0}:"+str2);
 
        System.out.println("相似度 {0} %:"+ new LevenshteinDistance().LevenshteinDistancePercent(str1, str2) * 100);          
 
	}
 
        private int LowerOfThree(int first, int second, int third)
        {
            int min = Math.min(first, second);
 
            return Math.min(min, third);
        }
 
        private int Levenshtein_Distance(String str1, String str2)
        {
            int[][] Matrix;
            int n = str1.length();
            int m = str2.length();
 
            int temp = 0;
            char ch1;
            char ch2;
            int i = 0;
            int j = 0;
            if (n == 0)
            {
                return m;
            }
            if (m == 0)
            {
 
                return n;
            }
            Matrix = new int[n + 1][ m + 1];
 
            for (i = 0; i <= n; i++)
            {
                //初始化第一列
                Matrix[i][ 0] = i;
            }
 
            for (j = 0; j <= m; j++)
            {
                //初始化第一行
                Matrix[0][j] = j;
            }
 
            for (i = 1; i <= n; i++)
            {
                ch1 = str1.charAt(i - 1);
                for (j = 1; j <= m; j++)
                {
                    ch2 = str2.charAt(j-1);
                    if (ch1==ch2)
                    {
                        temp = 0;
                    }
                    else
                    {
                        temp = 1;
                    }
                    Matrix[i][j] = LowerOfThree(Matrix[i - 1][ j] + 1, Matrix[i][ j - 1] + 1, Matrix[i - 1][j - 1] + temp);
                }
            }
 	   for (i = 0; i <= n; i++)
            {
                for (j = 0; j <= m; j++)
                {
                	System.out.println(" {0} :"+Matrix[i][j]);
                }
                System.out.println("");
            }
 
            return Matrix[n][ m];
        }
 
 
        public double LevenshteinDistancePercent(String str1, String str2)
        {
            //int maxLenth = str1.Length > str2.Length ? str1.Length : str2.Length;
            int val = Levenshtein_Distance(str1, str2);
            return 1 - (double)val / Math.max(str1.length(), str2.length());
        }
}