测试类 GitDiffTest2.java：

import java.io.BufferedReader;
import java.io.FileReader;
import java.util.ArrayList;
import java.util.List;public class GitDiffTest2 {private static String folder = "\\xxx\\";private static List<String> lines_v1 = loadTxtFile2List(folder + "DemoClass1.java" );private static List<String> lines_v2 = loadTxtFile2List(folder + "DemoClass2.java");public static void main(String[] args) {/* lines_v1 = new ArrayList<>();lines_v2 = new ArrayList<>();lines_v1.add( "m" );lines_v1.add( "o" );lines_v1.add( "t" );lines_v1.add( "h" );lines_v1.add( "e" );lines_v1.add( "r" );lines_v2.add( "m" );lines_v2.add( "o" );lines_v2.add( "n" );lines_v2.add( "s" );lines_v2.add( "t" );lines_v2.add( "e" );lines_v2.add( "r" );*/int size_v1 = lines_v1.size();int size_v2 = lines_v2.size();int[][] dp = new int[size_v1][size_v2];for (int index_v1 = 0; index_v1 < size_v1; index_v1++) {for (int index_v2 = 0; index_v2 < size_v2; index_v2++) {String line_v1 = lines_v1.get(index_v1);String line_v2 = lines_v2.get(index_v2);if ( line_v1.equals( line_v2 ) ) {if( index_v1 == 0 || index_v2 == 0 ){// v1：...a// v2：   adp[index_v1][index_v2] = 1;}else {// v1：...a// v2：...adp[index_v1][index_v2] = dp[index_v1 - 1][index_v2 - 1] + 1;}} else {if( index_v1==0 || index_v2==0 ){// v1：...a// v2：   bdp[index_v1][index_v2] = 0;}else {// v1：...a// v2：...b// v1： ...   a// v2：...b        此时，v1 的 a 前面的部分 "..." 和 v2 的 "...b" 来求最长公共子串长度int lcs1 = dp[index_v1 - 1][index_v2];// v1：...a// v2： ...   b    此时，v2 的 b 前面的部分 "..." 和 v1 的 "...a" 来求最长公共子串长度int lcs2 = dp[index_v1][index_v2 - 1];dp[index_v1][index_v2] = Math.max( lcs1,lcs2 );}}}}List<String> result = new ArrayList<>();int index_v1 = lines_v1.size() - 1;int index_v2 = lines_v2.size() - 1;while (index_v1 >= 0 && index_v2 >= 0) {String line_v1 = lines_v1.get(index_v1);String line_v2 = lines_v2.get(index_v2);if ( line_v1.equals( line_v2 ) ) {// v1：..... a// v2：  ... a// 原封不动的输出行 a，因为 新旧版本文本中都有 a 行result.add( "  " + line_v1 );index_v1--;index_v2--;}else {// v1：..... a// v2：  ... b// v1：  ..... a// v2：  ... b      如果 lcs1 更长，则最长公共子串中不包含 行a,意味着 v2版本中需要删除v1版本中的行aint lcs1 = dp[index_v1 - 1][index_v2];// v1：..... a// v2：    ... b    如果 lcs2更长，则最长公共子串中不包含行b，意味着v2版本中需要新增 行bint lcs2 = dp[index_v1][index_v2-1];if ( lcs1 > lcs2 ) {result.add( "- " + line_v1 );index_v1--;} else {result.add( "+ " + line_v2 );index_v2--;}}}while (index_v2 >= 0) {result.add("+ " + lines_v2.get(index_v2));index_v2--;}while (index_v1 >= 0) {result.add("- " + lines_v1.get(index_v1));index_v1--;}for (int k = result.size() - 1; k >= 0; k--) {System.out.println(result.get(k));}}private static List<String> loadTxtFile2List(String filePath) {BufferedReader reader = null;List<String> lines = new ArrayList<>();try {reader = new BufferedReader(new FileReader(filePath));String line = reader.readLine();while (line != null) {lines.add( line );line = reader.readLine();}return lines;} catch (Exception e) {e.printStackTrace();return null;} finally {if (reader != null) {try {reader.close();} catch (Exception e) {e.printStackTrace();}}}}
}

旧版本文本样例文件 DemoClass1.java：

import lombok.extern.slf4j.Slf4j;
import org.apache.commons.text.similarity.LevenshteinDistance;@Slf4j
public class DemoClass1 {private static final LevenshteinDistance LEVENSHTEIN_DISTANCE = LevenshteinDistance.getDefaultInstance();public static String null2emptyWithTrim( String str ){if( str == null ){str = "";}str = str.trim();return str;}public static String requiredStringParamCheck(String param, String paramRemark) {param = null2emptyWithTrim( param );if( param.length() == 0 ){String msg = "操作失败，请求参数 \"" + paramRemark + "\" 为空";log.error( msg );throw new BusinessLogicException( msg );}return param;}public static double calculateSimilarity( String str1,String str2 ){int distance = LEVENSHTEIN_DISTANCE.apply(str1, str2);double similarity = 1 - (double) distance / Math.max(str1.length(), str2.length());System.out.println("相似度：" + similarity);return similarity;}
}

新版本文本样例文件 DemoClass2.java：

import lombok.extern.slf4j.Slf4j;
import org.apache.commons.text.similarity.LevenshteinDistance;@Slf4j
public class DemoClass2 {private static final LevenshteinDistance LEVENSHTEIN_DISTANCE = LevenshteinDistance.getDefaultInstance();private static final LevenshteinDistance LEVENSHTEIN_DISTANCE1 = LevenshteinDistance.getDefaultInstance();private static final LevenshteinDistance LEVENSHTEIN_DISTANCE2 = LevenshteinDistance.getDefaultInstance();public static String null2emptyWithTrim( String str ){// if( str == null ){//     str = "";// }// str = str.trim();return str;}public static String requiredStringParamCheck(String param, String paramRemark) {return null;}public static double calculateSimilarity( String str1,String str2 ){try {int distance = LEVENSHTEIN_DISTANCE.apply(str1, str2);double similarity = 1 - (double) distance / Math.max(str1.length(), str2.length());return similarity;}catch ( Exception e ){e.printStackTrace();return 0d;}}
}

测试输出：

  import lombok.extern.slf4j.Slf4j;import org.apache.commons.text.similarity.LevenshteinDistance;@Slf4j
- public class DemoClass1 {
+ public class DemoClass2 {private static final LevenshteinDistance LEVENSHTEIN_DISTANCE = LevenshteinDistance.getDefaultInstance();
+     private static final LevenshteinDistance LEVENSHTEIN_DISTANCE1 = LevenshteinDistance.getDefaultInstance();
+     private static final LevenshteinDistance LEVENSHTEIN_DISTANCE2 = LevenshteinDistance.getDefaultInstance();public static String null2emptyWithTrim( String str ){
-         if( str == null ){
-             str = "";
-         }
-         str = str.trim();
+         // if( str == null ){
+         //     str = "";
+         // }
+         // str = str.trim();return str;}public static String requiredStringParamCheck(String param, String paramRemark) {
-         param = null2emptyWithTrim( param );
-         if( param.length() == 0 ){
-             String msg = "操作失败，请求参数 \"" + paramRemark + "\" 为空";
-             log.error( msg );
-             throw new BusinessLogicException( msg );
-         }
-         return param;
+         return null;}public static double calculateSimilarity( String str1,String str2 ){
-         int distance = LEVENSHTEIN_DISTANCE.apply(str1, str2);
-         double similarity = 1 - (double) distance / Math.max(str1.length(), str2.length());
-         System.out.println("相似度：" + similarity);
-         return similarity;
+         try {
+             int distance = LEVENSHTEIN_DISTANCE.apply(str1, str2);
+             double similarity = 1 - (double) distance / Math.max(str1.length(), str2.length());
+             return similarity;
+         }catch ( Exception e ){
+             e.printStackTrace();
+             return 0d;
+         }}}