java实现文件比较1，根据文件路径与md5判断是否是同一个文件

冷不防 2023-09-28 12:24 95阅读 0赞

思路部分来自于[怎样用java实现文件比较，判断是否是同一个文件][java]  
该链接中仅以两个文件夹下不同文件，进行互相比较，  
仅以文件名为区别点，

我于其基础上，  
1.增加递归获取文件夹下所有文件  
2.对获取的所有文件增加md5值获取并比对md5值  
即本文

但有更快的方法，  
[java实现文件比较2，仅根据文件路径判断][java_2]  
java实现文件比较2,使用set的去重属性，同样递归获取所有文件，但大批量文件比对更快

也有最新的的思路方法  
[java实现文件比较3，判断文件是否新增减少修改][java_3]

package com.tausoft;
    
    import java.io.File;
    import java.io.FileInputStream;
    import java.security.DigestInputStream;
    import java.security.MessageDigest;
    import java.util.Iterator;
    import java.util.LinkedList;
    
    public class a {
        
        private static LinkedList<String> linkedList1 = new LinkedList<String>();
        private static LinkedList<String> linkedList2 = new LinkedList<String>();
        private static String path1 = "C:\\Users\\tau\\Desktop\\文件1";
        private static String path2 = "C:\\Users\\tau\\Desktop\\文件3";
    
        public static void main(String[] args) {
        
    
            readFileSum1(new File(path1));
            readFileSum2(new File(path2));
            LinkedList<String> compare = compare(linkedList1, linkedList2);
            int num = compare.size()-1;
            if (num == 0) {
        
                System.out.println("无差异文件");
            } else {
        
                System.out.println("差异文件数量为：" + num);
                System.out.println("=============================================");
                for (String s : compare) {
        
                    if(new File(s).exists()){
        
                        System.out.println(s+"  "+getMD5File(new File(s)));
                    }else{
        
                        System.out.println(s);
                    }
    
                }
            }
        }
        private static void readFileSum1(File root) {
        
            if (root.exists()) {
        
                if (root.isDirectory()) {
        
                    File[] files = root.listFiles();
                    if (files != null) {
        
                        for (int i = 0; i < files.length; i++) {
        
                            if (files[i].isFile()) {
        
                                linkedList1.addLast(files[i].toString());
                            } else if (files[i].isDirectory()) {
        
                                readFileSum1(files[i]);
                            }
                            files[i] = null;
                        }
                    }
                    files = null;
                } else if (root.isFile()) {
        
                    linkedList1.addLast(root.toString().replace(path1, ""));
                }
            }
        }
        private static void readFileSum2(File root) {
        
            if (root.exists()) {
        
                if (root.isDirectory()) {
        
                    File[] files = root.listFiles();
                    if (files != null) {
        
                        for (int i = 0; i < files.length; i++) {
        
                            if (files[i].isFile()) {
        
                                linkedList2.addLast(files[i].toString());
                            } else if (files[i].isDirectory()) {
        
                                readFileSum2(files[i]);
                            }
                            files[i] = null;
                        }
                    }
                    files = null;
                } else if (root.isFile()) {
        
                    linkedList2.addLast(root.toString());
                }
            }
        }
        //比对
        private static LinkedList<String> compare(LinkedList<String> list1, LinkedList<String> list2) {
        
            Iterator<String> it1 = list1.iterator();
            while (it1.hasNext()) {
        
                String s1 = it1.next();
                File f1 = new File(s1);
                for (int i = 0; i < list2.size(); i++) {
        
                    String s2 = list2.get(i);
                    File f2 = new File(s2);
                    if (s1.replace(path1, "").equals(s2.replace(path2, ""))){
        
    //            f1.lastModified();
    //                    System.out.println(getMD5File(f1));
    //                    System.out.println(getMD5File(f2));
                        if(getMD5File(f1).equals(getMD5File(f2))){
        
                            it1.remove();
                            list2.remove(i);
                            break;
                        }
    //                       f1.lastModified()==f2.lastModified()
                    }
                }
            }
            list1.add("===============================以上为文件夹1的差异文件，以下为文件夹2的差异文件===============================");
            list1.addAll(list2);
            return list1;
        }
        /**
         * 获取文件MD5
         */
        public static String getMD5File(File file) {
        
    
            String inputFile = file.getPath();
            String result = "";
            // 缓冲区大小
            int bufferSize = 256 * 1024;
            FileInputStream fis = null;
            DigestInputStream dis = null;
    
            try {
        
                // 拿到一个MD5转换器
                MessageDigest md = MessageDigest.getInstance("MD5");
    
                // 使用DigestInputStream
                fis = new FileInputStream(inputFile);
                dis = new DigestInputStream(fis, md);
    
                // read 过程中进行MD5处理，直到读完文件
                byte[] buffer = new byte[bufferSize];
                while (dis.read(buffer) > 0)
    
                    // 获取最终的MessageDigest
                    md = dis.getMessageDigest();
                // 拿到结果，也是字节数组，包含16个元素
                byte[] resultByteArray = md.digest();
                // 同样，把字节组转换成字符串
                result = byteArrayToHex(resultByteArray);
    
            } catch (Exception e) {
        
                e.printStackTrace();
            } finally {
        
                try {
        
                    dis.close();
                    fis.close();
                } catch (Exception e) {
        
                    e.printStackTrace();
                }
            }
            return result;
        }
    
        // 将字节数组转换成字符串
        private static String byteArrayToHex(byte[] b) {
        
            String hs = "";
            String stmp = "";
            for (int i = 0; i < b.length; i++) {
        
                stmp = (Integer.toHexString(b[i] & 0xFF));
                if (stmp.length() == 1) {
        
                    hs = hs + "0" + stmp;
                } else {
        
                    hs = hs + stmp;
                }
                if (i < b.length - 1) {
        
                    hs = hs + "";
                }
            }
            return hs;
        }
    }

[java]: https://blog.csdn.net/seeol/article/details/106455502?ops_request_misc=&request_id=&biz_id=102&utm_term=java%E6%96%87%E4%BB%B6%E5%AF%B9%E6%AF%94&utm_medium=distribute.pc_search_result.none-task-blog-2~all~sobaiduweb~default-1-106455502.142%5Ev21%5Econtrol,157%5Ev15%5Enew_3&spm=1018.2226.3001.4187
[java_2]: https://blog.csdn.net/m0_54765221/article/details/125507473?spm=1001.2014.3001.5502
[java_3]: https://blog.csdn.net/m0_54765221/article/details/125507552?spm=1001.2014.3001.5502