java判断文件是否相同的方法

Java  /  管理员 发布于 8年前   192

java判断文件是否相同的方法:

1、计算MD5或SHA-1然后对比判断

 // 计算文件的 MD5 值 根据MD5值 判断文件是否是同一个文件public static String getFileMD5(File file) {        if (!file.isFile()) {return null;        }        MessageDigest digest = null;        FileInputStream in = null;        byte buffer[] = new byte[8192];        int len;        try {digest =MessageDigest.getInstance("MD5");in = new FileInputStream(file);while ((len = in.read(buffer)) != -1) {    digest.update(buffer, 0, len);}BigInteger bigInt = new BigInteger(1, digest.digest());return bigInt.toString(16);        } catch (Exception e) {e.printStackTrace();return null;        } finally {try {    in.close();} catch (Exception e) {    e.printStackTrace();}        }    }

// 计算文件的 SHA-1 值 根据SHA-1值 判断文件是否是同一个文件    public static String getFileSha1(File file) {        if (!file.isFile()) {return null;        }        MessageDigest digest = null;        FileInputStream in = null;        byte buffer[] = new byte[8192];        int len;        try {digest =MessageDigest.getInstance("SHA-1");in = new FileInputStream(file);while ((len = in.read(buffer)) != -1) {    digest.update(buffer, 0, len);}BigInteger bigInt = new BigInteger(1, digest.digest());return bigInt.toString(16);        } catch (Exception e) {e.printStackTrace();return null;        } finally {try {    in.close();} catch (Exception e) {    e.printStackTrace();}        }    }

2、直接判断内容是否相同

 public class  IOOperation  {      public static void main(String[] args)       {          FileInputStream File1 = null;          FileInputStream File2 = null;          BufferedReader in = null;          String sFile;          if(args.length != 2)          {  System.out.println("The command line should be: java IOOperation testX.txt testX.txt");  System.out.println("X should be one of the array: 1, 2, 3");  System.exit(0);          }          try          {  File1 = new FileInputStream(args[0]);  File2 = new FileInputStream(args[1]);  try  {      if(File1.available() != File2.available())      {         //长度不同内容肯定不同          System.out.println(args[0] + " is not equal to " + args[1]);      }      else      {          boolean tag = true;          while( File1.read() != -1 && File2.read() != -1)          {  if(File1.read() != File2.read())  {      tag = false;      break;  }          }          if(tag == true)  System.out.println(args[0] + " equals to " + args[1]);          else  System.out.println(args[0] + " is not equal to " + args[1]);      }  }  catch(IOException e)  {      System.out.println(e);  }          }          catch (FileNotFoundException e)          {  System.out.println("File can't find..");          }          finally          {  try  {      if(File1 != null)          File1.close();      if(File2 != null)          File2.close();  }  catch (IOException e)  {      System.out.println(e);  }          }      }

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