读取文件，然后跳转到结尾

Question

我想读取文本文件，然后获得文件读取的偏移量。我尝试了下面的程序，但事情是我不想使用RandomAccessFile，我该怎么做。

RandomAccessFile access = null; 
       try { 
        access = new RandomAccessFile(file, "r"); 

        if (file.length() < addFileLen) { 
         access.seek(file.length()); 
        } else { 
         access.seek(addFileLen); 
        } 
       } catch (Exception e) { 
        e.printStackTrace(); 
       } 
       String line = null; 
       try { 

        while ((line = access.readLine()) != null) { 

         System.out.println(line); 
         addFileLen = file.length(); 

        } 

Answer 1

如果要连续读取文件，可以执行以下操作。这通过不实际阅读文件的结尾来工作。您遇到的问题是，您可能在最后没有完整的行或者甚至没有完整的多字节字符。

class FileUpdater { 
    private static final long MAX_SIZE = 64 * 1024; 
    private static final byte[] NO_BYTES = {}; 

    private final FileInputStream in; 
    private long readSoFar = 0; 

    public FileUpdater(File file) throws FileNotFoundException { 
     this.in = new FileInputStream(file); 
    } 

    public byte[] read() throws IOException { 
     long size = in.getChannel().size(); 
     long toRead = size - readSoFar; 
     if (toRead > MAX_SIZE) 
      toRead = MAX_SIZE; 
     if (toRead == 0) 
      return NO_BYTES; 
     byte[] bytes = new byte[(int) toRead]; 
     in.read(bytes); 
     readSoFar += toRead; 
     return bytes; 
    }  
}