org.apache.hadoop.fs-PositionedReadable

 

 

 1 package org.apache.hadoop.fs;
 2 
 3 import java.io.*;
 4 import org.apache.hadoop.fs.*;
 5 
 6 /** Stream that permits positional reading. */
 7 //定位流式读取
 8 public interface PositionedReadable {
 9   /**
10    * Read upto the specified number of bytes, from a given
11    * position within a file, and return the number of bytes read. This does not
12    * change the current offset of a file, and is thread-safe.
13    */
14   public int read(long position, byte[] buffer, int offset, int length)
15     throws IOException;
16   //读取文件流中最多到length大小的字节，到字节缓冲区buffer中,它是从给定的position位置开始读取的。  
17   //该读取方式不改变文件的当前偏移位置offset，并且该方法是线程安全的
18   /**
19    * Read the specified number of bytes, from a given
20    * position within a file. This does not
21    * change the current offset of a file, and is thread-safe.
22    */
23   public void readFully(long position, byte[] buffer, int offset, int length)
24     throws IOException;
25   /** 
26    * 读取文件流中length大小的字节，到字节缓冲区buffer中,它是从给定的position位置开始读取的。 
27    * 该读取方式不改变文件的当前偏移位置offset，并且该方法是线程安全的。 
28    */ 
29   /**
30    * Read number of bytes equalt to the length of the buffer, from a given
31    * position within a file. This does not
32    * change the current offset of a file, and is thread-safe.
33    */
34   public void readFully(long position, byte[] buffer) throws IOException;
35   /** 
36    * 读取文件流中buffer长度的字节，到字节缓冲区buffer中,它是从给定的position位置开始读取的 
37    * 该读取方式不改变文件的当前偏移位置offset，并且该方法是线程安全的。 
38    */  
39 
40 }

 

 

posted @ 2014-10-13 15:26  Daem0n  阅读(490)  评论(0)  编辑  收藏  举报