[英]How to read a file from a certain offset in Java?
嘿,我正在尝试打开一个文件并从一定长度的偏移量中读取! 我阅读了这个主题: How to read a specific line using the specific line number from a file in Java? 在那里它说不可能在不阅读之前阅读某一行的情况下阅读某一行,但我想知道字节!
FileReader location = new FileReader(file);
BufferedReader inputFile = new BufferedReader(location);
// Read from bytes 1000 to 2000
// Something like this
inputFile.read(1000,2000);
是否可以从已知偏移量读取某些字节?
RandomAccessFile公开一个函数:
seek(long pos)
Sets the file-pointer offset, measured from the beginning of this file, at which the next read or write occurs.
FileInputStream.getChannel().position(123)
除了RandomAccessFile
之外,这是另一种可能性:
File f = File.createTempFile("aaa", null);
byte[] out = new byte[]{0, 1, 2};
FileOutputStream o = new FileOutputStream(f);
o.write(out);
o.close();
FileInputStream i = new FileInputStream(f);
i.getChannel().position(1);
assert i.read() == out[1];
i.close();
f.delete();
这应该没问题,因为FileInputStream#getChannel
的文档说:
显式或通过读取更改通道的位置将更改此流的文件位置。
但是,我不知道这种方法与RandomAccessFile
相比如何。
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