您知道可以使用AsynchronousFileChannel将整个文件读取为String:
AsynchronousFileChannel fileChannel = AsynchronousFileChannel.open(filePath, StandardOpenOption.READ);
long len = fileChannel.size();
ReadAttachment readAttachment = new ReadAttachment();
readAttachment.byteBuffer = ByteBuffer.allocate((int) len);
readAttachment.asynchronousChannel = fileChannel;
CompletionHandler<Integer, ReadAttachment> completionHandler = new CompletionHandler<Integer, ReadAttachment>() {
@Override
public void completed(Integer result, ReadAttachment attachment) {
String content = new String(attachment.byteBuffer.array());
try {
attachment.asynchronousChannel.close();
} catch (IOException e) {
e.printStackTrace();
}
completeCallback.accept(content);
}
@Override
public void failed(Throwable exc, ReadAttachment attachment) {
exc.printStackTrace();
exceptionError(errorCallback, completeCallback, String.format("error while reading file [%s]: %s", path, exc.getMessage()));
}
};
fileChannel.read(
readAttachment.byteBuffer,
0,
readAttachment,
completionHandler);
假设现在,我不想分配整个
ByteBuffer
,而是逐行读取。我可以使用固定宽度的ByteBuffer
,并一直调用read
,每次都将其复制并附加到StringBuffer中,直到我无法得到新行... 我唯一关心的是:因为我正在读取的文件的编码可能是每个字符多字节(UTF something),所以读取的字节可能以不完整的字符结尾。如何确保我将正确的字节转换为字符串,而不会弄乱编码?
更新:答案在所选答案的评论中,但基本上指向CharsetDecoder。
BufferedReader.readLine()
每秒读取数百万行。 - user207421