下面是我的代码。我能够成功地读取文件。但无法使用bufferedwriter用替换的内容重新写入。但我可以用bytebuffer。请告诉我哪里出了问题。
myfile.txt内容:
Key1-Value1
Key2-Value2
Key3-Value3
java代码如下:
String fileAbsolutePath = "C:\\myPath\\myFile.txt";
try {
RandomAccessFile file = new RandomAccessFile(fileAbsolutePath, "rw");
FileChannel fileChannel = file.getChannel();
FileLock lock = fileChannel.lock();
// read from the channel
BufferedReader bufferedReader = new BufferedReader(Channels.newReader(fileChannel, "UTF-8"));
List<String> filteredList = bufferedReader.lines().filter(line -> !line.contains("KEY1-VALUE1")).onClose(() -> {
try {
bufferedReader.close();
} catch (IOException ex) {
throw new UncheckedIOException(ex);
}
}).collect(Collectors.toList());
fileChannel.truncate(0);
BufferedWriter bufferedWriter = new BufferedWriter(Channels.newWriter(fileChannel, "UTF-8"));
for (String string : list) {
bufferedWriter.write(string);//does n't work
bufferedWriter.newLine();
}
lock.release();
file.close();
fileChannel.close();
} catch (Exception e) {
e.printStackTrace();
}
bytebuffer工作部件:
ByteBuffer buff = null;
for (int i = 0; i < filteredList.size(); i++) {
buff = ByteBuffer.wrap(filteredList.get(i).concat("\n").getBytes(StandardCharsets.UTF_8));
fileChannel.write(buff);
}
我们面临的挑战是,在政府的帮助下实现同样的目标 BufferedWriter
在尝试使用资源后更新了代码
try (RandomAccessFile file = new RandomAccessFile(fileAbsolutePath, "rw");
FileChannel fileChannel = file.getChannel();
FileLock lock = fileChannel.lock();
BufferedReader bufferedReader = new BufferedReader(Channels.newReader(fileChannel, "UTF-8"));
BufferedWriter bufferedWriter = new BufferedWriter(Channels.newWriter(fileChannel, "UTF-8"))) {
// read from the channel
List<String> list = bufferedReader.lines().filter(line -> !line.contains("Key1-Value1"))
.collect(Collectors.toList());
fileChannel.truncate(0);
list.forEach(item -> {
try {
bufferedWriter.write(item.concat("\n"));
} catch (IOException e) {
e.printStackTrace();
}
});
bufferedWriter.flush();
}
1条答案
按热度按时间wgmfuz8q1#
您不会在结尾刷新bufferedwriter,这意味着它包含您希望写回的部分或全部行。在关闭通道之前添加flush(),以确保缓冲区已写入:
理想情况下,你应该使用
try()
使用资源,以便在适当的时间完全关闭所有文件。