做开发的经常碰到文件的操作,非凡是文件的“读”操作。在Java中,读文件有很多种方法,有FileReader、BufferReader等,当然,各种方法的效率是不一样的,FileReader经BufferReader包装后效率明显提高,在个别时候,我们可以用java.nio包进行文件操作,如下:
private static String fileReader(File fileName) {
String fileContent = null;
FileInputStream fis = null;
FileChannel fc = null;
try {
fis = new FileInputStream(fileName);
// get a file channel
fc = fis.getChannel();
// create a ByteBuffer that is large enough
// and read the contents of the file into it
// test
// System.out.println(fc.size());
ByteBuffer bb = ByteBuffer.allocate((int) fc.size() + 1);
fc.read(bb);
bb.flip();
// save the content of the file as a String
// if we want to change the encode
// we can directly add a second parameter here
// which is of course more efficent
// System.out.println(bb.capacity());
fileContent = new String(bb.array());
} catch (Exception e) {
e.printStackTrace();
} finally {
// release the FileChannel
try {
fc.close();
} catch (Exception ex) {
}
try {
fis.close();
} catch (Exception ex) {
}
}
// write out the contents of this file
return fileContent;
}
使用这种方法有个致命的弱点,当所读文件较大时,将消耗大量内存,甚至发生OutOfMemory Error,而当文件较小时,使用该方法的效率就明显高得多。
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