Java 文件读写最好是用buffer对于大文件可以加快速度

参考例子：

FileReader fileReader = new FileReader(filename);
        BufferedReader bufferedReader = new BufferedReader(fileReader);
        List<String> lines = new ArrayList<String>();
        String line = null;
        while ((line = bufferedReader.readLine()) != null) {
            lines.add(line);
        }
        bufferedReader.close();FileReader fileReader = new FileRead