文件输入输出（java）

文件输入输出（RandomAccessFile类） 1.使用RandomAccessFile流将一个文本文件倒置读出。

import java.io.*; import java.util.Scanner; public class Test { public static void main(String args[]){ RandomAccessFile in = null; String str = "hello jsjfosfnso12345fijsmsjijdifjsfm hello"; try { File file = new File("D:\\java","text.txt"); if(!file.exists()) { file.createNewFile(); } in = new RandomAccessFile(file,"rw"); for(int i = 0;i < str.length();i++) { in.write(str.charAt(i)); //把字符串写入文件中 } in.writeUTF(str); long len = str.length(); //获得字符串长度 for(long i = len-1;i >= 0;i--) { in.seek(i); //设置文件指针，定位文件的读写位置 char c = (char)in.read(); System.out.print(c); } /*long length = in.length(); long position = 0; in.seek(position); while(position < length){ String ss = in.readLine(); byte[] b = ss.getBytes("ISO-8859-1"); //若文件中有汉字，则需要重新编码 ss = new String(b); position = in.getFilePointer(); System.out.println(ss); } */ in.close(); }catch(IOException e) { e.printStackTrace(); } } }

2.使用Java的输入流、输出流将一个文本文件的内容按行读出，每读出一行就顺序添加行号，并写入到另一个文件中。

import java.io.*; import java.util.Scanner; public class Test { public static void main(String args[]) throws IOException{ File file = new File("D:\\java\\text.txt"); File file1 = new File("D:\\java\\text1.txt"); if(!file1.exists()) { file1.createNewFile(); } if(!file.exists()) { file.createNewFile(); } try { FileReader inOne = new FileReader(file); BufferedReader inTwo = new BufferedReader(inOne); //读入文件 BufferedWriter outTwo = new BufferedWriter(new FileWriter(file1)); //写入新的文件 String s = " "; int i = 0; while((s = inTwo.readLine()) != null) { i++; outTwo.write(i+" "); outTwo.write(s); System.out.println(s); outTwo.newLine(); } outTwo.flush(); outTwo.close(); inOne.close(); inTwo.close(); }catch(IOException e) { e.printStackTrace(); } } }