java读写txt文件

本文转载自：http://www.blogjava.net/kenzhh/archive/2007/12/21/169364.htmljava创建TXT文件并进行读、写、修改操作

????????这周忙的连滚带爬的，终于在周末前把项目完工了。这次主要做的是一个UDP协议的转发器，是一个纯java写的程序，没有任何的框架在里面。其中为了保留住传进来的数据，我们用TXT文本记录下这些数据。文件代码传上来，需要的朋友直接下载就可以用。

import?java.io.*;


/**
?*?
?*?功能描述：创建TXT文件并进行读、写、修改操作
?*??????
?*?@author?<a?href="mailto:zhanghhui@126.com">KenZhang</a>
?*?@version?1.0?
?*?Creation?date:?2007-12-18?-?下午06:48:45
?*/
public?class?ReadWriteFile?{
????public?static?BufferedReader?bufread;
????//指定文件路径和名称
????private?static?String?path?=?"D:/suncity.txt";
????private?static??File?filename?=?new?File(path);
????private?static?String?readStr?="";


????/**
?????*?创建文本文件.
?????*?@throws?IOException?
?????*?
?????*/
????public?static?void?creatTxtFile()?throws?IOException{
????????if?(!filename.exists())?{
????????????filename.createNewFile();
????????????System.err.println(filename?+?"已创建！");
????????}
????}
????
????/**
?????*?读取文本文件.
?????*?
?????*/
????public?static?String?readTxtFile(){
????????String?read;
????????FileReader?fileread;
????????try?{
????????????fileread?=?new?FileReader(filename);
????????????bufread?=?new?BufferedReader(fileread);
????????????try?{
????????????????while?((read?=?bufread.readLine())?!=?null)?{
????????????????????readStr?=?readStr?+?read+?"\r\n";
????????????????}
????????????}?catch?(IOException?e)?{
????????????????//?TODO?Auto-generated?catch?block
????????????????e.printStackTrace();
????????????}
????????}?catch?(FileNotFoundException?e)?{
????????????//?TODO?Auto-generated?catch?block
????????????e.printStackTrace();
????????}

????????System.out.println("文件内容是:"+?"\r\n"?+?readStr);
????????return?readStr;
????}
????
????/**
?????*?写文件.
?????*?
?????*/
????public?static?void?writeTxtFile(String?newStr)?throws?IOException{
????????//先读取原有文件内容，然后进行写入操作
????????String?filein?=?newStr?+?"\r\n"?+?readStr?+?"\r\n";
????????RandomAccessFile?mm?=?null;
????????try?{
????????????mm?=?new?RandomAccessFile(filename,?"rw");
????????????mm.writeBytes(filein);
????????}?catch?(IOException?e1)?{
????????????//?TODO?自动生成?catch?块
????????????e1.printStackTrace();
????????}?finally?{
????????????if?(mm?!=?null)?{
????????????????try?{
????????????????????mm.close();
????????????????}?catch?(IOException?e2)?{
????????????????????//?TODO?自动生成?catch?块
????????????????????e2.printStackTrace();
????????????????}
????????????}
????????}
????}
????
????/**
?????*?将文件中指定内容的第一行替换为其它内容.
?????*?
?????*?@param?oldStr
?????*????????????查找内容
?????*?@param?replaceStr
?????*????????????替换内容
?????*/
????public?static?void?replaceTxtByStr(String?oldStr,String?replaceStr)?{
????????String?temp?=?"";
????????try?{
????????????File?file?=?new?File(path);
????????????FileInputStream?fis?=?new?FileInputStream(file);
????????????InputStreamReader?isr?=?new?InputStreamReader(fis);
????????????BufferedReader?br?=?new?BufferedReader(isr);
????????????StringBuffer?buf?=?new?StringBuffer();

????????????//?保存该行前面的内容
????????????for?(int?j?=?1;?(temp?=?br.readLine())?!=?null
????????????????????&&?!temp.equals(oldStr);?j++)?{
????????????????buf?=?buf.append(temp);
????????????????buf?=?buf.append(System.getProperty("line.separator"));
????????????}

????????????//?将内容插入
????????????buf?=?buf.append(replaceStr);

????????????//?保存该行后面的内容
????????????while?((temp?=?br.readLine())?!=?null)?{
????????????????buf?=?buf.append(System.getProperty("line.separator"));
????????????????buf?=?buf.append(temp);
????????????}

????????????br.close();
????????????FileOutputStream?fos?=?new?FileOutputStream(file);
????????????PrintWriter?pw?=?new?PrintWriter(fos);
????????????pw.write(buf.toString().toCharArray());
????????????pw.flush();
????????????pw.close();
????????}?catch?(IOException?e)?{
????????????e.printStackTrace();
????????}
????}
????/**
?????*?main方法测试
?????*?@param?s
?????*?@throws?IOException
?????*/
????public?static?void?main(String[]?s)?throws?IOException?{
????????ReadWriteFile.creatTxtFile();
????????ReadWriteFile.readTxtFile();
????????ReadWriteFile.writeTxtFile("20080808:12:13");
//????????ReadWriteFile.replaceTxtByStr("ken",?"zhang");
????}
}