java创建TXT文件并进行读、写、修改操作

前言：

　　 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。

代码：

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:[email protected]">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");

    }

}

清空txt文件的内容：

File f = new File("c:/abc.txt");
FileWriter fw =  new FileWriter(f);
fw.write("");fw.close();