JAVA读写改文件（IO）

import java.io.*;/** *  * 功能描述：创建TXT文件并进行读、写、修改操作 *       */public class ReadWriteFile {    public static BufferedReader bufread;    //指定文件路径和名称    private static String path = "C:\\Users\\Administrator\\Desktop\\aa.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");    }}