java創建TXT文件並進行讀、寫、修改操作



java創建TXT文件並進行讀、寫、修改操作

        這周忙的連滾帶爬的，終於在週末前把項目完工了。這次主要做的是一個UDP協議的轉發器，是一個純java寫的程序，沒有任何的框架在裏面。其中爲了保留住傳進來的數據，我們用TXT文本記錄下這些數據。文件代碼傳上來，需要的朋友直接下載就可以用。

import java.io.*;

/**
 *
 * 功能描述：創建TXT文件並進行讀、寫、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;
    //指定文件路徑和名稱
    private static String path = "D:/suncity.txt";
    private static  File filename = new File(path);
    private static String readStr ="";

    /**
     * 創建文本文件.
     * @throws IOException
     *
     */
    public static void creatTxtFile() throws IOException{
        if (!filename.exists()) {
            filename.createNewFile();
            System.err.println(filename + "已創建！");
        }
    }
   
    /**
     * 讀取文本文件.
     *
     */
    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("文件內容是:"+ "\r\n" + readStr);
        return readStr;
    }
   
    /**
     * 寫文件.
     *
     */
    public static void writeTxtFile(String newStr) throws IOException{
        //先讀取原有文件內容，然後進行寫入操作
        String filein = newStr + "\r\n" + readStr + "\r\n";
        RandomAccessFile mm = null;
        try {
            mm = new RandomAccessFile(filename, "rw");
            mm.writeBytes(filein);
        } catch (IOException e1) {
            // TODO 自動生成 catch 塊
            e1.printStackTrace();
        } finally {
            if (mm != null) {
                try {
                    mm.close();
                } catch (IOException e2) {
                    // TODO 自動生成 catch 塊
                    e2.printStackTrace();
                }
            }
        }
    }
   
    /**
     * 將文件中指定內容的第一行替換爲其它內容.
     *
     * @param oldStr
     *            查找內容
     * @param replaceStr
     *            替換內容
     */
    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();

            // 保存該行前面的內容
            for (int j = 1; (temp = br.readLine()) != null
                    && !temp.equals(oldStr); j++) {
                buf = buf.append(temp);
                buf = buf.append(System.getProperty("line.separator"));
            }

            // 將內容插入
            buf = buf.append(replaceStr);

            // 保存該行後面的內容
            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方法測試
     * @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");
    }
}