java修改原有txt文件_(转)Java创建txt文件并进行读、写、修改操作

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"); }

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