用Java将字符串复制到文件开头

Question

我想在文件开头写一个字符串，我该怎么做

我根本不知道如何添加字符串。。这就是我目前所做的：

  public static void prepend (String filename, String data) throws IOException{

    FileOutputStream file= new FileOutputStream(filename);

}

（i）write()方法只接受字节——我应该怎么做才能在我的情况下使用它

（ii）-如何将字符串复制到文件开头

而且——如果有人知道一个网站，它有所有的作者/读者，以及所有这些经过精心安排和解释的信息流——我会非常感激，我快疯了

谢谢

Answer 1

下面是运行代码

私有静态void addHeader（文件名）{

    FileOutputStream fileOutputStream =null;

    BufferedReader br = null;
    FileReader fr = null;
    String newFileName = fileName.getAbsolutePath() + "@";

    try {

        fileOutputStream = new FileOutputStream(newFileName);
        fileOutputStream.write("yourCopiedDataHere".getBytes());

        fr = new FileReader(fileName);
        br = new BufferedReader(fr);

        String sCurrentLine;

        while ((sCurrentLine = br.readLine()) != null) {
            fileOutputStream.write(("\n"+sCurrentLine).getBytes());

        }
        fileOutputStream.flush();


    } catch (IOException e) {

        e.printStackTrace();

    } finally {
        try {
            fileOutputStream.close();
            if (br != null)
                br.close();

            if (fr != null)
                fr.close();

            System.out.println(fileName+" is deleted "+ fileName.delete());
            new File(newFileName).renameTo(new File(newFileName.replace("@", "")));


        } catch (IOException ex) {

            ex.printStackTrace();

        }

    }

}

Answer 2

您可以使用缓冲写入程序，即

// read the existing contents of the file into a string builder   
BufferedReader is = new BufferedReader
    (new InputStreamReader(new FileInputStream(filename)));

StringBuilder sb = new StringBuilder();
String line;
while ((line = is.readLine()) != null) {
    sb.append(line);
}

// open the file for writing
BufferedWriter s = new BufferedWriter
    (new OutputStreamWriter(new FileOutputStream(filename)));

// prepend your text
s.writeLine("some line of text to prepend");

// rewrite the file contents
s.writeLine(sb.toString());