java 修改文件

這裏藉助了RandomAccessFile 類，實現了對文件的部分內容的修改

 

/**
     * 修改文件內容
     * @param fileName
     * @param oldstr
     * @param newStr
     * @return
     */
    private static boolean modifyFileContent(String fileName, String oldstr, String newStr) {
        RandomAccessFile raf = null;
        try {
            raf = new RandomAccessFile(FILEPATH+"/"+fileName, "rw");
            String line = null;
            long lastPoint = 0; //記住上一次的偏移量
            while ((line = raf.readLine()) != null) {
                final long ponit = raf.getFilePointer();
                if(line.contains(oldstr)){
                      String str=line.replace(oldstr, newStr);
                raf.seek(lastPoint);
                raf.writeBytes(str);
                }
                lastPoint = ponit; 
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                raf.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return true;
    }