java 写入与读取txt文件

写入：

    File writefile;  
    String path = request.getSession().getServletContext().getRealPath("/") + "log";
    String content = "123";
    try
    {
        writefile = new File(path);
        if (writefile.exists() == false)  // 如果文本文件不存在则创建它
        {
        writefile.mkdir();
        writefile = new File(path);  // 重新实例化
        }
        FileWriter filewriter = new FileWriter(writefile + "//log.txt");// 写入新的文件内容
        filewriter.write(content);
        filewriter.close();
        filewriter.flush();
    }
    catch (Exception d)
    {
        System.out.println(d.getMessage());
    }

request.getSession().getServletContext().getRealPath("/")为获取程序路径

读取：

    try
    {
        String encoding = "GBK";
        File file = new File(request.getSession().getServletContext().getRealPath("/") + "log" + "//log.txt");
        if (file.isFile() && file.exists())
        { // 判断文件是否存在
        InputStreamReader read = new InputStreamReader(new FileInputStream(file), encoding);// 考虑到编码格式
        BufferedReader bufferedReader = new BufferedReader(read);
        String lineTxt = null;
        while ((lineTxt = bufferedReader.readLine()) != null)
        {
            System.out.println(lineTxt);
        }
        read.close();
        }
        else
        {
        System.out.println("找不到指定的文件");
        }
    }
    catch (Exception e)
    {
        System.out.println("读取文件内容出错");
        e.printStackTrace();
    }