输入输出流

//从文件先读出原有的内容,然后再写入新的内容+上老内容
    public boolean regUser(String user[])
    {
       
        String filename = "G://zhnagtao//test.txt";
        File file = new File(filename);
       
        try
        {
            String s;
            StringBuffer bf = new StringBuffer();
            FileInputStream is = new FileInputStream("G://zhnagtao//test.txt"); // 读出指定的文件，二进制流
            InputStreamReader ir = new InputStreamReader(is); // 读取二进制格式，字符流
            BufferedReader in = new BufferedReader(ir); // 读取字符流，变成反冲字符流
            while ((s = in.readLine()) != null)
            {
                bf.append(s);
                bf.append("\n");
            }
           
            // 取出以前的+上现在的资料一起再次存入数据库
            FileWriter fw = new FileWriter(file);
            BufferedWriter bw = new BufferedWriter(fw);
            PrintWriter out = new PrintWriter(fw);
            out.append(bf);
            for (int i = 0; i < user.length; i++)
            {
               
                out.append(user[i]);
                out.append(" ");
            }
            // out.append("\r\n");
           
            out.close();
            fw.close();
            return true;
           
        }
        catch (IOException e)
        {
           
            System.out.println("Uh oh, got an IOException error!");
            e.printStackTrace();
            return false;
        }
       
    }