【初學javaEE】用戶登陸註冊 javaee如何實現簡單的寫入寫出文件

寫入文件：
這個是我簡單的從頁面表單獲取用戶註冊的用戶名和密碼，再把其寫入文件的簡單操作

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		response.setContentType("text/html;charset=gb2312");
		response.setCharacterEncoding("gb2312");
		request.setCharacterEncoding("UTF-8");
		  String user = request.getParameter("user");   //從表單獲取用戶名
		String pass = request.getParameter("password");   //從表單獲取密碼
		//response.getWriter().println(user+pass);	//測試
		//把用戶名密碼寫入文件
		 File file = new File("D:\\學習\\javaee上機環境\\eclipse-workspace\\project_1\\WebContent\\WEB-INF\\myCounter.txt");  //存放數組數據的文件
		  FileWriter out = new FileWriter(file,true);  //文件寫入流
		  response.setContentType("text/html;charset=gb2312");
		   out.write(user+"\n");
		   out.write(pass+"\n");
		  out.close();
		  response.getWriter().println("註冊成功");
		  response.getWriter().println("<br/><a href='http://localhost:8080/project_1/login.jsp'>返回登陸頁面");
	}

寫出文件：
這個是我把文件中的用戶名和密碼寫出，順帶判斷用戶登陸時填寫的用戶名和密碼是否匹配

//讀取文件，進行判斷
	protected int select(String username, String password) {
		File file = new File("D:\\學習\\javaee上機環境\\eclipse-workspace\\project_1\\WebContent\\WEB-INF\\myCounter.txt");
		String user = "";
		String psw = "";
		InputStreamReader reader;
		try {
			reader = new InputStreamReader(new FileInputStream(file));
			BufferedReader br = new BufferedReader(reader);
			try {
				user = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			try {
				psw = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			//如果用戶名非空
			while (user != null) {
				//用戶名相等
				if (user.equals(username))
					//密碼正確，返回1
					if (psw.equals(password))
						return 1;
					else
						//密碼錯誤，返回2
						return 2;
				try {
					user = br.readLine();
				} catch (IOException e) {
					e.printStackTrace();
				}
				try {
					psw = br.readLine();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		} 
		catch (FileNotFoundException e) {
			e.printStackTrace();
		}
		return 0;
	}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		response.setContentType("text/html;charset=gb2312");
		response.setCharacterEncoding("gb2312");
		request.setCharacterEncoding("UTF-8");
		// TODO Auto-generated method stub
		String user = request.getParameter("user");   //從表單獲取用戶名
		String pass = request.getParameter("password");   //從表單獲取密碼
		System.out.println(user+pass);	//測試
		//判斷函數
		if (select(user, pass) == 1){
			response.getWriter().println("登陸成功！"+"Hello " + user + "!");
			response.getWriter().println("<br/><a href='http://localhost:8080/project_1/login.jsp'>返回登陸頁面");
		}
		
			
		else if (select(user, pass) == 2) {
			response.getWriter().println("密碼錯誤！請重新輸入");
			response.getWriter().println("<br/><a href='http://localhost:8080/project_1/login.jsp'>返回登陸頁面");
		}
		else {
			response.getWriter().println("登陸失敗！"+"Sorry " + user + "!"+"請先進行註冊");
			response.getWriter().println("<br/><a href='http://localhost:8080/project_1/login.jsp'>返回登陸頁面");
		}
	}

這個是我文件存儲的內容，用戶名一行，密碼一行

這樣一個簡單的通過文件寫入寫出來實現用戶登陸註冊功能就實現了~