【初学javaEE】用户登陆注册 javaee如何实现简单的写入写出文件

写入文件：
这个是我简单的从页面表单获取用户注册的用户名和密码，再把其写入文件的简单操作

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");   //从表单获取用户名
String pass = request.getParameter("password");   //从表单获取密码
//response.getWriter().println(user+pass);	//测试
//把用户名密码写入文件
File file = new File("D:\\学习\\javaee上机环境\\eclipse-workspace\\project_1\\WebContent\\WEB-INF\\myCounter.txt");  //存放数组数据的文件
FileWriter out = new FileWriter(file,true);  //文件写入流
response.setContentType("text/html;charset=gb2312");
out.write(user+"\n");
out.write(pass+"\n");
out.close();
response.getWriter().println("注册成功");
response.getWriter().println("<br/><a href='http://localhost:8080/project_1/login.jsp'>返回登陆页面");
}

写出文件：
这个是我把文件中的用户名和密码写出，顺带判断用户登陆时填写的用户名和密码是否匹配

//读取文件，进行判断
protected int select(String username, String password) {
File file = new File("D:\\学习\\javaee上机环境\\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();
}
//如果用户名非空
while (user != null) {
//用户名相等
if (user.equals(username))
//密码正确，返回1
if (psw.equals(password))
return 1;
else
//密码错误，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");   //从表单获取用户名
String pass = request.getParameter("password");   //从表单获取密码
System.out.println(user+pass);	//测试
//判断函数
if (select(user, pass) == 1){
response.getWriter().println("登陆成功！"+"Hello " + user + "!");
response.getWriter().println("<br/><a href='http://localhost:8080/project_1/login.jsp'>返回登陆页面");
}

else if (select(user, pass) == 2) {
response.getWriter().println("密码错误！请重新输入");
response.getWriter().println("<br/><a href='http://localhost:8080/project_1/login.jsp'>返回登陆页面");
}
else {
response.getWriter().println("登陆失败！"+"Sorry " + user + "!"+"请先进行注册");
response.getWriter().println("<br/><a href='http://localhost:8080/project_1/login.jsp'>返回登陆页面");
}
}

这个是我文件存储的内容，用户名一行，密码一行

这样一个简单的通过文件写入写出来实现用户登陆注册功能就实现了~