而不是两次搜索文件我相信它更好地保存第一个用户名和下一行密码。读取它们时,您可以创建具有以下属性的用户对象(用户名和密码(字符串))。您也可以在系统处于活动状态时将其保存在链接列表中。以便您可以轻松访问用户帐户。一旦用户需要登录,您将扫描该列表并使用userList.get(i).equals(textfield.getText())来确定用户提问。之后,如果上述语句成立,您将检查userList.get(i).getPassword()。equals(textfield2.getText())是否为true,并相应地授予或拒绝访问。
我在下面提供了一些有用的部分。
public void readFromFile(String fileName, ListInterface<User> userList) {
String oneLine, oneLine2;
User user;
try {
/*
* Create a FileWriter object that handles the low-level details of
* reading
*/
FileReader theFile = new FileReader(fileName);
/*
* Create a BufferedReader object to wrap around the FileWriter
* object
*/
/* This allows the use of high-level methods like readline */
BufferedReader fileIn = new BufferedReader(theFile);
/* Read the first line of the file */
oneLine = fileIn.readLine();
/*
* Read the rest of the lines of the file and output them on the
* screen
*/
while (oneLine != null) /* A null string indicates the end of file */
{
oneLine2 = fileIn.readLine();
user = new User(oneLine, oneLine2);
oneLine = fileIn.readLine();
userList.append(user);
}
/* Close the file so that it is no longer accessible to the program */
fileIn.close();
}
/*
* Handle the exception thrown by the FileReader constructor if file is
* not found
*/
catch (FileNotFoundException e) {
System.out.println("Unable to locate the file: " + fileName);
}
/* Handle the exception thrown by the FileReader methods */
catch (IOException e) {
System.out.println("There was a problem reading the file: "
+ fileName);
}
} /* End of method readFromFile */
public void writeToFile(String fileName, ListInterface<User> userList) {
try {
/*
* Create a FileWriter object that handles the low-level details of
* writing
*/
FileWriter theFile = new FileWriter(fileName);
/* Create a PrintWriter object to wrap around the FileWriter object */
/* This allows the use of high-level methods like println */
PrintWriter fileOut = new PrintWriter(theFile);
/* Print some lines to the file using the println method */
for (int i = 1; i <= userList.size(); i++) {
fileOut.println(userList.get(i).getUsername());
fileOut.println(userList.get(i).getPassword());
}
/* Close the file so that it is no longer accessible to the program */
fileOut.close();
}
/* Handle the exception thrown by the FileWriter methods */
catch (IOException e) {
System.out.println("Problem writing to the file");
}
} /* End of method writeToFile */
你的问题是什么? –
如果我的密码是“usrnm:”,该怎么办? – Catchwa