java检查文本文件中的输入字符串

Question

我正在使用jsp，想检查输入是否存在于整个文本文件的第一列中

假设我有用户。文本并包含

测试，名字，姓氏
Test02，用户，用户08

如果用户输入“Test”，它将打印存在。否则，它会将输入添加到文件中

这是我的代码：

    <% 
    String user= request.getParameter("user");
    String firstname = request.getParameter("firstname");
    String lastname= request.getParameter("lastname");

    File file = new File("/user.txt");
    BufferedReader read = new BufferedReader(new FileReader(path));
    PrintWriter out = new PrintWriter(new FileWriter(file, true));

    String line = read.readLine();

    if(line.contains(user)) {
        %>
        <H3>User Already exist...</H3>
        <%
    }
    else{
    outt.println(User + "," + firstname + "," + lastname + "\n");        
    outt.close();
    br.close();
    %> 
      <p> Done...</p>
     <%
   }
   %>

问题是它只检查第一行

Answer 1

您需要添加一个循环：

<% 
String user= request.getParameter("user");
String firstname = request.getParameter("firstname");
String lastname= request.getParameter("lastname");

File file = new File("/user.txt");
BufferedReader read = new BufferedReader(new FileReader(path));
PrintWriter out = new PrintWriter(new FileWriter(file, true));

String line = null;
while((line = read.readLine()) != null) {
    if(line.contains(user)) {
        %>
        <H3>User Already exist...</H3>
        <%
        break;
    }
}
if(line == null)
    outt.println(User + "," + firstname + "," + lastname + "\n");        
outt.close();
br.close();
%> 
  <p> Done...</p>

此外，验证（line.contains(user)）看起来太容易出错