如何将值写入文本文件并将值存储为 inputStream

Question

I need your help in writing the values to a text file and to convert the written data to inputStream in order to attach it to a button. I was able to do that for a String whihc is hard-coded, refer to the below method:

private StreamedContent txtFile;
        public void createTxt(ActionEvent actionEvent) {

    try {
        String string = "This is a String.\nWe are going to convert it to InputStream.\n";
        InputStream inputStream = new ByteArrayInputStream(string.getBytes(Charset.forName("UTF-8")));
        txtFile = new DefaultStreamedContent(inputStream, "application/txt", "sample.txt");
    } catch (Exception e) {
        e.printStackTrace();
    }

}

Now, i need to read the data from the database, so I have done the following:

private StreamedContent txtFile;
        public void createTxt(ActionEvent actionEvent) {

    try {
        Class.forName("com.mysql.jdbc.Driver");
        conn = DriverManager.getConnection(DB_URL, USER, PASS);
        stmt = conn.createStatement();

        String sql = "SELECT id, name, amount FROM Employee";
        ResultSet rs = stmt.executeQuery(sql);

            while(rs.next()){
                int id  = rs.getInt("id");
                int age = rs.getString("name");
                String first = rs.getInt("amount");
               } 
            rs.close();
        InputStream inputStream = new ByteArrayInputStream(string.getBytes(Charset.forName("UTF-8")));
        txtFile = new DefaultStreamedContent(inputStream, "application/txt", "sample.txt");
    } catch (Exception e) {
        e.printStackTrace();
    }

}

So now I need your help to write the fetched values from the database separated by "|"and a new line after reading each record and to convert the full to inputStream .

Answer 1

Here is the answer:

private StreamedContent txtFile;
        public void createTxt(ActionEvent actionEvent) {

try {
    Class.forName("com.mysql.jdbc.Driver");
    StringBuilder builder = new StringBuilder();
    conn = DriverManager.getConnection(DB_URL, USER, PASS);
    stmt = conn.createStatement();

    String sql = "SELECT id, name, amount FROM Employee";
    ResultSet rs = stmt.executeQuery(sql);

        while(rs.next()){
            int id  = rs.getInt("id");
            int age = rs.getString("name");
            String first = rs.getInt("amount");
            builder.append(id+"|"+age+"|"+first+"\n");
           } 
        rs.close();
        String result = builder.toString();
    InputStream inputStream = new ByteArrayInputStream(result.getBytes(Charset.forName("UTF-8")));
    txtFile = new DefaultStreamedContent(inputStream, "application/txt", "sample.txt");
} catch (Exception e) {
    e.printStackTrace();
}

}