如何将值写入文本文件并将值存储为 inputStream

Question

我需要你的帮助将值写入文本文件并将写入的数据转换为 inputStream 以便将其附加到按钮。对于硬编码的字符串，我能够做到这一点，请参考以下方法：

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();
    }

}

现在，我需要从数据库中读取数据，所以我做了以下操作：

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();
    }

}

所以现在我需要你的帮助来写从数据库中获取的值，用“|”分隔和读取每条记录后的新行并将完整转换为 inputStream.

Answer 1

答案如下：

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();
}

}

如何将值写入文本文件并将值存储为 inputStream

How to write values to text file and to store the values as inputStream

java

file-io

text

inputstream

file