美好的一天。我有以下代码，我正在努力工作。我必须阅读文本文件的内容，其中包含问题并将其保存到数据库测试系统。
我面临的主要问题是它没有插入数据库中。而且我不确定它是否正在阅读文本文件。
任何帮助都会受到赞赏
JFrame和主要
public class StudentTestSystems {
public static void main(String[] args) {
try {
Lecturer panel = new Lecturer();
panel.setVisible(true);
panel.setLocationRelativeTo(null);
panel.setResizable(false);
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
讲师班
public class Lecturer extends JFrame implements ActionListener {
Font font = null;
private JTextField fileField;
private JButton uploadBtn;
private JLabel message;
private JPanel panel;
public Lecturer() {
super("LECTURE MENU");
this.setSize(500, 270);
this.setResizable(false);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
font = new Font("Times New Roman", Font.BOLD, 14);
panel = new JPanel();
panel.setLayout(null);
panel.setOpaque(true);
fileField = new JTextField();
fileField.setFont(font);
fileField.setBounds(130, 110, 200, 25);
Font font2 = new Font("Times New Roman", Font.BOLD + Font.ITALIC, 12);
message = new JLabel("Type in the file name with it's extension. eg: File.txt");
message.setFont(font2);
message.setBounds(130, 140, 280, 25);
message.setOpaque(true);
uploadBtn = new JButton("UPLOAD");
uploadBtn.setFont(font);
uploadBtn.setBounds(340, 110, 95, 21);
panel.add(fileField);
panel.add(uploadBtn);
panel.add(message);
add(panel);
/////// register event
uploadBtn.addActionListener(this);
exit.addActionListener(this);
}
public void actionPerformed(ActionEvent ev) {
String file = fileField.getText();
SetGetQuestionFileName setGet = new SetGetQuestionFileName(file);
FileInputStream fis = null;
PreparedStatement preparedStmt = null;
try {
String myUrl = "jdbc:mysql://localhost:3306/testsystem";
Connection conn = DriverManager.getConnection(myUrl, "root", "cput");
if (ev.getActionCommand().equals("UPLOAD")) {
File filePathString = new File(file);
fis = new FileInputStream(filePathString);
if (fileField.getText().length() == 0) {
JOptionPane.showMessageDialog(null, "File field can't be empty. Try again", "ERROR", JOptionPane.INFORMATION_MESSAGE);
} else {
if (filePathString.exists() && filePathString.isFile()) {
try {
// the mysql insert statement
String query = " insert into users (category_questions, questions, quest_opt_a, , quest_opt_b, , quest_opt_c, quest_opt_d, correct_option_answer )"
+ " values (?, ?, ?, ?, ?)";
// create the mysql insert preparedstatement
preparedStmt = conn.prepareStatement(query);
preparedStmt.setString(1, "JDBC");
preparedStmt.setString(2, fileField.getText());
preparedStmt.setAsciiStream(3, fis, (int) filePathString.length());
//preparedStmt.setString (3, "a");
preparedStmt.setString(4, "b");
preparedStmt.setString(5, "c");
preparedStmt.setString(6, "d");
preparedStmt.setString(7, "a");
preparedStmt.executeUpdate();
// execute the preparedstatement
preparedStmt.executeUpdate();
// myfile.closing();
conn.close();
JOptionPane.showMessageDialog(null, "File successfuly uploaded", "INFORMATION", JOptionPane.INFORMATION_MESSAGE);
fileField.setText("");
} catch (Exception ex) {
} finally {
preparedStmt.close();
fis.close();
conn.close();
}
} else {
JOptionPane.showMessageDialog(null, "File coudn't be found. Do check file name.", "ERROR", JOptionPane.INFORMATION_MESSAGE);
}
}
}
} catch (Exception ex) {
}
if (ev.getActionCommand().equals("LOGOUT")) {
System.exit(0);
}
}
}
SetQuestionFileName class
public class SetGetQuestionFileName {
String myfile;
public SetGetQuestionFileName(String file) {
setFileName(file);
}
public void setFileName(String file) {
myfile = file;
}
public String getFileName() {
return myfile;
}
}
答案 0 :(得分：1)
这是一个关于如何读取文件的简短版本（逐行）：
Scanner scanner = new Scanner(filename);
while (scanner.hasNextLine()) {
String line = scanner.nextLine();
}
这是您的查询。那里有太多,或空列名称以及列数和？不匹配：
String query = " insert into users (
category_questions,
questions,
quest_opt_a,
, // empty column name
quest_opt_b,
, // empty column name
quest_opt_c,
quest_opt_d,
correct_option_answer
)" + " values (?, ?, ?, ?, ?)"; // you have 7 columns (without the empty ones) but only 5 ?
这是您的查询的重新格式化版本。我刚删除了,并添加了2 ?
String query = "INSERT INTO users (
category_questions,
questions,
quest_opt_a,
quest_opt_b,
quest_opt_c,
quest_opt_d,
correct_option_answer
) VALUES (?, ?, ?, ?, ?, ?, ?)";
现在我正在尝试了解您要添加的值：
preparedStmt.setString(1, "JDBC"); // so JDBC is your category ?
preparedStmt.setString(2, fileField.getText()); // I guess this should be the question?
preparedStmt.setString(3, "a"); // according to the column names this needs to be option A
preparedStmt.setString(4, "b"); // option b
preparedStmt.setString(5, "c"); // option c
preparedStmt.setString(6, "d"); // option d
preparedStmt.setString(7, "a"); // answer
到目前为止一切顺利。如果我正确解释列名称，这应该工作。现在唯一剩下的就是获取第2列的真正问题文本（来自文件）。
我不知道你的文件是怎么样的，所以我可以给你一个例子：
textfile in this format: question? answerA, answerB, answerC, answerD, correctAnswer
-------------------------------------------------------------------------------------
What is the color of the sun? pink, blue, yellow, green, c
What is the smallest number? 3, 1, 7, 200, b
这就是你可以一次读取文件并填充数据库的方法：
// prepare the query
String query = "INSERT INTO users (
category_questions,
questions,
quest_opt_a,
quest_opt_b,
quest_opt_c,
quest_opt_d,
correct_option_answer
) VALUES (?, ?, ?, ?, ?, ?, ?)";
// load the file
Scanner scanner = new Scanner(filename);
// read the file line by line
while (scanner.hasNextLine()) {
String line = scanner.nextLine();
String[] questionAnswer = line.split("?")[ // line.split["?"] will split the line into two strings, right at the ? and put those two strings into an array.
String question = questionAnswer[0] // so [0] will access the first element in that array - the question
String[] answers = questionAnswer[1].split(","); // now we split the string after the ? into many strings divided by comma
preparedStmt.setString(1, "JDBC");
preparedStmt.setString(2, question);
preparedStmt.setString(3, answers[0]);
preparedStmt.setString(4, answers[1]);
preparedStmt.setString(5, answers[2]);
preparedStmt.setString(6, answers[3]);
preparedStmt.setString(7, answers[4]);
preparedStmt.executeUpdate();
}
有很多方法可以从文本文件中读取该行并将其拆分为问题和答案。这取决于您从中读取的文件及其格式。
FIY：你最后两次执行preparedStmt.executeUpdate();：）