從 JDBC 數據庫檢索數據到 Jtable

Question

嗨，我已經成功地將我的 jTable 鏈接到了 JDBC 數據庫。 但是，我無法檢索它們。 我希望在重新啟動程序時顯示保存的數據，但它不起作用。

alarm.setText("");  
    DefaultTableModel model =(DefaultTableModel) hwList.getModel();
    if(!className.getText().trim().equals(""))
    {
        model.addRow(new Object[]{className.getText(), homeWork.getText(), dueDate.getText()});
    }
    else
    {
        alarm.setText("Class Name should not be blank.");
    }

        Connection conn;
        Statement st;

        try
    {
        String myDriver = "com.mysql.jdbc.Driver";
        String myUrl = "jdbc:mysql://localhost:3306/mysql";
        Class.forName("com.mysql.jdbc.Driver");
        System.out.println("Connecting to database");
        conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mysql", "root", "");
        System.out.println("Connected to databse");


        String a = className.getText();
        String b = homeWork.getText();
        String c = dueDate.getText();            

        System.out.println("Inserting into the table");
        st = conn.createStatement();
        String stmt="INSERT INTO hwList (className, homeWork, dueDate)"+ "VALUES ("+"\'"+a+"\',"+"\'"+b+"\',"+"\'"+c+"\')";
        System.out.println(stmt);
        st.executeUpdate(stmt);

        System.out.println("Saved!");

    }
    catch (Exception e)
    {
        System.err.println("Got an exception!");
        System.err.println(e.getMessage());
    }    

這是我保存文檔的代碼！

有什么辦法可以檢索JDBC數據庫中的數據並通過Jtable顯示嗎？ 我很抱歉問這么簡單的問題，但我是 Java 新手，我迫切需要幫助！

非常感謝！

用於加載數據的代碼...

順便說一句，我的 jtable 是一個 3 列表，分別包含三列——className、homeWork、dueDate。 謝謝！

String sql="SELECT * FROM hwList";
ResultSet rs = st.executeQuery(sql);
while(rs.next())
{
    String d = rs.getString("className");
    String e = rs.getString("homeWork");
    String f = rs.getString("dueDate");
}

Answer 1

首先創建一個新的TableModel ...

DefaultTableModel model = new DefaultTableModel(new String[]{"Class Name", "Home work", "Due Date"}, 0);

從數據庫加載數據...

String sql="SELECT * FROM hwList";
ResultSet rs = st.executeQuery(sql);

將每一行數據添加到表模型中...

while(rs.next())
{
    String d = rs.getString("className");
    String e = rs.getString("homeWork");
    String f = rs.getString("dueDate");
    model.addRow(new Object[]{d, e, f});
}

將模型應用於您的JTable ...

table.setModel(model);

您可能還想查看try-with-resources 聲明並確保您正確管理您的資源

Answer 2

第1步

import javax.swing.*;
import java.awt.*;
import javax.swing.table.DefaultTableModel;
import java.sql.*;
public class UserList extends JFrame {
    DefaultTableModel model = new DefaultTableModel();
    Container cnt = this.getContentPane();
    JTable jtbl = new JTable(model);
    public UserList() {
        cnt.setLayout(new FlowLayout(FlowLayout.LEFT));
        model.addColumn("Id");
        model.addColumn("Username");
        model.addColumn("Password");
        model.addColumn("Create");
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection con = DriverManager.getConnection("jdbc:mysql://localhost/java_db", "root", "");
            PreparedStatement pstm = con.prepareStatement("SELECT * FROM users");
            ResultSet Rs = pstm.executeQuery();
            while(Rs.next()){
                model.addRow(new Object[]{Rs.getInt(1), Rs.getString(2),Rs.getString(3),Rs.getString(4)});
            }
        } catch (Exception e) {
            System.out.println(e.getMessage());
        }
        JScrollPane pg = new JScrollPane(jtbl);
        cnt.add(pg);
        this.pack();
    }
}

第2步

import javax.swing.JFrame;
public class Main {
    public static void main(String[] args) {
        JFrame frame = new UserList();
        frame.setTitle("Swing Example");
        frame.setSize(500, 300);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}

演示

Answer 3

String myDriver = "com.mysql.jdbc.Driver";
String myUrl = "jdbc:mysql://localhost:3306/mysql";
Class.forName("com.mysql.jdbc.Driver");
System.out.println("Connecting to database");
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mysql", "root", "");
System.out.println("Connected to databse");
Statement st;
Vector data = new Vector();
try {
    st = connection.createStatement();
    ResultSet res = st.executeQuery("SELECT col_name FROM table_name");
    ResultSetMetaData metaData = res.getMetaData();
    int columns = metaData.getColumnCount();
    while (res.next()) {
       Vector row = new Vector(columns);
       for (int i = 1; i <= columns; i++) {
        row.addElement(res.getObject(i));
       }
       data.addElement(row);
    }
} catch (SQLException e) {
    e.printStackTrace();
}
Vector columnNames = new Vector();
columnNames.addElement("col_1");
columnNames.addElement("col_name_n");
table = new JTable(data,columnNames);

您可以使用類似上面的代碼從數據庫中檢索數據並將其存儲在 jtable 中。

Answer 4

嗨，

1. 將您的ResultSet更改為ArrayList
2. 為使用來自ArrayList數據的JTalbe創建模型

那應該工作。

Answer 5

首先創建表模型，然后使用該fetch_data()函數。 確保您的數據庫連接正常工作。 在主構造函數中調用該函數。 就是這樣。

DefaultTableModel dm;

dm=(DefaultTableModel) jTable1.getModel();

public void fetch_data(){

    try{
        String sql= "select * from tbl_name";
        ResultSet rs=st.executeQuery(sql);
        YourjTableName.setModel(DbUtils.resultSetToTableModel(rs));
    }catch(Exception e){
        System.out.println(e);
    }
}

Answer 6

問題陳述：從數據庫中檢索數據並在java中顯示在JTable上。

CODE：（用於檢索）*根據您的需要更改代碼

String tquery = "SELECT * FROM Member";
        DbConnection obj = new DbConnection();
        ResultSet r = obj.Retrive(tquery);
        while (r.next()) {
            int i = r.getInt(1);
            String d = r.getString(2);
            String e = r.getString(3);
            String f = r.getString(4);
            String h = r.getString(5);
            String w = r.getString(6);
            DefaultTableModel model = (DefaultTableModel) (Member_table.getModel());
            model.addRow(new Object[]{i, d, e, f, h, w});
        }

代碼（簡化）：

        String tquery = "SELECT * FROM Member";
        ResultSet rs = st.executeQuery(sql);
        while (r.next()) {
            int i = r.getInt(1);
            String d = r.getString(2);
            DefaultTableModel model = (DefaultTableModel) (Member_table.getModel());
            model.addRow(new Object[]{i, d);//add row to JTable
        }

如果這個DefaultTableModel model = new DefaultTableModel(); 不工作使用DefaultTableModel model = (DefaultTableModel) (Member_table.getModel());

希望對你有幫助！