簡單連接資料庫（swing）

• 組態檔

  driver=com.mysql.jdbc.Driver
  username=root
  passwd=root
  url=jdbc:mysql://localhost:3306/data_employee
  

• 工具類（用戶獲取資料庫連接、釋放資源）

  package shixun.zuizhong;
  
  import java.io.FileReader;
  import java.io.IOException;
  import java.net.URL;
  import java.sql.*;
  import java.util.Properties;
  
  public class Mysql_driver_utils {
  
      static String url,username,passwd;
  
  
      static {
  
          try {
              ClassLoader classLoader = Mysql_driver_utils.class.getClassLoader();
              URL resource = classLoader.getResource("mysql_driver.properties");
              String path = resource.getPath();
  
              Properties properties = new Properties();
              properties.load(new FileReader(path));
  
              url = properties.getProperty("url");
              username = properties.getProperty("username");
              passwd = properties.getProperty("passwd");
  
              String driver = properties.getProperty("driver");
              Class.forName(driver);
          } catch (IOException e) {
              e.printStackTrace();
          } catch (ClassNotFoundException e) {
              e.printStackTrace();
          }
      }
  
  
      public static  Connection getconnetion() throws SQLException {
  
          return DriverManager.getConnection(url,username,passwd);
      }
  
      public static void close(Connection connection, Statement statement, ResultSet resultSet){
  
          if(resultSet!=null){
              try {
                  resultSet.close();
              } catch (SQLException throwables) {
                  throwables.printStackTrace();
              }
          }
  
          if(statement!=null){
              try {
                  resultSet.close();
              } catch (SQLException throwables) {
                  throwables.printStackTrace();
              }
          }
  
          if(connection!=null){
              try {
                  resultSet.close();
              } catch (SQLException throwables) {
                  throwables.printStackTrace();
              }
          }
  
      }
      public static void close(Connection connection, Statement statement){
  
  
          if(statement!=null){
              try {
                  statement.close();
              } catch (SQLException throwables) {
                  throwables.printStackTrace();
              }
          }
  
          if(connection!=null){
              try {
                  connection.close();
              } catch (SQLException throwables) {
                  throwables.printStackTrace();
              }
          }
  
      }
      public static void close(Statement statement){
          if (statement!=null){
              try {
                  statement.close();
              } catch (SQLException throwables) {
                  throwables.printStackTrace();
              }
          }
      }
  
  }
  
  

• 界面和事件

  package shixun.zuizhong;
  
  import javax.swing.*;
  import java.awt.event.ActionEvent;
  import java.awt.event.ActionListener;
  import java.sql.Connection;
  import java.sql.PreparedStatement;
  import java.sql.ResultSet;
  import java.sql.SQLException;
  
  public class Register_employee {
      public static void main(String[] args) {
  
          JFrame jFrame = new JFrame("員工資訊注冊");
          jFrame.setSize(250,400);
          jFrame.setVisible(true);
          jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  
  
          JLabel username = new JLabel("用戶名:");
          JTextField user_n = new JTextField(20);
  
          JLabel passwd = new JLabel("密碼:");
          JTextField passwd_p = new JTextField(20);
  
          JButton register_btn = new JButton("注冊");
  
  
          JPanel jPanel = new JPanel();
  
          jPanel.add(username);
          jPanel.add(user_n);
          jPanel.add(passwd);
          jPanel.add(passwd_p);
  
          jPanel.add(register_btn);
  
          jFrame.add(jPanel);
  
          ActionListener actionListener_re = new ActionListener() {
              @Override
              public void actionPerformed(ActionEvent e) {
                  String user_text = user_n.getText();
                  String passwd_text = passwd_p.getText();
  
                  Connection connection = null;
                  PreparedStatement preparedStatement = null;
                  PreparedStatement preparedStatement2 = null;
                  ResultSet resultSet = null;
                  try {
                      connection = Mysql_driver_utils.getconnetion();  //獲取資料庫連接物件
                      connection.setAutoCommit(false);  //開啟事務 手動提交
                      String sql_str = "select * from table_employee where username=?";
  
                      preparedStatement = connection.prepareStatement(sql_str);
                      preparedStatement.setString(1,user_text);
                      //preparedStatement.setString(2,passwd_text);
                      resultSet = preparedStatement.executeQuery();
  
                      if(resultSet.next()){
                          user_n.setText("賬戶已存在");
                      }else {  //沒有記錄，注冊成功 賬號密碼寫入資料庫
                          String sqlinster_str = "insert into table_employee(username,passwd) values (?,?)";
                          preparedStatement2 = connection.prepareStatement(sqlinster_str);
                          preparedStatement2.setString(1,user_text);
                          preparedStatement2.setString(2,passwd_text);
                          int i = preparedStatement2.executeUpdate();
                          if(i>0){
                              user_n.setText("注冊成功！");
                          }else {
                              user_n.setText("注冊失敗!");
                          }
                      }
                      connection.commit();  //提交事務
                  } catch (SQLException throwables) {
                      throwables.printStackTrace();
                      try {
                          connection.rollback();  //事務回滾
                      } catch (SQLException sqlException) {
                          sqlException.printStackTrace();
                      }
                  }finally {//釋放資源
                      Mysql_driver_utils.close(connection,preparedStatement,resultSet);
                      Mysql_driver_utils.close(preparedStatement2);
                  }
              }
          };
  
          register_btn.addActionListener(actionListener_re);
      }
  }