JComboBox动态绑定数据库

package comboxsql; import java.sql.Connection; import javax.swing.JOptionPane; import java.sql.DriverManager; import java.sql.SQLException; import java.sql.ResultSet; import java.sql.Statement; public class dbsql { Connection con = null; String user = "sa"; String pwd = ""; String url = "jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=zcmt"; public boolean connect() { try { Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver"); con = DriverManager.getConnection(url, user, pwd); } catch (ClassNotFoundException ex) { JOptionPane.showMessageDialog(null, ex.toString()); } catch (SQLException ex) { JOptionPane.showMessageDialog(null, ex.toString()); } return true; } public ResultSet query(String sql) { ResultSet rs = null; Statement st; if (con == null) { connect(); } try { st = con.createStatement(); rs = st.executeQuery(sql); return rs; } catch (SQLException ex) { JOptionPane.showMessageDialog(null, ex.toString()); return null; } } public boolean update(String sql) { Statement st; int mcount; if (con == null) { connect(); } try { st = con.createStatement(); mcount = st.executeUpdate(sql); if (mcount < 1) { return false; } } catch (SQLException ex) { JOptionPane.showMessageDialog(null, ex.toString()); } return true; } public boolean close() { try { con.close(); } catch (SQLException ex) { JOptionPane.showMessageDialog(null, ex.toString()); } con = null; return false; } }