JAVA中JDBC鏈接sql server之登錄界面，做了一個圖形的登錄界面，通過調(diào)用數(shù)據(jù)庫的unpw表檢查用戶是否可以登錄。下圖是數(shù)據(jù)庫中unpw表相關(guān)屬性然后運行，等一次成功了，再運行就是很多很多的警告。不知道哪里出錯了，大神們，可以幫我看看么？源代碼如下：package?student1; import?java.awt.BorderLayout; import?java.awt.Font; import?java.awt.GridLayout; import?java.awt.event.ActionEvent; import?java.awt.event.ActionListener; import?java.awt.event.ItemEvent; import?java.awt.event.ItemListener; import?java.sql.Connection; import?java.sql.DriverManager; import?java.sql.ResultSet; import?java.sql.SQLException; import?java.sql.Statement; import?javax.swing.JButton; import?javax.swing.JComboBox; import?javax.swing.JFrame; import?javax.swing.JLabel; import?javax.swing.JOptionPane; import?javax.swing.JPanel; import?javax.swing.JPasswordField; import?javax.swing.JTextField; import?javax.swing.SwingConstants; //登錄界面 public?class?Entry?extends?JFrame?implements?ActionListener{ int?width?=?400;?//?窗體的寬度 int?height?=?220;//?高度 Connection?con?=?null;//?conn獲取鏈接 Statement?stmt?=?null;//?通過鏈接創(chuàng)建Statement對象stmt,在通過stmt對象執(zhí)行sql語句 ResultSet?rs?=?null;//?定義rs接收executeQuery()方法返回的ResultSet對象,查詢的數(shù)據(jù)就存放在rs對象中 int?qxian?=?0;//?獲取序號 //?最大的面板 JPanel?pan?=?new?JPanel(); //?系統(tǒng)登錄標(biāo)題面板 JPanel?title_pan?=?new?JPanel(); JLabel?title_lab?=?new?JLabel("學(xué)生信息管理系統(tǒng)登錄",?SwingConstants.CENTER); //?放按鈕的面板 JPanel?button_pan?=?new?JPanel(); JButton?btnLogin?=?new?JButton("登錄"); JButton?cancel_btn?=?new?JButton("取消"); //?放置用戶名和密碼，角色的面板 JPanel?content_pan?=?new?JPanel(); JPanel?username_pan?=?new?JPanel(); JPanel?password_pan?=?new?JPanel(); JPanel?role_pan?=?new?JPanel(); JLabel?username_lab?=?new?JLabel("用戶名：",?SwingConstants.RIGHT); JLabel?passowrd_lab?=?new?JLabel("密碼：?",?SwingConstants.RIGHT); JLabel?role?=?new?JLabel("角色：?",?SwingConstants.RIGHT); JComboBox?cbrole?=?new?JComboBox();//?制作下拉列表 JTextField?username?=?new?JTextField();//?接收用戶名的文本框 JPasswordField?password?=?new?JPasswordField();//?接收密碼的密碼框 public?Entry()?{ super("登陸"); init(); this.setVisible(true); this.setDefaultCloseOperation(EXIT_ON_CLOSE); } public?void?init()?{ pan.setLayout(new?BorderLayout()); title_lab.setFont(new?Font("黑體",?Font.BOLD,?20)); btnLogin.addActionListener(this);//?為登錄，取消注冊事件監(jiān)聽器 cancel_btn.addActionListener(this); //?采用三行一列的表格布局 content_pan.setLayout(new?GridLayout(3,?1)); cbrole.addItem("管理員"); cbrole.addItem("學(xué)生");//?下拉列表添加，學(xué)生，管理員角色 username.setColumns(6); password.setColumns(6); role_pan.add(role); role_pan.add(cbrole); username_pan.add(username_lab); username_pan.add(username); password_pan.add(passowrd_lab); password_pan.add(password); content_pan.add(username_pan); content_pan.add(password_pan); content_pan.add(role_pan); button_pan.add(btnLogin); button_pan.add(cancel_btn); title_pan.add(title_lab); pan.add(title_pan,?BorderLayout.NORTH); pan.add(button_pan,?BorderLayout.SOUTH); pan.add(content_pan,?BorderLayout.CENTER); this.add(pan); this.setSize(width,?height); int?screen_width?=?(int)?this.getToolkit().getScreenSize().getWidth();?//?得到屏幕的寬度 int?screen_height?=?(int)?this.getToolkit().getScreenSize().getHeight();?//?得到屏幕的高度 this.setLocation((screen_width?-?width)?/?2,?(screen_height?-?height)?/?2); this.setResizable(false); this.setVisible(true); } public?void?connDB()?{?//?連接數(shù)據(jù)庫 try?{ Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver"); }?catch?(ClassNotFoundException?e)?{ e.printStackTrace(); } try?{ con?=?DriverManager.getConnection("jdbc:sqlserver://localhost:1434;DatabaseName=DBstudent",?"sa", "1234567890"); stmt?=?con.createStatement(); }?catch?(SQLException?e)?{ e.printStackTrace(); } } public?void?closeDB()?//?關(guān)閉連接 { try?{ stmt.close(); con.close(); }?catch?(SQLException?e)?{ e.printStackTrace(); } } @Override public?void?actionPerformed(ActionEvent?e)?{ //?TODO?Auto-generated?method?stub Object?source?=?e.getSource(); String?un?=?null; String?pw?=?null; int?qx?=?0; boolean?success?=?false;//?用于判斷是否登錄成功 if?(source?==?btnLogin)?{ if?(username.getText().equals("")?||?password.getText().equals(""))?{//?判斷是否輸入了用戶名和密碼 JOptionPane.showMessageDialog(null,?"登錄名和密碼不能為空！"); }?else?{ this.connDB(); try?{ rs?=?stmt.executeQuery("select?*?from?unpw"); while?(rs.next())?{ un?=?rs.getString("un").trim(); pw?=?rs.getString("pw").trim(); qx?=?rs.getInt("qx"); if?(username.getText().equals(un))?{ if?(password.getText().equals(pw))?{ //?actionCode?=?OK; this.setVisible(false);?//?隱藏登錄窗體 qxian?=?cbrole.getSelectedIndex(); if?(qxian?==?0)?{ JOptionPane.showConfirmDialog(null,?"您點擊了管理員界面",?"提示信息",?JOptionPane.DEFAULT_OPTION, JOptionPane.OK_OPTION); } if?(qxian?==?1)?{ JOptionPane.showConfirmDialog(null,?"進入學(xué)生界面",?"提示信息",?JOptionPane.DEFAULT_OPTION, JOptionPane.OK_OPTION); } success?=?true; break; }?else?{ JOptionPane.showMessageDialog(null,?"密碼錯誤！"); password.setText(""); success?=?true; } } } if?(!success)?{ JOptionPane.showMessageDialog(null,?"登錄名錯誤！"); username.setText(""); password.setText(""); } }?catch?(SQLException?e1)?{ e1.printStackTrace(); } } /* ?*?重置那些框?}?else?if?(source?==?btncz)?{?txtUser.setText(""); ?*?txtPwd.setText(""); ?*/ }?else?if?(source?==?cancel_btn)?{ System.exit(0); } } }