public class Login extends JFrame implements ActionListener{
//定义组件
JPanel jp1,jp2,jp3,jp4;//面板
JLabel jlb1,jlb2,jlb3;//标签
JButton jb1,jb2,jb3;//按钮
JTextField jtf;//文本
JPasswordField jpf;//密码
JRadioButton jrb1,jrb2=null;//
ButtonGroup bg=null;
//设定用户名和密码
static String userword;
static String password;
Connection ct=null;
Statement st=null;
ResultSet rs=null;
//构造函数
public Login(){
//创建面板
jp1=new JPanel();
jp2=new JPanel();
jp3=new JPanel();
jp4=new JPanel();
//创建标签
jlb1=new JLabel("用户名");
jlb2=new JLabel("密 码");
jlb3=new JLabel("权 限：");
//创建按钮
jb1=new JButton("登录");
jb2=new JButton("重置");
jb3=new JButton("退出");
jb1.addActionListener(this);
jb2.addActionListener(this);
jb3.addActionListener(this);
jrb1=new JRadioButton("教师");
jrb2=new JRadioButton("学生");
bg=new ButtonGroup();
bg.add(jrb1);
bg.add(jrb2);
jrb2.setSelected(true);
//创建文本框
jtf=new JTextField(10);
//创建密码框
jpf=new JPasswordField(10);
//设置布局管理
this.setLayout(new GridLayout(4, 1));//网格式布局
//加入各个组件
jp1.add(jlb1);
jp1.add(jtf);
jp2.add(jlb2);
jp2.add(jpf);
jp3.add(jlb3);
jp3.add(jrb1);
jp3.add(jrb2);
jp4.add(jb1);
jp4.add(jb2);
jp4.add(jb3);
//加入到JFrame
this.add(jp1);
this.add(jp2);
this.add(jp3);
this.add(jp4);
//给窗口设置标题
this.setTitle("学生成绩管理系统");
//设置窗体大小
this.setSize(300,200);
//设置窗体初始位置
this.setLocation(200, 150);
//设置当关闭窗口时，保证JVM也退出
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//显示窗体
this.setVisible(true);
this.setResizable(true);
//建立数据库
try {
Class.forName("org.gjt.mm.mysql.Driver");
ct=DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/studentmanager","root","123456");
} catch (Exception e) {
// TODO: handle exception
System.out.println(e);
}
}
public static void main(String[] args) {
new Login();
}
@Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
if(e.getActionCommand()=="登录"){
//如果选中教师登录
if(jrb1.isSelected())
{
//创建火箭车
try {
st=ct.createStatement();
上面那句有错createStatement红线
Type mismatch: cannot convert from java.sql.Statement to java.beans.Statement
rs=s.executeQuery("select * from info where quanxian = '老师'");
有错s.executeQuery 红线
The method executeQuery(String) is undefined for the type Statement
//循环取出
while(rs.next()){
userword=rs.getString(2);
password=rs.getString(3);
System.out.println("教师"+"\t"+userword+"\t"+password);
}
} catch (SQLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
System.out.println(e);
}
//从数据库得到用户名和密码后调用登录方法，与输入的用户名和密码作比较
tealogin();
}else if(jrb2.isSelected()) //学生在登录系统
{//http://blog.csdn.net/qq_25827845/article/details/50836362
//创建火箭车
try {
st=ct.createStatement();
这里和上面一样
rs= st.executeQuery("select * from info where qunxian = '学生'");
//循环取出
while(rs.next()){
userword=rs.getString(2);
password=rs.getString(3);
System.out.println("学生"+"\t"+userword+"\t"+password);
}
} catch (SQLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
System.out.println(e);
}
//从数据库得到用户名和密码后调用登录方法，与输入的用户名和密码作比较
stulogin();
}
}
if(e.getActionCommand()=="重置"){
clear();
}
if(e.getActionCommand()=="退出")
{
System.exit(0);
}
}
//清空文本框和密码框
private void clear() {
// TODO Auto-generated method stub
jtf.setText("");
jpf.setText("");
}
//学生登录判断方法
private void stulogin() {
// TODO Auto-generated method stub
if(userword.equals(jtf.getText())&&password.equals(jpf.getText()))
{
// System.out.println("登录成功");
JOptionPane.showMessageDialog(null,"登录成功！","提示消息",JOptionPane.WARNING_MESSAGE);
clear();
//关闭当前界面
dispose();
//创建一个新界面
UI ui=new UI();
}else if(jtf.getText().isEmpty()&&jpf.getText().isEmpty())
{
JOptionPane.showMessageDialog(null,"请输入用户名和密码！","提示消息",JOptionPane.WARNING_MESSAGE);
}else if(jtf.getText().isEmpty())
{
JOptionPane.showMessageDialog(null,"请输入用户名！","提示消息",JOptionPane.WARNING_MESSAGE);
}else if(jpf.getText().isEmpty())
{
JOptionPane.showMessageDialog(null,"请输入密码！","提示消息",JOptionPane.WARNING_MESSAGE);
}else
{
JOptionPane.showMessageDialog(null,"用户名或者密码错误！\n请重新输入","提示消息",JOptionPane.ERROR_MESSAGE);
//清空输入框
clear();
}
}
//教师登录判断方法
private void tealogin() {
// TODO Auto-generated method stub
if(userword.equals(jtf.getText())&&password.equals(jpf.getText()))
{
// System.out.println("登录成功");
JOptionPane.showMessageDialog(null,"登录成功！","提示消息",JOptionPane.WARNING_MESSAGE);
clear();
//关闭当前界面
dispose();
//创建一个新界面
UI ui=new UI();
}else if(jtf.getText().isEmpty()&&jpf.getText().isEmpty())
{
JOptionPane.showMessageDialog(null,"请输入用户名和密码！","提示消息",JOptionPane.WARNING_MESSAGE);
}else if(jtf.getText().isEmpty())
{
JOptionPane.showMessageDialog(null,"请输入用户名！","提示消息",JOptionPane.WARNING_MESSAGE);
}else if(jpf.getText().isEmpty())
{
JOptionPane.showMessageDialog(null,"请输入密码！","提示消息",JOptionPane.WARNING_MESSAGE);
}else
{
JOptionPane.showMessageDialog(null,"用户名或者密码错误！\n请重新输入","提示消息",JOptionPane.ERROR_MESSAGE);
//清空输入框
clear();
}
}
}
就上面两个地方红线无法运行，求大神指点。
附上错误
Exception in thread "AWT-EventQueue-0" java.lang.Error: Unresolved compilation problems:
Type mismatch: cannot convert from java.sql.Statement to java.beans.Statement
The method executeQuery(String) is undefined for the type Statement
at Login.actionPerformed(Login.java:174)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
at java.awt.Component.processMouseEvent(Component.java:6216)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3265)
at java.awt.Component.processEvent(Component.java:5981)
at java.awt.Container.processEvent(Container.java:2041)
at java.awt.Component.dispatchEventImpl(Component.java:4583)
at java.awt.Container.dispatchEventImpl(Container.java:2099)
at java.awt.Component.dispatchEvent(Component.java:4413)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4556)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4220)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4150)
at java.awt.Container.dispatchEventImpl(Container.java:2085)
at java.awt.Window.dispatchEventImpl(Window.java:2475)
at java.awt.Component.dispatchEvent(Component.java:4413)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
