在ecplise中连接Mysql的问题
package test;import java.awt.Dimension;
import java.awt.GraphicsConfiguration;
import java.awt.Image;
import java.awt.Toolkit;
import javax.swing.*;
import java.awt.HeadlessException;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import java.sql.*;
public class Login extends JFrame implements ActionListener {
private ResultSet rs;
private Statement st;
private Connection conn;
private String host;
private JPanel jp = new JPanel();
private JLabel[] jl = { new JLabel("端口号"), new JLabel("数据库服务器IP"),
new JLabel("用户名"), new JLabel("密码") };
private JLabel jl2 = new JLabel("");
private JTextField[] jf = { new JTextField(), new JTextField(),
new JTextField()};
private JPasswordField jpwd = new JPasswordField();
private JRadioButton[] jrb ={new JRadioButton("普通学生",true),
new JRadioButton("管理人员")
};
private ButtonGroup bg = new ButtonGroup();//此类用于为一组按钮创建一个多斥（multiple-exclusion）作用域。使用相同的 ButtonGroup 对象创建一组按钮意味着“开启”其中一个按钮时，将关闭组中的其他所有按钮。
private JButton jb1 = new JButton("登录");
private JButton jb2 = new JButton("重置");
public Login() {
this.initialConnection();
this.addListener();
this.initialFrame();
this.setFocus();
}
public void setFocus() {
this.jf[2].requestFocus(true);
}
public void addListener() {
this.jb1.addActionListener(this);
this.jb2.addActionListener(this);
this.jf[2].addActionListener(this);
this.jpwd.addActionListener(this);
this.jf[0].addActionListener(this);
this.jf[1].addActionListener(this);
}
public void initialFrame() {
jp.setLayout(null);
for(int i=0; i<jl.length; i++) {
jl[i].setBounds(20, 30+i*30, 100, 30);
jp.add(jl[i]);
}
for(int j=0; j<jf.length; j++) {
jf[j].setBounds(150, 30+j*30, 150, 30);
jp.add(jf[j]);
}
jpwd.setBounds(150, 120, 150, 30);
this.add(jpwd);
jpwd.setEchoChar('*');
this.bg.add(jrb[0]);
this.bg.add(jrb[1]);
jrb[0].setBounds(20, 180, 100, 30);
jp.add(jrb[0]);
jrb[1].setBounds(140, 180, 100, 30);
jp.add(jrb[1]);
jb1.setBounds(20, 240, 100, 30);
jp.add(jb1);
jb2.setBounds(140, 240, 100, 30);
jp.add(jb2);
jp.setBounds(20, 20, 500, 500);
this.add(jp);
this.setTitle("登录");
Image image =new ImageIcon("").getImage();
this.setIconImage(image);
this.setResizable(false);
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
int centerX =screenSize.width/2;
int centerY = screenSize.height/2;
int w=300;
int h=320;
this.setBounds(centerX-w/2,centerY-h/2-100,w,h);
this.setVisible(true);
this.jf[1].requestFocus(true);
this.jf[1].setText("127.0.0.1");
this.jf[0].setText("3306");
}
public void actionPerformed(ActionEvent e) {
if(e.getSource() == this.jb1) {
this.jl2.setText("正在验证，请稍后……");
String hostadd = this.jf[1].getText().trim();
if(hostadd.equals("")) {
JOptionPane.showMessageDialog(this,"请输入端口号","错误",JOptionPane.ERROR_MESSAGE);
return;
}
String hostport = this.jf[0].getText().trim();
if(hostport.equals("")) {
JOptionPane.showMessageDialog(this,"请输入端口号","错误",JOptionPane.ERROR_MESSAGE);
return;
}
String username = this.jf[2].getText().trim();
if(username.equals("")) {
JOptionPane.showMessageDialog(this,"请输入用户名","错误",JOptionPane.ERROR_MESSAGE);
return;
}
String password =this.jpwd.getText().trim();
if(password.equals("")) {
JOptionPane.showMessageDialog(this,"请输入密码","错误",JOptionPane.ERROR_MESSAGE);
return;
}
try {
int type = this.jrb[0].isSelected()? 0:1;
if(type == 0) {
String sql="select * from user_stu where "+
"stu_id='"+username+"' and pwd='"+password+"'";
rs=st.executeQuery(sql);
if(rs.next()){
new StudentChint(username,host);//创建学生客户短窗口
this.dispose();//关闭登陆窗口并释放资源
}
else{//弹出错误提示窗口
JOptionPane.showMessageDialog(this,"用户名或密码错误","错误",
JOptionPane.ERROR_MESSAGE);
jl2.setText("");
}
this.closeConn();//关闭连接，语句及结果集
}
else{//教师登陆
//创建sql语句并查询
String sql="select coll_id from user_teacher where "+
"uid='"+username+"' and pwd='"+password+"'";
rs=st.executeQuery(sql);
if(rs.next()){
String coll_id=rs.getString(1);
new TeacherChint(coll_id,host);//创建教师客户端窗口
this.dispose();//关闭登陆窗口并释放资源
}
else{//弹出错误提示窗口
JOptionPane.showMessageDialog(this,"用户名或密码错误","错误",
JOptionPane.ERROR_MESSAGE);
jl2.setText("");
}
this.closeConn(); //关闭连接，语句及结果集
}
}
catch(SQLException ea){ea.printStackTrace();}
}
else if(e.getSource() == this.jf[0]) {
this.jf[1].requestFocus(true);
}
else if(e.getSource() == this.jf[1]) {
this.jf[2].requestFocus(true);
}
else if(e.getSource() == this.jf[2]) {
this.jf[3].requestFocus(true);
}
else if(e.getSource() == this.jpwd) {
this.jf[0].requestFocus(true);
}
else if(e.getSource() == jb1) {
this.jf[2].setText("");
this.jf[3].setText("");
}
}
public void initialConnection()
{
try
{//加载驱动，创建Connection及Statement
Class.forName("com.mysql.jdbc.Driver");
conn=DriverManager.getConnection("jdbc:mysql://"+host+"/test","root","520");
st=conn.createStatement();
}
catch(SQLException e)
{
JOptionPane.showMessageDialog(this,"连接失败，请检查主机地址是否正确","错误",JOptionPane.ERROR_MESSAGE);
e.printStackTrace();
}
catch(ClassNotFoundException e)
{
e.printStackTrace();
}
}
public void closeConn()
{
try
{
if(rs!=null)
{
rs.close();
}
if(st!=null)
{
st.close();
}
if(conn!=null)
{
conn.close();
}
}
catch(SQLException e)
{
e.printStackTrace();
}
}
public static void main(String args[])
{
//创建登陆窗体对象
Login login=new Login();
}
}
然后出现了下面的错误：
com.mysql.jdbc.exceptions. Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1121)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:357)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2482)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2519)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2304)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:834)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:416)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:346)
at java.sql.DriverManager.getConnection(Unknown Source)
at java.sql.DriverManager.getConnection(Unknown Source)
at test.Login.initialConnection(Login.java:184)
at test.Login.<init>(Login.java:37)
at test.Login.main(Login.java:224)
Caused by: null
at (Native Method)
at (Unknown Source)
at (Unknown Source)
at (Unknown Source)
at (Unknown Source)
at (Unknown Source)
at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:249)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:307)
... 17 more
