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import java.awt.*
import javax.swing.*
import java.awt.event.*
import java.sql.*
class LoginFrm extends JFrame implements ActionListener// throws Exception
{
JLabel lbl1 = new JLabel("用户名:")
JLabel lbl2 = new JLabel("密码:")
JTextField txt = new JTextField(5)
JPasswordField pf = new JPasswordField()
JButton btn1 = new JButton("确定")
JButton btn2 = new JButton("取消")
public LoginFrm() {
this.setTitle("登陆")
JPanel jp = (JPanel) this.getContentPane()
jp.setLayout(new GridLayout(3, 2, 5, 5))
jp.add(lbl1)
jp.add(txt)
jp.add(lbl2)
jp.add(pf)
jp.add(btn1)
jp.add(btn2)
btn1.addActionListener(this)
btn2.addActionListener(this)
}
public void actionPerformed(ActionEvent ae) {
if (ae.getSource() == btn1) {
try {
Class.forName("com.mysql.jdbc.Driver")// mysql数据库
Connection con = DriverManager.getConnection(
"jdbc:mysql://localhost/Car_zl", "root", "1")// 数据库名为Car_zl，密码为1
System.out.println("com : "+ con)
Statement cmd = con.createStatement()
String sql = "select * from user where User_ID='"
+ txt.getText() + "' and User_ps='"
+ pf.getText() + "'"
ResultSet rs = cmd
.executeQuery(sql)// 表名为user，user_ID和User_ps是存放用户名和密码的字段名
if (rs.next()) {
JOptionPane.showMessageDialog(null, "登陆成功！")
} else
JOptionPane.showMessageDialog(null, "用户名或密码错误！")
} catch (Exception ex) {
}
if (ae.getSource() == btn2) {
System.out.println("1111111111111")
//txt.setText("")
//pf.setText("")
System.exit(0)
}
}
}
public static void main(String arg[]) {
JFrame.setDefaultLookAndFeelDecorated(true)
LoginFrm frm = new LoginFrm()
frm.setSize(400, 200)
frm.setVisible(true)
}
}
java的用户登录记住上次登录的用户名和密码的方式是使用cookie来保存在本地，并且需要加密保存，实例如下：
HttpServletRequest request = ServletActionContext.getRequest()Cookie cookies[]=request.getCookies()//声明一个cookie对象
String login=null//登录的用户名
String password=null //登录的密码
for (int i = 0 i < cookies.length i++){ //取最后一次保存的用户名和密码
if(cookies[i].getName().equals("userName")){
login = cookies[i].getValue()
}
if (cookies[i].getName().equals("password")){
password = cookies[i].getValue()
break
}
}
if(!AssertUtil.isEmpty(login)&&!login.equals("JSESSIONID")){
request.setAttribute("login", login)
request.setAttribute("password", password)
}
同意楼上的说法，具体点可以这样：创建一个用户表，里边包括LoginName（登录名），UserName（用户名），Password（密码），Age（年龄），Address（地址）。然后编写Java程序（用MVC架构）模型层（M）：DBConnection.java（负责连接数据库）import java.sql.Connection
import java.sql.DriverManager
import java.sql.*
public class DBConnection {
private static final String DRIVER_CLASS = "sun.jdbc.odbc.JdbcOdbcDriver"
private static final String DB_URL = "jdbc:odbc:text"
public DBConnection() {
}
public static Connection getConnection() {
Connection conn = null
try {
Class.forName(DRIVER_CLASS)
conn = DriverManager.getConnection(DB_URL)
} catch (SQLException ex) {
System.out.println(ex.getMessage())
} catch (ClassNotFoundException ex) {
System.out.println(ex.getMessage())
}
return conn
}
}
第2个负责数据库查询操作的类：DBUserManager.java
import edu.systop.text.model.entity.User
import edu.systop.text.model.dao.DBConnection
import java.sql.Connection
import java.sql.PreparedStatement
import java.sql.ResultSet
import java.sql.DriverManager
import java.sql.*
public class DBUserManager {
private static final String SQL_SELECT =
"SELECT LoginName,UserName,PassWord,Age,Address FROM UserInfo WHERE LoginName = ? AND PassWord = ?"
public DBUserManager() {
}
public boolean checkDB(User u) {
boolean b = false
Connection conn = null
PreparedStatement psmt = null
ResultSet rs = null
conn = DBConnection.getConnection()
try {
psmt = conn.prepareStatement(SQL_SELECT)
psmt.setString(1, u.getLoginName())
psmt.setString(2, u.getPassWord())
rs = psmt.executeQuery()
b = rs.next()
if (rs.next()) {
b = true
}
} catch (SQLException ex) {
System.out.println(ex.getMessage())
} finally {
cleanDB(rs, psmt, conn)
}
return b
}
public User checkBC(User u) {
Connection conn = null
PreparedStatement psmt = null
ResultSet rs = null
User tmp = new User()
conn = DBConnection.getConnection()
try {
psmt = conn.prepareStatement(SQL_SELECT)
psmt.setString(1, u.getLoginName())
psmt.setString(2, u.getPassWord())
rs = psmt.executeQuery()
if (rs.next()) {
tmp.setLoginName(rs.getString(1))
tmp.setUserName(rs.getString(2))
tmp.setAge(rs.getInt(4))
tmp.setAddress(rs.getString(5))
}
} catch (SQLException ex) {
System.out.println(ex.getMessage())
} finally {
cleanDB(rs, psmt, conn)
}
return tmp
}
public void cleanDB(ResultSet rs, PreparedStatement psmt, Connection conn) {
try {
if (rs != null) {
rs.close()
}
if (psmt != null) {
psmt.close()
}
if (conn != null) {
conn.close()
}
} catch (SQLException ex) {
System.out.println(ex.getMessage())
}
}
第3个实体用户类：User.java
package edu.systop.text.model.entity
public class User {
private String loginName
private String userName
private String passWord
private int age
private String address
public User() {
}
public void setLoginName(String loginName) {
this.loginName = loginName
}
public void setUserName(String userName) {
this.userName = userName
}
public void setPassWord(String passWord) {
this.passWord = passWord
}
public void setAge(int age) {
this.age = age
}
public void setAddress(String address) {
this.address = address
}
public String getLoginName() {
return loginName
}
public String getUserName() {
return userName
}
public String getPassWord() {
return passWord
}
public int getAge() {
return age
}
public String getAddress() {
return address
}
}
然后编写控制层（C）：GetInfoServlet.java
package edu.systop.text.control
import javax.servlet.*
import javax.servlet.http.*
import java.io.*
import java.util.*
import edu.systop.text.model.entity.User
import edu.systop.text.model.service.UserManager
public class GetInfoServlet extends HttpServlet {
private static final String CONTENT_TYPE = "text/htmlcharset=GBK"
//Initialize global variables
public void init() throws ServletException {
}
//Process the HTTP Get request
public void doGet(HttpServletRequest request, HttpServletResponse response) throws
ServletException, IOException {
}
//Process the HTTP Post request
public void doPost(HttpServletRequest request, HttpServletResponse response) throws
ServletException, IOException {
String loginName = request.getParameter("loginName")
String passWord = request.getParameter("passWord")
User u = new User()
u.setLoginName(loginName)
u.setPassWord(passWord)
UserManager m = new UserManager()
RequestDispatcher d
if (m.checkUser(u)) {
User o = m.checkBC(u)
request.setAttribute("JavaBEAN",o)
d = request.getRequestDispatcher("GetInfoUser.jsp")
} else {
d = request.getRequestDispatcher("GetInfoFinale.jsp")
}
d.forward(request, response)
}
//Clean up resources
public void destroy() {
}
}
最后，创建表示层（V）：包括3个Jsp（登录页面GetInfo.jsp、登录成功页面GetInfoUser.jsp、登录失败页面GetInfoFinale.jsp）
上面的就是Jsp结合Servlet用MVC架构写的用户登录程序。
