❶ 用java编写一个登陆系统。
第一个java文件LogoingDemo.java
importjava.util.Scanner;
publicclassLogoingDemo{
publicstaticvoidmain(String[]args){
System.out.println("请输入用户名");
Scannersc=newScanner(System.in);
Stringname=sc.nextLine();
System.out.println("请输入密码");
Stringpsw=sc.nextLine();
sc.close();
CheckDemocd=newCheckDemo(name,psw);//用户名和密码传入验证类
booleanbo=cd.check();//调用方法进行验证
if(bo){
System.out.println("登录成功");
}else{
System.out.println("登录失败:提示用户名admin密码123");
}
}
}
第二个java文件CheckDemo.java
publicclassCheckDemo{
publicStringname;
publicStringpsw;
publicCheckDemo(Stringname,Stringpsw){//构造器
this.name=name;
this.psw=psw;
}
publicbooleancheck(){
//用户名密码不能为空.用户名=admin密码=123
if(name!=null&&psw!=null&&name.equals("admin")&&psw.equals("123")){
returntrue;
}
returnfalse;
}
}
效果
请输入用户名
admin
请输入密码
123
登录成功
------------------------------------
请输入用户名
add
请输入密码
123
登录失败:提示用户名admin密码123
❷ 怎么用JAVA写一个用户登入程序
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 e.systop.text.model.entity.User;
import e.systop.text.model..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 e.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 e.systop.text.control;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
import e.systop.text.model.entity.User;
import e.systop.text.model.service.UserManager;
public class GetInfoServlet extends HttpServlet {
private static final String CONTENT_TYPE = "text/html; charset=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。
❸ 用java怎么实现QQ登录界面
用java做QQ登录界面的写法如下:
package ch10;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
1、//定义该类继承自JFrame,实现ActionListener接口
public class LoginTest extends JFrame implements ActionListener
{
2、//创建JPanel对象
private JPanel jp=new JPanel();
3、//创建3个标并加入数组
JLabel name = new JLabel("请输入用户名");
JLabel password = new JLabel("请输入密码");
JLabel show = new JLabel("");
private JLabel[] jl={name,password,show};
4、//创建登陆和重置按扭并加入数组
JButton login = new JButton("登陆");
JButton reset = new JButton("重置");
private JButton[] jb={login,reset};
5、//创建文本框以及密码框
private JTextField jName=new JTextField();
private JPasswordField jPassword =new JPasswordField();
public LoginTest()
{
6、//设置布局管理器为空布局,这里自己摆放按钮、标签和文本框
jp.setLayout(null);
for(int i=0;i<2;i++)
{
7、//设置标签和按扭的位置与大小
jl[i].setBounds(30,20+40*i,180,20);
jb[i].setBounds(30+110*i,100,80,20);
8、//添加标签和按扭到JPanel容器中
jp.add(jl[i]);
jp.add(jb[i]);
//为2个按钮注册动作事件监听器
jb[i].addActionListener(this);
}
9、//设置文本框的位置和大小,注意满足美观并足够用户名的长度
jName.setBounds(130,15,100,20);
10、//添加文本框到JPanel容器中
jp.add(jName);
11、//为文本框注册动作事件监听器
jName.addActionListener(this);
12、//设置密码框的位置和大小,注意满足美观和足够密码的长度
jPassword.setBounds(130,60,100,20);
13、//添加密码框到JPanel容器中
jp.add(jPassword);
14、//设置密码框中的回显字符,这里设置美元符号
jPassword.setEchoChar('$');
15、//为密码框注册动作事件监听器
jPassword.addActionListener(this);
16、//设置用于显示登陆状态的标签大小位置,并将其添加进JPanel容器
jl[2].setBounds(10,180,270,20);
jp.add(jl[2]);
17、//添加JPanel容器到窗体中
this.add(jp);
18、//设置窗体的标题、位置、大小、可见性及关闭动作
this.setTitle("登陆窗口");
this.setBounds(200,200,270,250);
this.setVisible(true);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
19、//实现动作监听器接口中的方法actionPerformed
public void actionPerformed(ActionEvent e)
{
20、//如果事件源为文本框
if(e.getSource()==jName)
{
21、//切换输入焦点到密码框
jPassword.requestFocus();
}
22、//如果事件源为重置按扭
else if(e.getSource()==jb[1])
{
23、//清空姓名文本框、密码框和show标签中的所有信息
jl[2].setText("");
jName.setText("");
jPassword.setText("");
24、//让输入焦点回到文本框
jName.requestFocus();
}
25、//如果事件源为登陆按钮,则判断登录名和密码是否正确
else
{
26、//判断用户名和密码是否匹配
if(jName.getText().equals("lixiangguo")&&
String.valueOf(jPassword.getPassword()).equals("19801001"))
{
27、jl[2].setText("登陆成功,欢迎您的到来!");
}
else
{
28、jl[2].setText("对不起,您的用户名或密码错误!");
}
}
}
public static void main(String[] args)
{
29、//创建LoginTest窗体对象
new LoginTest();
}
}
❹ 如何用JAVA编写一个简单用户登陆界面
什么都不说了 直接给你代码吧x0dx0apackage com.moliying.ui;x0dx0aimport java.awt.BorderLayout;x0dx0aimport java.awt.Container;x0dx0aimport java.awt.FlowLayout;x0dx0aimport java.awt.List;x0dx0aimport java.awt.event.ActionEvent;x0dx0aimport java.awt.event.ActionListener;x0dx0aimport java.io.BufferedWriter;x0dx0aimport java.io.FileOutputStream;x0dx0aimport java.io.OutputStreamWriter;x0dx0aimport java.util.ArrayList;x0dx0aimport java.util.Arrays;x0dx0aimport javax.swing.JButton;x0dx0aimport javax.swing.JFrame;x0dx0aimport javax.swing.JLabel;x0dx0aimport javax.swing.JPanel;x0dx0aimport javax.swing.JPasswordField;x0dx0aimport javax.swing.JTextField;x0dx0apublic class Login {x0dx0aprivate JFrame frame = new JFrame("登录");x0dx0aprivate Container c = frame.getContentPane();x0dx0aprivate JTextField username = new JTextField();x0dx0aprivate JPasswordField password = new JPasswordField();x0dx0aprivate JButton ok = new JButton("确定");x0dx0aprivate JButton cancel = new JButton("取消");x0dx0apublic Login() {x0dx0aframe.setSize(300, 200);x0dx0aframe.setBounds(450, 300, 300, 200);x0dx0ac.setLayout(new BorderLayout());x0dx0ainitFrame();x0dx0aframe.setVisible(true);x0dx0a}x0dx0aprivate void initFrame() {x0dx0a// 顶部x0dx0aJPanel titlePanel = new JPanel();x0dx0atitlePanel.setLayout(new FlowLayout());x0dx0atitlePanel.add(new JLabel("系统管理员登录"));x0dx0ac.add(titlePanel, "North");x0dx0a// 中部表单x0dx0aJPanel fieldPanel = new JPanel();x0dx0afieldPanel.setLayout(null);x0dx0aJLabel a1 = new JLabel("用户名:");x0dx0aa1.setBounds(50, 20, 50, 20);x0dx0aJLabel a2 = new JLabel("密 码:");x0dx0aa2.setBounds(50, 60, 50, 20);x0dx0afieldPanel.add(a1);x0dx0afieldPanel.add(a2);x0dx0ausername.setBounds(110, 20, 120, 20);x0dx0apassword.setBounds(110, 60, 120, 20);x0dx0afieldPanel.add(username);x0dx0afieldPanel.add(password);x0dx0ac.add(fieldPanel, "Center");x0dx0a// 底部按钮x0dx0aJPanel buttonPanel = new JPanel();x0dx0abuttonPanel.setLayout(new FlowLayout());x0dx0abuttonPanel.add(ok);x0dx0abuttonPanel.add(cancel);x0dx0ac.add(buttonPanel, "South");x0dx0ax0dx0aok.addActionListener(new ActionListener() {x0dx0ax0dx0a@Overridex0dx0apublic void actionPerformed(ActionEvent e) {x0dx0aSystem.out.println(username.getText().toString());x0dx0a}x0dx0a});x0dx0ax0dx0acancel.addActionListener(new ActionListener() {x0dx0ax0dx0a@Overridex0dx0apublic void actionPerformed(ActionEvent e) {x0dx0aframe.setVisible(false);x0dx0a}x0dx0a});x0dx0a}x0dx0apublic static void main(String[] args) {x0dx0a//new Login();x0dx0ax0dx0aString ss = "abbabbbaabbbccba";x0dx0ax0dx0aSystem.out.println(ss.split("b").length);x0dx0ax0dx0a}x0dx0a}
❺ 用java写一个登陆界面代码。
具体框架使用jframe,文本框组件:JTextField;密码框组件:JPasswordField;标签组件:JLabel;复选框组件:JCheckBox;单选框组件:JRadioButton;按钮组件JButton。
登录界面:
Swing 是一个为Java设计的GUI工具包。
Swing是JAVA基础类的一部分。
Swing包括了图形用户界面(GUI)器件如:文本框,按钮,分隔窗格和表。
Swing提供许多比AWT更好的屏幕显示元素。它们用纯Java写成,所以同Java本身一样可以跨平台运行,这一点不像AWT。它们是JFC的一部分。它们支持可更换的面板和主题(各种操作系统默认的特有主题),然而不是真的使用原生平台提供的设备,而是仅仅在表面上模仿它们。这意味着你可以在任意平台上使用JAVA支持的任意面板。轻量级组件的缺点则是执行速度较慢,优点就是可以在所有平台上采用统一的行为。
概念解析:
JFrame_ java的GUI程序的基本思路是以JFrame为基础,它是屏幕上window的对象,能够最大化、最小化、关闭。
JPanel_ Java图形用户界面(GUI)工具包swing中的面板容器类,包含在javax.swing 包中,可以进行嵌套,功能是对窗体中具有相同逻辑功能的组件进行组合,是一种轻量级容器,可以加入到JFrame窗体中。。
JLabel_ JLabel 对象可以显示文本、图像或同时显示二者。可以通过设置垂直和水平对齐方式,指定标签显示区中标签内容在何处对齐。默认情况下,标签在其显示区内垂直居中对齐。默认情况下,只显示文本的标签是开始边对齐;而只显示图像的标签则水平居中对齐。
JTextField_一个轻量级组件,它允许编辑单行文本。
JPasswordField_ 允许我们输入了一行字像输入框,但隐藏星号(*) 或点创建密码(密码)
JButton_ JButton 类的实例。用于创建按钮类似实例中的 "Login"。
❻ java语言实现用户注册和登录
//这个是我写的,里面有连接数据库的部分。你可以拿去参考一下
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.(true);
LoginFrm frm = new LoginFrm();
frm.setSize(400, 200);
frm.setVisible(true);
}
}
❼ java编写一个程序模拟用户登录操作,用户名和密码从键盘输入
import java.util.Scanner;
public class LoginTest {
/**
* @param args
*/
public static void main(String[] args) {
String loginName = "admin";
String passWord = "123456";
Scanner sc = new Scanner(System.in);
boolean isSuccess = false;
int index = 0;
while(!isSuccess){
System.out.println("请输入用户名:");
String name = sc.nextLine(); //读取字符串型输入
System.out.println("请输入密码:");
String passW = sc.nextLine();
if(loginName.equals(name)&&passWord.equals(passW)){
System.out.println("户名密码正确,退出程序");
isSuccess = true;
}else{
if(++index>=3){
System.out.println("用户名密码错误,程序即将退出");
return;
}else{
System.out.println("用户名密码错误,请重新输入");
}
}
}
}
}
❽ 用Java编写注册登录程序
什么都不说了 直接给你代码吧
package com.moliying.ui;
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.List;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedWriter;
import java.io.FileOutputStream;
import java.io.OutputStreamWriter;
import java.util.ArrayList;
import java.util.Arrays;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;
public class Login {
private JFrame frame = new JFrame("登录");
private Container c = frame.getContentPane();
private JTextField username = new JTextField();
private JPasswordField password = new JPasswordField();
private JButton ok = new JButton("确定");
private JButton cancel = new JButton("取消");
public Login() {
frame.setSize(300, 200);
frame.setBounds(450, 300, 300, 200);
c.setLayout(new BorderLayout());
initFrame();
frame.setVisible(true);
}
private void initFrame() {
// 顶部
JPanel titlePanel = new JPanel();
titlePanel.setLayout(new FlowLayout());
titlePanel.add(new JLabel("系统管理员登录"));
c.add(titlePanel, "North");
// 中部表单
JPanel fieldPanel = new JPanel();
fieldPanel.setLayout(null);
JLabel a1 = new JLabel("用户名:");
a1.setBounds(50, 20, 50, 20);
JLabel a2 = new JLabel("密 码:");
a2.setBounds(50, 60, 50, 20);
fieldPanel.add(a1);
fieldPanel.add(a2);
username.setBounds(110, 20, 120, 20);
password.setBounds(110, 60, 120, 20);
fieldPanel.add(username);
fieldPanel.add(password);
c.add(fieldPanel, "Center");
// 底部按钮
JPanel buttonPanel = new JPanel();
buttonPanel.setLayout(new FlowLayout());
buttonPanel.add(ok);
buttonPanel.add(cancel);
c.add(buttonPanel, "South");
ok.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
System.out.println(username.getText().toString());
}
});
cancel.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
frame.setVisible(false);
}
});
}
public static void main(String[] args) {
// new Login();
String ss = "abbabbbaabbbccba";
System.out.println(ss.split("b").length);
}
}
❾ 用java程序编写一个简单的登录界面怎么写
程序如下:
mport java.awt.HeadlessException;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.ImageIcon;
import javax.swing.JButton;
@SuppressWarnings("serial")
public class MainFrame extends JFrame {
JLabel lbl1 = new JLabel("用户名:");
JLabel lbl2 = new JLabel("密 码:");
JTextField txt = new JTextField("admin",20);
JPasswordField pwd = new JPasswordField(20);
JButton btn = new JButton("登录");
JPanel pnl = new JPanel();
private int error = 0;
public MainFrame(String title) throws HeadlessException {
super(title);
init();
}
private void init() {
this.setResizable(false);
pwd.setEchoChar('*');
pnl.add(lbl1);
pnl.add(txt);
btn.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
if ("admin".equal花憨羔窖薏忌割媳公颅s(new String(pwd.getPassword()))){
pnl.removeAll();
JLabel lbl3 = new JLabel();
ImageIcon icon = new ImageIcon(this.getClass().getResource("pic.jpg"));
lbl3.setIcon(icon);
pnl.add(lbl3);
}
else{
if(error < 3){
JOptionPane.showMessageDialog(null,"密码输入错误,请再试一次");
error++;
}
else{
JOptionPane.showMessageDialog(null,"对不起,您不是合法用户");
txt.setEnabled(false);
pwd.setEnabled(false);
btn.setEnabled(false);
}
}
}
});
}
public static void main(String[] args) {
MainFrame frm = new MainFrame("测试");
frm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frm.setBounds(100, 100, 300, 120);
frm.setVisible(true);
}
}