HttpSession案例：用户登陆应用

时间 2019-11-12

标签 httpsession 案例用户登陆应用栏目网站开发繁體版

原文原文链接

用户登陆案例：html

user描述类：数据库

public class User {session

private String username;app

private String psw;dom

private String NikeName;post

public User(){}网站

public User(String username, String psw, String nikeName) {this

this.username = username;spa

this.psw = psw;code

NikeName = nikeName;

}

public String getUsername() {

return username;

}

public void setUsername(String username) {

this.username = username;

}

public String getPsw() {

return psw;

}

public void setPsw(String psw) {

this.psw = psw;

}

public String getNikeName() {

return NikeName;

}

public void setNikeName(String nikeName) {

NikeName = nikeName;

}

UserDB(模仿数据库):

public class UserDB {

private static List<User> list=new ArrayList<User>();

static{

list.add(new User("djw", "123", "day"));

list.add(new User("zb", "123", "bb"));

}

//判断用户名和密码是否正确

public static User findUser(String username,String psw){

for(User u:list){

if(username.equals(u.getUsername())&&psw.equals(u.getPsw())){

return u;

}

return null;

}

html登陆界面：

<body>

<h1>xxx主页</h1>

用户名<input type="text" name="username"/><br/>

密码<input type="password" name="psw"/><br/>

</form>

</body>

登陆Servlet类：

public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

response.setContentType("text/html;charset=UTF-8");

PrintWriter out=response.getWriter();

//判断是否已经登陆，

HttpSession session =request.getSession();

//建立登陆标记

User user=(User) session.getAttribute("user");

//已经登陆的话，显示昵称，告知跳转到登陆界面

if(user!=null){

response.setHeader("Refresh", "2;URL=/TextSession/servlet/IndexServlet");

out.write(user.getNikeName()+"您已经登陆了，2秒后跳转到主页面");

}

//将正确的用户名和密码封装到beanutils中

User u=new User();

try {

BeanUtils.populate(u, request.getParameterMap());

} catch (Exception e) {

e.printStackTrace();

}

//判断验证吗是否正确

String code=(String) session.getAttribute("code");

String TextCode=request.getParameter("code");

if(!TextCode.equals(code)){

out.write("验证码错误，2秒后跳转到登陆页面");

response.setHeader("Refresh", "2;URL=/TextSession/1.html");

return;

}

//判断用户名密码是否正确

if(UserDB.findUser(u.getUsername(),u.getPsw())==null){

response.setHeader("Refresh", "2;URL=/TextSession/1.html");

out.write("账号密码错误，2秒后跳转到登陆页面");

}else{

//将bean对象写入Session中，

HttpSession new_session=request.getSession();

new_session.setAttribute("user", u);

//登陆成功，跳转到主界面

out.write("登陆成功,2秒后跳转到主页面");

response.setHeader("Refresh", "2;URL=/TextSession/servlet/IndexServlet");

}

主页面servlet代码：

public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

response.setContentType("text/html;charset=UTF-8");

PrintWriter out=response.getWriter();

out.write("恭喜你来到xxxx网站");

out.write("<a href='"+request.getContextPath()+"/servlet/CancelServlet'>注销</a>");

}

注销类代码：

public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

response.setContentType("text/html;charset=UTF-8");

PrintWriter out=response.getWriter();

HttpSession session=request.getSession();

session.removeAttribute("user");

out.write("成功注销,2秒后回到登陆页面");

response.setHeader("Refresh", "2;URL=/TextSession/1.html");

}

CodeServlet类：生成验证码：

public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

int width=120;

int height=20;

BufferedImage bi=new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

//获取画笔对象

Graphics gs=bi.getGraphics();

//画边框颜色

gs.setColor(Color.blue);

gs.drawRect(0, 0, width, height);

//设置背景色

gs.setColor(Color.yellow);

gs.fillRect(1, 1, width-2, height-2);

//获取随机线条

Random rd=new Random();

gs.setColor(Color.gray);

for(int x=0;x<15;x++){

gs.drawLine(rd.nextInt(width), rd.nextInt(height), rd.nextInt(width), rd.nextInt(height));

}

//获取随机数字

gs.setColor(Color.red);

gs.setFont(new Font("宋体",Font.BOLD,18));

int new_width=20;

StringBuffer sb=new StringBuffer();

for(int x=0;x<4;x++){

int num= rd.nextInt(10);

sb.append(num);

gs.drawString(num+"", new_width, 20);

new_width+=16;

}

HttpSession session=request.getSession();

session.setAttribute("code", sb.toString());

response.setHeader("Expires", "-1");

response.setHeader("Cache-Control", "no-cache");

response.setHeader("Pragma", "no-cache");

ServletOutputStream out=response.getOutputStream();

//Image对象：输出流输出图片

ImageIO.write(bi, "jpg", out);

}