实现Java登录页面的步骤

Java登录页面要怎样实现？极悦小编来告诉大家。首先准备好对应的资料，之前的页面、连接数据库的配置文件和日志的配置文件。

实体类，登录用到的用户表字段：设置get和set方法：

private Integer UserID;private Integer EmployeeID;// 员工ID
private String UserName;// 用户名private String Password;// 密码
private String UserCode;// 用户编码private String UserState;// 用户状态
private String UnifiedVerificationCode;// 统一验证码
public Integer getUserID() { return UserID; }
public void setUserID(Integer userID) {UserID = userID;}......

Java封装实现类继承接口后实现，用于实现登录分方法，查询登录的用户名、密码和验证码：

Sql查询语句：

@Override public User findByName(String name) {
User user = null;
try {conn =DBUtils.getConnection();ps = conn.prepareStatement(findByName);//调用sql语句
ps.setString(1, name);rs = ps.executeQuery();
while (rs.next()) {
user = new User();//调用实体类的set、get方法获取用户名和用户信息
user.setUserID(rs.getInt("UserID")); user.setUserName(rs.getString("UserName"));
user.setPassword(rs.getString("Password")); ......
}} catch (SQLException e) {e.printStackTrace();}
finally {DBUtils.close(rs, conn, ps);}//关流return user;}

在创建一个用于Servlet调用的Service实现类匹配获取加密的密码数据库对比(使用封装好的加密的工具类)MD5Util：

@Overridepublic User login(String name, String password) {
User user=null; User dbUser=userDao.findByName(name);
if (dbUser!=null) {password=MD5Util.getMD5(password);
//设置为MD5密码与数据库对比等于则返回user=dbUser
if (password.equals(dbUser.getPassword().trim())) {user=dbUser;}
} return user;}

Servlet调用用户登录的方法：

doGet方法调用doPost使用doPost请求数据

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response);}

doPost方法：判断要登录的页面或请求数据进行跳转的方法

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//解决乱码问题
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
String strfun=request.getParameter("fun");
if ("login".equals(strfun)) {login(request, response);//登录页面
}else if ("identity".equals(strfun)) {identity(request, response);//验证码
}else if ("userLogin".equals(strfun)) {userLogin(request, response);//登录请求数据}
else {login(request, response);//重定向}}

获取验证码：

private void identity(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//调用生成验证码工具类方法
GifCaptcha captcha=new GifCaptcha(290, 35, 5);
ServletOutputStream out= response.getOutputStream();
String identityKey= captcha.out(out);
request.getSession().setAttribute("identityKey", identityKey);
out.flush();
out.close();}

跳转登录页面：

private void login(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.getRequestDispatcher("/jsp/login.jsp").forward(request, response);}
//登录验证private void userLogin(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
JsonReturn jsonReturn=new JsonReturn();
IUserService userService=new UserServiceImpl();//调用登录方法的实现类
String userName=request.getParameter("username");//用户名
String password=request.getParameter("password");//密码
String identityKey=request.getParameter("identityKey");//验证码
HttpSession session=request.getSession();
try {
String sessionIdentityKey=session.getAttribute("identityKey").toString();
if(Tools.isNotNull(identityKey)&&identityKey.equalsIgnoreCase(sessionIdentityKey)) {User user=userService.login(userName, password);
if (user!=null) {
session.setAttribute("SESSION_USER", user);
jsonReturn.setState(true);jsonReturn.setMsg("登录成功");
}else {jsonReturn.setState(false); jsonReturn.setMsg("输入用户或密码错误");}
}else {jsonReturn.setState(false); jsonReturn.setMsg("验证码错误");
}} catch (Exception e) { jsonReturn.setState(false);
jsonReturn.setMsg("参数错误");}
PrintWriter out=response.getWriter();
JSONObject jObject=JSONObject.fromObject(jsonReturn);//转成json字符串
out.write(jObject.toString());
out.close(); }

通过上述介绍，相信大家对实现Java登录页面的步骤已经有所了解，大家如果对此比较感兴趣，想了解更多相关知识，不妨来关注一下极悦的Java极悦在线学习，里面的课程从入门到精通，通俗易懂，适合没有基础的小伙伴学习，希望对大家能够有所帮助。