Javaweb Simple Login Example

Jsp+servlet+javabean Simple Program Example-user name password login, from the "Tomcat&javaweb Technical Manual", pro-Test available.

IDE Environment: MYECLIPSE10

1, build Web Project, named Login_test. To create a Userlogn table:

CREATE TABLE Userlogin (

User_name varchar (TEN) is not NULL,

User_pwd varchar (TEN) is not NULL,

Constraint USER_PK primary KEY (USER_NAME)

);

2. Add JavaBean file to create new class Userloginbean,java

Package Login;import java.sql.*;p ublic class Userloginbean {private Connection con;     Database connection private ResultSet RS;      Result set private Statement stmt;    private static final String driver_name= "Com.mysql.jdbc.Driver";    private static final String url_str= "Jdbc:mysql://localhost/test";            Constructor public Userloginbean () {try{//load driver class.forname (driver_name);    Get database connection con=drivermanager.getconnection (URL_STR, "root", "Jiangshan");        own user name and password} catch (SQLException se) {se.printstacktrace ();        } catch (ClassNotFoundException Cnfe) {cnfe.printstacktrace ();        }}//Business method public boolean login (String username,string password) {Boolean b = false;            try{stmt=con.createstatement ();            String sql= "Select User_pwd from Userlogin Where user_name= '" +username+ "'";            Rs=stmt.executequery (SQL);      while (Rs.next ()) {          String pwd= rs.getstring (1);                if (pwd.equals (password)) {b=true;            }}}catch (SQLException se) {se.printstacktrace ();        B=false;   }finally{This.close (CON,RS,STMT);    The following defines the Close method} return B; The//close method is used to close the corresponding resource public void close (Connection con,resultset rs,statement stmt) {try{if (con!=nu            ll) {con.close ();            } if (Rs!=null) {rs.close ();            } if (Stmt!=null) {stmt.close ();        }} catch (SQLException se) {se.printstacktrace (); }    }}

 3, add servlet class, name Userloginservlet.java

Import java.io.*;import javax.servlet.*;import javax.servlet.http.*;import login. Userloginbean;public class Userloginservlet extends httpservlet{public void doget (HttpServletRequest request,httpserv    Letresponse response) throws servletexception,ioexception{This.dopost (request, response); } public void DoPost (HttpServletRequest request,httpservletresponse response) throws Servletexception,ioexc        eption{PrintWriter out=response.getwriter ();            try{String username=request.getparameter ("UserName"). Trim ();            String password=request.getparameter ("PassWord"). Trim ();            Userloginbean ubl=new Userloginbean ();            Boolean b =ubl.login (UserName, PassWord);            if (b) {This.forward (Request,response, "/loginok.jsp");                            } else{This.forward (Request,response, "/loginfail.jsp"); }} catch (Exception e) {Out.println ("Login fail.<br>");        Out.println (E.tostring ());  }}//private void Forward (httpservletrequest request,httpservletresponse response,string URL) throws        servletexception,ioexception{requestdispatcher rd=request.getrequestdispatcher (URL);    Rd.forward (request, response); }}

Import java.io.*;import javax.servlet.*;import javax.servlet.http.*;import login. Userloginbean;public class Userloginservlet extends httpservlet{public void doget (HttpServletRequest request,httpserv    Letresponse response) throws servletexception,ioexception{This.dopost (request, response); } public void DoPost (HttpServletRequest request,httpservletresponse response) throws Servletexception,ioexc        eption{PrintWriter out=response.getwriter ();            try{String username=request.getparameter ("UserName"). Trim ();            String password=request.getparameter ("PassWord"). Trim ();            Userloginbean ubl=new Userloginbean ();            Boolean b =ubl.login (UserName, PassWord);            if (b) {This.forward (Request,response, "/loginok.jsp");                            } else{This.forward (Request,response, "/loginfail.jsp"); }} catch (Exception e) {Out.println ("Login fail.<br>");        Out.println (E.tostring ());  }}//private void Forward (httpservletrequest request,httpservletresponse response,string URL) throws        servletexception,ioexception{requestdispatcher rd=request.getrequestdispatcher (URL);    Rd.forward (request, response); }}

4. Write Login interface: Create index.jsp

<%@ page contenttype= "text/html; CHARSET=GBK "%>
<%@ page contenttype= "text/html; CHARSET=GBK "%>
5. Login Successful Interface: loginok.jsp
<%@ page contenttype= "text/html; CHARSET=GBK "%>

<%@ page contenttype= "text/html; CHARSET=GBK "%>
6, Login failure interface: loginfail.jsp
%@ page contenttype= "text/html; CHARSET=GBK "%>

<%@ page contenttype= "text/html; CHARSET=GBK "%>
7. Start Tomcat, deploy this project to Tomcat's WebApps file, open the Web-inf folder in the project under WebApps, modify the Web. xml file, <web-app> and </web-app> Add the following code between them:
<servlet>
<servlet-name>UserLoginServlet</servlet-name>
<servlet-class>UserLoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>UserLoginServlet</servlet-name>
<url-pattern>/UserLoginServlet</url-pattern>
</servlet-mapping>

You can also add the following code to set the home page to index.jsp:
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>

8, open the browser, enter the http://localhost:8080/Login_test/can enter the login interface.
Javaweb Simple Login Example