jsp+servlet+JavaBean+MySQL实现登陆实例
运行环境：
jdk8.0
eclipse4.0
tomcat7.0
Windows2007
需要的jar包是：
mysql-connector-java-5.1.28.jar
①：首先创建在MySQL中创建一张tusers表
DROP TABLE IF EXISTS `tusers`;
CREATE TABLE `tusers` (
`username` varchar(20) NOT NULL,
`userid` int(20) NOT NULL AUTO_INCREMENT,
`password` varchar(20) NOT NULL,
PRIMARY KEY (`userid`)
) ENGINE=MyISAM AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;
然后在其中插入一个用户：用户名：admin 密码：admin
-- ----------------------------
-- Records of tusers
-- ----------------------------
INSERT INTO `tusers` VALUES ('admin', '1', 'admin');
②、在eclipse中创建一个web工程，其工程目录格式如下图：
1、在WebContent下创建其登陆页面及其相关的登陆成功页面和登陆失败页面：login.jsp、success.jsp、error.jsp
login.jsp
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>登陆</title>
<script type="text/javascript">
function check(form){
//取得form1中username的值并判断是否为空
if(document.forms.form1.username.value==""){
alert("请输入用户名");
document.forms.form1.username.focus();
return false;
}
if(document.forms.form1.password.value==""){
alert("请输入密码");
document.forms.form1.password.focus();
return false;
}
}
</script>
</head>
<body>
<form action="LoginServlet" method="post" name="form1">
<label>username</label>
<input type="text" name="username" />
<label>password</label>
<input type="password" name="password" />
<input type="submit" name="submit" onclick="return check(this);" value="登陆" />
<input type="reset" name="reset" value="重置" />
</form>
</body>
</html>
success.jsp
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<jsp:useBean id="user" class="model.Tusers" scope="request"/>
<jsp:setProperty name="user" property="*"/>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
</head>
<body>
<%
session.setAttribute("user",user);
String username=user.getUsername();
%>
<%=username %>,欢迎您来到成功页面!<br>
您的IP是:<%=request.getRemoteAddr() %><br>
你的主机是:<%=request.getRemoteHost() %><br>
你使用的协议是:<%=request.getProtocol() %><br>
你目前的地址是:<%=request.getRealPath("/") %>
你的主机端口是:<%=request.getRemotePort() %>
</body>
</html>
error.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<h6>ERROR</h6>
</body>
</html>
2、在model包中创建tusers表的实体类：Tusers.java
package model;
public class Tusers {
private Integer userid;
private String username;
private String password;
public Integer getUserid() {
return userid;
}
public void setUserid(Integer userid) {
this.userid = userid;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
3、在util包中创建一个DBConn封装类来链接MySQL：DBConn.java
package util;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class DBConn {
public static String driver;//定义驱动
public static String url;//定义链接URL
public static String username;//定义数据库用户名
public static String password;//定义数据库密码
public static Connection connection;//定义链接
public static Statement statement;//定义statement
public static ResultSet result;//定义结果集
//设置connection
static{
driver="com.mysql.jdbc.Driver";
url="jdbc:mysql://localhost:3306/test?characterEncoding=utf-8";
username="test";
password="test";
try {
Class.forName(driver);
connection=DriverManager.getConnection(url,username,password);
System.out.println("链接成功--------------------------------");
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}catch(SQLException ex){
ex.printStackTrace();
}
}
public DBConn(){
this.connection=this.getConn();
}
public Connection getConn(){
return this.connection;
}
public void doInsert(String sql) {
try {
statement = connection.createStatement();
int i = statement.executeUpdate(sql);
} catch(SQLException sqlexception) {
System.err.println("db.executeInset:" + sqlexception.getMessage());
}finally{
}
}
public void doDelete(String sql) {
try {
statement = connection.createStatement();
int i = statement.executeUpdate(sql);
} catch(SQLException sqlexception) {
System.err.println("db.executeDelete:" + sqlexception.getMessage());
}
}
public void doUpdate(String sql) {
try {
statement = connection.createStatement();
int i = statement.executeUpdate(sql);
} catch(SQLException sqlexception) {
System.err.println("db.executeUpdate:" + sqlexception.getMessage());
}
}
public ResultSet doSelect(String sql) {
try {
connection=DriverManager.getConnection(url,username,password);
statement = connection.createStatement(java.sql.ResultSet.TYPE_SCROLL_INSENSITIVE,java.sql.ResultSet.CONCUR_READ_ONLY);
result = statement.executeQuery(sql);
System.out.println("取得结果集");
} catch(SQLException sqlexception) {
System.err.println("db.executeQuery: " + sqlexception.getMessage());
}
return result;
}
/**
*关闭数据库结果集，数据库操作对象，数据库链接
@Function: Close all the statement and conn int this instance and close the parameter ResultSet
@Param: ResultSet
@Exception: SQLException,Exception
**/
public void close(ResultSet rs) throws SQLException, Exception {
if (rs != null) {
rs.close();
rs = null;
}
if (statement != null) {
statement.close();
statement = null;
}
if (connection != null) {
connection.close();
connection = null;
}
}
/**
*关闭数据库操作对象，数据库连接对象
* Close all the statement and conn int this instance
* @throws SQLException
* @throws Exception
*/
public void close() throws SQLException, Exception {
if (statement != null) {
statement.close();
statement = null;
}
if (connection != null) {
connection.close();
connection = null;
}
}
public static void main(String[] args){
DBConn db=new DBConn();
db.getConn();
ResultSet rs=db.doSelect("select userid,username,password from tusers where username='admin'");
try{
while(rs.next()){
System.out.println(rs.getInt(1));
System.out.println(rs.getString(3));
}
}catch(SQLException e){
e.printStackTrace();
}
}
}
4、在model包下创建一个类来对 登陆用户进行判断：CheckUser.java
package model;
import java.sql.ResultSet;
import java.sql.SQLException;
import util.DBConn;
public class CheckUser {
public boolean checkUser(Tusers user){
if(user.getUsername().equals("") || user.getUsername()!=null){
ResultSet rs=null;
DBConn db=new DBConn();
rs=db.doSelect("select userid,username,password from tusers where username='"+user.getUsername()+"'");
try{
while(rs.next()){
if(user.getPassword().equals("")|| user.getPassword()!=null){
rs=db.doSelect("select userid,username,password from tusers where password="+user.getPassword());
return true;
}
}
}catch(SQLException e){
e.printStackTrace();
}
}
return false;
}
}
5、在controller中创建一个servlet：LoginServlet.java
package controller;
import java.io.IOException;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import model.CheckUser;
import model.Tusers;
/**
* Servlet implementation class LoginServlet
*/
@WebServlet(name = "LoginServlet1", urlPatterns = { "/LoginServlet1" })
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
/* public LoginServlet() {
super();
// TODO Auto-generated constructor stub
}
*/
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
//设置HTTP响应的文档类型,此处为Text/html,如果更改为application\msword则设置为word文档格式
response.setContentType("text/html");
//设置响应所采用的编码方式
response.setCharacterEncoding("utf-8");
Tusers user=new Tusers();
String userid=request.getParameter("userid");
String username=request.getParameter("username");
String password=request.getParameter("password");
user.setUsername(username);
user.setPassword(password);
CheckUser ck=new CheckUser();
boolean bool=ck.checkUser(user);
String forward;
if(bool){
forward="success.jsp";
}
else{
forward="error.jsp";
}
RequestDispatcher rd=request.getRequestDispatcher(forward);
rd.forward(request, response);
}
}
6、然后在web.xml中配置servlet：
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
<display-name>authority</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
<servlet>
<servlet-name>LoginServlet</servlet-name>
<servlet-class>controller.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/LoginServlet</url-pattern>
</servlet-mapping>
</web-app>其中login.jsp中的action中的值要和url-pattern的值相对应
到此这个简单的登陆案例就完成了，比较简单吧。如果用到spring+springmvc+mybatis结合一起那就更简单了。这个项目这是为了熟悉一下链接数据库的那块代码。