上次写了一篇jdbc工具类实现登录功能，但是只能在控制台实现输入用户名密码。这次使用了servlet来实现登录功能，可以通过在页面上输入账号密码，然后提交表单，查询数据库，从而实现登录功能。
1、配置文件，导入jar包
2、创建数据库环境
use student;
create table user(
id int primary key auto_increment,
username varchar(32),
password varchar(32)
);
insert into user values(null,'zhangsan','123');
insert into user values(null,'lisi','234');
3、在web目录下创建html页面
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>登录页面</title>
</head>
<body>
<form action="/day14_request/loginservlet" method="post">
用户名：<input type="text" name="username"><br>
密码：<input type="password" name="password"><br>
<input type="submit" value="登录">
</form>
</body>
</html>
4、在src下编写druid.properties文件
driverclassname=com.mysql.jdbc.driver url=jdbc:mysql://localhost:3306/student username=root password=root maxactive=10 maxwait=1000
5、创建包cn.itcast.domain，创建类user
package cn.itcast.domain;
/*
用户的实体类
*/
public class user {
private int id;
private string username;
private string password;
public int getid() {
return id;
}
public void setid(int id) {
this.id = id;
}
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;
}
@override
public string tostring() {
return "user{" +
"id=" + id +
", username='" + username + '\'' +
", password='" + password + '\'' +
'}';
}
}
6、创建包cn.itcast.util，编写工具类jdbcutils
package cn.itcast.util;
import com.alibaba.druid.pool.druiddatasourcefactory;
import javax.sql.datasource;
import java.io.ioexception;
import java.io.inputstream;
import java.sql.connection;
import java.sql.sqlexception;
import java.util.properties;
/*
jdbc工具类，使用durid连接池
*/
public class jdbcutils {
private static datasource datasource;
static {
try {
//1、加载配置文件
properties properties = new properties();
inputstream resourceasstream = jdbcutils.class.getclassloader().getresourceasstream("druid.properties");
properties.load(resourceasstream);
//2、初始化连接池对象
datasource = druiddatasourcefactory.createdatasource(properties);
} catch (ioexception e) {
e.printstacktrace();
} catch (exception e) {
e.printstacktrace();
}
}
/**
* 获取连接池对象
*/
public static datasource getdatasource() {
return datasource;
}
/**
* 获取连接connection对象
*/
public static connection getconnection() throws sqlexception {
return datasource.getconnection();
}
}
7、创建包cn.itcast.dao，创建类userdao，提供login方法
package cn.itcast.dao;
import cn.itcast.domain.user;
import cn.itcast.util.jdbcutils;
import org.springframework.dao.dataaccessexception;
import org.springframework.jdbc.core.beanpropertyrowmapper;
import org.springframework.jdbc.core.jdbctemplate;
/**
* 操作数据库中user表的类
*/
public class userdao {
//声明jdbctemplate对象共用
private jdbctemplate jdbctemplate = new jdbctemplate(jdbcutils.getdatasource());
/**
* 登录方法
* @param loginuser 只有用户和密码
* @return user 包含用户全部信息，没有查询到，返回null
*/
public user login(user loginuser) {
try {
//1、编写sql
string sql = "select * from user where username = ? and password = ?";
//2、调用query方法
user user = jdbctemplate.queryforobject(sql,
new beanpropertyrowmapper<user>(user.class),
loginuser.getusername(),loginuser.getpassword());
return user;
} catch (dataaccessexception e) {
e.printstacktrace();//记录日志
return null;
}
}
}
8、编写cn.itcast.web.servlet.loginservlet类
package cn.itcast.web.servlet;
import cn.itcast.dao.userdao;
import cn.itcast.domain.user;
import org.apache.commons.beanutils.beanutils;
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 java.io.ioexception;
import java.lang.reflect.invocationtargetexception;
import java.util.map;
@webservlet("/loginservlet")
public class loginservlet extends httpservlet {
protected void dopost(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {
//1、设置编码
request.setcharacterencoding("utf-8");
/*//2、获取请求参数
string username = request.getparameter("username");
string password = request.getparameter("password");
//3、封装对象
user loginuser = new user();
loginuser.setusername(username);
loginuser.setpassword(password);*/
//2、获取所有请求参数(这里使用beanutils来简化操作)
map<string, string[]> parametermap = request.getparametermap();
//3.1 创建user对象
user loginuser = new user();
//3.2 使用beanutils对象
try {
beanutils.populate(loginuser,parametermap);
} catch (illegalaccessexception e) {
e.printstacktrace();
} catch (invocationtargetexception e) {
e.printstacktrace();
}
//4、调用userdao的login方法
userdao userdao = new userdao();
user user = userdao.login(loginuser);
//5、判断user
if (user == null) {
//登录失败
request.getrequestdispatcher("/failservlet").forward(request,response);
} else {
//登录成功
//存储数据
request.setattribute("user",user);
//转发
request.getrequestdispatcher("/successservlet").forward(request,response);
}
}
protected void doget(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {
this.dopost(request,response);
}
}
运行结果：
1、目录结构
2、运行界面
3、输入用户名密码均正确
4、跳转到成功登录界面
5、输入用户名或密码错误时
6、跳转登录失败界面
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