一、http协议

1、概述

HTTP协议，全称"超文本传输协议(HyperText Transfer Protocol)"

协议版本：

- [x] HTTP/1.0，发送请求，创建一次连接，获得一个web资源，连接断开。

- [x] HTTP/1.1，发送请求，创建一次连接，获得多个web资源，连接断开。

HTTP协议的特点

基于请求/响应模型的协议。请求和响应必须成对，先有请求后有响应。

浏览器是通过请求协议将数据传递到服务器，浏览器访问服务器几种方式：，其中掌握的就是get和post方式，

下面我们使用抓包工具来分析get和post请求有何不同。

请求方式	请求说明
OPTIONS	返回服务器针对特定资源所支持的HTTP请求方法。也可以利用向Web服务器发送'*'的请求来测试服务器的功能性。
HEAD	向服务器索要与GET请求相一致的响应，只不过响应体将不会被返回。这一方法可以在不必传输整个响应内容的情况下，就可以获取包含在响应消息头中的元信息
GET	向特定的资源发出请求(a href="servlet"标签/js location.href="servlet"，在浏览器输入网址)
POST	向指定资源提交数据进行处理请求（例如提交表单或者上传文件）。数据被包含在请求体中。POST请求可能会导致新的资源的创建和/或已有资源的修改
PUT	向指定资源位置上传其最新内容
DELETE	请求服务器删除Request-URI所标识的资源
TRACE	回显服务器收到的请求，主要用于测试或诊断
CONNECT	HTTP/1.1协议中预留给能够将连接改为管道方式的代理服务器

HTTP协议的结构

请求报文：浏览器给服务器发送的请求数据的格式。请求报文主要包括：请求行 ，请求头 ，请求体 。

响应报文：服务器给客户端（浏览器）响应的报数据格式。响应报文主要包括：响应行 ，响应头 ，响应体 ；

2、浏览器抓包（重要）

方法一：浏览器抓包

打开网页按F12、我使用的是360

方案二、模拟GET和POST方式提交并抓取数据

GET提交抓取数据：

demo.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<h2>GET请求</h2>
<form action="/getServlet" method="get">
    用户名：<input type="text" name="userName" value="zhangsan" /><br>
    密码：<input type="text" name="pwd" value="123" /><br>
    <input type="submit" value="提交"/>
</form>


<h2>POST请求</h2>
<form action="postServlet" method="post">
    用户名：<input type="text" name="userName" value="zhangsan"/><br>
    密码：<input type="text" name="pwd" value="123"/><br>
    <input type="submit" value="提交"/>
</form>

</body>
</html>

java代码：

package com.sswblog.demo01;

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;

@WebServlet("/getServlet")
public class GetServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

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

    }
}

html如图

POST提交获取数据

html如上：

java代码：

package com.sswblog.demo01;

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;

@WebServlet("/postServlet")
public class GetServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

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

    }
}

3、请求报文

【请求行】

请求行位于请求报文的第一行，由：请求方式 url 协议/版本 组成

Request URL: http://localhost:8080/postServlet
Request Method: POST

【请求头】

位于请求行的下面，以键值对 的形式给服务器传递信息，有些请求头信息是非必须的。

Accept:text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8
Accept-Encoding:gzip, deflate, br
Accept-Language:zh-CN,zh;q=0.9
Cache-Control:max-age=0
Connection:keep-alive
Content-Length:25
Content-Type:application/x-www-form-urlencoded
Cookie:__guid=111872281.4307970305335101400.1535763888139.0208; JSESSIONID=01E036ABE43DC944D8BD94F70009665F
Host:localhost:8080
Origin:http://localhost:8080
Referer:http://localhost:8080/demo.html
Upgrade-Insecure-Requests:1
User-Agent:Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36

【请求体】

get请求请求体为空；post请求的请求体传递请求参数 。

userName:zhangsan
pwd:123

二、request请求数据获取

1、概述

HttpServletRequest 对象代表客户端的请求，当客户端通过HTTP协议访问服务器时，HTTP请求中的所有信息都封装在这个对象中，开发人员通过这个对象的方法，可以获得客户这些信息。

HttpServletRequest作用：

1. 获取请求行信息：请求方式，url和HTTP版本。
2. 获取请求头信息：浏览器类型，ip地址等。
3. 获取请求参数：url后面拼接的参数或者请求体中提交的参数；

2、获取数据

2.1、获取请求行信息、url、协议、版本

方法	说明
String getMethod()	获取请求方式的类型
StringBuffer getRequestURL()	获取客户端发出请求完整URL
String getRemoteAddr()	获取IP地址
String getProtocol()	获取当前协议的名称和版本

代码：

package com.sswblog.demo01;

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;

@WebServlet("/rowServlet")
public class rowServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       //获取请求行的请求方式
        String method = request.getMethod();
        System.out.println("method = " + method);
        //获取请求行的请求URL
        StringBuffer requesturl = request.getRequestURL();
        System.out.println("requesturl = " + requesturl);
        //获取请求行的IP
        String getaddr = request.getRemoteAddr();
        System.out.println("getaddr = " + getaddr);
        //获取请求行的协议版本号
        String getprotocol = request.getProtocol();
        System.out.println("getprotocol = " + getprotocol);
    }
}

2.2、获取请求头信息

请求头是以 键值对 组成的

方法	作用
String getHeader(String name)	根据请求头的k关键字获取请求头信息
Enumeration getHeaderNames()	返回此请求包含的所有头信息的枚举

请求头以键关键字如下表所示：

请求头key	请求头value
referer	浏览器通知服务器，当前请求来自何处,如果是直接访问，则不会有这个头。常用于：防盗链
If-modified-Since	浏览器通知服务器，本地缓存的最后变更时间。与另一个响应头组合控制浏览器页面的缓存。
cookie	与会话有关技术，用于存放浏览器缓存的cookie信息。
user‐agent	浏览器通知服务器，客户端浏览器与操作系统相关信息
connection	保持连接状态。Keep-Alive 连接中，close 已关闭
host	请求的服务器主机名
content-length	请求体的长度
content-type	如果是POST请求，会有这个头，默认值为application/x-www-form-urlencoded，表示请求体内容使用url编码
accept	浏览器可支持的MIME类型。文件类型的一种描述方式。
mime格式	浏览器请求数据的类型，例如： text/html ，html文件 text/css，css文件 text/javascript，js文件 image/*，所有图片文件
accept-encoding	浏览器通知服务器，浏览器支持的数据压缩格式。如：GZIP压缩
accept-language	浏览器通知服务器，浏览器支持的语言。各国语言（国际化i18n）

演示：

package com.sswblog.demo01;

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.util.Enumeration;

@WebServlet("/headerServlet")
public class HeaderServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取user-agent对应的value值
        String header = request.getHeader("user-agent");
        System.out.println("header = " + header);
        System.out.println("-------------");
        //获取所有请求key信息
        Enumeration<String> headerNames = request.getHeaderNames();
        while (headerNames.hasMoreElements()){
            System.out.println(headerNames.nextElement());
        }
    }
}

2.3、获取请求体

get请求：get请求提交的数据是拼接在url后面的，如下图所示：

post请求：post请求的数据是在请求体中发送到后台的：

【请求体】
username: lisi
password: 1234

2.4、获取请求参数的方法：

方法名	描述
String getParameter(String name)	getParameter获得指定参数名对应的值。如果没有返回null，如果只有多个获得第一个。例如：username=jack
String[] getParameterValues(name)	getParameterValues[] 获取请求数据key相同的多个数据
request.getParameterMap();	获得所有表单的数据

演示：

demo1.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="requestServlet" method="post">

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

    密码：<input type="text" name="password"/><br/>

    爱好：<input type="checkbox" name="hobby"value="smoking"/> 抽烟

    <input type="checkbox" name="hobby"value="drinking"/> 喝酒

    <input type="checkbox" name="hobby" value="tangtou"/> 烫头  <br/>

    学历：<select name="education">

    <option value="gaozhong">高中</option>

    <option value="dazhuan">大专</option>

    <option value="benke">本科</option>

</select><br>

    <input type="submit"value="post提交" />
</form>
</body>
</html>

Java代码：

package com.sswblog.demo01;

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.util.Arrays;
import java.util.Map;

@WebServlet("/requestServlet")
public class RequestServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取用户名
        String username = request.getParameter("username");
        System.out.println("username = " + username);

        String password = request.getParameter("password");
        System.out.println("password = " + password);

        //请求爱好
        String[] hobby = request.getParameterValues("hobby");
        System.out.println(Arrays.toString(hobby));

        //获取表单所有信息
        Map<String, String[]> maps = request.getParameterMap();

        for (String[]  map : maps.values()){
            System.out.println(Arrays.toString(map));
        }
    }
}

三、request作用域

1、request生命周期

【一次请求和响应的完整流程】
1、浏览器向servlet发送请求
2、tomcat收到请求后，创建Request和Response两个对象，并将请求数据封装到request对象中，然后传递给Servlet
3、Servlet接收到请求后，调用doget或者dopost方法。处理浏览器的请求信息，然后通过Response返回信息
4、tomcat接收到返回的信息，返回给浏览器。
5、浏览器接收到返回消息后，tomcat销毁Request和Response两个对象，同时销毁这两个对象所获得的信息。

2、request域对象（重要）

request域对象,一个存储数据的区域对象.是把request当成一个容器来存储数据，request域存储数据主要是用于在两个servlet之间传递数据。request作为域对象，常用的方法如下

方法	说明
void setAttribute(String name, Object o)	往request域中设置值
Object getAttribute(String name)	从request域中取值
void removeAttribute(String name)	从request域中移除值

演示：

student类

package com.sswblog.demo01;

public class Student {
    private int id;
    private String name;
    private String password;

    public Student(String name, String password) {
        this.name = name;
        this.password = password;
    }

    public Student() {
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "Student{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

Java代码：

package com.sswblog.demo01;

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;

@WebServlet("/valueServlet")
public class ValueServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        Student student1 = new Student("zhansan","1234");

        //向request存储值
        request.setAttribute("msg","王五");
        request.setAttribute("student",student1);

        //获取值
        String msg = (String)request.getAttribute("msg");
        System.out.println("msg = " + msg);

        //移除request值
        request.removeAttribute("msg");

        if (null == request.getAttribute("msg")){
            System.out.println("没有获取到值");
        }

        Student student = (Student)request.getAttribute("student");
        System.out.println("student = " + student);
    }
}

3、请求转发（重要）

请求转发：在Servlet中。请求也可以从一个Servlet发起，然后请求到另一个Servlet或静态页面。

方法	说明
RequestDispatcher getRequestDispatcher(String path)	获取请求转发器（request对象方法）
void forward(ServletRequest request, ServletResponse response)	将请求转发到另一个资源（Servlet）上

演示一：从一个aServlet转发到bServlet

aServlet代码：

package com.sswblog.demo01;

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;

@WebServlet("/aServlet")
public class AServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setAttribute("msg","张三");
        request.getRequestDispatcher("/bServlet").forward(request,response);
    }
}

bServlet代码：

package com.sswblog.demo01;

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;

@WebServlet("/bServlet")
public class BServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String msg = (String) request.getAttribute("msg");
        System.out.println("msg = " + msg);
    }
}

回车后，aServlet会转发到bServlet，我们可以从bServlet中获取域对象中的数据，查看控制台：

演示二：从一个Servlet转发到dispatcher.html

dispatcher.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h1>转发到html静态资源</h1>
</body>
</html>

java代码：

package com.sswblog.demo01;

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;

@WebServlet("/aServlet")
public class AServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

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

        request.getRequestDispatcher("/dispatcher.html").forward(request,response);
    }
}

浏览器访问：

四、登录案例

1、需求

完成一个完整的从前端到后台的登录案例

开发准备：

2、开发步骤：

1、新建数据库
2、前端js html css web文件夹
3、新建包 web  service dao domain/entity utils
4、导入配置文件 c3p0-config.xml
5、导入jar包
6、启动tomcat查看页面和测试数据库连接

3、业务逻辑图：

4、用户登录实现

4.1、数据库设计

DROP TABLE IF EXISTS `t_user`;
CREATE TABLE `t_user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(20) NOT NULL,
  `password` varchar(32) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of t_user
-- ----------------------------
INSERT INTO `t_user` VALUES ('1', 'zhangsan', '123456');
INSERT INTO `t_user` VALUES ('2', 'lisi', '123456');
INSERT INTO `t_user` VALUES ('3', 'wangwu', '123456');
INSERT INTO `t_user` VALUES ('4', 'zhaoliu', '123456');

4.2、登录页面

login.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>登录页面</title>

    <link href="css/bootstrap.min.css" rel="stylesheet">
    <link href="css/login.css" rel="stylesheet">
    <script src="js/jquery.js"></script>
    <script src="js/bootstrap.js"></script>
</head>
<body>

    <div class="container text-center">
        <form class="form-signin" action="http://localhost:8080/loginServlet">
            <h2 class="form-signin-heading">登录页面</h2>
            <input type="email"  name="username" class="form-control" placeholder="用户名" required autofocus>
            <input type="password"  name="password" class="form-control" placeholder="密码" required>
            <button class="btn btn-lg btn-primary btn-block" type="submit">登录</button>
        </form>
    </div>

</body>
</html>

error.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <h1>用户名或密码错误，请重新登录！</h1>
</body>
</html>

success.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <h1>登录成功！</h1>
</body>
</html>

4.3、后台环境

在src下创建如下包：

com.heima.login.web
com.heima.login.service
com.heima.login.dao
com.heima.login.bean
com.heima.login.utils

在WEB-INF目录下新建lib包、将jar包导入、并添加到library中、如下图：

4.4、工具类和c3p0-config.xml

创建JDBCUtils工具类、c3p0-config.xml复制到src目录下。代码如下

package com.sswblog.login.utils;

import com.mchange.v2.c3p0.ComboPooledDataSource;
import org.springframework.jdbc.core.JdbcTemplate;

public class JDBCUtils {
    private static ComboPooledDataSource dataSource = null;
    private static JdbcTemplate jdbcTemplate = null;

    static {
       dataSource = new ComboPooledDataSource();
    }
    public static JdbcTemplate getJdbcTemplate(){
         jdbcTemplate = new JdbcTemplate(dataSource);
        return jdbcTemplate;
    }
}

c3p0-config.xml

<c3p0-config>
    <default-config>
        <property name="driverClass">com.mysql.jdbc.Driver</property>
        <property name="jdbcUrl">jdbc:mysql://localhost:3306/db1</property>
        <property name="user">root</property>
        <property name="password">sswqzx</property>
    </default-config>
</c3p0-config>

全部环境图：

5、编码

做好上面的准备后。我们就可以开始码代码了。

5.1、实体类User

package com.sswblog.login.bean;

public class User {
    private int id;
    private String username;
    private String password;
    public User(){}

    public User(int id, String username, String password) {
        this.id = id;
        this.username = username;
        this.password = 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 + '\'' +
                '}';
    }
}

5.2、web层LoginServlet

package com.sswblog.login.web;

import com.sswblog.login.service.UserService;

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;

@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //修改字符集
        request.setCharacterEncoding("utf-8");

        //得到用户名和密码
        String username = request.getParameter("username");
        String password = request.getParameter("password");

        //将用户名和密码传到service层
        UserService service = new UserService();
        boolean ulogin = service.login(username,password);

        //判断ulogin状态
        if (ulogin) {
            request.getRequestDispatcher("/success.html").forward(request,response);
        }else {
            request.getRequestDispatcher("/error.html").forward(request,response);
        }
    }
}

5.3、service层

package com.sswblog.login.service;

import com.sswblog.login.bean.User;
import com.sswblog.login.dao.UserDao;

import java.util.List;

public class UserService {
    public boolean login(String username, String password) {
        //将数据传到dao层

        UserDao  userDao = new UserDao();
        List<User> udao = userDao.login(username,password);

        if (udao.size() == 0) {
            return false;
        }else {
            return true;
        }
    }
}

5.4、Dao层代码

package com.sswblog.login.dao;

import com.sswblog.login.bean.User;
import com.sswblog.login.utils.JDBCUtils;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;

import java.util.List;

public class UserDao {
    public List<User> login(String username, String password) {
        //连接数据库返回查询数据
        JdbcTemplate jdbcTemplate = JDBCUtils.getJdbcTemplate();
        String sql = "select * from t_user where username = ? and password = ?";
        List<User> list = jdbcTemplate.query(sql, new BeanPropertyRowMapper<>(User.class), username, password);
        return list;
    }
}

效果图：

五、面向接口编程

1、编程思想

面向接口编程：面向接口意味着面向抽象，将各个实体之间的耦合程度由组件之间的耦合提升到接口层次，由接口做为粘合剂去维护关系，让一个实体由依赖另一个实体，转变成依赖一个接口，将被依赖实体的变化隔绝于接口之外。

接口就是标准规范，一种规范约束，有了标准去遵守就容易扩展！我们只需要面向标准编程，而不用针对具体的实现类！面向接口编程好处：（1）抽象；（2）高内聚，低耦合，降低开发成本/维护成本

接口

package com.sswblog.login.Test;

public interface Database {
    public abstract void getConnection();
}

实现类

package com.sswblog.login.Test;

public class Mysql implements Database {
    @Override
    public void getConnection() {
        System.out.println("mysql数据库。。。");
    }
}

实现类

package com.sswblog.login.Test;

public class Oracle implements Database {
    @Override
    public void getConnection() {
        System.out.println("oracle数据库。。。。");
    }
}

测试类

package com.sswblog.login.Test;

public class TestData {
    public static void main(String[] args) {
       // Database database = new Mysql();
        Database database = new Oracle();
        database.getConnection();
    }
}

2、用户登录代码优化

数据库同上

html代码

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>登录页面</title>

    <link href="css/bootstrap.min.css" rel="stylesheet">
    <link href="css/login.css" rel="stylesheet">
    <script src="js/jquery.js"></script>
    <script src="js/bootstrap.js"></script>
</head>
<body>

<div class="container text-center">
    <form class="form-signin" action="/loginStudentServlet" method="post">
        <h2 class="form-signin-heading">登录页面</h2>
        <input type="text"  name="username" class="form-control" placeholder="用户名" required autofocus>
        <input type="password"  name="password" class="form-control" placeholder="密码" required>
        <button class="btn btn-lg btn-primary btn-block" type="submit">登录</button>
    </form>
</div>

</body>
</html>

susscess.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h1>登录成功！</h1>
</body>
</html>

error.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <h1>用户名或密码错误，请重新登录！</h1>
</body>
</html>

JDBCUtils

package com.sswblog.login.utils;

import com.mchange.v2.c3p0.ComboPooledDataSource;
import org.springframework.jdbc.core.JdbcTemplate;

public class JDBCUtils {
    private static ComboPooledDataSource dataSource = null;
    private static JdbcTemplate jdbcTemplate = null;

    static {
       dataSource = new ComboPooledDataSource();
    }
    public static JdbcTemplate getJdbcTemplate(){
         jdbcTemplate = new JdbcTemplate(dataSource);
        return jdbcTemplate;
    }
}

c3p0-config.xml

<c3p0-config>
    <default-config>
        <property name="driverClass">com.mysql.jdbc.Driver</property>
        <property name="jdbcUrl">jdbc:mysql://localhost:3306/db1</property>
        <property name="user">root</property>
        <property name="password">sswqzx</property>
    </default-config>
</c3p0-config>

bean类Student

package com.sswblog.login.bean;

public class Student {
    private int id;
    private String username;
    private String password;

    public Student(int id, String username, String password) {
        this.id = id;
        this.username = username;
        this.password = password;
    }
    public Student(){}

    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 "Student{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

web层LoginStudentServlet

package com.sswblog.login.web;

import com.sswblog.login.service.StudentService;
import com.sswblog.login.service.StudentServiceImpl;

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;

@WebServlet("/loginStudentServlet")
public class LoginStudentServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");

        String username = request.getParameter("username");
        String password = request.getParameter("password");

        StudentService service = new StudentServiceImpl();
        boolean result = service.login(username,password);

        if (result) {
            request.getRequestDispatcher("/succes.html").forward(request,response);
        }else {
            request.getRequestDispatcher("/error.html").forward(request,response);
        }
    }
}

service层接口StudentService

package com.sswblog.login.service;

public interface StudentService {
    boolean login(String username, String password);
}

service层实现类StudentServiceImpl

package com.sswblog.login.service;

import com.sswblog.login.bean.Student;
import com.sswblog.login.dao.StudentDao;
import com.sswblog.login.dao.StudentDaoImpl;

import java.util.List;

public class StudentServiceImpl implements StudentService {
    @Override
    public boolean login(String username, String password) {
        StudentDao dao = new StudentDaoImpl();
        List<Student> studentList = dao.login(username,password);
        if (studentList.size() ==0){
            return false;
        }else {
            return true;
        }
    }
}

dao层接口StudentDao

package com.sswblog.login.dao;

import com.sswblog.login.bean.Student;

import java.util.List;

public interface StudentDao {
    List<Student> login(String username, String password);
}

Dao层实现类StudentDaoImpl

package com.sswblog.login.dao;

import com.sswblog.login.bean.Student;
import com.sswblog.login.utils.JDBCUtils;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;

import java.util.List;

public class StudentDaoImpl implements StudentDao {
    @Override
    public List<Student> login(String username, String password) {
        JdbcTemplate jdbcTemplate = JDBCUtils.getJdbcTemplate();
        String sql = "select * from t_user where username = ? and password = ?";
        List<Student> list = jdbcTemplate.query(sql, new BeanPropertyRowMapper<>(Student.class), username, password);
        return list;
    }
}

Java EE Web部分--02.http、request

一、http协议

1、概述

2、浏览器抓包（重要）

3、请求报文

二、request请求数据获取

1、概述

2、获取数据

三、request作用域

1、request生命周期

2、request域对象（重要）

3、请求转发（重要）

四、登录案例

1、需求

2、开发步骤：

3、业务逻辑图：

4、用户登录实现

5、编码

五、面向接口编程

1、编程思想

2、用户登录代码优化

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