小黑子—JavaWeb：第四章 Request与Response-Toy模板网

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1. Request(请求)& Response (响应)

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

2. Request

2.1 Request 继承体系

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

Tomcat需要解析请求数据，封装为request对象，并且创建request对象传递到service方法中
使用request对象，查阅JavaEE API文档的 HttpServletRequest 接口

2.2 Request 获取请求数据

请求数据分为3部分：

1、请求行： 小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

String getMethod()：获取请求方式：GET
String getContextPath()：获取虚拟目录(项目访问路径):/request-demo
StringBuffer getRequestURL():获取URL(统一资源定位符)：http://localhost:8080/request-demo/req1
String getRequestURI()：获取URI(统一资源标识符)： /request-demo/req1
String getQueryString()：获取请求参数(GET方式): username=zhangsan&password=123

案例：

@WebServlet("/req1")
public class RequestDemo1 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String method = req.getMethod();
        System.out.println(method);

        String contextPath = req.getContextPath();
        System.out.println(contextPath);

        StringBuffer url = req.getRequestURL();
        System.out.println(url);

        String uri = req.getRequestURI();
        System.out.println(uri);

        String queryString = req.getQueryString();
        System.out.println(queryString);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

    }
}

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

2、请求头：
小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

String getHeader(String name)：根据请求头名称，获取值

@WebServlet("/req1")
public class RequestDemo1 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String method = req.getMethod();
        System.out.println(method);

        String contextPath = req.getContextPath();
        System.out.println(contextPath);

        StringBuffer url = req.getRequestURL();
        System.out.println(url);

        String uri = req.getRequestURI();
        System.out.println(uri);

        String queryString = req.getQueryString();
        System.out.println(queryString);

        //获取请求头：uer-getHeader：浏览器的版本信息
        String agent = req.getHeader("user-agent");
        System.out.println(agent);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

    }
}

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

3、请求体：
小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

ServletInoutStream getInputStream()：获取字节输入流
BufferedReader getReader()：获取字符输入流

案例：
RequestDemo1类：

@WebServlet("/req1")
public class RequestDemo1 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String method = req.getMethod();
        System.out.println(method);

        String contextPath = req.getContextPath();
        System.out.println(contextPath);

        StringBuffer url = req.getRequestURL();
        System.out.println(url);

        String uri = req.getRequestURI();
        System.out.println(uri);

        String queryString = req.getQueryString();
        System.out.println(queryString);

        //获取请求头：uer-getHeader：浏览器的版本信息
        String agent = req.getHeader("user-agent");
        System.out.println(agent);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //获取post 请求体：请求参数

        //1.获取字符输入流
        BufferedReader br = req.getReader();//该流会自动关闭

        //2.读取数据
        String line = br.readLine();
        System.out.println(line);
    }
}

req.html：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="/request_demo_war/req1" method="post">
    <input type="text" name="username">
    <input type="password" name="password">
    <input type="submit">
</form>
</body>
</html>

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

2.2.1 通用方式获取请求参数

请求参数获取方式：

GET 方式：

String getQueryString()

POST 方式：

BufferedReader getReader()

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

思考：
GET请求方式和POST请求方式区别主要在于获取请求参数的方式不一样，是否可以提供一种统一获取请求参数的方式，从而统一doGet和doPost方法内的代码？

Map<String, String[ ]> getParameterMap()：获取所有参数Map集合

String[ ] getParameterValues(String name)︰根据名称获取参数值（数组)

String getParameter(String name)：根据名称获取参数值（单个值)

案例：
RequestDemo2类：

package com.itheima.web;

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.BufferedReader;
import java.io.IOException;
import java.util.Map;

@WebServlet("/req2")
public class RequestDemo2 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //get请求逻辑

//        System.out.println("get....");

        //1.获取所有参数的map集合
        Map<String, String[]> map = req.getParameterMap();
        for (String key : map.keySet()) {
            //比如：username:zhangsan
            System.out.print(key+":");

            //获取value值
            String[] values = map.get(key);
            for (String value : values) {
                System.out.print(value+" ");
            }
            System.out.println();
        }
        System.out.println("----------------------------");

        //2.根据key获取参赛值，数组
        String[] hobbies = req.getParameterValues("hobby");
        for (String hobby : hobbies) {
            System.out.println(hobby);
        }

        //3.根据key 获取单个参数值
        String username = req.getParameter("username");
        String password = req.getParameter("password");
        System.out.println(username);
        System.out.println(password);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //获取post 请求体：请求参数
        this.doGet(req,resp);//一样法典复用即可
//        System.out.println("post....");
//
//        //1.获取所有参数的map集合
//        Map<String, String[]> map = req.getParameterMap();
//        for (String key : map.keySet()) {
//            //比如：username:zhangsan
//            System.out.print(key+":");
//
//            //获取value值
//            String[] values = map.get(key);
//            for (String value : values) {
//                System.out.print(value+" ");
//            }
//            System.out.println();
//        }
//        System.out.println("----------------------------");
//
//        //2.根据key获取参赛值，数组
//        String[] hobbies = req.getParameterValues("hobby");
//        for (String hobby : hobbies) {
//            System.out.println(hobby);
//        }
//
//        //3.根据key 获取单个参数值
//        String username = req.getParameter("username");
//        String password = req.getParameter("password");
//        System.out.println(username);
//        System.out.println(password);

    }
}

html：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="/request_demo_war/req2" method="get">
    <input type="text" name="username"><br>
    <input type="password" name="password"><br>
    <input type="checkbox" name="hobby" value="1">游水
    <input type="checkbox" name="hobby" value="2">开冲<br>
    <input type="submit">
</form>
</body>
</html>

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

2.2.2 IDEA模板创建Servlet

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

便捷创建
在设置里面的代码样式下>文件和代码模板：自定义快捷修改

2.2.3 请求参数中文乱码处理

URL编码

将字符串按照编码方式转为二进制
每个字节转为2个16进制数并在前边加上%

演示UTF编码转换：

public class URLDemo {
    public static void main(String[] args) throws UnsupportedEncodingException {
        String username = "张三";

        //1.URL编码
        String encode = URLEncoder.encode(username, "utf-8");
        System.out.println(encode);

        //2.URL编码
        String decode = URLDecoder.decode(encode, "utf-8");
        String decode2 = URLDecoder.decode(encode, "ISO-8859-1");//å¼ ä¸‰
        System.out.println(decode);
    }
}

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

解决思路：

package com.itheima.web;

import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;

public class URLDemo {
    public static void main(String[] args) throws UnsupportedEncodingException {
        String username = "张三";

        //1.URL编码
        String encode = URLEncoder.encode(username, "utf-8");
        System.out.println(encode);

        //2.URL编码
        String decode = URLDecoder.decode(encode, "ISO-8859-1");//å¼ ä¸‰
        System.out.println(decode);

        //3.转换为字节数据，编码过程
        byte[] bytes = decode.getBytes("ISO-8859-1");

        //4.将字节数组转换为字符串，解码过程
        String s = new String(bytes, "utf-8");
        System.out.println(s);
    }
}

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

2.2.3 - I POST解决方案

请求参数如果存在中文数据，则会乱码
解决方案:

POST：设置输入流的编码

request.setCharacterEncoding("UTF-8");

案例：

@WebServlet("/req4")
public class RequestDemo4 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1.解决乱码：POST getReader()
        request.setCharacterEncoding("UTF-8");//设置字符输入流的参数

        //2.获取username
        String username = request.getParameter("username");
        System.out.println(username);

    }

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

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

2.2.3 - II GET解决方案

@WebServlet("/req4")
public class RequestDemo4 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1.解决乱码：POST getReader()
        request.setCharacterEncoding("UTF-8");//设置字符输入流的参数

        //2.获取username
        String username = request.getParameter("username");
        System.out.println("解决乱码前："+username);

        //3.GET 获取参数的方式：getQueryString
        //乱码原因：tomcat进行URL解码时，默认的字符集ISO-8859-1
        //3.1 先对乱码数据进行解码：转为字节数组
//        byte[] bytes = username.getBytes(StandardCharsets.ISO_8859_1);

        //3.2 字节数组解码
        username = new String(username.getBytes(StandardCharsets.ISO_8859_1),StandardCharsets.UTF_8);
        System.out.println("解决乱码后："+username);
    }

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

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

小结：

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

2.3 Request 请求转发

请求转发（forward）：一种在服务器内部的资源跳转方式
小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

实现方式：

req.getRequestDispatcher("资源B路径").forward(req,resp);

案例：
RequestDemo5类：

@WebServlet("/req5")
public class RequestDemo5 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("demo5...");

        //请求转发
        request.getRequestDispatcher("/req6").forward(request,response);
    }

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

RequestDemo6类：

@WebServlet("/req6")
public class RequestDemo6 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("Demo6....");
    }

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

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

请求转发资源共享数据：使用Request对象

- void setAttribute(String name, Object o)：存储数据到request域中
- Object getAttribute(String name)：根据key，获取值
- void removeAttribute(String name)：根据key，删除该键值对

案例：

@WebServlet("/req5")
public class RequestDemo5 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("demo5...");

        //存储数据
        request.setAttribute("msg","helloworld");

        //请求转发
        request.getRequestDispatcher("/req6").forward(request,response);
    }

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

@WebServlet("/req6")
public class RequestDemo6 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("Demo6....");

        //获取数据
        Object msg = request.getAttribute("msg");
        System.out.println(msg);
    }

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

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

请求转发的特点：

浏览器地址栏路径不发生变化
只能转发到当前服务器的内部资源
一次请求，可以在转发的资源间使用request共享数据

3. Response

3.1 Response 设置响应数据功能

响应数据分为3部分:
1、响应行:HTTP/1.1 200 oK

void setStatus(int sc)∶设置响应状态码

2、响应头: Content-Type: text/html

void setHeader(String name,String value)∶设置响应头键值对

3、响应体: <html><head>head><body></body></html>

PrintWriter getWriter():获取字符输出流
ServletOutputStream getOutputStream():获取字节输出流

3.2 Response 完成重定向

重定向（Redirect）：一种资源跳转方式

案例：
ResponseDemo1类：

@WebServlet("/resp1")
public class ResponseDemo1 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("resp1......");

        //重定向
        //1.设置响应状态码302
        response.setStatus(302);
        //2.设置响应头 Location
//        response.setHeader("Location","/request_demo_war/resp2"); request_demo_war为自己的启动目录

        //简化方式完成重定向
        response.sendRedirect("/request_demo_war/resp2");
    }

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

ResponseDemo2类：

@WebServlet("/resp2")
public class ResponseDemo2 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("resp2......");
    }

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

重定向特点：
- 浏览器地址栏路径发生变化
- 可以重定向到在意位置的资源（服务器内部、外部均可)
- 两次请求，不能在多个资源使用request共享数据

对比：
小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

3.2.1 资源路径问题

明确路径谁使用?

浏览器使用:需要加虚拟目录(项目访问路径)
服务端使用:不需要加虚拟目录

例如：

@WebServlet("/resp1")
public class ResponseDemo1 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("resp1......");

        //重定向
        //1.设置响应状态码302
        response.setStatus(302);
        //2.设置响应头 Location
//        response.setHeader("Location","/request_demo_war/resp2"); request_demo_war为自己的启动目录

        //简化方式完成重定向
        //动态获取虚拟目录
        String contextPath = request.getContextPath();

        response.sendRedirect(contextPath+"/resp2");
    }

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

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

3.3 Response 响应字符数据

使用：

通过Response对象获取字符输出流

PrintWriter writer = resp.getWriter();

写数据

writer.write("aaa");

例子：

@WebServlet("/resp3")
public class ResponseDemo3 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //设置流中文编码
        response.setContentType("text/html;charset=utf-8");

        //1.获取字符输入流
        PrintWriter writer = response.getWriter();

        //content-type 识别html标签
//        response.setHeader("content-type","text/html");

        writer.write("你吗的");
        writer.write("<h1>aaaa</h1>");

    }

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

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

注意:

该流不需要关闭，随着响应结束，response对象销毁，由服务器关闭

中文数据乱码:原因通过Response获取的字符输出流默认编码:ISO-8859-1

resp.setContentType("text/html;charset=utf-8");

3.4 Response 响应字节数据

使用:

通过Response对象获取字符输出流

ServletOutputStream outputStream = resp.getOutputStream();

写数据

outputStream.write(字节数据);

例子：

@WebServlet("/resp4")
public class ResponseDemo4 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1.读取文件
        FileInputStream fis = new FileInputStream("F://常用文件夹//图片//Saved Pictures//1.jpg");
        //2.获取response字节输出流
        ServletOutputStream os = response.getOutputStream();

        //3.完成流的copy
        byte[] buff = new byte[1024];
        int len = 0;
        while ((len = fis.read(buff))!=-1){
            os.write(buff,0,len);
        }

        fis.close();

    }

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

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

但是将来不用写完成copy流的步骤了，太麻烦，一般会采用工具类

lOUtils工具类使用
导入坐标

<dependency>
	<groupld>commons-io</groupld>
	<artifactld>commons-io</artifactld>
	<versign>2.6</version>
</dependency>

使用：

IOUtils.copy(输入流,输出流);

例如：
小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

4. Request与Response 案例

4.1 用户登录

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

4.1.1 环境准备

环境准备
小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet
静态页面：

css代码：
- login

* {
    margin: 0;
    padding: 0;
}

html {
    height: 100%;
    width: 100%;
    overflow: hidden;
    margin: 0;
    padding: 0;
    background: url(../imgs/Desert.jpg) no-repeat 0px 0px;
    background-repeat: no-repeat;
    background-size: 100% 100%;
    -moz-background-size: 100% 100%;
}

body {
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100%;
}

#loginDiv {
    width: 37%;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 300px;
    background-color: rgba(75, 81, 95, 0.3);
    box-shadow: 7px 7px 17px rgba(52, 56, 66, 0.5);
    border-radius: 5px;
}

#name_trip {
    margin-left: 50px;
    color: red;
}

p {
    margin-top: 30px;
    margin-left: 20px;
    color: azure;
}

input {
    margin-left: 15px;
    border-radius: 5px;
    border-style: hidden;
    height: 30px;
    width: 140px;
    background-color: rgba(216, 191, 216, 0.5);
    outline: none;
    color: #f0edf3;
    padding-left: 10px;
}
#username{
    width: 200px;
}
#password{
    width: 202px;
}
.button {
    border-color: cornsilk;
    background-color: rgba(100, 149, 237, .7);
    color: aliceblue;
    border-style: hidden;
    border-radius: 5px;
    width: 100px;
    height: 31px;
    font-size: 16px;
}

#subDiv {
    text-align: center;
    margin-top: 30px;
}
#loginMsg{
    text-align: center;color: aliceblue;
}

- register：

* {
    margin: 0;
    padding: 0;
    list-style-type: none;
}
.reg-content{
    padding: 30px;
    margin: 3px;
}
a, img {
    border: 0;
}

body {
    background-image: url("../imgs/reg_bg_min.jpg") ;
    text-align: center;
}

table {
    border-collapse: collapse;
    border-spacing: 0;
}

td, th {
    padding: 0;
    height: 90px;

}
.inputs{
    vertical-align: top;
}

.clear {
    clear: both;
}

.clear:before, .clear:after {
    content: "";
    display: table;
}

.clear:after {
    clear: both;
}

.form-div {
    background-color: rgba(255, 255, 255, 0.27);
    border-radius: 10px;
    border: 1px solid #aaa;
    width: 424px;
    margin-top: 150px;
    margin-left:1050px;
    padding: 30px 0 20px 0px;
    font-size: 16px;
    box-shadow: inset 0px 0px 10px rgba(255, 255, 255, 0.5), 0px 0px 15px rgba(75, 75, 75, 0.3);
    text-align: left;
}

.form-div input[type="text"], .form-div input[type="password"], .form-div input[type="email"] {
    width: 268px;
    margin: 10px;
    line-height: 20px;
    font-size: 16px;
}

.form-div input[type="checkbox"] {
    margin: 20px 0 20px 10px;
}

.form-div input[type="button"], .form-div input[type="submit"] {
    margin: 10px 20px 0 0;
}

.form-div table {
    margin: 0 auto;
    text-align: right;
    color: rgba(64, 64, 64, 1.00);
}

.form-div table img {
    vertical-align: middle;
    margin: 0 0 5px 0;
}

.footer {
    color: rgba(64, 64, 64, 1.00);
    font-size: 12px;
    margin-top: 30px;
}

.form-div .buttons {
    float: right;
}

input[type="text"], input[type="password"], input[type="email"] {
    border-radius: 8px;
    box-shadow: inset 0 2px 5px #eee;
    padding: 10px;
    border: 1px solid #D4D4D4;
    color: #333333;
    margin-top: 5px;
}

input[type="text"]:focus, input[type="password"]:focus, input[type="email"]:focus {
    border: 1px solid #50afeb;
    outline: none;
}

input[type="button"], input[type="submit"] {
    padding: 7px 15px;
    background-color: #3c6db0;
    text-align: center;
    border-radius: 5px;
    overflow: hidden;
    min-width: 80px;
    border: none;
    color: #FFF;
    box-shadow: 1px 1px 1px rgba(75, 75, 75, 0.3);
}

input[type="button"]:hover, input[type="submit"]:hover {
    background-color: #5a88c8;
}

input[type="button"]:active, input[type="submit"]:active {
    background-color: #5a88c8;
}
.err_msg{
    color: red;
    padding-right: 170px;
}
#password_err,#tel_err{
    padding-right: 195px;
}

#reg_btn{
    margin-right:50px; width: 285px; height: 45px; margin-top:20px;
}

imgs图片

HTML部分：

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>login</title>
    <link href="css/login.css" rel="stylesheet">
</head>

<body>
<div id="loginDiv">
    <form action="" id="form">
        <h1 id="loginMsg">LOGIN IN</h1>
        <p>Username:<input id="username" name="username" type="text"></p>

        <p>Password:<input id="password" name="password" type="password"></p>

        <div id="subDiv">
            <input type="submit" class="button" value="login up">
            <input type="reset" class="button" value="reset">&nbsp;&nbsp;&nbsp;
            <a href="register.html">没有账号？点击注册</a>
        </div>
    </form>
</div>

</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>欢迎注册</title>
    <link href="css/register.css" rel="stylesheet">
</head>
<body>

<div class="form-div">
    <div class="reg-content">
        <h1>欢迎注册</h1>
        <span>已有帐号？</span> <a href="login.html">登录</a>
    </div>
    <form id="reg-form" action="#" method="get">

        <table>

            <tr>
                <td>用户名</td>
                <td class="inputs">
                    <input name="username" type="text" id="username">
                    <br>
                    <span id="username_err" class="err_msg" style="display: none">用户名不太受欢迎</span>
                </td>

            </tr>

            <tr>
                <td>密码</td>
                <td class="inputs">
                    <input name="password" type="password" id="password">
                    <br>
                    <span id="password_err" class="err_msg" style="display: none">密码格式有误</span>
                </td>
            </tr>


        </table>

        <div class="buttons">
            <input value="注 册" type="submit" id="reg_btn">
        </div>
        <br class="clear">
    </form>

</div>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="/request_demo_war/req4" method="get">
    <input type="text" name="username"><br>
    <input type="password" name="password"><br>
    <input type="checkbox" name="hobby" value="1">游水
    <input type="checkbox" name="hobby" value="2">开冲<br>
    <input type="submit">
</form>
</body>
</html>

mybatis环境：
小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

数据库创建：
pojo下的User.java

package com.itheima.pojo;

public class User {

    private Integer id;
    private String username;
    private String password;

    public Integer getId() {
        return id;
    }

    public void setId(Integer 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 + '\'' +
                '}';
    }
}

mybatis-config.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.dorg/dt/mybatis-3-config.dtd">
<configuration>
    <!--起别名-->
    <typeAliases>
        <package name="com.itheima.pojo"/>
    </typeAliases>

    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql:///db1?useSSL=false&amp;useServerPrepStmts=true"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <!--扫描mapper-->
        <package name="com.itheima.mapper"/>
    </mappers>
</configuration>

UserMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.itheima.mapper.UserMapper">

</mapper>

4.1.2 代码实现

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

核心配置文件：端口自行设置，如果端口被有的站点站了，那么后面网页登录提交后会报500错误

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>org.example</groupId>
  <artifactId>request-demo</artifactId>
  <version>1.0-SNAPSHOT</version>

  <packaging>war</packaging>

  <properties>
    <maven.compiler.source>17</maven.compiler.source>
    <maven.compiler.target>17</maven.compiler.target>
  </properties>

  <dependencies>
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.1.0</version>
      <scope>provided</scope>
    </dependency>

    <dependency>
      <groupId>commons-io</groupId>
      <artifactId>commons-io</artifactId>
      <version>2.6</version>
    </dependency>

    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.5.5</version>
    </dependency>

    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>8.0.30</version>
    </dependency>

  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.tomcat.maven</groupId>
        <artifactId>tomcat7-maven-plugin</artifactId>
        <version>2.2</version>

        <configuration>
          <port>85</port>
        </configuration>
      </plugin>
    </plugins>
  </build>

</project>

UserMapper.java:

package com.itheima.mapper;

import com.itheima.pojo.User;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;

public interface UserMapper {

    /*
    根据用户名和密码查询用户对象
     */
    @Select("select * from tb_user where username = #{username} and password = #{password}")
    User select(@Param("username") String username,@Param("password") String password);
}

loginServlet：

@WebServlet("/loginServlet")
public class loginServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1.接收用户名和密码
        String username = request.getParameter("username");
        String password = request.getParameter("password");

        //2.调用mybatis完成查询
        //2.1 获取SqlSessionFactory对象
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2.2 获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //2.3 获取Mapper
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

        //2.4 调用方法
        User user = userMapper.select(username, password);

        //2.5 释放资源
        sqlSession.close();

        //获取响应数据的字符输出流，并设置content type 防止乱码
        response.setContentType("text/html;charset=utf-8");
        PrintWriter Pwriter = response.getWriter();

        //3.判断user释放为null
        if (user!=null){
            // 登录成功
            Pwriter.write("登录成功");
        }else {
            // 登录失败
            Pwriter.write("登录失败");
        }
    }

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

Mavn 运行：
小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

登录成功：

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

4.2 用户注册

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

UserMapper

package com.itheima.mapper;

import com.itheima.pojo.User;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;

public interface UserMapper {

    /*
    根据用户名和密码查询用户对象
     */
    @Select("select * from tb_user where username = #{username} and password = #{password}")
    User select(@Param("username") String username,@Param("password") String password);


    /*
    根据用户名查询用户对象
     */
    @Select("select * from tb_user where username = #{username}")
    User selectByUsername(String username);

    //添加用户
    @Insert("insert into tb_user values(null,#{username},#{password})")
    void add(User user);
}

registerServlet类

@WebServlet("/registerServlet")
public class registerServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1.接收用户数据
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        //封装用户对象
        User user = new User();
        user.setUsername(username);
        user.setPassword(password);

        //2. 调用mapper 根据用户名查询用户对象
        //2.1 获取SqlSessionFactory对象
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2.2 获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //2.3 获取Mapper
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

        //2.4 调用方法
        User u = userMapper.selectByUsername(username);

        //3.判断用户对象释放是否为null
        if (u == null){
            //用户不存在，添加用户
            userMapper.add(user);
            //提交事务
            sqlSession.commit();
            //释放资源
            sqlSession.close();
        }else {
            //用户存在，给出提示信息
            response.setContentType("text/html;charset=utf-8");
            response.getWriter().write("用户名已存在");
        }
    }

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

register的html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>欢迎注册</title>
    <link href="css/register.css" rel="stylesheet">
</head>
<body>

<div class="form-div">
    <div class="reg-content">
        <h1>欢迎注册</h1>
        <span>已有帐号？</span> <a href="login.html">登录</a>
    </div>
    <form id="reg-form" action="/request-demo/registerServlet" method="post">

        <table>

            <tr>
                <td>用户名</td>
                <td class="inputs">
                    <input name="username" type="text" id="username">
                    <br>
                    <span id="username_err" class="err_msg" style="display: none">用户名不太受欢迎</span>
                </td>

            </tr>

            <tr>
                <td>密码</td>
                <td class="inputs">
                    <input name="password" type="password" id="password">
                    <br>
                    <span id="password_err" class="err_msg" style="display: none">密码格式有误</span>
                </td>
            </tr>


        </table>

        <div class="buttons">
            <input value="注 册" type="submit" id="reg_btn">
        </div>
        <br class="clear">
    </form>

</div>
</body>
</html>

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

注册成功：

4.3 SqlSessionFactory 工具类提取

创建SqlSessionFactory代码优化

小黑子—JavaWeb：第四章 Request与Response,JavaWeb,servlet

存在问题：

代码重复：工具类
SqlSessionFactory 工厂只创建一次，不要重复创建：静态代码块

案例：
在itheima下的util包创建：SqlSessionFactoryUtils类

public class SqlSessionFactoryUtils {

    private static SqlSessionFactory sqlSessionFactory;

    static {
        //静态代码块会随着类的加载而自动执行，且只执行一次
        try {
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static SqlSessionFactory getSqlSessionFactory(){
        return sqlSessionFactory;
    }
}