前后端交互
Apache Tomat
B/S目前主流。
tomat包含2部分：
- apache
- 容器
再认识servlet
抽象出的开发模式
项目创建配置
maven +javaee+tomcat
忽略一些不用的文件
webapp文件夹
HiServlet
这里面出现了webinfo，这个别删因为这个呢，是这这个这个文件特别重要。
Url–>uri(抽象)
虚拟地址——web.xml
TOmat启动前
注解版–SuperHiSevlet
*请求-响应
MyRequestServlet
HttpServletRequest
获取前端数据
request.getParameter("前端参数")
- form表单中name属性
<input name='username' value='abc'>
- a标签
<a href='localhost:8099/deep?name=abc&pass=123'
获取多个数据
获取请求方法
获取头
HttpServletRequest.class
package com.ffyc.servlet;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.Enumeration;@WebServlet(value = "/req")
public class MyRequestServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse resp) throws ServletException, IOException {String name = request.getParameter("name");String username = request.getParameter("username");System.out.println(name + ":" + username);System.out.println("------------------------------------------");String methodName = request.getMethod();System.out.println("method名称:" + methodName);String[] hobbies = request.getParameterValues("hobby");//多个数据System.out.println("爱好:" + Arrays.toString(hobbies));Enumeration<String> headerNames = request.getHeaderNames();System.out.println("----请求头----------------------");while(headerNames.hasMoreElements()){System.out.println(headerNames.nextElement());}}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {doGet(req, resp);}
}
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>测试请求</title>
</head>
<body><a href="http://localhost:8099/deep/req?name=abc">测试请求</a><hr/><form action="http://localhost:8099/deep/req" method="post"><input type="text" name="username" placeholder="请输入用户名"><input type="checkbox" name="hobby" value="basket-ball">basket-ball<input type="checkbox" name="hobby" value="TV">TV<input type="checkbox" name="hobby" value="GAME">GAME<input type="submit" value="提交">
请求乱码问题
request.setCharacterEncoding("utf-8");
过滤器–切面
过滤器–不同的功能块
配置 .xml
插在servlet之前响应
后台响应
乱码问题(HttpServletResponse)
servletRequest.setCharacterEncoding("utf-8");
servletResponse.setContentType("text/html;charset=utf-8");
filterChain.doFilter(servletRequest, servletResponse);
登录页面
过滤器
import javax.servlet.*;
import java.io.IOException;public class CodingFilter implements Filter {@Overridepublic void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {servletRequest.setCharacterEncoding("utf-8");servletResponse.setContentType("text/html;charset=utf-8");filterChain.doFilter(servletRequest, servletResponse);}
}
映射–index.html（LoginServlet.java）
《没有Web包》
代码
LoginServlet.java
package com.ffyc.servlet;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(value = "/login.do")
public class LoginServlet extends HttpServlet {final String USERNAME = "admin";final String PASSWORD = "123";@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {String username = req.getParameter("username");String password = req.getParameter("password");if (USERNAME.equals(username) && PASSWORD.equals(password)) {//successresp.sendRedirect("login-success.html");} else {//loginresp.sendRedirect("index.html");}}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {doGet(req, resp);}
}index.html
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>登录页面</title>
</head>
<body><form action="http://localhost:8099/login.do" method="post"><fieldset><legend>用户登录</legend><div><input type="text" name="username" placeholder="用户名"></div><div><input type="password" name="password" placeholder="密码"></div><div><input type="submit" value="登录"><input type="reset" value="取消"></div></fieldset>
</form></body>
</html>
login-success.html
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>登录成功页面</title>
</head>
<body><img src="https://img95.699pic.com/photo/40236/5997.jpg_wh300.jpg"/><h1>登录成功</h1></body>
</html>
CodingFilter.java
package com.ffyc.filter;import javax.servlet.*;
import java.io.IOException;public class CodingFilter implements Filter {@Overridepublic void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {servletRequest.setCharacterEncoding("utf-8");servletResponse.setContentType("text/html;charset=utf-8");filterChain.doFilter(servletRequest, servletResponse);}
}web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"version="4.0"><filter><filter-name>charset</filter-name><filter-class>com.ffyc.filter.CodingFilter</filter-class></filter><filter-mapping><filter-name>charset</filter-name><url-pattern>*.do</url-pattern></filter-mapping>
</web-app>
JDBC
引入JDBC
<dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.33</version></dependency>
创建表
创建用户类
<dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.18.34</version></dependency>
@Data
public class User {private Integer id;private String username;private String password;private String name;
}
1
private final String USERNAME="root";private final String PASSWORD = "123456";private final String URL ="jdbc:mysql://localhost:3306/kingdom_db?useSSL=true&useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai";2
try {Class.forName("com.mysql.cj.jdbc.Driver");conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);} catch (Exception e) {throw new RuntimeException(e);}
3
4
5
UserDaolmpl.java
package com.ffyc.dao.impl;import com.ffyc.dao.IUserDao;
import com.ffyc.entity.User;import java.sql.*;/*** 与数据库交互*/
public class UserDaoImpl implements IUserDao {private final String USERNAME = "root";private final String PASSWORD = "123456";private final String URL ="jdbc:mysql://localhost:3306/stu_db?useSSL=true&useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai";private Connection conn;private PreparedStatement pst;private ResultSet rs;public UserDaoImpl() {try {Class.forName("com.mysql.cj.jdbc.Driver");conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);} catch (Exception e) {throw new RuntimeException(e);}}@Overridepublic User findUsernameAndPassword(String username, String password) {try {String sql = "Select * FROM user_tab WHERE user_username=? AND user_password=?";pst = conn.prepareStatement(sql);pst.setString(1,username);pst.setString(2, password);rs = pst.executeQuery();if(!rs.next()){return null;}else{Integer id = rs.getInt("user_id");String u = rs.getString("user_username");String p = rs.getString("user_password");String name = rs.getString("user_name");User user = new User();user.setId(id);user.setUsername(u);user.setPassword(p);user.setName(name);return user;}} catch (Exception e) {throw new RuntimeException(e);}}
}
