0 JavaWeb项目目录
└──JavaWeb
├──resources
│ └──db.properties
├──src
│ └──com.sdust.web
│ ├──servlet
│ │ └──StudentServlet
│ ├──pojo
│ │ └──Student
│ └──util
│ └──JDBCUtil
├──web
│ ├──static
│ │ └──bootstrap-3.4.1-dist
│ ├──WEB-INF
│ │ ├──lib
│ │ │ └──mysql-connector-j-8.0.31.jar
│ │ └──web.xml
│ ├──index.jsp
│ └──student_list.jsp
└──JavaWeb.iml
bootstrap下载(美化包)
mysql-connector-j-8.0.31.jar
1 IDEA、Tomcat环境搭建
1.1 版本
IDEA：IntelliJ IDEA 2023.2.4
Tomcat：apache-tomcat-9.0.87官方下载地址
用IDEA进行JavaWeb的话，不需要配置Tomcat的环境变量，下载后解压就可以用了。
1.2 IDEA2023如何将项目变成Web项目
1.2.1 Help中点击Find Action
1.2.2 搜索Add Framework Support
1.2.3 勾选Web Application
1.3 配置Tomcat Server
1.3.1 点击Edit Configurations
1.3.2 点击加号，选择Tomcat Server Local
1.4 添加依赖
浏览器既可以访问JSP也可以访问Servlet，但是绝大部分情况下浏览器不直接访问JSP，JSP主要用来展示数据，
所以绝大部分情况是先访问Servlet查找出数据来之后转发到JSP页面进行展示。
2 Student类与数据库表
2.1 Student类
java
/*
* 适度编码益脑，沉迷编码伤身，合理安排时间，享受快乐生活。
* Copyright @TangXJ
* Created by TangXJ
* Created&Used date: 2024/4/2 上午11:31 ~ 2024/4/2 下午1:44
* Modified date: 2024/4/2 下午1:44
*/
package com.sdust.web.pojo;
public class Student {
private Integer id;
private String name;
private Integer age;
private String gender;
public Student() {
}
public Student(Integer id, String name, Integer age, String gender) {
this.id = id;
this.name = name;
this.age = age;
this.gender = gender;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
@Override
public String toString() {
return "Student{" +
"id=" + id +
", name='" + name + '\'' +
", age=" + age +
", gender='" + gender + '\'' +
'}';
}
}2.2 数据库student表
2.3 JDBCUtil
java
/*
* 适度编码益脑，沉迷编码伤身，合理安排时间，享受快乐生活。
* Copyright @TangXJ
* Created by TangXJ
* Created&Used date: 2024/3/27 下午4:00 ~ 2024/4/2 下午1:40
* Modified date: 2024/4/2 下午1:40
*/
package com.sdust.web.util;
import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;
public class JDBCUtil {
private static String driver;
private static String url;
private static String username;
private static String password;
private JDBCUtil(){}
//静态代码块，在类加载的时候只会执行一次，避免重复加载驱动 还没调方法就执行了
//读取配置文件
static {
try {
//1.通过当前的类获取类加载器
ClassLoader classLoader = JDBCUtil.class.getClassLoader();//反射 JVM会说 先当成固定的结论就行了
//2.通过类加载器的方法获得一个输入流
InputStream inputStream = classLoader.getResourceAsStream("db.properties");//不是因为叫了resource，是因为标识了Mark as
//3.创建一个Properties对象 对配置文件的封装
Properties properties = new Properties();
properties.load(inputStream);//配置文件
//4.获取配置文件中的参数的值
driver = properties.getProperty("driver");
url = properties.getProperty("url");
username = properties.getProperty("username");
password = properties.getProperty("password");
} catch (IOException e) {
throw new RuntimeException(e);
}
try {
Class.forName(driver);
} catch (ClassNotFoundException e) {
throw new RuntimeException(e);
}
}
public static Connection getConnection() throws SQLException {
Connection connection = DriverManager.getConnection(url, username, password);
return connection;
/*Connection connection = null;
try {
connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/study?useSSL=false&useUnicode=true&characterEncoding=utf8&serverTimezone=GMT%2b8", "root", "xiangjie");
} catch (SQLException e) {
throw new RuntimeException(e);
}
return connection;*/
}
public static void close(Connection connection, Statement statement, ResultSet resultSet) {
if (resultSet != null) {
try {
resultSet.close();
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
if (statement != null) {
try {
statement.close();
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
if (connection != null) {
try {
connection.close();
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
}
}2.4 resources/db.properties
java
driver=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/xxxx?useSSL=false&useUnicode=true&characterEncoding=utf8&serverTimezone=GMT%2b8
username=root
password=xxxxx
3 StudentServlet
java
@WebServlet("/student")
public class StudentServlet extends HttpServlet {
//默认访问service
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("StudentServlet.service");
Connection connection = null;
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
List<Student> list = new ArrayList<>();
try {
connection = JDBCUtil.getConnection();
String sql = "SELECT id,name,age,gender FROM student";
//预编译
preparedStatement = connection.prepareStatement(sql);
resultSet = preparedStatement.executeQuery();
while (resultSet.next()) {//判断下一个有没有，如果返回true而且指向下一个，没有返回false
int id = resultSet.getInt("id");
String name = resultSet.getString("name");
int age = resultSet.getInt("age");
String gender = resultSet.getString("gender");
Student student = new Student(id, name, age, gender);
list.add(student);
}
for (Student student : list) {
System.out.println(student);
}
} catch (SQLException throwables) {
throwables.printStackTrace();
} finally {
JDBCUtil.close(connection, preparedStatement, resultSet);
}
//把list数据放到req里面
req.setAttribute("list", list);
//转发到student_list.jsp页面进行展示
req.getRequestDispatcher("student_list.jsp").forward(req, resp);
}
}4 student_list.jsp
html
<%@ page import="com.situ.web.pojo.Student" %>
<%@ page import="java.util.List" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
<link rel="stylesheet" href="static/bootstrap-3.4.1-dist/css/bootstrap.css">
</head>
<body>
<%
//JSP页面中可以嵌套Java代码
//JSP脚本：在这里可以写任意的Java代码
//request、response:JSP页面的内置对象
List<Student> list = (List<Student>) request.getAttribute("list");
%>
<table class="table table-striped table-bordered table-hover table-condensed">
<tr>
<td>ID</td>
<td>名字</td>
<td>年龄</td>
<td>性别</td>
<td>编辑</td>
<td>删除</td>
</tr>
<%
for (Student student : list) {
%>
<tr>
<td><%=student.getId()%></td>
<td><%=student.getName()%></td>
<td><%=student.getAge()%></td>
<td><%=student.getGender()%></td>
<td>编辑</td>
<td>删除</td>
</tr>
<%
}
%>
</table>
</body>
</html>5 结果
6 tomcat中文乱码问题
6.1 方法一
添加一行代码-Dfile.encoding=UTF-8
添加同样的一行代码-Dfile.encoding=UTF-8
6.2 方法二
如果上面方法不管用，请先删掉加了的代码，再尝试方法二
按照路径找到logging.properties文件
有notepad++就用notepad++打开，没有记事本打开就行
把所有的UTF-8编码改成GBK，可以把原来的注释掉，方便出现其他情况时改回 。
