1. 创建 web-app 项目

导入初始4个 maven 依赖

	<dependency><groupId>javax.servlet</groupId><artifactId>javax.servlet-api</artifactId><version>3.1.0</version><scope>provided</scope></dependency><dependency><groupId>javax.servlet.jsp</groupId><artifactId>jsp-api</artifactId><version>2.2</version><scope>provided</scope></dependency><dependency><groupId>javax.servlet.jsp.jstl</groupId><artifactId>jstl-api</artifactId><version>1.2</version></dependency><dependency><groupId>taglibs</groupId><artifactId>standard</artifactId><version>1.1.2</version></dependency>

TestServlet.java

package com.beyond.nothing.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.ArrayList;
import java.util.List;@WebServlet("/test")
public class TestServlet extends HttpServlet {@Overrideprotected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {List<String> list = new ArrayList<>();list.add("张三");list.add("李四");list.add("王五");list.add("博瑞");// 将 list集合 放入request中req.setAttribute("list", list);// 转发到 test.jspreq.getRequestDispatcher("WEB-INF/jsp/test.jsp").forward(req, resp);}
}

test.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
<%--引入jstl标签库--%>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head><title>Title</title>
</head>
<body>
测试:
<c:forEach items="${list}" var="str">${str}
</c:forEach>
</body>
</html>

测试:

在这里插入图片描述

2. 连接数据库

导入依赖驱动

 	<dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>5.1.49</version></dependency>

编写连接类 JDBCUtil

package com.beyond.nothing.utils;import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;public class JDBCUtil {private static final String USERNAME = "root";private static final String PWD = "210374520";private static final String URL = "jdbc:mysql://localhost:3308/thedemo";private static final String DRIVER = "com.mysql.jdbc.Driver";static {// 注册驱动try {Class.forName(DRIVER);} catch (ClassNotFoundException e) {e.printStackTrace();}}public static Connection getCoon() throws SQLException {return DriverManager.getConnection(URL,USERNAME,PWD);}public static void main(String[] args) throws SQLException {Connection coon = getCoon();System.out.println(coon);}
}

测试连接

在这里插入图片描述

3. 开发一个简单的javaweb项目

Entity

package com.beyond.nothing.entity;public class Product {private Integer id;private String name;@Overridepublic String toString() {return "Product{" +"id=" + id +", name='" + name + '\'' +'}';}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;}
}

Service 层

package com.beyond.nothing.service;import com.beyond.nothing.dao.TestDao;
import com.beyond.nothing.entity.Product;import java.util.List;public class TestService {private TestDao dao = new TestDao();public List<Product> queryList(){return dao.queryList();}}

Dao

package com.beyond.nothing.dao;import com.beyond.nothing.entity.Product;
import com.beyond.nothing.utils.JDBCUtil;import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;public class TestDao {public List<Product> queryList() {Connection connection = null ;PreparedStatement preparedStatement = null;ResultSet resultSet = null;// 将结果转为 listList<Product> list = new ArrayList<>();try {// 获取 Connection 对象connection = JDBCUtil.getCoon();// 获取预编译对象preparedStatement = connection.prepareStatement("select * from product");// 执行查询,并且返回结果集resultSet = preparedStatement.executeQuery();// 迭代结果集while (resultSet.next()){Product product = new Product();product.setId(resultSet.getInt("id"));product.setName(resultSet.getString("name"));list.add(product);}} catch (SQLException e) {e.printStackTrace();}finally {JDBCUtil.close(resultSet,preparedStatement,connection);}return list;}
}

Controller

package com.beyond.nothing.servlet;import com.beyond.nothing.service.TestService;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.ArrayList;
import java.util.List;@WebServlet("/test")
public class TestServlet extends HttpServlet {private TestService testService = new TestService();@Overrideprotected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {// 将 list集合 放入request中req.setAttribute("list", testService.queryList());// 转发到 test.jspreq.getRequestDispatcher("WEB-INF/jsp/test.jsp").forward(req, resp);}
}

前端 test.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
<%--引入jstl标签库--%>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head><title>Title</title>
</head>
<body>
测试:
<c:forEach items="${list}" var="p">${p.id}${p.name}
</c:forEach>
</body>
</html>