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提示：以下是本篇文章正文内容，Java系列学习将会持续更新

程序的流程

1. 我们通过访问 127.0.0.1:8080/record.html来发送GET请求，访问到记录的页面
2. 填写页面中的表单并提交，向 /save 发起 POST 请求
3. Servlet 作出响应后重定向到 /list.html 页面，请求方法为 GET
4. list.html 动态资源通过HTML拼接，显示数据库中的数据

main

java

DBUtil

public class DBUtil {
    private static DataSource dataSource;

    static {
        MysqlDataSource mysqlDataSource = new MysqlDataSource();
        mysqlDataSource.setUrl("jdbc:mysql://127.0.0.1:3306/grades?characterEncoding=utf8&useSSL=false&serverTimezone=Asia/Shanghai");
        mysqlDataSource.setUser("root");
        mysqlDataSource.setPassword("123456");
        dataSource = mysqlDataSource;
    }

    public static Connection connection() throws SQLException {
        return dataSource.getConnection();
    }
}
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ListServlet

请求方法为 GET，通过拼接HTML来显示数据。

@WebServlet("/list.html")
public class ListServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setCharacterEncoding("utf-8");
        resp.setContentType("text/html");
        PrintWriter writer = resp.getWriter();

        List<Student> list = new ArrayList<>();
        try (Connection c = DBUtil.connection()) {
            String sql = "select name, grade from grades order by id";
            try (PreparedStatement ps = c.prepareStatement(sql)) {
                try (ResultSet rs = ps.executeQuery()) {
                    while (rs.next()) {
                        Student student = new Student();
                        student.name = rs.getString("name");
                        student.grade = rs.getInt("grade");

                        list.add(student);
                    }
                }
            }
        } catch (SQLException exc) {
            throw new RuntimeException(exc);
        }

		// 拼接 HTML
        writer.println("");
        writer.println("");
        writer.println("");
        writer.println("    ");
        writer.println("    ");
        writer.println("");
        writer.println("");
        writer.println("    ");
        writer.println("        ");for(Student student : list){
            writer.println("");
            writer.printf("\n\n", student.name, student.grade);
            writer.println("");}
        writer.println("        ");
        writer.println("    

          
%s
%d
        
");
        writer.println("");
        writer.println("");
    }
}
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回到目录…

SaveServlet

读取 form 表单发来的POST请求，响应：将数据存入数据库、重定向到 /list.html

@WebServlet("/save")
public class SaveServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // 1. 读取
        req.setCharacterEncoding("utf-8");
        String name = req.getParameter("name");
        String grade = req.getParameter("grade");
        if (name == null || name.trim().isEmpty()) {
            System.out.println("必须填写姓名");
            return;
        }

        if (grade == null || grade.trim().isEmpty()) {
            System.out.println("必须填写成绩");
            return;
        }

        int g;
        try {
            g = Integer.parseInt(grade);
        } catch (NumberFormatException exc) {
            System.out.println("成绩必须是数字");
            return;
        }
        // 2. 保存 (必须保证数据是同一份数据）
        String sql = "insert into grades (name, grade) values (?, ?)";
        try (Connection c = DBUtil.connection()) {
            try (PreparedStatement ps = c.prepareStatement(sql)) {
                ps.setString(1, name);
                ps.setInt(2, g);

                ps.executeUpdate();
            }
        } catch (SQLException exc) {
            throw new RuntimeException(exc);
        }
        // 3. 重定向
        resp.sendRedirect("/list.html");
    }
}
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Student

public class Student {
    public String name;
    public int grade;
}
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webapp

WEB-INF

web.xml

<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_3_1.xsd"
  version="3.1"
  metadata-complete="false">
web-app>
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record.html

通过GET请求访问HTML页面。其中的form表单发送 POST 请求，请求地址为 /save

DOCTYPE html>
<html lang="zh-hans">
<head>
    <meta charset="UTF-8">
    <title>成绩录入title>
head>
<body>
    <form method="post" action="/save">
        <input type="text" name="name">
        <input type="text" name="grade">
        <button>提交button>
    form>
body>
html>
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运行效果

1. 提交前
   
   

2. 提交后
   
   

回到目录…

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总结:
提示：这里对文章进行总结：
以上就是今天的学习内容，本文是JavaWeb的学习，写一个成绩录入的小程序，为了是对Servlet动态绑定学习的综合应用。之后的学习内容将持续更新！！！