使用JavaWeb进行增删改查操作

一、基本环境准备

1、配置pop.xml

pop文件可以直接复制使用不作修改，也可以根据自己的需求进行增删依赖和插件

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <project xmlns="http://maven.apache.org/POM/4.0.0"
 3          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 5     <modelVersion>4.0.0</modelVersion>
 6 
 7     <groupId>org.tree</groupId>
 8     <artifactId>A-lin</artifactId>
 9     <version>1.0-SNAPSHOT</version>
10     <packaging>war</packaging>
11 
12     <properties>
13         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
14         <maven.compiler.source>17</maven.compiler.source>
15         <maven.compiler.target>17</maven.compiler.target>
16     </properties>
17 
18 
19     <dependencies>
20         <!--mybatis-->
21         <dependency>
22             <groupId>org.mybatis</groupId>
23             <artifactId>mybatis</artifactId>
24             <version>3.5.11</version>
25         </dependency>
26         <!--mySql-->
27         <dependency>
28             <groupId>mysql</groupId>
29             <artifactId>mysql-connector-java</artifactId>
30             <version>8.0.30</version>
31         </dependency>
32         <!--servlet-->
33         <dependency>
34             <groupId>javax.servlet</groupId>
35             <artifactId>javax.servlet-api</artifactId>
36             <version>3.1.0</version>
37             <scope>provided</scope>
38         </dependency>
39         <!--jsp-->
40         <dependency>
41             <groupId>javax.servlet.jsp</groupId>
42             <artifactId>jsp-api</artifactId>
43             <version>2.2</version>
44             <scope>provided</scope>
45         </dependency>
46         <!--jstl-->
47         <dependency>
48             <groupId>jstl</groupId>
49             <artifactId>jstl</artifactId>
50             <version>1.2</version>
51         </dependency>
52 
53         <dependency>
54             <groupId>taglibs</groupId>
55             <artifactId>standard</artifactId>
56             <version>1.1.2</version>
57         </dependency>
58 
59         <dependency>
60             <groupId>com.alibaba</groupId>
61             <artifactId>fastjson</artifactId>
62             <version>1.2.62</version>
63         </dependency>
64 
65     </dependencies>
66 
67     <build>
68         <plugins>
69             <plugin>
70                 <groupId>org.apache.tomcat.maven</groupId>
71                 <artifactId>tomcat7-maven-plugin</artifactId>
72                 <version>2.2</version>
73             </plugin>
74         </plugins>
75     </build>
76 
77 </project>

2、配置mybatis.xml

mybatis文件要修改为自己的包名和数据库配置(database,username,password)

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE configuration
 3         PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
 4         "http://mybatis.org/dtd/mybatis-3-config.dtd">
 5 <configuration>
 8 <!--    1.改包名
 9         2.数据库配置，数据库名称，用户名，密码
10 -->
12     <!--起别名-->
13     <typeAliases>  <!--改包名-->
14         <package name="com.tree.entity"/>
15     </typeAliases>
16 
17     <environments default="development">
18         <environment id="development">
19             <transactionManager type="JDBC"/>
20             <dataSource type="POOLED">
21                 <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
22                 <property name="url" value="jdbc:mysql:///tree?useSSL=false&amp;useServerPrepStmts=true"/>
23                 <property name="username" value="root"/>
24                 <property name="password" value="root"/>
25             </dataSource>
26         </environment>
27     </environments>
28     <mappers>
29         <!--扫描mapper-->
30         <package name="com.tree.mapper"/><!--改包名-->
31     </mappers>
32 </configuration>

3、创建工厂类(简化获取数据库对象和连接，也减少资源占用，直接调用内部方法)

 1 package com.tree.utils;
 2 
 3 import org.apache.ibatis.io.Resources;
 4 import org.apache.ibatis.session.SqlSessionFactory;
 5 import org.apache.ibatis.session.SqlSessionFactoryBuilder;
 6 
 7 import java.io.IOException;
 8 import java.io.InputStream;
 9 
10 public class SqlSessionFactoryUtils {
11     private static SqlSessionFactory sqlSessionFactory;
12 
13     static {
14         //静态代码块会随着类的加载而自动执行，且只执行一次
15         try {
16             String resource = "mybatis-config.xml";
17             InputStream inputStream = Resources.getResourceAsStream(resource);
18             sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
19         } catch (IOException e) {
20             e.printStackTrace();
21         }
22     }

　　　　//调用getSqlSessionFactory方法

23 public static SqlSessionFactory getSqlSessionFactory(){ 24 return sqlSessionFactory; 25 } 26 }

4.编写index.html和 jsp页面

index.html:

<a href="/A-lin/selectAllServlet">查询所有</a>

selectAll.jsp:

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<input type="button" value="新增" id="add">
<input type="button" value="刷新" id="refresh"><br>

<hr>
<table border="1" cellspacing="0" width="80%">
    <tr>
        <th>学号</th>
        <th>姓名</th>
        <th>年龄</th>
        <th>操作</th>
    </tr>

    <c:forEach items="${students}" var="student">
        <tr align="center">
            <td id="${student.id}" name="id">${student.id}</td>
            <td>${student.name}</td>
            <td id="age">${student.age}</td>
            <td><a href="/A-lin/selectByIdServlet?id=${student.id}">修改</a>
                <a href="/A-lin/deleteByIdServlet?id=${student.id}">删除</a></td>
        </tr>

    </c:forEach>

</table>

<script>
    document.getElementById("add").onclick = function () {
        location.href = "addBrand.jsp";
    }
    document.getElementById("refresh").onclick = function () {
        location.href = "/A-lin/selectAllServlet";
    }


</script>
</body>
</html>

add.jsp:

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>添加信息</title>
</head>
<body>
<h3>添加信息</h3>
<form action="/A-lin/addServlet" method="post">
    学号：<input name="id"><br>
    姓名：<input name="name"><br>
    年龄：<input name="age"><br>

    <input type="submit" value="提交">
</form>
</body>
</html>

update.jsp:

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

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

<head>
    <meta charset="UTF-8">
    <title>修改信息</title>
</head>
<body>
<h3>修改信息</h3>

<form action="/A-lin/updateByIdServlet" method="get">
        <input type="hidden" name="id" value="${student.id}">
        姓名： <input readonly name="name" value="${student.name}"><br>
        年龄: <input name="age" value="${student.age}"><br><br>
        <input type="submit" value="提交">

</form>


</body>
</html>

二、创建类和接口

1、编写实体类entity（有参无参构造方法、toString方法、set、get方法）

public class Student {
    private Integer id;
    private String name;
    private Integer age;

2、编写mapper接口和mapper.xml

 1 public interface StudentMapper {
 2 
 3     boolean add(Student student);
 4 
 5     void deleteById(int id);
 6 
 7     List<Student> selectAll();
 8 
 9     Student selectById(int id);
10 
11     void updateById(Student student);

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE mapper
 3         PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
 4         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 5 <mapper namespace="com.tree.mapper.StudentMapper">
 6 
 7     <resultMap id="studentResultMap" type="Student">
 8 
 9     </resultMap>
10 
11 <!--    增加-->
12     <insert id="add">
13         insert into student1 values (#{id},#{name},#{age});
14     </insert>
15 
16 <!--    根据id删除-->
17     <delete id="deleteById">
18         delete from student1 where id = #{id};
19     </delete>
20 
21 <!--    查询所有-->
22     <select id="selectAll" resultMap="studentResultMap">
23         select * from student1;
24     </select>
25     <select id="selectById" resultType="com.tree.entity.Student">
26         select * from student1 where id = #{id};
27     </select>
28     <!--    更改年龄-->
29     <update id="updateById">
30         update student1 set age = #{age} where id = #{id};
31     </update>
32 
33 </mapper>

3、创建service层，调用mapper接口的方法

  1 package com.tree.service;
  2 
  3 import com.tree.entity.Student;
  4 import com.tree.mapper.StudentMapper;
  5 import com.tree.utils.SqlSessionFactoryUtils;
  6 import org.apache.ibatis.session.SqlSession;
  7 import org.apache.ibatis.session.SqlSessionFactory;
  8 
  9 import java.util.List;
 10 
 11 /**
 12  * @author Tree
 13  * @date 2022/12/10  00:11
 14  */
 15 public class StudentService {
 16 
 17     SqlSessionFactory factory = SqlSessionFactoryUtils.getSqlSessionFactory();
 18 
 19     /**
 20      * 增加
 21      *
 22      * @param student
 23      * @return
 24      */
 25     public void add(Student student) {
 26         //2. 获取SqlSession
 27         SqlSession sqlSession = factory.openSession();
 28         //3. 获取BrandMapper
 29         StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
 30         //4. 调用方法
 31         mapper.add(student);
 32         //5.提交并关闭事务
 33         sqlSession.commit();
 34         sqlSession.close();
 35     }
 36 
 37     /**
 38      * 查询所有
 39      */
 40     public List<Student> selectAll() {
 41         //2. 获取SqlSession
 42         SqlSession sqlSession = factory.openSession();
 43         //3. 获取BrandMapper
 44         StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
 45         //4. 调用方法
 46         List<Student> students = mapper.selectAll();
 47         //5.提交事务
 48         sqlSession.close();
 49 
 50         return students;
 51     }
 52 
 53     /**
 54      * 查询id
 55      */
 56     public Student selectById(int id) {
 57         //2. 获取SqlSession
 58         SqlSession sqlSession = factory.openSession();
 59         //3. 获取BrandMapper
 60         StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
 61         //4. 调用方法
 62         Student student = mapper.selectById(id);
 63         //5.提交事务关闭资源
 64         sqlSession.close();
 65         //返回对象
 66         return student;
 67     }
 68 
 69 
 70     /**
 71      * 修改年龄
 72      */
 73     public void updateById(Student student) {
 74         //2. 获取SqlSession
 75         SqlSession sqlSession = factory.openSession();
 76         //3. 获取BrandMapper
 77         StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
 78         //4. 调用方法
 79         mapper.updateById(student);
 80         //5.提交并关闭事务
 81         sqlSession.commit();
 82         sqlSession.close();
 83 
 84     }
 85 
 86 
 87     /**
 88      * 删除
 89      *
 90      * @param id
 91      */
 92     public void deleteById(int id) {
 93         //2. 获取SqlSession
 94         SqlSession sqlSession = factory.openSession();
 95         //3. 获取BrandMapper
 96         StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
 97         //4. 调用方法
 98         mapper.deleteById(id);
 99         //5.提交并关闭事务
100         sqlSession.commit();
101         sqlSession.close();
102 
103     }
104 }

4、创建servlet类，调用service文件

addServlet：

package com.tree.servlet;
import com.tree.entity.Student;
import com.tree.service.StudentService;

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("/addServlet")
public class addServlet extends HttpServlet {
    private StudentService service = new StudentService();
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //处理POST请求的乱码问题
        request.setCharacterEncoding("utf-8");
        // 1.接收并设置参数
        int id = Integer.parseInt(request.getParameter("id"));
        String name = request.getParameter("name");
        int age = Integer.parseInt(request.getParameter("age"));

        Student student = new Student();
        student.setId(id);
        student.setName(name);
        student.setAge(age);
        // 2.调用BrandService完成查询
        service.add(student);
        // 3. 存入request域中
        request.setAttribute("Student", student);
        // 4. 转发到brand.jsp
        request.getRequestDispatcher("/selectAllServlet").forward(request, response);
    }

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

deleteServlet

package com.tree.servlet;


import com.tree.service.StudentService;

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("/deleteByIdServlet")
public class deleteByIdServlet extends HttpServlet {
    private StudentService service = new StudentService();

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //处理POST请求的乱码问题
        request.setCharacterEncoding("utf-8");
        // 1.接收参数
        int id = Integer.parseInt(request.getParameter("id"));
        System.out.println(id);
        // 2.调用BrandService完成查询
        service.deleteById(id);
        // 4. 转发到brand.jsp
        request.getRequestDispatcher("/selectAllServlet").forward(request, response);
    }

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

selectAll

 1 package com.tree.servlet;
 2 
 3 
 4 import com.tree.entity.Student;
 5 import com.tree.service.StudentService;
 6 
 7 import javax.servlet.ServletException;
 8 import javax.servlet.annotation.WebServlet;
 9 import javax.servlet.http.HttpServlet;
10 import javax.servlet.http.HttpServletRequest;
11 import javax.servlet.http.HttpServletResponse;
12 import java.io.IOException;
13 import java.util.List;
14 
15 @WebServlet("/selectAllServlet")
16 public class selectAllServlet extends HttpServlet {
17     private StudentService service = new StudentService();
18 
19     @Override
20     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
21         //处理POST请求的乱码问题
22         request.setCharacterEncoding("utf-8");
23 
24         // 1.接收参数
25 
26         // 2.调用BrandService完成查询
27         List<Student> students = service.selectAll();
28         // 3. 存入request域中
29         request.setAttribute("students", students);
30         // 4. 转发到brand.jsp
31         request.getRequestDispatcher("/selectAll.jsp").forward(request, response);
32     }
33 
34     @Override
35     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
36         this.doGet(request, response);
37     }
38 }

selectById:

package com.tree.servlet;


import com.tree.entity.Student;
import com.tree.service.StudentService;

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.List;

@WebServlet("/selectByIdServlet")
public class selectByIdServlet extends HttpServlet {
    private StudentService service = new StudentService();
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //处理POST请求的乱码问题
        request.setCharacterEncoding("utf-8");
        //1.接收参数
        String id = request.getParameter("id");
        // 2.调用BrandService完成查询
        Student student = service.selectById(Integer.parseInt(id));
        // 3. 存入request域中
        request.setAttribute("student", student);
        // 4. 转发到brand.jsp
        request.getRequestDispatcher("/updateStudent.jsp").forward(request, response);
    }

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

update:

package com.tree.servlet;


import com.tree.entity.Student;
import com.tree.service.StudentService;

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.List;

@WebServlet("/updateByIdServlet")
public class updateByIdServlet extends HttpServlet {
    private StudentService service = new StudentService();

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //处理POST请求的乱码问题
        request.setCharacterEncoding("utf-8");
        // 1.接收参数
        String id = request.getParameter("id");
        String name = request.getParameter("name");
        String age = request.getParameter("age");

        //设置参数
        Student student = new Student();
        student.setId(Integer.valueOf(id));
        student.setName(name);
        student.setAge(Integer.valueOf(age));

        // 2.调用BrandService完成查询
        service.updateById(student);

        // 4. 转发到brand.jsp
        request.getRequestDispatcher("/selectAllServlet").forward(request, response);
    }

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