在数据库ssm中建立一张学生 表student,该表有如下字段: id, name, stuid, age; 利用mybatis知识，完成数据库表的增删改操作。核心java代码文件即可。

以下是核心Java代码文件：

StudentMapper.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.example.mapper.StudentMapper">
    <resultMap id="studentMap" type="com.example.entity.Student">
        <id property="id" column="id"/>
        <result property="name" column="name"/>
        <result property="stuid" column="stuid"/>
        <result property="age" column="age"/>
    </resultMap>
    <select id="getStudentById" resultMap="studentMap">
        SELECT * FROM student WHERE id=#{id}
    </select>
    <select id="getAllStudents" resultMap="studentMap">
        SELECT * FROM student
    </select>
    <insert id="addStudent" parameterType="com.example.entity.Student">
        INSERT INTO student(name, stuid, age) VALUES(#{name}, #{stuid}, #{age})
    </insert>
    <update id="updateStudent" parameterType="com.example.entity.Student">
        UPDATE student SET name=#{name}, stuid=#{stuid}, age=#{age} WHERE id=#{id}
    </update>
    <delete id="deleteStudentById" parameterType="int">
        DELETE FROM student WHERE id=#{id}
    </delete>
</mapper>

StudentMapper.java

package com.example.mapper;

import com.example.entity.Student;
import org.apache.ibatis.annotations.*;

import java.util.List;

@Mapper
public interface StudentMapper {
    @Select("SELECT * FROM student WHERE id=#{id}")
    Student getStudentById(int id);

    @Select("SELECT * FROM student")
    List<Student> getAllStudents();

    @Insert("INSERT INTO student(name, stuid, age) VALUES(#{name}, #{stuid}, #{age})")
    void addStudent(Student student);

    @Update("UPDATE student SET name=#{name}, stuid=#{stuid}, age=#{age} WHERE id=#{id}")
    void updateStudent(Student student);

    @Delete("DELETE FROM student WHERE id=#{id}")
    void deleteStudentById(int id);
}

Student.java

package com.example.entity;

public class Student {
    private int id;
    private String name;
    private String stuid;
    private int age;

    public Student() {}

    public Student(int id, String name, String stuid, int age) {
        this.id = id;
        this.name = name;
        this.stuid = stuid;
        this.age = age;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getStuid() {
        return stuid;
    }

    public void setStuid(String stuid) {
        this.stuid = stuid;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}