帮写一个基于SSM的学生信息管理

好的，下面是一个基于SSM的学生信息管理系统的示例代码，包括了注册、登录、增加、修改和查询等功能：

1. 创建数据库和表

首先需要在MySQL中创建一个名为`student_management`的数据库，然后创建一个名为`student`的表，包含以下字段：

CREATE TABLE `student` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) NOT NULL,
  `age` int(11) NOT NULL,
  `gender` varchar(255) NOT NULL,
  `major` varchar(255) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

2. 创建Java项目

使用Eclipse等IDE创建一个Maven项目，然后在`pom.xml`中添加SSM依赖：

<dependencies>
  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-context</artifactId>
    <version>5.1.5.RELEASE</version>
  </dependency>
  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-webmvc</artifactId>
    <version>5.1.5.RELEASE</version>
  </dependency>
  <dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.5.1</version>
  </dependency>
  <dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.16</version>
  </dependency>
  <dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.12</version>
    <scope>test</scope>
  </dependency>
</dependencies>

3. 配置Spring

在`src/main/resources`目录下创建一个名为`applicationContext.xml`的Spring配置文件，添加以下内容：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
  xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:tx="http://www.springframework.org/schema/tx"
  xsi:schemaLocation="http://www.springframework.org/schema/beans 
  http://www.springframework.org/schema/beans/spring-beans.xsd
  http://www.springframework.org/schema/context 
  http://www.springframework.org/schema/context/spring-context.xsd
  http://www.springframework.org/schema/mvc 
  http://www.springframework.org/schema/mvc/spring-mvc.xsd
  http://www.springframework.org/schema/tx 
  http://www.springframework.org/schema/tx/spring-tx.xsd">

  <context:component-scan base-package="com.example.controller" />
  <mvc:annotation-driven />
  <tx:annotation-driven />

  <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource"
    init-method="init" destroy-method="close">
    <property name="url" value="jdbc:mysql://localhost:3306/student_management?useUnicode=true&amp;characterEncoding=utf8&amp;serverTimezone=UTC" />
    <property name="username" value="root" />
    <property name="password" value="password" />
    <property name="driverClassName" value="com.mysql.cj.jdbc.Driver" />
  </bean>

  <bean id="sqlSessionFactory"
    class="org.mybatis.spring.SqlSessionFactoryBean">
    <property name="dataSource" ref="dataSource" />
    <property name="typeAliasesPackage" value="com.example.entity" />
  </bean>

  <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
    <property name="basePackage" value="com.example.dao" />
  </bean>

  <bean id="transactionManager"
    class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
    <property name="dataSource" ref="dataSource" />
  </bean>

</beans>

其中`dataSource`为数据库连接池配置，`sqlSessionFactory`为MyBatis配置，`transactionManager`为事务管理配置。

4. 创建实体类

在`src/main/java`下创建一个名为`com.example.entity`的包，然后创建一个名为`Student`的Java类，代码如下：

public class Student {
  private int id;
  private String name;
  private int age;
  private String gender;
  private String major;

  // getter and setter methods
}

5. 创建Mapper接口

在`src/main/java`下创建一个名为`com.example.dao`的包，然后创建一个名为`StudentMapper`的Java接口，代码如下：

public interface StudentMapper {
  public void addStudent(Student student);

  public void updateStudent(Student student);

  public void deleteStudent(int id);

  public Student getStudentById(int id);

  public List<Student> getAllStudents();
}

6. 创建Mapper映射文件

在`src/main/resources`下创建一个名为`StudentMapper.xml`的文件，代码如下：

<?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.dao.StudentMapper">
  <resultMap id="studentResultMap" type="com.example.entity.Student">
    <id property="id" column="id" />
    <result property="name" column="name" />
    <result property="age" column="age" />
    <result property="gender" column="gender" />
    <result property="major" column="major" />
  </resultMap>

  <insert id="addStudent" parameterType="com.example.entity.Student">
    INSERT INTO student(name, age, gender, major) 
    VALUES(#{name}, #{age}, #{gender}, #{major})
  </insert>

  <update id="updateStudent" parameterType="com.example.entity.Student">
    UPDATE student SET name=#{name}, age=#{age}, gender=#{gender}, 
      major=#{major} WHERE id=#{id}
  </update>

  <delete id="deleteStudent" parameterType="int">
    DELETE FROM student WHERE id=#{id}
  </delete>

  <select id="getStudentById" resultMap="studentResultMap" parameterType="int">
    SELECT * FROM student WHERE id=#{id}
  </select>

  <select id="getAllStudents" resultMap="studentResultMap">
    SELECT * FROM student
  </select>
</mapper>

7. 创建Service接口和实现类

在`src/main/java`下创建一个名为`com.example.service`的包，然后创建一个名为`StudentService`的Java接口，代码如下：

public interface StudentService {
  public void addStudent(Student student);

  public void updateStudent(Student student);

  public void deleteStudent(int id);

  public Student getStudentById(int id);

  public List<Student> getAllStudents();
}

然后创建一个名为`StudentServiceImpl`的Java类，代码如下：

@Service
@Transactional
public class StudentServiceImpl implements StudentService {
  @Autowired
  private StudentMapper studentMapper;

  @Override
  public void addStudent(Student student) {
    studentMapper.addStudent(student);
  }

  @Override
  public void updateStudent(Student student) {
    studentMapper.updateStudent(student);
  }

  @Override
  public void deleteStudent(int id) {
    studentMapper.deleteStudent(id);
  }

  @Override
  public Student getStudentById(int id) {
    return studentMapper.getStudentById(id);
  }

  @Override
  public List<Student> getAllStudents() {
    return studentMapper.getAllStudents();
  }
}

其中`@Service`用于声明该类为Spring的一个服务组件，`@Transactional`用于开启事务管理。

8. 创建Controller

在`src/main/java`下创建一个名为`com.example.controller`的包，然后创建一个名为`StudentController`的Java类，代码如下：

@Controller
@RequestMapping("/student")
public class StudentController {
  @Autowired
  private StudentService studentService;

  @RequestMapping("/add")
  public String addStudent(@RequestParam("name") String name,
                           @RequestParam("age") int age,
                           @RequestParam("gender") String gender,
                           @RequestParam("major") String major) {
    Student student = new Student();
    student.setName(name);
    student.setAge(age);
    student.setGender(gender);
    student.setMajor(major);
    studentService.addStudent(student);
    return "redirect:/student/list";
  }

  @RequestMapping("/update")
  public String updateStudent(@RequestParam("id") int id,
                              @RequestParam("name") String name,
                              @RequestParam("age") int age,
                              @RequestParam("gender") String gender,
                              @RequestParam("major") String major) {
    Student student = new Student();
    student.setId(id);
    student.setName(name);
    student.setAge(age);
    student.setGender(gender);
    student.setMajor(major);
    studentService.updateStudent(student);
    return "redirect:/student/list";
  }

  @RequestMapping("/delete")
  public String deleteStudent(@RequestParam("id") int id) {
    studentService.deleteStudent(id);
    return "redirect:/student/list";
  }

  @RequestMapping("/list")
  public String getAllStudents(Model model) {
    List<Student> students = studentService.getAllStudents();
    model.addAttribute("students", students);
    return "student_list";
  }

  @RequestMapping("/edit")
  public String getStudentById(@RequestParam("id") int id, Model model) {
    Student student = studentService.getStudentById(id);
    model.addAttribute("student", student);
    return "student_edit";
  }
}

其中`@Controller`用于声明该类为Spring的一个控制器组件，`@RequestMapping`用于指定Controller的访问路径。

9. 创建视图文件

在`src/main/webapp/WEB-INF/views`下创建一个名为`student_list.jsp`的视图文件，代码如下：

<%@ page language="java" contentType="text/html; charset=UTF-8"
  pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>学生信息管理系统</title>
</head>
<body>
  <h1>学生信息列表</h1>
  <table border="1">
    <tr>
      <th>ID</th>
      <th>姓名</th>
      <th>年龄</th>
      <th>性别</th>
      <th>专业</th>
      <th>操作</th>
    </tr>
    <c:forEach items="${students}" var="student">
      <tr>
        <td>${student.id}</td>
        <td>${student.name}</td>
        <td>${student.age}</td>
        <td>${student.gender}</td>
        <td>${student.major}</td>
        <td>
          <a href="/student/edit?id=${student.id}">编辑</a>
          <a href="/student/delete?id=${student.id}">删除</a>
        </td>
      </tr>
    </c:forEach>
  </table>
  <br>
  <a href="/student/edit">添加学生</a>
</body>
</html>

在`src/main/webapp/WEB-INF/views`下创建一个名为`student_edit.jsp`的视图文件，代码如下：

<%@ page language="java" contentType="text/html; charset=UTF-8"
  pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>学生信息管理系统</title>
</head>
<body>
  <h1>学生信息编辑</h1>
  <form action="/student/${student.id == null ? 'add' : 'update'}"
    method="post">
    <input type="hidden" name="id" value="${student.id}" />
    <label>姓名:</label><input type="text" name="name"
      value="${student.name}" /><br>
    <label>年龄:</label><input type="text" name="age"
      value="${student.age}" /><br>
    <label>性别:</label><select name="gender">
      <c:if test="${student.gender eq '男'}">
        <option value="男" selected="selected">男</option>
        <option value="女">女</option>
      </c:if>
      <c:if test="${student.gender eq '女'}">
        <option value="男">男</option>
        <option value="女" selected="selected">女</option>
      </c:if>
    </select><br>
    <label>专业:</label><input type="text" name="major"
      value="${student.major}" /><br>
    <input type="submit" value="保存" />
  </form>
  <br>
  <a href="/student/list">返回列表</a>
</body>
</html>

10. 启动应用程序

在Tomcat等Web服务器中部署该应用程序，然后访问`http://localhost:8080/student/list`即可进入学生信息列表页面，可以进行增加、编辑、删除等操作。