使用Spring框架写学生信息管理系统

学生信息管理系统是一个比较典型的MVC应用，使用Spring框架可以快速地实现应用程序的开发。下面是一个简单的学生信息管理系统的实现示例：

1. 首先，定义一个学生类，包含学生的基本信息：

public class Student {
    private int id;
    private String name;
    private int age;
    private String gender;
    //getters and setters
}

2. 创建一个控制器类，处理用户请求并调用相应的服务方法：

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

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

    @GetMapping("/{id}")
    public String getStudentById(@PathVariable int id, Model model) {
        Student student = studentService.getStudentById(id);
        model.addAttribute("student", student);
        return "student";
    }

    @PostMapping
    public String addStudent(@ModelAttribute Student student) {
        studentService.addStudent(student);
        return "redirect:/students";
    }

    @PutMapping("/{id}")
    public String updateStudent(@PathVariable int id, @ModelAttribute Student student) {
        student.setId(id);
        studentService.updateStudent(student);
        return "redirect:/students";
    }

    @DeleteMapping("/{id}")
    public String deleteStudent(@PathVariable int id) {
        studentService.deleteStudent(id);
        return "redirect:/students";
    }
}

3. 创建一个服务类，实现对学生信息的增删改查操作：

@Service
public class StudentServiceImpl implements StudentService {
    @Autowired
    private StudentDao studentDao;

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

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

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

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

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

4. 创建一个数据访问对象类，实现对学生信息的持久化操作：

@Repository
public class StudentDaoImpl implements StudentDao {
    private static final Map<Integer, Student> students = new HashMap<>();

    @Override
    public List<Student> getAllStudents() {
        return new ArrayList<>(students.values());
    }

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

    @Override
    public void addStudent(Student student) {
        students.put(student.getId(), student);
    }

    @Override
    public void updateStudent(Student student) {
        students.put(student.getId(), student);
    }

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

5. 配置Spring框架，定义相关组件的依赖关系：

<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"
       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">

    <context:component-scan base-package="com.example"/>

    <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/views/"/>
        <property name="suffix" value=".jsp"/>
    </bean>

    <bean id="studentDao" class="com.example.dao.StudentDaoImpl"/>

    <bean id="studentService" class="com.example.service.StudentServiceImpl">
        <property name="studentDao" ref="studentDao"/>
    </bean>

    <bean id="handlerMapping" class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping"/>

    <bean id="handlerAdapter" class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter"/>
</beans>

6. 编写JSP页面，展示学生信息和处理用户输入：

<!-- students.jsp -->
<table>
    <tr>
        <th>ID</th>
        <th>Name</th>
        <th>Age</th>
        <th>Gender</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>
        </tr>
    </c:forEach>
</table>

<form action="/students" method="post">
    <label for="name">Name:</label>
    <input type="text" id="name" name="name"><br>

    <label for="age">Age:</label>
    <input type="text" id="age" name="age"><br>

    <label for="gender">Gender:</label>
    <select id="gender" name="gender">
        <option value="male">Male</option>
        <option value="female">Female</option>
    </select><br>

    <button type="submit">Add Student</button>
</form>

<!-- student.jsp -->
<h1>${student.name}</h1>
<p>ID: ${student.id}</p>
<p>Age: ${student.age}</p>
<p>Gender: ${student.gender}</p>

<form action="/students/${student.id}" method="post">
    <input type="hidden" name="_method" value="put">

    <label for="name">Name:</label>
    <input type="text" id="name" name="name" value="${student.name}"><br>

    <label for="age">Age:</label>
    <input type="text" id="age" name="age" value="${student.age}"><br>

    <label for="gender">Gender:</label>
    <select id="gender" name="gender">
        <option value="male" ${student.gender == "male" ? "selected" : ""}>Male</option>
        <option value="female" ${student.gender == "female" ? "selected" : ""}>Female</option>
    </select><br>

    <button type="submit">Update Student</button>
</form>

<form action="/students/${student.id}" method="post">
    <input type="hidden" name="_method" value="delete">
    <button type="submit">Delete Student</button>
</form>

7. 启动应用程序，访问http://localhost:8080/students即可查看学生列表，点击学生名称可以查看学生详细信息，点击Add Student可以添加新的学生，点击Update Student可以更新学生信息，点击Delete Student可以删除学生记录。