StudentSystem学生管理系统_V1(三)

业务类设计

• 问题： 为什么不直接使用 Dao 类而是还要在上面封装一层 Service 层呢？
• 回答：
  基于责任分离的原则，Dao 层就应该专注于对数据库的操作，而在 Service 层我们可以增加一些非 CRUD 的方法去更好的完成本身抽离出来的 service 服务（业务处理）。

在【com.ray.service】包下创建【StudentService】接口：

/**
 * @author Ray
 * @date 2018/5/27 0027
 * Service 层我们可以增加一些非 CRUD 的方法去更好的完成本身抽离出来的 service 服务
 */
public interface StudentService {

    /**
     * 获取到 Student 的总数
     * @return
     */
    int getTotal();

    /**
     * 增加一条数据
     * @param student
     */
    void addStudent(Student student);

    /**
     * 删除一条数据
     * @param id
     */
    void deleteStudent(int id);

    /**
     * 更新一条数据
     * @param student
     */
    void updateStudent(Student student);

    /**
     * 找到一条数据
     * @param id
     * @return
     */
    Student getStudent(int id);

    /**
     * 列举出从 start 位置开始的 count 条数据
     * @param start
     * @param count
     * @return
     */
    List list(int start, int count);
}

在【com.ray.service.impl】包下创建【StudentServiceImpl】：

/**
 * @author Ray
 * @date 2018/5/27 0027
 * StudentService 的实现类
 */
@Service
public class StudentServiceImpl implements StudentService {

    @Autowired
    StudentDao studentDao;

    public int getTotal() {
        return studentDao.getTotal();
    }

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

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

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

    public Student getStudent(int id) {
        return studentDao.getStudent(id);
    }

    public List list(int start, int count) {
        return studentDao.list(start, count);
    }
}

功能开发

在【com.ray.controller】包下创建【StudentController】控制器：

/**
 * @author Ray
 * @date 2018/5/27 0027
 * Student 控制器
 */
@Controller
public class StudentController {

    @Autowired
    private StudentService studentService;

    /**
     * 新增学生视图
     */
    @RequestMapping("/addStudentView")
    public ModelAndView addStudentView(){
        ModelAndView modelAndView = new ModelAndView("addStudentView");
        return modelAndView;
    }

    /**
     * 新增学生操作
     */
    @RequestMapping("/addStudent")
    public String addStudent(HttpServletRequest request, HttpServletResponse response){

        Student student = new Student();

        int studentId = Integer.parseInt(request.getParameter("student_id"));
        String name = request.getParameter("name");
        int age = Integer.parseInt(request.getParameter("age"));
        String sex = request.getParameter("sex");
        Date birthday = null;
        // String 类型按照 yyyy-MM-dd 的格式转换为 java.util.Date 类
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
        try{
            birthday = simpleDateFormat.parse(request.getParameter("birthday"));
        }catch (Exception e){
            e.printStackTrace();
        }

        student.setStudent_id(studentId);
        student.setName(name);
        student.setAge(age);
        student.setSex(sex);
        student.setBirthday(birthday);

        studentService.addStudent(student);

        return "redirect:listStudent"; // 重定向
    }

    /**
     * 列出所有学生操作
     */
    @RequestMapping("/listStudent")
    public String listStudent(HttpServletRequest request, HttpServletResponse response){

        // 获取分页参数
        int start = 0;
        int count = 10;

        try{
            start = Integer.parseInt(request.getParameter("page.start"));
            count = Integer.parseInt(request.getParameter("page.count"));
        }catch (Exception e){
            e.printStackTrace();
        }

        Page page = new Page(start, count);

        List students = studentService.list(page.getStart(), page.getCount());
        int total = studentService.getTotal();
        page.setTotal(total);

        request.setAttribute("students", students);
        request.setAttribute("page", page);

        return "listStudent";
    }

    /**
     * 修改学生信息视图
     */
    @RequestMapping("/editStudent")
    public ModelAndView editStudent(int id){
        ModelAndView modelAndView = new ModelAndView("editStudent");
        Student student = studentService.getStudent(id);
        modelAndView.addObject("student",student);
        return modelAndView;
    }

    /**
     *  修改学生信息操作
     */
    @RequestMapping("/updateStudent")
    public String updateStudent(HttpServletRequest request, HttpServletResponse response){
        Student student = new Student();

        int id = Integer.parseInt(request.getParameter("id"));
        int student_id = Integer.parseInt(request.getParameter("student_id"));
        String name = request.getParameter("name");
        int age = Integer.parseInt(request.getParameter("age"));
        String sex = request.getParameter("sex");

        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
        Date birthday = null;
        try{
            birthday = simpleDateFormat.parse(request.getParameter("birthday"));
        }catch (Exception e){
            e.printStackTrace();
        }

        student.setId(id);
        student.setStudent_id(student_id);
        student.setName(name);
        student.setAge(age);
        student.setSex(sex);
        student.setBirthday(birthday);

        studentService.updateStudent(student);
        return "redirect:listStudent";
    }

    /**
     *  删除学生信息操作
     */
    @RequestMapping("/deleteStudent")
    public String deleteStudent(int id){
        studentService.deleteStudent(id);
        return "redirect:listStudent";
    }
}

分页功能

• 首先在 Packge【util】包下创建一个 Page 工具类：

package com.ray.util;

/**
 * @author Ray
 * @date 2018/5/27 0027
 * 分页功能
 */
public class Page {

    int start; // 开始数据
    int count; // 每一页的数量
    int total; // 总共的数据量

    public Page(int start, int count){
        super();
        this.start = start;
        this.count = count;
    }

    public boolean isHasPreviouse(){
        if(start == 0){
            return false;
        }
        return true;
    }

    public boolean isHasNext(){
        if(start == getLast()){
            return false;
        }
        return true;
    }

    public int getTotalPage(){
        int totalPage;

        //假设总数50,是能够被5整除的,那么就有10页
        if(0 == total % count){
            totalPage = total / count;
        }else{
            //假设总数51,不能被5整除的,那么就有11页
            totalPage = total / count + 1;
        }

        if(0 == totalPage){
            totalPage = 1;
        }

        return totalPage;
    }

    public int getLast(){
        int last;
        //假设总数是50,能够被5整除的,那么最后一页的开始就是40
        if(0 == total % count){
            last = total - count;
        }else{
            //假设总数是51,不能够被5整除的,那么最后一个的开始就是50
            last = total - total % count;
        }

        last = last < 0 ? 0:last;
        return last;
    }

    public int getStart() {
        return start;
    }

    public void setStart(int start) {
        this.start = start;
    }

    public int getCount() {
        return count;
    }

    public void setCount(int count) {
        this.count = count;
    }

    public int getTotal() {
        return total;
    }

    public void setTotal(int total) {
        this.total = total;
    }
}