三层架构 —— 具体代码

  1 package com.itheima.web.servlet;
  2 
  3 import cn.hutool.core.io.IoUtil;
  4 import com.fasterxml.jackson.databind.ObjectMapper;
  5 import com.itheima.domain.Student;
  6 import com.itheima.service.StudentService;
  7 import com.itheima.service.impl.StudentServiceImpl;
  8 
  9 import javax.servlet.ServletException;
 10 import javax.servlet.ServletInputStream;
 11 import javax.servlet.annotation.WebServlet;
 12 import javax.servlet.http.HttpServlet;
 13 import javax.servlet.http.HttpServletRequest;
 14 import javax.servlet.http.HttpServletResponse;
 15 import java.io.IOException;
 16 import java.util.List;
 17 
 18 @WebServlet("/studentServlet")
 19 public class StudentServlet extends HttpServlet {
 20     @Override
 21     protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
 22         // 接收action,确定请求目的
 23         String action = req.getParameter("action");
 24         if ("findAll".equals(action)) {
 25             findAll(req, resp);
 26         } else if ("save".equals(action)) {
 27             save(req, resp);
 28         } else if ("deleteById".equals(action)) {
 29             deleteById(req, resp);
 30         } else if ("findById".equals(action)) {
 31             findById(req, resp);
 32         } else if ("update".equals(action)) {
 33             update(req, resp);
 34         } else {
 35             resp.getWriter().write("方法请求错误");
 36         }
 37     }
 38 
 39     // 修改
 40     private void update(HttpServletRequest req, HttpServletResponse resp) throws IOException {
 41         // 1. 获取请求参数
 42         ServletInputStream is = req.getInputStream();
 43         String json = IoUtil.read(is, "utf-8");
 44         Student student = new ObjectMapper().readValue(json, Student.class);
 45         // 2. 调用业务逻辑
 46         StudentService studentService = new StudentServiceImpl();
 47         studentService.update(student);
 48         // 3. 响应结果
 49         resp.getWriter().write("OK");
 50     }
 51 
 52     // 根据id查询学生(回显)
 53     private void findById(HttpServletRequest req, HttpServletResponse resp) throws IOException {
 54         // 1. 获取请求参数
 55         String id = req.getParameter("id");
 56         // 2. 调用业务逻辑
 57         StudentService studentService = new StudentServiceImpl();
 58         Student student = studentService.findById(id);
 59         // 3. 响应结果
 60         String json = new ObjectMapper().writeValueAsString(student);
 61         resp.getWriter().write(json);
 62     }
 63 
 64     // 根据id删除
 65     private void deleteById(HttpServletRequest req, HttpServletResponse resp) throws IOException {
 66         // 1. 获取请求参数
 67         String id = req.getParameter("id");
 68         // 2. 调用业务逻辑
 69         StudentService studentService = new StudentServiceImpl();
 70         studentService.deleteById(id);
 71         // 3. 响应结果
 72         resp.getWriter().write("OK");
 73 
 74     }
 75 
 76     // 新增
 77     private void save(HttpServletRequest req, HttpServletResponse resp) throws IOException {
 78         // 1. 获取请求参数(如果页面提交的数据为json格式,则req.getPXXX方法不能用了,只能使用字节流获取)
 79 //        String id = req.getParameter("id");
 80         ServletInputStream is = req.getInputStream();
 81         // 把字节数据转换为指定编码格式的字符串{key:value}
 82         String json = IoUtil.read(is, "utf-8");
 83         Student student = new ObjectMapper().readValue(json, Student.class);
 84         // 2. 调用业务逻辑
 85         StudentService studentService = new StudentServiceImpl();
 86         studentService.save(student);
 87         // 3. 响应结果
 88         resp.getWriter().write("OK");
 89     }
 90 
 91     // 查询所有
 92     private void findAll(HttpServletRequest req, HttpServletResponse resp) throws IOException {
 93         // 1. 获取请求参数(无)
 94 
 95         // 2. 调用业务逻辑
 96         StudentService studentService = new StudentServiceImpl();
 97         List<Student> studentList = studentService.findAll();
 98         // 3. 响应结果
 99         String json = new ObjectMapper().writeValueAsString(studentList);
100         resp.getWriter().write(json);
101     }
102 }

 1 package com.itheima.service;
 2 
 3 import com.itheima.domain.Student;
 4 
 5 import java.util.List;
 6 
 7 public interface StudentService {
 8 
 9     List<Student> findAll();
10 
11     void save(Student student);
12 
13     void deleteById(String id);
14 
15     Student findById(String id);
16 
17     void update(Student student);
18 }

 1 package com.itheima.service.impl;
 2 
 3 import com.itheima.domain.Student;
 4 import com.itheima.mapper.StudentMapper;
 5 import com.itheima.service.StudentService;
 6 import com.itheima.util.MyBatisUtil;
 7 import org.apache.ibatis.session.SqlSession;
 8 
 9 import java.util.List;
10 
11 public class StudentServiceImpl implements StudentService {
12     @Override
13     public List<Student> findAll() {
14         SqlSession sqlSession = MyBatisUtil.getSqlSession();
15         StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);
16         List<Student> list = studentMapper.findAll();
17         MyBatisUtil.close(sqlSession);
18         return list;
19     }
20 
21     @Override
22     public void save(Student student) {
23         SqlSession sqlSession = MyBatisUtil.getSqlSession();
24         StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);
25         studentMapper.save(student);
26         MyBatisUtil.close(sqlSession);
27     }
28 
29     @Override
30     public void deleteById(String id) {
31         SqlSession sqlSession = MyBatisUtil.getSqlSession();
32         StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);
33         studentMapper.deleteById(id);
34         MyBatisUtil.close(sqlSession);
35     }
36 
37     @Override
38     public Student findById(String id) {
39         SqlSession sqlSession = MyBatisUtil.getSqlSession();
40         StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);
41         Student student = studentMapper.findById(id);
42         MyBatisUtil.close(sqlSession);
43         return student;
44     }
45 
46     @Override
47     public void update(Student student) {
48         SqlSession sqlSession = MyBatisUtil.getSqlSession();
49         StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);
50         studentMapper.update(student);
51         MyBatisUtil.close(sqlSession);
52     }
53 }

 1 package com.itheima.mapper;
 2 
 3 import com.itheima.domain.Student;
 4 import org.apache.ibatis.annotations.Delete;
 5 import org.apache.ibatis.annotations.Insert;
 6 import org.apache.ibatis.annotations.Select;
 7 import org.apache.ibatis.annotations.Update;
 8 
 9 import java.util.List;
10 
11 public interface StudentMapper {
12     @Select("select * from student")
13     List<Student> findAll();
14 
15     @Insert("insert into student values(#{id},#{name},#{birthday},#{address})")
16     void save(Student student);
17 
18     @Delete("delete from student where id = #{id}")
19     void deleteById(String id);
20 
21     @Select("select * from student where id = #{id}")
22     Student findById(String id);
23 
24     @Update("update student set name = #{name}, birthday = #{birthday}, address = #{address} where id = #{id}")
25     void update(Student student);
26 }