Java Project Student Management System Six Backend Supplements

Class management

1 Class List: Backend

Write JavaBean【Existing】
Writing Mapper【Existing】
Write Service
Write controller

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Write Service

interface

package com.czxy.service;

import com.czxy.domain.Classes;

import java.util.List;

/**
 * @author 桐叔
 * @email [email protected]
 * @description
 */
public interface ClassesService {
        
        

    /**
     * 查询所有
     * @return
     */
    public List<Classes> selectAll();
}

Implementation class

package com.czxy.service.impl;

import com.czxy.domain.Classes;
import com.czxy.mapper.ClassesMapper;
import com.czxy.service.ClassesService;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.util.List;

/**
 * @author 桐叔
 * @email [email protected]
 * @description
 */
@Service
@Transactional
public class ClassesServiceImpl implements ClassesService {
        
        
    @Resource
    private ClassesMapper classesMapper;

    @Override
    public List<Classes> selectAll() {
        
        
        List<Classes> classesList = classesMapper.selectAll();
        return classesList;
    }
}

Write controller

package com.czxy.controller;

import com.czxy.domain.Classes;
import com.czxy.service.ClassesService;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;
import java.util.List;

/**
 * @author 桐叔
 * @email [email protected]
 * @description
 */
@RestController
@RequestMapping("/classes")
public class ClassesController {
      
      
    @Resource
    private ClassesService classesService;

    @GetMapping
    public ResponseEntity<List<Classes>> selectAll() {
      
      
        // 查询
        List<Classes> classesList = classesService.selectAll();
        // 返回
        return ResponseEntity.ok(classesList);
    }
}

city management

1 Query all cities: backend

1 JavaBean

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package com.czxy.domain;

import javax.persistence.Column;
import javax.persistence.Id;
import javax.persistence.Table;
import java.util.ArrayList;
import java.util.List;

/**
 * @author 桐叔
 * @email [email protected]
 * @description
 */
@Table(name = "tb_city")
public class City {
    
    
    @Id
    @Column(name = "c_id")
    private String cid;                 //城市ID

    private String cityName;            //城市名称

    private String parentId;            //父ID

    //一对多：一个城市(省/市)拥有多个子城市(多个市/多个县) ，new对象为了操作【方便】
    private List<City> children = new ArrayList<>();

    //....
}

/*
CREATE TABLE tb_city(
  c_id VARCHAR(32) PRIMARY KEY COMMENT '城市ID',
  city_name VARCHAR(20) COMMENT '城市名称' ,
  parent_id VARCHAR(32) COMMENT '父ID'
);
 */

2 Mapper

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package com.czxy.mapper;

import com.czxy.domain.City;
import tk.mybatis.mapper.common.Mapper;

/**
 * @author 桐叔
 * @email [email protected]
 * @description
 */
public interface CityMapper extends Mapper<City> {
    
    
}

3 Service

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interface

package com.czxy.service;

import com.czxy.domain.City;

import java.util.List;

/**
 * @author 桐叔
 * @email [email protected]
 * @description
 */
public interface CityService {
      
      

    /**
     * 查询所有（省、市、县）
     * @return
     */
    public List<City> selectAll();
}

Implementation class

package com.czxy.service.impl;

import com.czxy.domain.City;
import com.czxy.mapper.CityMapper;
import com.czxy.service.CityService;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import tk.mybatis.mapper.entity.Example;

import javax.annotation.Resource;
import java.util.List;

/**
 * @author 桐叔
 * @email [email protected]
 * @description
 */
@Service
@Transactional
public class CityServiceImpl implements CityService {
      
      
    @Resource
    private CityMapper cityMapper;

    @Override
    public List<City> selectAll() {
      
      
        //1 条件查询：排序
        Example example = new Example(City.class);
        example.orderBy("parentId").asc();      //升序

        //2 查询
        List<City> cityList = cityMapper.selectByExample(example);

        return cityList;
    }
}

4 Controller

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package com.czxy.controller;

import com.czxy.domain.City;
import com.czxy.service.CityService;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * @author 桐叔
 * @email [email protected]
 * @description
 */
@RestController
@RequestMapping("/city")
public class CityController {
    
    

    @Resource
    private CityService cityService;

    @GetMapping
    public ResponseEntity<List<City>> selectAll() {
    
    
        // 1 查询所有 省/市/县
        List<City> cityList = cityService.selectAll();

        // 2 处理数据 省(市(县))
        // 2.1.1 提供Map，用于缓存所有城市，目的：方便子城市找到父城市
        // map.id 城市id，方便子获得， map.value 城市
        Map<String, City> cacheMap = new HashMap<>();
        // 2.1.2 提供List，存放所有的省
        List<City> provinceList = new ArrayList<>();

        // 2.2 遍历所有城市
        for(City city: cityList) {
    
    
            // 2.3.1 从map获得父城市
            City parentCity = cacheMap.get(city.getParentId());
            if(parentCity == null) {
    
    
                // 2.3.2 1)如果没有获得父城市，表示就是省，直接添加List
                provinceList.add(city);
            } else {
    
    
                // 2.3.2 2)如果获得父城市，表示市、县，将器追加到父城市的子列表中
                parentCity.getChildren().add(city);
            }
            // 2.3.3 当前城市添加到map中，方便下一次自己的子城市可以获得自己
            cacheMap.put(city.getCid(), city);
        }

        //3 返回所有的省
        return ResponseEntity.ok(provinceList);
    }
}

Query all cities with specified parent id: backend

1 Service

interface

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    /**
     * 通过父id查询所有
     * @param parentId
     * @return
     */
    public List<City> selectByParentId(String parentId);

Implementation class

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    @Override
    public List<City> selectByParentId(String parentId) {
      
      
        //1 条件
        Example example = new Example(City.class);
        Example.Criteria criteria = example.createCriteria();
        criteria.andEqualTo("parentId", parentId);

        //2 查询
        List<City> cityList = cityMapper.selectByExample(example);

        //3 返回
        return cityList;
    }

2 Controller

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    /**
     * 通过父id查询
     * @param pid
     * @return
     */
    @GetMapping("/parent/{pid}")
    public ResponseEntity<List<City>> selectAllByParentId(@PathVariable("pid") String pid) {
    
    
        //查询
        List<City> cityList = cityService.selectByParentId(pid);
        //返回
        return ResponseEntity.ok(cityList);
    }

Course management

1 Query all: backend

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1 Service

interface

package com.czxy.service;

import com.czxy.domain.Course;

import java.util.List;

/**
 * @author 桐叔
 * @email [email protected]
 * @description
 */
public interface CourseService {
      
      

    /**
     * 查询所有课程
     * @return
     */
    public List<Course> selectAll();
}

Implementation class

package com.czxy.service.impl;

import com.czxy.domain.Course;
import com.czxy.mapper.CourseMapper;
import com.czxy.service.CourseService;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.util.List;

/**
 * @author 桐叔
 * @email [email protected]
 * @description
 */
@Service
@Transactional
public class CourseServiceImpl implements CourseService {
      
      
    @Resource
    private CourseMapper courseMapper;
    @Override
    public List<Course> selectAll() {
      
      
        List<Course> courseList = courseMapper.selectAll();
        return courseList;
    }
}

2 Controller

package com.czxy.controller;

import com.czxy.domain.Course;
import com.czxy.service.CourseService;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;
import java.util.List;

/**
 * @author 桐叔
 * @email [email protected]
 * @description
 */
@RestController
@RequestMapping("/course")
public class CourseController {
    
    

    @Resource
    private CourseService courseService;

    /**
     * 查询所有课程
     * @return
     */
    @GetMapping
    public ResponseEntity<List<Course>> selectAll() {
    
    
        //查询
        List<Course> courseList = courseService.selectAll();
        //返回
        return ResponseEntity.ok(courseList);
    }
}

2 Query all courses of a specified student: backend

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1 Mapper【Existing】

2 Service

interface

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    /**
     * 查询指定学生的所有课程
     * @param sid
     * @return
     */
    public List<Course> selectAllBySid(Integer sid);

Implementation class

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    @Override
    public List<Course> selectAllBySid(Integer sid) {
      
      
        List<Course> courseList = courseMapper.selectAllBySid(sid);
        return courseList;
    }