Java项目学生管理系统六后端补充

班级管理

1 班级列表：后端

• 编写JavaBean【已有】
• 编写Mapper【已有】
• 编写Service
• 编写controller

• 编写Service

  • 接口

    package com.czxy.service;
    
    import com.czxy.domain.Classes;
    
    import java.util.List;
    
    /**
     * @author 桐叔
     * @email liangtong@itcast.cn
     * @description
     */
    public interface ClassesService {
    
        /**
         * 查询所有
         * @return
         */
        public List<Classes> selectAll();
    }
    
    

  • 实现类

    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 liangtong@itcast.cn
     * @description
     */
    @Service
    @Transactional
    public class ClassesServiceImpl implements ClassesService {
        @Resource
        private ClassesMapper classesMapper;
    
        @Override
        public List<Classes> selectAll() {
            List<Classes> classesList = classesMapper.selectAll();
            return classesList;
        }
    }
    
    

• 编写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 liangtong@itcast.cn
   * @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);
      }
  }
  
  

城市管理

1 查询所有城市：后端

1 JavaBean

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 liangtong@itcast.cn
 * @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

package com.czxy.mapper;

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

/**
 * @author 桐叔
 * @email liangtong@itcast.cn
 * @description
 */
public interface CityMapper extends Mapper<City> {
}

3 Service

• 接口

  package com.czxy.service;
  
  import com.czxy.domain.City;
  
  import java.util.List;
  
  /**
   * @author 桐叔
   * @email liangtong@itcast.cn
   * @description
   */
  public interface CityService {
  
      /**
       * 查询所有（省、市、县）
       * @return
       */
      public List<City> selectAll();
  }
  
  

• 实现类

  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 liangtong@itcast.cn
   * @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

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 liangtong@itcast.cn
 * @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);
    }
}

查询指定父id的所有城市：后端

1 Service

• 接口

  

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

• 实现类

  

      @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

    /**
     * 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);
    }

课程管理

1查询所有：后端

1 Service

• 接口

  package com.czxy.service;
  
  import com.czxy.domain.Course;
  
  import java.util.List;
  
  /**
   * @author 桐叔
   * @email liangtong@itcast.cn
   * @description
   */
  public interface CourseService {
  
      /**
       * 查询所有课程
       * @return
       */
      public List<Course> selectAll();
  }
  
  

• 实现类

  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 liangtong@itcast.cn
   * @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 liangtong@itcast.cn
 * @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 查询指定学生的所有课程：后端

1 Mapper【已有】

2 Service

• 接口

  

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

• 实现类

  

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