如何利用泛型封裝通用的service層

2022-06-21 18:02:04

一、首先建立一個實體類WebVisitRecordEntity

繼承BaseEntity.BaseEntity在專案裡面，是所有實體類的最頂層.裡面是封裝了一些通用的屬性.

1.BaseEntity

package cn.yxw.function; 
import cn.yxw.function.Enum.status.StatusEnum; 
import javax.persistence.Column;
import javax.persistence.Id;
import javax.persistence.MappedSuperclass;
import java.io.Serializable;
import java.util.Date;
 
/**
 * @Author : yuanxw
 * @Description: 所有實體的父類別
 * @Date: Created in 17:03 2018/5/15
 */
@MappedSuperclass
public abstract class BaseEntity implements Serializable{
 
    /**
     * id
     */
    @Id
    @Column(length = 32 )
    private String id;
 
    /**
     * 建立時間
     */
    private Date createTime;
 
    /**
     * 建立人
     */
    @Column(length = 32 )
    private String createUser;
 
    /**
     * 更新時間
     */
    private Date updateTime;
 
    /**
     * 更新人
     */
    @Column(length = 32 )
    private String updateUser;
 
    /**
     * 刪除標記 --系統只做邏輯刪除
     */
    @Column(length = 8 )
    private String delStatus = StatusEnum.FALSE.getStatus();
 
    /**
     * 啟用標記 --預設已啟用
     */
    @Column(length = 8 )
    private String enAbleStatus = StatusEnum.TRUE.getStatus();
 
    public String getId() {
        return id;
    }
 
    public void setId(String id) {
        this.id = id;
    }
 
    public Date getCreateTime() {
        return createTime;
    }
 
    public void setCreateTime(Date createTime) {
        this.createTime = createTime;
    }
 
    public String getCreateUser() {
        return createUser;
    }
 
    public void setCreateUser(String createUser) {
        this.createUser = createUser;
    }
 
    public Date getUpdateTime() {
        return updateTime;
    }
 
    public void setUpdateTime(Date updateTime) {
        this.updateTime = updateTime;
    }
 
    public String getUpdateUser() {
        return updateUser;
    }
 
    public void setUpdateUser(String updateUser) {
        this.updateUser = updateUser;
    }
 
    public String getDelStatus() {
        return delStatus;
    }
 
    public void setDelStatus(String delStatus) {
        this.delStatus = delStatus;
    }
 
    public String getEnAbleStatus() {
        return enAbleStatus;
    }
 
    public void setEnAbleStatus(String enAbleStatus) {
        this.enAbleStatus = enAbleStatus;
    }
}

2.WebVisitRecordEntity

package cn.yxw.function.domain.plugins; 
import cn.yxw.function.BaseEntity; 
import javax.persistence.Entity;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;
import javax.persistence.Table;
 
/**
 * @Author : yuanxw
 * @Description:
 * @Date: Created in 15:16 2018/6/20
 */
@Entity()
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
@Table(name = "web_visit_Record")
public class WebVisitRecordEntity extends BaseEntity {
 
    private static final long serialVersionUID = 341666498307329777L;
    /**
     * 存取次數
     */
    private int count = 0;
 
    public int getCount() {
        return count;
    }
 
    public void setCount(int count) {
        this.count = count;
    }
}

二、有了實體類之後

首先建立一個頂層的api介面。所有通用的api方法，可以放在這裡(ResultBean是一個封裝了一個結果的資料類，裡面包含了定義執行是否成功，執行返回的資料，執行錯誤提示的訊息)

package cn.yxw.function; 
import cn.yxw.function.result.ResultBean;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
 
/**
 * @Author : yuanxw
 * @Description:
 * @Date: Created in 10:32 2018/5/25
 */
public interface BaseApi<T extends BaseEntity> {
 
    /**
     * 查詢
     * @param id
     * @return
     */
    T get(String id);
 
    /**
     * 查詢
     * @param id
     * @return
     */
    T find(String id);
 
    /**
     * 刪除
     * @param id
     * @return
     */
    ResultBean<T> delete(String id);
 
    ResultBean<T> delete(T entity);
 
    /**
     * 建立
     * @param entity
     * @return
     */
    ResultBean<T> create(T entity);
 
    /**
     * 更新
     * @param entity
     * @return
     */
    ResultBean<T> update(T entity);
 
    /**
     * 讀取所有
     * @param pageable
     * @return
     */
    Page<T> page(Pageable pageable);
 
    /**
     * 判斷id是否存在
     * @param id
     * @return
     */
    boolean exists(String id);
 
}

三、實現BaseApi

既然是要定義通用的api，那麼不僅僅只是一套介面，我們需要在定義一個可以實現BaseApi的BaseServiceImpl，之後的所有實現類，都可以繼承這個BaseServiceImpl.java的泛型，給了我們的專案很好的擴充套件性，而頂層BaseEntity也給了我很好的實現方案，將BaseEntity作為泛型的入口

1.基本時限BaseApi

package cn.yxw.function.service.impl.domain.userCenter; 
import cn.yxw.function.BaseApi;
import cn.yxw.function.BaseEntity;
import cn.yxw.function.result.ResultBean;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable; 
 
/**
 * @Author : yuanxw
 * @Description:
 * @Date: Created in 14:31 2018/6/20
 */
public class BaseServiceImpl<T extends BaseEntity> implements BaseApi<T> { 
 
    @Override
    public T get(String id) {
        return null;
    }
 
    @Override
    public T find(String id) {
        return null;
    }
 
    @Override
    public ResultBean<T> delete(String id) {
        return null;
    }
 
    @Override
    public ResultBean<T> delete(T entity) {
        return null;
    }
 
    @Override
    public ResultBean<T> create(T entity) {
        return null;
    }
 
    @Override
    public ResultBean<T> update(T entity) {
        return null;
    }
 
    @Override
    public Page<T> page(Pageable pageable) {
        return null;
    }
 
    @Override
    public boolean exists(String id) {
        return false;
    }
}

2.使用jpa作為BaseServiceImpl的屬性.

package cn.yxw.function.service.impl.domain.userCenter; 
import cn.yxw.function.BaseApi;
import cn.yxw.function.BaseEntity;
import cn.yxw.function.Enum.code.ServiceCodeEnum;
import cn.yxw.function.result.ResultBean;
import cn.yxw.function.util.ObjectUtil;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.jpa.repository.JpaRepository;
 
/**
 * @Author : yuanxw
 * @Description:
 * @Date: Created in 14:31 2018/6/20
 */
public class BaseServiceImpl<T extends BaseEntity> implements BaseApi<T> {
 
    @Autowired
    private JpaRepository<T, String> baseRepository;
 
 
    @Override
    public T get(String id) {
        T entity =  this.baseRepository.getOne(id);
        return entity;
    }
 
    @Override
    public T find(String id) {
        return this.baseRepository.findById(id).get();
    }
 
    @Override
    public ResultBean<T> delete(String id) {
        this.baseRepository.deleteById(id);
        return ResultBean.success("");
    }
 
    @Override
    public ResultBean<T> delete(T entity) {
        this.baseRepository.delete(entity);
        return ResultBean.success(entity);
    }
 
    @Override
    public ResultBean<T> create(T entity) {
        if(ObjectUtil.isNull(entity)){
            return ResultBean.failfure("資料為空,無法建立!");
        }
        if(this.exists(entity.getId())){
            return ResultBean.failfure("實體id相同,無法重複建立!");
        }
        entity = this.baseRepository.saveAndFlush(entity);
        if(ObjectUtil.isNull(entity)){
            return ResultBean.failfure(ServiceCodeEnum.CORE_SYSTEM_FAILURE);
        }
        return ResultBean.success(entity);
    }
 
    @Override
    public ResultBean<T> update(T entity) {
        if(ObjectUtil.isNull(entity)){
            return ResultBean.failfure("資料為空,無法建立!");
        }
        if(!this.exists(entity.getId())){
            return ResultBean.failfure("資料庫不存在該資料,無法執行更新");
        }
        entity = this.baseRepository.saveAndFlush(entity);
        if(ObjectUtil.isNull(entity)){
            return ResultBean.failfure(ServiceCodeEnum.CORE_SYSTEM_FAILURE);
        }
        return ResultBean.success(entity);
    }
 
    @Override
    public Page<T> page(Pageable pageable) {
        return null;
    }
 
    @Override
    public boolean exists(String id) {
        return this.baseRepository.existsById(id);
    }
}

四、定義類自己的api

繼承BaseApi，定義實現類，繼承BaseServiceImpl.並實現自己的api

package cn.yxw.function.domain.userCenter; 
import cn.yxw.function.BaseApi;
import cn.yxw.function.domain.plugins.WebVisitRecordEntity;
 
/**
 * @Author : yuanxw
 * @Description:
 * @Date: Created in 14:44 2018/6/22
 */
public interface WebVisitRecordApi extends BaseApi<WebVisitRecordEntity> {
}

package cn.yxw.function.service.impl.domain.userCenter; 
import cn.yxw.function.domain.plugins.WebVisitRecordEntity;
import cn.yxw.function.domain.userCenter.WebVisitRecordApi;
import org.springframework.stereotype.Service;
 
/**
 * @Author : yuanxw
 * @Description:
 * @Date: Created in 15:22 2018/6/20
 */
@Service
public class WebVisitRecordServiceImpl extends BaseServiceImpl<WebVisitRecordEntity> implements WebVisitRecordApi {   
}

五、測試

到這裡，程式碼已經結束. 測試一下，構建下controller層. 並進行測試

package cn.yxw.function.controller.System.admin; 
import cn.yxw.function.controller.BaseController;
import cn.yxw.function.domain.plugins.WebVisitRecordEntity;
import cn.yxw.function.result.ResultBean;
import cn.yxw.function.service.impl.domain.userCenter.WebVisitRecordServiceImpl;
import cn.yxw.function.util.ObjectUtil;
import com.alibaba.druid.util.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
 
import java.util.Date;
import java.util.Map;
 
/**
 * @Author : yuanxw
 * @Description:
 * @Date: Created in 15:23 2018/6/20
 */
@RestController()
@RequestMapping(value = "web/record")
public class WebVisitRecordsController extends BaseController {
 
    @Autowired
    private WebVisitRecordServiceImpl webVisitRecordService; 
 
    @GetMapping(value = "/get")
    public Map get(String id){
        if(StringUtils.isEmpty(id)){
            return this.errorWithMsg("引數不得為空");
        }
        WebVisitRecordEntity entity = this.webVisitRecordService.find(id);
        return this.result(entity,"");
    }
 
    @PostMapping(value = "/create")
    public Map create(int num){
        WebVisitRecordEntity entity = new WebVisitRecordEntity();
        entity.setId(System.currentTimeMillis()+"");
        entity.setCreateTime(new Date());
        entity.setCount(num);
        ResultBean<WebVisitRecordEntity> result = this.webVisitRecordService.create(entity);
        return this.result(result.getDate(),result.getMsg());
    } 
 
    @PostMapping(value = "/update")
    public Map update(String id, int num){
        if(StringUtils.isEmpty(id)){
            return this.errorWithMsg("引數不得為空");
        }
        WebVisitRecordEntity entity = this.webVisitRecordService.find(id);
        if(ObjectUtil.isNull(entity)){
            return this.errorWithMsg("不存在該資料");
        }
        entity.setUpdateTime(new Date());
        entity.setCount(entity.getCount()+num);
        ResultBean<WebVisitRecordEntity> result = this.webVisitRecordService.update(entity);
        return this.result(result.getDate(),result.getMsg());
    } 
}

三次測試都已經成功,但是我們真實的專案不可能這麼簡單.所以我們再次測試下擴充套件性

等等,不知道你們發現沒有,上面的程式碼有一段是錯誤的.

我在controller層的屬性不是api,而是實現類.......

雖然不影響,但是就無法擴充套件了...此處做修正

六、擴充套件性

1. WebVisitRecordApi

package cn.yxw.function.domain.userCenter; 
import cn.yxw.function.BaseApi;
import cn.yxw.function.domain.plugins.WebVisitRecordEntity;
 
/**
 * @Author : yuanxw
 * @Description:
 * @Date: Created in 14:44 2018/6/22
 */
public interface WebVisitRecordApi extends BaseApi<WebVisitRecordEntity> {
 
    /**
     * 統計所有的記錄之和
     * @return
     */
    int countAll();
}

2. WebVisitRecordServiceImpl

package cn.yxw.function.service.impl.domain.userCenter;
 
import cn.yxw.function.domain.plugins.WebVisitRecordEntity;
import cn.yxw.function.domain.userCenter.WebVisitRecordApi;
import cn.yxw.function.util.ObjectUtil;
import org.springframework.stereotype.Service; 
import java.util.List;
 
/**
 * @Author : yuanxw
 * @Description:
 * @Date: Created in 15:22 2018/6/20
 */
@Service
public class WebVisitRecordServiceImpl extends BaseServiceImpl<WebVisitRecordEntity> implements WebVisitRecordApi { 
 
    @Override
    public int countAll() {
        List<WebVisitRecordEntity> list = super.baseRepository.findAll();
        int count = 0;
        if(ObjectUtil.isNull(list) || list.size() <= 0){
            return count;
        }
        for (WebVisitRecordEntity entity : list){
            count += entity.getCount();
        }
        return count;
    }
}

3. WebVisitRecordController

    @GetMapping(value = "count")
    public Map count(){
        return this.result(this.webVisitRecordService.countAll(),"執行成功");
    }

4.測試

七、總結

emmmm.....其實我上面還有個小錯誤，就留給你們尋找吧

其實，封裝的這個service層，也有很大的侷限性，比如說，如果我需要自定義dao層的方法，怎麼辦?需要執行sql語句怎麼辦，仔細想想，我們能不能再封裝一個BaseRepository呢?然後作為BaseServiceImpl中的屬性傳入??????

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