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发表于 更新于 分类于

接上一篇, 上一篇文章写了Dao、Service、Controller的实现, 这篇讲述其中用到的Query以及Page

还是以app表为例, 表结构如下

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`id` bigint(20)
`gmt_create` datetime
`gmt_modified` datetime
`name` varchar(32)

Query 查询类

Query是select查询信息 如limit, page, order by的封装

AppQuery.java

省略其中get, set方法, Query的属性是DO的扩展,如其中nameLike为name字段的模糊查询, toBean()实现Query转换为DO

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public class AppQuery extends BaseQuery<AppDO> {

    private Long id;
    private Date gmtCreate;
    private Date gmtModified;
    private String name;
    private String nameLike;

    // ...get()
    // ...set()

    @Override
    public ClassifyDO toBean() {
        return JSON.parseObject(JSON.toJSONString(this),ClassifyDO.class);
    }
}

BaseQuery.java

BaseQuery中包含公共的查询属性, 例如分页, 排序, 省略其他默认的get, set

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public abstract class BaseQuery<D> implements Query<D> {

    private Integer limit = 1;
    private Integer page = 0;
    private Integer offset = 0;
    private String sort;
    private String order;

    public void setLimit(Integer limit) {
        this.limit = limit > 0 ? limit : 1;
        this.offset = this.page * this.limit;
    }

    public void setPage(int page) {
        this.page = page >= 0 ? page : 0;
        this.offset = this.page * this.limit;
    }

    // ...get()
    // ...set()

    @Override
    public String toString() {
        return JSON.toJSONString(this);
    }
}

Query.java

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public interface Query<D> {

    D toBean();
}

Page 分页查询结果类

由于前端分页显示时常常同时需要每页数据以及总条目数, 所以对分页查询结果简单封装

Page.java

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public class Page<D> {

    private List<D> list;
    private Integer total;

    // ...get()
    // ...set()
}

发表于 更新于 分类于

简述

若手动编写数据库层是繁琐, 重复且容易出错。这里尝试实现通用的Dao、Service、Controllerc 减少重复的代码。使用generator来生成Mapper.xml、DO、Query。使编写数据库层自动化。

下面以app表为例

Dao 层

编写Dao层泛型接口, 对于每一个Mapper.xml 建一个Dao继承该接口, 其中无需编写代码

AppDao.java

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@Mapper
public interface AppDao extends Dao<AppDO> {

}

Dao.java

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public interface Dao<D> {

    D selectById(Long id);

    List<D> select(D bean);

    int selectCount(D bean);

    List<D> select(Query<D> query);

    int selectCount(Query<D> query);

    int insert(D bean);

    int update(D bean);

    int delete(Long id);
}

Service 层

service层编写 Service接口以及BaseService, service中在dao的基础上实现扩展方法, 详见service接口

AppService.java

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@Service
public class AppService extends BaseService<AppDO> {

}

BaseService.java

此处注入dao 需要使用@Autowired, 若使用@Resource则会报错

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public abstract class BaseService<D> implements Service<D> {

    @Autowired
    private Dao<D> mapper;

    @Override
    public D selectById(Long id){
        return mapper.selectById(id);
    }

    @Override
    public List<D> select(D bean){
        return mapper.select(bean);
    }

    @Override
    public int selectCount(D bean){
        return mapper.selectCount(bean);
    }

    @Override
    public List<D> selectByQuery(Query<D> query){
        return mapper.select(query);
    }

    @Override
    public int selectCountByQuery(Query<D> query){
        return mapper.selectCount(query);
    }

    @Override
    public List<D> selectAll(){
        return select(null);
    }

    @Override
    public D selectOne(D bean){
        if(selectCount(bean)!=1){
            return null;
        }
        List<D> list = select(bean);
        return list.get(0);
    }

    @Override
    public D selectOneByQuery(Query<D> query){
        if(selectCountByQuery(query)!=1){
            return null;
        }
        List<D> list = selectByQuery(query);
        return list.get(0);
    }

    @Override
    public Page<D> selectPageByQuery(Query<D> query){
        Page<D> page = new Page<>();
        page.setList(selectByQuery(query));
        page.setTotal(selectCountByQuery(query));
        return page;
    }

    @Override
    public int insert(D bean){
        return mapper.insert(bean);
    }

    @Override
    public int update(D bean){
        return mapper.update(bean);
    }

    @Override
    public int delete(Long id){
        return mapper.delete(id);
    }
}

Service.java

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public interface Service<D> {

    D selectById(Long id);

    List<D> select(D bean);

    int selectCount(D bean);

    List<D> selectByQuery(Query<D> query);

    int selectCountByQuery(Query<D> query);

    List<D> selectAll();

    D selectOne(D bean);

    D selectOneByQuery(Query<D> query);

    Page<D> selectPageByQuery(Query<D> query);

    int insert(D bean);

    int update(D bean);

    int delete(Long id);
}

Controller 层

有了 编写Controller接口和BaseController, 普通增删改查控制器只需继承BaseController

AppController.java

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@RestController
@RequestMapping("app")
public class AdminAppController extends BaseController<AppDO,AppQuery> {

}

BaseController.java

这里注入service同样要用@Autowired

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public abstract class BaseController<D, Q extends Query<D>> implements Controller<D,Q> {

    @Autowired
    private Service<D> service;

    @Override
    @RequestMapping("list")
    public ResponseData list(@RequestBody Q query) {
        return ResponseData.successResponse(service.selectPageByQuery(query));
    }

    @Override
    @RequestMapping("save")
    public ResponseData save(@RequestBody D bean) {
        service.insert(bean);
        return ResponseData.successResponse();
    }

    @Override
    @RequestMapping("update")
    public ResponseData update(@RequestBody D bean) {
        service.update(bean);
        return ResponseData.successResponse();
    }
}

Controller.java

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public interface Controller<D, Q extends Query<D>> {

    ResponseData list(Q query);

    ResponseData save(D bean);

    ResponseData update(D bean);
}
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