Coding style: SSM environment in MVC mode, code hierarchical management

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In this paper, the source code ：GitHub· Click here || GitEE· Click here

One 、 Layering strategy

MVC Pattern and code layering strategy ,MVC The full name is ModelViewController The model － View － controller , As a software design paradigm , Using a business logic 、 data 、 The interface displays the separated method organization code , Gather business logic into a component , While improving and personalizing the interface and user interaction , No need to rewrite business logic , It's a development model , But it's not the layered pattern of code in actual development , Usually SSM The framework's back-end code layers are as follows ：

• controller Control layer ： Define the server interface , In and out , And some input parameters ;
• service Business services layer ： Assemble business logic , Business verification , The parameter model needed to build the control layer ;
• dao Data interaction layer ： Provide the data query method needed by the service layer , Dealing with logic related to data interaction conditions ;
• mapper Persistence layer ： be based on mybatis The framework needs native support , The most commonly used persistence layer component at present ;

Two 、 Control layer

1、Rest The interface style

Based on the logic of resource access and processing , Use different styles of annotations . For example, new resources , to update , Inquire about , Delete .

/**
 *  newly added 
 */
@PostMapping("/insert")
public Integer insert (@RequestBody BaseInfo baseInfo){
    return baseInfoService.insert(baseInfo);
}
/**
 *  to update 
 */
@PutMapping("/update/{id}")
public String update(@PathVariable(value = "id") Integer id,
                     @RequestBody BaseInfo baseInfo) {
    if (id<1){
        return "error";
    }
    baseInfo.setId(id);
    return "update="+baseInfoService.update(baseInfo);
}
/**
 *  Primary key query 
 */
@GetMapping("/detail/{id}")
public InfoModel detail(@PathVariable(value = "id") Integer id) {
    return baseInfoService.detail(id) ;
}
/**
 *  Delete primary key 
 */
@DeleteMapping("/delete/{id}")
public String delete(@PathVariable(value = "id") Integer id) {
    baseInfoService.delete(id) ;
    return "SUS" ;
}

2、 Interface reuse

High reuse of interfaces is not recommended , For example, add, delete, modify and check all the interfaces , The basic principle of , Different client side operations , For independent interfaces .

/**
 *  List loading 
 */
@GetMapping("/list")
public List<BaseInfo> list() {
    return baseInfoService.list(new BaseInfoExample()) ;
}
/**
 *  List search 
 */
@PostMapping("/search")
public List<BaseInfo> search (@RequestParam("userName") String userName,
                              @RequestParam("phone") String phone) {
    return baseInfoService.search(userName,phone) ;
}

For example, common list Interface ,list Usually, there will be conditional loading search Mechanism , And the search criteria are complex , It is suggested that there are two interfaces , From a practical point of view , Most of the scenarios are only used list Interface , Rarely used search Search for .

3、 In and out

Verification client must be conditional , For example, a certain condition is required , If there are questions , Quickly block the request link , The program entrance control layer intercepts and returns .

@PutMapping("/update/{id}")
public String update(@PathVariable(value = "id") Integer id,
                     @RequestBody BaseInfo baseInfo) {
    if (id<1){
        return "error";
    }
    baseInfo.setId(id);
    return "update="+baseInfoService.update(baseInfo);
}

The parameters are less than three , It can be displayed directly into the reference , If there are three or more parameters, entity classes can be used to encapsulate them .

@PostMapping("/search")
public List<BaseInfo> search (@RequestParam("userName") String userName,
                              @RequestParam("phone") String phone) {
    return baseInfoService.search(userName,phone) ;
}

4、 Processing parameters

The basic principle of the processing degree of the output parameter format , Servers as public resources , Avoid unnecessary operations , For example, the client can judge whether the return value is empty ,null etc. , Or some common format processing , Use the client to share the server pressure properly .

3、 ... and 、 Business services layer

1、 Business verification

For example, pass in the order number , Through the database layer query , No order data , This is called a business nature exception , There's no problem with the code itself , But business logic doesn't work properly .

public InfoModel detail(Integer id){
    BaseInfo baseInfo = baseInfoDao.selectByPrimaryKey(id) ;
    if (baseInfo != null){
        DetailInfoEntity detailInfoEntity = detailInfoDao.getById(id);
        if (detailInfoEntity == null){
            LOG.info("id="+id+" Missing data  DetailInfo");
        }
        return buildModel(baseInfo,detailInfoEntity) ;
    }
    LOG.info("id="+id+" The data is completely missing ");
    return null ;
}

2、 Assemble business logic

Usually, the service layer is a complex piece of logic , Used to splice business core steps , It can be determined by business logic that , Step by step, step by step , Avoid doing a lot of object creation and requirement data query at the program entrance .

public int insert (BaseInfo record){
    record.setCreateTime(new Date());
    int insertFlag = baseInfoDao.insert(record);
    if (insertFlag > 0){
        DetailInfoEntity detailInfoEntity = new DetailInfoEntity();
        detailInfoEntity.setUserId(record.getId());
        detailInfoEntity.setCreateTime(record.getCreateTime());
        if(detailInfoDao.save(detailInfoEntity)){
            return insertFlag ;
        }
    }
    return insertFlag;
}

3、 Data model construction

Usually, the business layer is more complex , If you want to quickly understand the business layer , Can be used for complex business methods , In this paper, we provide a method to return the parameters to build , It is used to process the parameters returned by the service layer to the control layer , This will make the heavy service layer approach clearer .

private InfoModel buildModel (BaseInfo baseInfo,DetailInfoEntity detailInfo){
    InfoModel infoModel = new InfoModel() ;
    infoModel.setBaseInfo(baseInfo);
    infoModel.setDetailInfoEntity(detailInfo);
    return infoModel ;
}

Four 、 Data interaction layer

1、 Reverse engineering

Here to use mybatis Frame or mybatis-plus Frame as a reference . If it is mybatis frame , It is suggested that the template code of reverse engineering should not be modified by user , If you need a custom method , stay mapper and xml Level to customize an extension file , Used to store custom methods and SQL Logic , This avoids the strong discomfort caused by large changes in the table structure .

Now, of course, most of them will mybatis-plus As a persistence layer component , These problems can be avoided .

2、 Data interaction

For the needs of the business layer , Provide the corresponding data query method , Only deal with the logic of interacting with the database , Avoid business logic , Especially in the distributed architecture , Data query and assembly of different services , It shouldn't be on this layer .

public interface BaseInfoDao {

    int insert(BaseInfo record);

    List<BaseInfo> selectByExample(BaseInfoExample example);

    int updateByPrimaryKey(BaseInfo record);

    BaseInfo selectByPrimaryKey(Integer id);

    int deleteByPrimaryKey(Integer id);

    BaseInfo getById (Integer id) ;
}

5、 ... and 、 Source code address

GitHub· Address 
https://github.com/cicadasmile/data-manage-parent
GitEE· Address 
https://gitee.com/cicadasmile/data-manage-parent