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SpringBoot+Mybatis-plus写数据库的函数调用过程

发布时间 2023-08-26 00:14:27作者: Nemuzuki

比如我们SpringBoot的一个接口层为DataCollectController，它通过调用服务层DataCollectManager的create()和update()方法对数据库进行写操作

@RestController
@Api(tags="数据采集")
@RequestMapping("/dataCollect/")
@ApiGroup(group= {ApiGroupInner.GROUP_TEMPLATE})
public class DataCollectController extends BaseController<DataCollectManager, DataCollect> {
    @Resource
    DataCollectManager dataCollectManager;

    @Autowired//使用@Autowired将另一个Controller类的实例注入进来，并直接调用该实例的方法
    DataSourceController dataSourceController;

    @RequestMapping(value="start", method= RequestMethod.POST, produces = { "application/json; charset=utf-8" })
    @ApiOperation(value = "开始数据库采集", httpMethod = "POST", notes = "开始数据库采集")
    public CommonResult<String> StartDataCollect(
            @ApiParam(name="dataCollect", value="数据采集对象", required = true)
            @RequestBody DataCollect dataCollect) throws Exception{
        if (StringUtil.isEmpty(dataCollect.getId())) {//如果请求中不填id
            //将参数存入数据库data_collect
            dataCollectManager.create(dataCollect);
        }
        else {
            dataCollectManager.update(dataCollect);
        }
        ...
    }
}

DataCollectManager的实现类DataCollectManagerImpl继承了BaseManagerImpl的create和update方法

@Service
public class DataCollectManagerImpl extends BaseManagerImpl<DataCollectDao, DataCollect> implements DataCollectManager {
    protected static final Logger LOGGER = LoggerFactory.getLogger(DataCollectManagerImpl.class);
    @Override
    public void create(DataCollect dataCollect) {
        super.create(dataCollect);//调用BaseManagerImpl.create
    }
    @Override
    public void update(DataCollect dataCollect) {
        super.update(dataCollect);
    }
}

BaseManagerImpl的create和update方法则继承自ServiceImpl的save和updateById，从这里开始就是Mybatis-plus的代码了

public class BaseManagerImpl<M extends BaseMapper<T>, T extends Model<T>> extends ServiceImpl<M, T> implements BaseManager<T>, QueryFilterHelper<T> {
    public BaseManagerImpl() {
    }

    public T get(Serializable id) {
        return (Model)this.getById(id);
    }

    public void create(T t) {
        this.save(t);
    }

    public void update(T t) {
        this.updateById(t);
    }
    ...
}

ServiceImpl继承自IService，可以看到save操作调用了getBaseMapper()，该函数会自动关联DataCollectMapper.xml文件，在调用insert()时自动生成写数据库的SQL语句并执行。

public interface IService<T> {

    /**
     * 默认批次提交数量
     */
    int DEFAULT_BATCH_SIZE = 1000;

    /**
     * 插入一条记录（选择字段，策略插入）
     *
     * @param entity 实体对象
     */
    default boolean save(T entity) {
        return SqlHelper.retBool(getBaseMapper().insert(entity));
    }