Java 查询代码优化

通常我们查询是把所有的查询条件，校验后拼SQL，这篇文章做使用设计模式做一些优化。

springboot 1.5.9   java8  mybatis-generator

1、以下图第一个查询条件为例，通过姓名、工号、手机号查询。这些属于员工的基本信息存在user表中，查询的主表只存user_id , 所以我们应该先通过姓名、工号、手机号查到user_id，最后在查询主表。

2、查询传输实体、枚举设计

public class RecordQueryVO {

    @ApiModelProperty(value = "日期区间类型[ADJUST:调动时间,OPERATE:操作时间],为空表示全部")
    private enum1 intervalType;

    @ApiModelProperty(value = "起始日期")
    private LocalDate from;

    @ApiModelProperty(value = "结束日期")
    private LocalDate to;

    @ApiModelProperty(value = "关键字筛选类型[NAME:姓名,CODE:工号,MOBILE:手机号]")
    private enum2 queryType;

    @ApiModelProperty(value = "关键字")
    private String keyword;
}

public enum enum1 {

    ADJUST("调动时间"),

    OPERATE("操作时间"),
    ;

    private String description;

    enum1(String description) {
        this.description = description;
    }

}


public enum enum2 {

    NAME("姓名"),

    CODE("工号"),

    MOBILE("手机号"),
    ;

    private String description;

    enum2(String description) {
        this.description = description;
    }
	
}

3、处理查询条件接口，这里我把查询条件放到上下文context中

public interface IEmployeePositionAdjustCriteriaHandler {

    /**
     * 处理查询条件
     *
     * @param context 上下文
     * @param example 查询条件
     */
    void handle(EmployeeAdjustPaginctaContext context, WaysHrmEmployeeChangeApplyExample example);
}

4、抽象类实现接口

abstract class AbstractEmployeePositionAdjustInfoCriteriaHandler implements IEmployeePositionAdjustCriteriaHandler {

    @Autowired
    private IHrmEmployeeCrudService iHrmEmployeeCrudService;

    @Override
    public void handle(EmployeeAdjustPaginctaContext context, WaysHrmEmployeeChangeApplyExample example) {
        String keyword = context.getKeyword();
        WaysHrmEmployeeExample employeeExample = new WaysHrmEmployeeExample();
        //抽象方法、通过关键字查询，这里将会有不同的实现类，来继承抽象接口
        this.queryStaffIds(employeeExample, keyword);
        List ids = Optional.ofNullable(iHrmEmployeeCrudService.listByExample(employeeExample))
                .filter(CollectionUtils::isNotEmpty)
                .map(list -> list.stream().map(WaysHrmEmployee::getEmployeeId).collect(Collectors.toList()))
                .orElse(Lists.newArrayListWithExpectedSize(0));
        Optional.of(ids)
                .filter(CollectionUtils::isNotEmpty)
                .map(employeeIds -> {
                    example.getOredCriteria().forEach(criteria -> criteria.andStaffIdIn(employeeIds));
                    return example;
                }).orElseGet(() -> {
                    example.clear();
                    return null;
        });
    }

    /**
     * 
     * @param keyword
     */

    protected abstract void queryStaffIds(WaysHrmEmployeeExample employeeExample, String keyword);
}

5、具体的查询条件处理接口实现  bean命名以   接口名: 查询类型的枚举name，这样的好处后边可以看到

//工号
@Service(value = EmployeeCodeCriteriaHandlerImpl.SERVICE_QUALIFIER)
public class EmployeeCodeCriteriaHandlerImpl extends AbstractEmployeePositionAdjustInfoCriteriaHandler {

    public static final String SERVICE_QUALIFIER = "AbstractEmployeePositionAdjustInfoCriteriaHandler:CODE";

    @Override
    protected void queryStaffIds(WaysHrmEmployeeExample employeeExample, String keyword) {
        employeeExample.createCriteria().andEmployeeCodeEqualTo(keyword);
    }
}

//手机号

@Service(value = EmployeeMobileCriteriaHandlerImpl.SERVICE_QUALIFIER)
public class EmployeeMobileCriteriaHandlerImpl extends AbstractEmployeePositionAdjustInfoCriteriaHandler {

    public static final String SERVICE_QUALIFIER = "AbstractEmployeePositionAdjustInfoCriteriaHandler:MOBILE";

    @Override
    protected void queryStaffIds(WaysHrmEmployeeExample employeeExample, String keyword) {
        employeeExample.createCriteria().andMobileEqualTo(keyword);
    }
}


//姓名
@Service(value = EmployeeNameCriteriaHandlerImpl.SERVICE_QUALIFIER)
public class EmployeeNameCriteriaHandlerImpl extends AbstractEmployeePositionAdjustInfoCriteriaHandler {

    public static final String SERVICE_QUALIFIER = "AbstractEmployeePositionAdjustInfoCriteriaHandler:NAME";

    @Override
    protected void queryStaffIds(WaysHrmEmployeeExample employeeExample, String keyword) {
        employeeExample.createCriteria().andEmployeeNameLike("%" + keyword + "%");
    }
}

6、不同查询条件的 查询都写好了，解下来看service层的使用

      首先需要将不同实现的bean注入进来，可以通过bean Name 获取

    @Autowired
    private Map iEmployeePositionAdjustCriteriaHandlerMap;

根据我们前端传的条件进行查询，通过查询条件类型的枚举名称，获取对应的实现

        //员工基本信息
        Optional.of(context)
                .map(EmployeeAdjustPaginctaContext::getKeyword)
                .ifPresent(keyword -> {
                    IEmployeePositionAdjustCriteriaHandler infoHandler = Optional.of(context)
                            .map(EmployeeAdjustPaginctaContext::getQueryType)
                            .map(Enum::name)
                            .map(enumName -> Joiner.on(":").join(AbstractEmployeePositionAdjustInfoCriteriaHandler.class.getSimpleName(), enumName))
                            .map(this.iEmployeePositionAdjustCriteriaHandlerMap::get)
                            .orElseThrow(HrmEmployeeChangeException.INVALID_QUERY_TYPE.exception());
                    infoHandler.handle(context, example);
                });