Fluent Mybatis實際開發中的優勢對比

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之前文章介紹過瞭Fluent基本框架等，其中有幾個重要的方法用到瞭IQuery和IUpdate對象。 這2個對象是FluentMybatis實現復雜和動態sql的構造類，通過這2個對象fluent mybatis可以不用寫具體的xml文件， 直接通過java api可以構造出比較復雜的業務sql語句，做到代碼邏輯和sql邏輯的合一。下面接著介紹如何通過IQuery和IUpdate定義強大的動態SQL語句。

表結構 假如有學生成績表結構如下:

create table `student_score`
(
    id           bigint auto_increment comment '主鍵ID' primary key,
    student_id   bigint            not null comment '學號',
    gender_man   tinyint default 0 not null comment '性別, 0:女; 1:男',
    school_term  int               null comment '學期',
    subject      varchar(30)       null comment '學科',
    score        int               null comment '成績',
    gmt_create   datetime          not null comment '記錄創建時間',
    gmt_modified datetime          not null comment '記錄最後修改時間',
    is_deleted   tinyint default 0 not null comment '邏輯刪除標識'
) engine = InnoDB default charset=utf8;

統計2000年到2019年, 三門學科(‘英語’, ‘數學’, ‘語文’)分數按學期,學科統計最低分，最高分和平均分,統計結果按學期和學科排序
SQL：

select school_term, subject, count(score), min(score), max(score), avg(score)
from student_score
where school_term between 2000 and 2019
  and subject in ('英語', '數學', '語文')
  and is_deleted = 0
group by school_term, subject
order by school_term, subject
  1. 通過FluentMybatis來具體實現
  2. 在StudentScoreDao類上定義接口
@Data
public class ScoreStatistics {
    private int schoolTerm;
    private String subject;
    private long count;
    private Integer minScore;
    private Integer maxScore;
    private BigDecimal avgScore;
}
public interface StudentScoreDao extends IBaseDao<StudentScoreEntity> {
    /**
     * 統計從fromYear到endYear年間學科subjects的統計數據
     *
     * @param fromYear 統計年份區間開始
     * @param endYear  統計年份區間結尾
     * @param subjects 統計的學科列表
     * @return 統計數據
     */
    List<ScoreStatistics> statistics(int fromYear, int endYear, String[] subjects);
}

在StudentScoreDaoImpl上實現業務邏輯

@Repository
public class StudentScoreDaoImpl extends StudentScoreBaseDao implements StudentScoreDao {
    @Override
    public List<ScoreStatistics> statistics(int fromSchoolTerm, int endSchoolTerm, String[] subjects) {
        return super.listPoJos(ScoreStatistics.class, super.query()
            .select.schoolTerm().subject()
            .count("count")
            .min.score("min_score")
            .max.score("max_score")
            .avg.score("avg_score")
            .end()
            .where.isDeleted().isFalse()
            .and.schoolTerm().between(fromSchoolTerm, endSchoolTerm)
            .and.subject().in(subjects)
            .end()
            .groupBy.schoolTerm().subject().end()
            .orderBy.schoolTerm().asc().subject().asc().end()
        );
    }
}
  1. DaoImpl實現中，除瞭根據條件返回統計結果，還講結果按照下劃線轉駝峰的規則自動轉換為ScoreStatistics對象返回。
  2. 測試
@RunWith(SpringRunner.class)
@SpringBootTest(classes = QuickStartApplication.class)
public class StudentScoreDaoImplTest {
    @Autowired
    private StudentScoreDao dao;

    @Test
    public void statistics() {
        List<ScoreStatistics> list = dao.statistics(2000, 2019, new String[]{"語文", "數學", "英語"});
        System.out.println(list);
    }
}

查看控制臺輸出結果：

DEBUG – ==>  Preparing: SELECT school_term, subject, count(*) AS count, MIN(score) AS min_score, MAX(score) AS max_score, AVG(score) AS avg_score
    FROM student_score
    WHERE is_deleted = ?
    AND school_term BETWEEN ? AND ?
    AND subject IN (?, ?, ?)
    GROUP BY school_term, subject
    ORDER BY school_term ASC, subject ASC 
DEBUG – ==> Parameters: false(Boolean), 2000(Integer), 2019(Integer), 語文(String), 數學(String), 英語(String)
DEBUG – <==      Total: 30
[ScoreStatistics(schoolTerm=2000, subject=數學, count=17, minScore=1, maxScore=93, avgScore=36.0588),
 …
 ScoreStatistics(schoolTerm=2009, subject=語文, count=24, minScore=3, maxScore=100, avgScore=51.2500)]

到此這篇關於Fluent Mybatis實際開發中的優勢的文章就介紹到這瞭,更多相關Fluent Mybatis開發內容請搜索WalkonNet以前的文章或繼續瀏覽下面的相關文章希望大傢以後多多支持WalkonNet！

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