spring data jpa使用Pageable，ExampleMatcher進行分頁多條件查詢

原創

2020-02-21 15:36

一般簡單的查詢，可以使用，findByName,findById等方法，但是當這種方法越來越多的時候，就會顯得特別冗雜，這個時候就需要把方法進行合併，spring data jpa提供了一種Query by Example的方法。

當僅使用簡單查詢的時候

@Override
public Page queryByPage(T t, Pageable pageable) {
    Example<T> example = Example.of(t);
    return baseDao.findAll(example, pageable);
}

這種查詢會將實體中所有不爲空的屬性（包括父類的）都作爲查詢條件

SELECT roleentity0_.id AS id1_7_, roleentity0_.delete_flag AS delete_f2_7_, roleentity0_.system_id AS system_i3_7_, roleentity0_.create_time AS create_t4_7_, roleentity0_.create_user_id AS create_u5_7_, roleentity0_.update_time AS update_t6_7_, roleentity0_.update_user AS update_u7_7_, roleentity0_.content AS content8_7_, roleentity0_.org_id AS org_id9_7_, roleentity0_.role_name AS role_na10_7_, roleentity0_.role_type AS role_ty11_7_, roleentity0_.weight AS weight12_7_
FROM dafangzi_role roleentity0_
WHERE roleentity0_.update_time=? AND roleentity0_.create_time=? AND roleentity0_.delete_flag=?
ORDER BY roleentity0_.update_time DESC
LIMIT ?

上述內容可以看到，由於修改時間和創建時間有默認值，也當成了查詢條件，這並不是我們想要的，於是做出修改如下，

@Override
public Page queryByPage(T t, Pageable pageable) {
    //Example<T> example = Example.of(t);
    ExampleMatcher matcher = ExampleMatcher.matching().withIgnorePaths("createTime", "updateTime");
    Example<T> example = Example.of(t, matcher);
    return baseDao.findAll(example, pageable);
}

再查看查詢結果，就是我們想要的結果了

SELECT roleentity0_.id AS id1_7_, roleentity0_.delete_flag AS delete_f2_7_, roleentity0_.system_id AS system_i3_7_, roleentity0_.create_time AS create_t4_7_, roleentity0_.create_user_id AS create_u5_7_, roleentity0_.update_time AS update_t6_7_, roleentity0_.update_user AS update_u7_7_, roleentity0_.content AS content8_7_, roleentity0_.org_id AS org_id9_7_, roleentity0_.role_name AS role_na10_7_, roleentity0_.role_type AS role_ty11_7_, roleentity0_.weight AS weight12_7_
FROM dafangzi_role roleentity0_
WHERE roleentity0_.delete_flag=?
ORDER BY roleentity0_.update_time DESC
LIMIT ?

但是有很多時候我們查詢的時候是需要模糊查詢的，這個時候需要再次對需要模糊查詢的字段進行特殊的處理

ExampleMatcher matcher = ExampleMatcher.matching().withIgnorePaths("createTime", "updateTime").withMatcher("roleName", match -> match.contains());
Example<RoleEntity> example = Example.of(roleEntity, matcher);
Page<RoleEntity> entityPage = roleService.queryByPage(example, PageRequest.of(page-1, limit, sort));

這樣，就變成模糊查詢了

SELECT roleentity0_.id AS id1_7_, roleentity0_.delete_flag AS delete_f2_7_, roleentity0_.system_id AS system_i3_7_, roleentity0_.create_time AS create_t4_7_, roleentity0_.create_user_id AS create_u5_7_, roleentity0_.update_time AS update_t6_7_, roleentity0_.update_user AS update_u7_7_, roleentity0_.content AS content8_7_, roleentity0_.org_id AS org_id9_7_, roleentity0_.role_name AS role_na10_7_, roleentity0_.role_type AS role_ty11_7_, roleentity0_.weight AS weight12_7_
FROM dafangzi_role roleentity0_
WHERE (roleentity0_.role_name LIKE ?) AND roleentity0_.delete_flag=?
ORDER BY roleentity0_.update_time DESC
LIMIT ?