Java，CriteriaBuilder，带有可选参数的查询 "where"

Question

我必须重写一些代码，但在互联网上找不到正确的信息。原始部分如下所示:

String query = "select * from sublog_type_map_v where 1 = 1";
if (responsibleGroupId != null && responsibleGroupId.length() != 0 && !responsibleGroupId.equals("0")) {
    query += " and responsible_group_id = " + responsibleGroupId;
}
if (categoryId != null && categoryId.length() != 0 && !categoryId.equals("0")) {
    query += " and category_id = " + categoryId;
}
if (typeId != null && typeId.length() != 0 && !typeId.equals("0")) {
    query += " and type_id = " + typeId;
}
if (subtypeId != null && subtypeId.length() != 0 && !subtypeId.equals("0")) {
    query += " and subtype_id = " + subtypeId;
}

我已经继续执行此代码:

CriteriaBuilder builder = entityManager.getCriteriaBuilder();
CriteriaQuery<SublogTypeMapV> query = builder.createQuery(SublogTypeMapV.class);
Root<SublogTypeMapV> root = query.from(SublogTypeMapV.class);
query.select(root).where(builder.equal(root.get("responsibleGroupId"), responsibleGroupId));

但是这个“where”应该被认为是可选的，使用“if”表达式，以及其他三个参数(我将在稍后添加)。我不知道该怎么做，有人可以帮助我吗？

Answer 1

我想这可以满足需要 -

CriteriaBuilder builder = entityManager.getCriteriaBuilder();
CriteriaQuery<SublogTypeMapV> query = builder.createQuery(SublogTypeMapV.class);
Root<SublogTypeMapV> root = query.from(SublogTypeMapV.class);
query = query.select(root);
if("some boolean expression") {
    query = query.where(builder.equal(root.get("responsibleGroupId"), responsibleGroupId));
}

类似地，您可以处理内部的其他条件。