1、裝配實例化JPAQueryFactory

private final BaseDao dao; private final JPAQueryFactory factory; private final QUser qUser; private final QFile qFile;@Autowired public UserServiceImpl(BaseDao dao) {this.factory = new JPAQueryFactory(dao.getEntityManager());this.dao = dao;this.qFile = QFile.file;this.qUser = QUser.user; }

2、單表簡單查詢

User user = factory.from(qUser).select(Projections.bean(User.class,qUser.username)).where(qUser.id.eq("8f98b857fa954cfb986b88a2692e9d81")).where(qUser.tel.eq("4646464")).fetchOne();

3、單表分頁查詢

JPAQuery listQuery = factory//tel字段去重（6條數據）.selectDistinct(qUser.tel).from(qUser).select(//封裝映射到UserViewModel中Projections.bean(UserViewModel.class,qUser.id,qUser.username))//where可多個參數.where(predicate,qUser.createdTime.before(new Date())).orderBy(qUser.id.desc()).offset(pageIndex).limit(pageSize); List<UserViewModel> list = listQuery.fetch(); //fetchCount不會執行orderBy、offset、limit參數也不會去重(7條數據) int count = (int) listQuery.fetchCount();

4、多表簡單查詢

UserViewModel userViewModel = factory.select(Projections.bean(UserViewModel.class,qUser.id,qUser.creator,qUser.tel,qUser.username,qUser.address,qFile.name.as("name"),qUser.createdTime.stringValue())).from(qUser,qFile).where(qFile.name.eq("test").and(qUser.username.eq(qFile.creator))).fetchOne();

5、子查詢

List<FileViewModel> selectDome = factory.from(qFile).select(Projections.bean(FileViewModel.class,qFile.id,qFile.name,qFile.size)).where(qFile.size.lt(JPAExpressions.select(qFile.size.avg()).from(qFile))).fetch();

6、聚合函數

Long getCount = factory.from(qUser).select(qUser.id.count()).fetchOne(); Double getAvg = factory.from(qFile).select(qFile.size.avg()).fetchOne(); Long getMin = factory.select(qFile.size.min()).from(qFile).fetchOne(); Long getSum = factory.select(qFile.size.sum()).from(qFile).fetchOne();

7、更新操作

factory.update(qMoldsUsage).set(qMoldsUsage.returneeId,model.getReturneeId()).set(qMoldsUsage.returnTime,model.getReturnTime()).where(qMoldsUsage.id.eq(model.getId())).execute();

8、刪除操作

factory.delete(qExitStorage).where(qExitStorage.materialId.eq(model.getMaterialId())).execute();

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總結

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