Spring Data Jpa 的简单查询多表查询HQL，SQL ，动态查询， QueryDsl ，自定义查询笔记
基本知识：
- Repository：仅仅只是一个标识，没有任何方法，方便Spring自动扫描识别
- CrudRepository：继承Repository，实现一组CRUD相关方法
- PagingAndStortingRepository：继承CrudRepository，实现一组分页排序相关方法
- JpaRepository：继承PagingAndStortingRepository，QueryByExampleExecutor 实现一组JPA规范方法
下面是一个AppUser 的 Dao接口，除了简单的findBy 接口查询外，还有@Query的查询，查询返回一个自定义的结果Useinfo，UserInfo 从2个表中获取，从AppUser 中获取 phone ，name 等信息，从 HearUrl 表中获取userid 对应的头像地址；
@Repository
public interface AppUserRepository extends JpaRepository{
AppUser findByUserid(String userid);
//根据电话和客户名查询
AppUser findByPhoneAndCustomName(String phone, String customName);
//分页查询
Page findByCustomName(String customName,Pageable pageable);
//查询2个表的指定字段，组成新的对象UserInfo
@Query(value = "select new com.cxx.beans.UserInfo(u.userid, u.phone,u.name, u.address, u.info,head.headUrl) "
+ "from AppUser u, HeadUrl head where u.userid = head.userid and"
+ " u.userid = :userid")
UserInfo findUserInfoByUserid(@Param("userid") String userid);
//查询2个表具有同一个userid 的内容，并组成新的对象
@Query(value = "select new com.cxx.beans.UserInfo(u.userid, u.phone,u.name, u.address, u.info,head.headUrl) "
+ "from AppUser u, HeadUrl head where u.userid = head.userid")
List findUserInfo();
@Query(value = "select u.userid, u.phone,u.name, u.address, u.info,head.headUrl from AppUser u, HeadUrl head"
+ " where u.userid = head.userid and"
+ " u.userid = :userid",nativeQuery = true)
List findUserInfos2(@Param("userid") String userid);
//删除用户，根据name 和city 删除全部匹配的用户
@Modifying
@Transactional
@Query(value="delete from AppUser where name =?1 and city= ?2")
void deleteUser(String name,String city);
//去重查询，查询city 列表
@Query(value="select distinct city from AppUser")
List getCityList();
}
public class UserInfo implements Serializable{
private String userid;
private String phone;
private String name;
private String address;
private String info;
private String headUrl;
public UserInfo()
{
}
public UserInfo(String userid, String phone, String name, String address, String info, String headUrl) {
super();
this.userid = userid;
this.phone = phone;
this.name = name;
this.address = address;
this.info = info;
this.headUrl = headUrl;
}
...
} findUserInfo 返回的数据结构
{
"userid": "e4d6f4eef48c4408985b65f6997891bb",
"phone": "13760234541",
"name": "张三",
"address": null,
"info": null,
"headUrl": "http://cbc-huanan-image.oss-cn-shenzhen.aliyuncs.com/15337983334421.png"
}
findUserinfos2 返回的数据结构：
[
[
"e4d6f4eef48c4408985b65f6997891bb",
"13760234541",
"张三",
null,
null,
"http://cbc-huanan-image.oss-cn-shenzhen.aliyuncs.com/15337983334421.png"
],
[ ... ]
] 查询到多个去重后，比如我需要查包含密码信息的房间和包含指纹信息的房间，查找结果再去重，得到所有的房间号
//set去重
Set set = new HashSet();
List listNew=new ArrayList<>();
set.addAll(list1);
set.addAll(list2);
listNew.addAll(set);
更正：
我想从 A表(AppUser)中获取一些字段（name ，等）， 再根据B表（HeadUrl）中获取一些字段(headUrl)，组成查询结果，上面的这个方法，在有一个表中不存在相应的记录是无法得到想要的结果 @Query(value = "select new com.cxx.beans.UserInfo(u.userid, u.phone,u.name, u.address, u.info,head.headUrl) "
+ "from AppUser u, HeadUrl head where u.userid = head.userid and"
+ " u.userid = :userid")
UserInfo findUserInfoByUserid(@Param("userid") String userid);
正确的SQL 查询语句如下：需要用LeftJoin 方式，这样当HeadUrl 中查询内容为空时也能正确返回。
所以正确的查询方法如下，但这个返回的是Object数组，需要根据这个数组内容，再手动转成我们需要的对象
@Query(select u.userid, u.phone,u.name, u.address, u.info, head.headUrl from AppUser u LEFT JOIN HeadUrl head USING(userid) where u.userid = :userid",nativeQuery =true)
List
Spring JPA方法名解析步骤
- 在进行方法名解析时会先去掉多余的前缀，比如find、findBy、read、readBy、get、getBy，然后对剩下部分进行解析，并且如果方法最后一个参数时 Sort 或 Pageable 类型，也会提取相关信息
- 比如：findByNameLikeAndAgeGreaterThan
- 剔除findBy
- 判断nameLikeAndAgeGreaterThan（根据POJO规范，首字母变小写）是否为返回对象 User 的一个属性，如果是，则根据该属性进行查询，如果没有该属性，则进行下一步
- 从右往左截取第一个大写字母开头的字符串（此处为Than），然后检查剩下的字符串是否为 User 的一个属性，如果是，则根据该属性进行查询，否则重复第2步，直到找出 name 为 User 的属性
- 从已截取的部分后面开始，重新第 1 步开始（剔除条件语句），循环，直到把方法名处理完毕
- 通过获取的操作、条件和属性、带入参数值，生成查询
| 关键字 | 例子 | 对应的JPQL语句 |
|---|---|---|
| And | findByLastnameAndFirstname | … where x.lastname = ?1 and x.firstname = ?2 |
| Or | findByLastnameOrFirstname | … where x.lastname = ?1 or x.firstname = ?2 |
| Is,Equals | findByFirstname,findByFirstnameIs,findByFirstnameEquals | … where x.firstname = ?1 |
| Between | findByStartDateBetween | … where x.startDate between ?1 and ?2 |
| LessThan | findByAgeLessThan | … where x.age < ?1 |
| LessThanEqual | findByAgeLessThanEqual | … where x.age ⇐ ?1 |
| GreaterThan | findByAgeGreaterThan | … where x.age > ?1 |
| GreaterThanEqual | findByAgeGreaterThanEqual | … where x.age >= ?1 |
| After | findByStartDateAfter | … where x.startDate > ?1 |
| Before | findByStartDateBefore | … where x.startDate < ?1 |
| IsNull | findByAgeIsNull | … where x.age is null |
| IsNotNull,NotNull | findByAge(Is)NotNull | … where x.age not null |
| Like | findByFirstnameLike | … where x.firstname like ?1 |
| NotLike | findByFirstnameNotLike | … where x.firstname not like ?1 |
| StartingWith | findByFirstnameStartingWith | … where x.firstname like ?1 (parameter bound with appended %) |
| EndingWith | findByFirstnameEndingWith | … where x.firstname like ?1 (parameter bound with prepended %) |
| Containing | findByFirstnameContaining | … where x.firstname like ?1 (parameter bound wrapped in %) |
| OrderBy | findByAgeOrderByLastnameDesc | … where x.age = ?1 order by x.lastname desc |
| Not | findByLastnameNot | … where x.lastname <> ?1 |
| In | findByAgeIn(Collection ages) | … where x.age in ?1 |
| NotIn | findByAgeNotIn(Collection age) | … where x.age not in ?1 |
| True | findByActiveTrue() | … where x.active = true |
| False | findByActiveFalse() | … where x.active = false |
| IgnoreCase | findByFirstnameIgnoreCase | … where UPPER(x.firstame) = UPPER(?1) |
关联外键查询
- 假设有两张表 address与 user
- address表中有一个 user_id 的外键列对应着 user 表的主键
- 若查询条件为 id 为 1 的 address且同时对应 id 为 2 的用户，如下列 SQL 语句：
SELECT a.* FROM address a JOIN user u ON a.user_id = u.id WHERE a.id = 1 AND u.id = 2
- 则使用 _ 来连接关联实体属性查询，上述 SQL 对应的 JPA 方法名为
Address findTopByIdAndUser_Id(int addressId,int userId);
限制查询结果数量
public interface PersonRepository extends JpaRepository{
//获得符合查询条件的前30条数据
ListfindTop30ByName(String name);
}
通过@query编写创建查询
- 可以通过@Query（若使用nativesql属性，则使用原生的sql语句）注解来创建查询（参数也可用 ?1 ?2 代替，则不需@Param），如：
@Query("select * from User u where u.name like :first and u.age>:age")
List findByNameLikeAndAgeGreaterThan(@Param("first")String firstName,@Param("age")Integer age);
@Modifying
@Transactional
@Query("update User u set u.name = ?1 where u.id = ?2")
public int increaseSalary(String name, int id);
@Modifying
@Transactional
@Query(value="delete from UserShips where userid =?1 and houseNo= ?2")
void deleteByUseridAndHouseNo(String userid ,String houseNo);- 更新、删除操作需要加上@Transactional @Modifying
复杂查询
多表联合查询，动态查询可以用QueryDsl 方式，也可以用Specification 方式来做。以下是动态查询的一个实例：
下面是人员Bean 的关键数据：
public class Person {
@Id
@GeneratedValue(generator="system-uuid")
private String id;
private String name;
....
@ManyToOne
private House house;
@ManyToOne
//@JsonIgnore
private Building building;
@ManyToMany(cascade = CascadeType.PERSIST,fetch=FetchType.EAGER)
private Set gate_device;
private String phone; Dao:
@Repository
public interface PersonDao extends JpaRepository,JpaSpecificationExecutor,QuerydslPredicateExecutor
{
Person findByName(String name);
List findByBuildingId(String id);
List findByIdIn(Collection ids);
//根据person ID 查询 person的概要信息
@Query(value="SELECT p.id as pid,"
+ "p.name as name, "
+ "p.sex as sex,"
+ "p.card_id as card_id,"
+ "file.url as url,"
+ "p.enable as enable,"
+ "p.permission_status,"
+ "h.name AS room_name,"
+ "b.name AS building_name "
+ "FROM Person p "
+ "LEFT JOIN FileUrl file ON p.id=file.owner.id "
+ "LEFT JOIN House h ON p.house.id = h.id "
+ "LEFT JOIN Building b ON p.building.id = b.id "
+ "WHERE p.id= ?1 "
)
List findAllInfo(String id);
/*
* personinfo 的构造函数 和QueryDsl 的自动构造函数有冲突（好像是）
*
*
*
//根据person id 查询获取person 的概要信息 personinfo
@Query(value="SELECT new com.cbest.cb025.entity.PersonInfo("
+ "p.id,"
+ "p.name,"
+ "p.card_id,"
+ "h.name,"
+ "b.name, "
+ "p.sex,"
+ "p.permission_status,"
+ "p.enable"
+ ") "
+ "FROM Person p "
+ "LEFT JOIN House h ON p.house.id = h.id "
+ "LEFT JOIN Building b ON p.building.id = b.id "
+ "WHERE p.id= ?1 GROUP BY p.id"
)
PersonInfo findOnePersonInfo(String id);
@Query(value="SELECT new com.cbest.cb025.entity.PersonInfo("
+ "p.id,"
+ "p.name,"
+ "p.card_id,"
+ "h.name,"
+ "b.name, "
+ "p.sex,"
+ "p.permission_status,"
+ "p.enable"
+ ") "
+ "FROM Person p "
+ "LEFT JOIN House h ON p.house.id = h.id "
+ "LEFT JOIN Building b ON p.building.id = b.id "
+ "WHERE p.id in (?1)"
)
List findPersonInfoByPersonIds(String[] id);
*/ 查询数据：
Specification s = new Specification() {
@Override
public Predicate toPredicate(Root root, CriteriaQuery query, CriteriaBuilder cb) {
Predicate p = cb.conjunction();
p.getExpressions()
.add(cb.equal(root.get("building").get("address").get("owner").get("company"),company));
if (!StringUtils.isEmpty(req.getProvince())) {
p.getExpressions().add(cb.like(root.get("building").get("address").get("province"),
"%" + req.getProvince() + "%"));
}
// 根据city 查询
if (!StringUtils.isEmpty(req.getCity())) {
p.getExpressions()
.add(cb.like(root.get("building").get("address").get("city"), "%" + req.getCity() + "%"));
}
if (!StringUtils.isEmpty(req.getDistrict())) {
p.getExpressions().add(cb.like(root.get("building").get("address").get("district"),
"%" + req.getDistrict() + "%"));
}
if (!StringUtils.isEmpty(req.getStreet())) {
p.getExpressions().add(
cb.like(root.get("building").get("address").get("street"), "%" + req.getStreet() + "%"));
}
if (!StringUtils.isEmpty(req.getVillage())) {
p.getExpressions().add(
cb.like(root.get("building").get("address").get("name"), "%" + req.getVillage() + "%"));
}
if (!StringUtils.isEmpty(req.getApartment())) {
p.getExpressions().add(cb.like(root.get("building").get("name"), "%" + req.getApartment() + "%"));
}
。。。
if (!StringUtils.isEmpty(req.getKeyword()))
{
Join person_room = root.join("house", JoinType.LEFT); // 这里必须要用JOIN 的形式，否则在house 外键为空时查询不到数据
/* p.getExpressions().add(cb.and(cb.isNotNull(root.get("house")),cb.like(root.get("house").get("name"), "%" + req.getRoom() + "%")));*/
p.getExpressions().add(
cb.or(
cb.like(root.get("phone"), "%" + req.getKeyword() + "%"),
cb.like(root.get("name"), "%" + req.getKeyword() + "%"),
cb.like(root.get("card_id"), "%" + req.getKeyword() + "%"),
cb.like(root.get("building").get("address").get("name"), "%" + req.getKeyword() + "%"),
cb.like(root.get("building").get("name"), "%" + req.getKeyword() + "%"),
cb.like(person_room.get("name"),"%" + req.getKeyword() + "%")
)
);
}
return p;
}
};
if (req.getSize() == 0) {
List devices = personDao.findAll(s);
return ResponseFactory.getBaseResponse(devices);
}
Sort sort = new Sort(Sort.Direction.ASC, "name");
Pageable pageable = PageRequest.of(req.getPage(), req.getSize(), sort);
Page devices = personDao.findAll(s, pageable); 上面就是动态查询的人员列表的重点代码；特别注意的是，Person 中有个 外键 House 是可以为Null 的； 这种情况下就必须选用Join 的方式来创建查询表达式，而上面的查询例子中 Building 因为不为空，所以可以用 直接创建表达式的形式。
2.多表联合查询，返回自定义分页数据：
人员文件信息
@Entity
@EntityListeners(AuditingEntityListener.class)
@GenericGenerator(name="system-uuid",strategy = "uuid")
public class FileUrl {
@Id
@GeneratedValue(generator="system-uuid")
private String id;
private String url;
@ManyToOne(optional = true,cascade = CascadeType.PERSIST)
@JsonIgnore
private Person owner;
....查询结果Bean 定义：
@Data
@Builder
public class PersonInfo {
private String pid;
private String name;
private String card_id;
private String room_name;
private String building_name;
private String start_time;
private String end_time;
private int sex;
private int permission_status;
private boolean enable;
private Set urls = new HashSet(); // 怎么查询出这个数据？ 一直没找到直接的方法。
public String getPid() {
return pid;
}
public void setPid(String pid) {
this.pid = pid;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getCard_id() {
return card_id;
}
public void setCard_id(String card_id) {
this.card_id = card_id;
}
public String getRoom_name() {
return room_name;
}
public void setRoom_name(String room_name) {
this.room_name = room_name;
}
public String getBuilding_name() {
return building_name;
}
public void setBuilding_name(String building_name) {
this.building_name = building_name;
}
public int getSex() {
return sex;
}
public void setSex(int sex) {
this.sex = sex;
}
public int getPermission_status() {
return permission_status;
}
public void setPermission_status(int permission_status) {
this.permission_status = permission_status;
}
public boolean isEnable() {
return enable;
}
public void setEnable(boolean enable) {
this.enable = enable;
}
public PersonInfo(String pid, String name, String card_id, String room_name, String building_name,
String start_time, String end_time, int sex, int permission_status, boolean enable,Set urls) {
super();
this.pid = pid;
this.name = name;
this.card_id = card_id;
this.room_name = room_name;
this.building_name = building_name;
this.start_time = start_time;
this.end_time = end_time;
this.sex = sex;
this.permission_status = permission_status;
this.enable = enable;
this.urls = urls;
}
public static PersonInfo transform(Tuple tuple) {
QPerson person = QPerson.person;
QHouse house = QHouse.house;
QBuilding building = QBuilding.building;
PersonInfo pinfo = new PersonInfo(
tuple.get(person.id),
tuple.get(person.name),
tuple.get(person.card_id),
tuple.get(house.name),
tuple.get(building.name),
tuple.get(person.start_time),
tuple.get(person.end_time),
tuple.get(person.sex),
tuple.get(person.permission_status),
tuple.get(person.enable),
new HashSet()
);
return pinfo;
}
... QueryDsl 方式分页查询获取数据： 没有一次性查找获得文件地址的数组，因为研究了好久还是不会，有人可以留言帮指导下吗？
public PageResult findPageablePersonInfoByDeviceId(String device_id,Pageable pageable) {
logger.info("findPageablePersonInfoByDeviceId id = " + device_id + " pageSize = " + pageable.getPageSize() + ",pageNumber = " + pageable.getPageNumber());
long time = System.currentTimeMillis();
QPerson person = QPerson.person;
QHouse house = QHouse.house;
QBuilding building = QBuilding.building;
QFileUrl fileUrl = QFileUrl.fileUrl;
String[] ids = personDao.findPersonIdsByDevicId(device_id);
logger.info("findPageablePersonInfoByDeviceId: findPersonIdsByDevicId costTime = " + (System.currentTimeMillis() - time));
QueryResults queryResults = jpaQueryFactory
.select(
person.id,
person.name,
house.name,
building.name,
person.card_id,
person.start_time,
person.end_time,
person.sex,
person.permission_status,
person.enable
)
.from(person)
.leftJoin(house).on(house.id.eq(person.house.id))
.leftJoin(building).on(person.building.id.eq(building.id))
.where(person.id.in(ids))
.offset(pageable.getOffset())
.limit(pageable.getPageSize())
.fetchResults()
;
Set info = queryResults.getResults().stream().map(PersonInfo::transform
)
.collect(Collectors.toSet());
Set pids = new HashSet();
for(PersonInfo p : info)
{
pids.add(p.getPid());
}
List res = jpaQueryFactory
.select(
person.id,
fileUrl.url
)
.from(fileUrl)
.leftJoin(person).on(fileUrl.owner.id.eq(person.id))
.where(person.id.in(pids))
.fetch();
for(PersonInfo p : info)
{
for (Tuple row : res) {
if(row.get(person.id).equals(p.getPid()))
p.addUrl(row.get(fileUrl.url));
}
}
int totalPage = 0;
if(queryResults.getTotal()%pageable.getPageSize() == 0)
totalPage = (int) (queryResults.getTotal()/pageable.getPageSize());
else
totalPage = (int) (queryResults.getTotal()/pageable.getPageSize()) + 1;
PageResult result = new PageResult(info,
totalPage,
(int)queryResults.getTotal(),
(pageable.getPageNumber() == totalPage -1) ? true :false,
pageable.getPageNumber(),
(pageable.getPageNumber() == 0) ? true :false,
info.size());
logger.info("findPageablePersonInfoByDeviceId: findTotal costTime = " + (System.currentTimeMillis() - time));
return result;
} 用到的复杂查询大概就是这些了。
还有一种情况，就是一对多的联合查询处理，可以用SetJoin 这样的方式
Specification s = new Specification() {
@Override
public Predicate toPredicate(Root root, CriteriaQuery query, CriteriaBuilder cb) {
Predicate p = cb.conjunction();
SetJoin join = root.joinSet("gate_device", JoinType.LEFT);
p.getExpressions().add(cb.equal(join.get("sn"), req.getDevice_sn()));
return p;
}
};