这里就滤过Spring Data JPA项目部署，不清楚的可以看一下开源项目AutoAdmin。
Entity(表实体类)
一个表对应一个实体类，这里以AutoAdmin的sys_user表为例：
import cn.songhaiqing.autoadmin.base.BaseEntity;
import org.hibernate.annotations.Where;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Table;
@Entity
@Table(name = "sys_user")
@Where(clause = "deleted=0")
public class SysUser extends BaseEntity {
// 账号
@Column(name = "account")
private String account;
// 密码
@Column(name = "password")
private String password;
// 姓名
@Column(name = "name")
private String name;
// 密码加密盐
@Column(name = "salt")
private String salt;
public String getAccount() {
return account;
}
public void setAccount(String account) {
this.account = account;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSalt() {
return salt;
}
public void setSalt(String salt) {
this.salt = salt;
}
}备注
- @Table注解：写表名，如果表是刚好使用驼峰命名的话可以不写，建议写上。
- @Where ：查询该表时会自动加个的条件，用来做软删除过滤是非常好的选择，但是在@ManyToOne get该实体时如果数据已删除就会有问题，注意区别使用。
- @Column 字段申明，可以写在不同的位置，但个人习惯写在字段上一行。属性名可以和数据库表字段名不一样。
BaseEntity
实体类继承了BaseEntity，该类写一些通用的字段，像ID、创建时间、更新时间、删除标注等。
import javax.persistence.*;
import java.util.Date;
@MappedSuperclass
public class BaseEntity {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
@Column(name = "create_time", nullable = false,updatable = false)
private Date createTime = new Date();
@Column(name = "update_time", nullable = false)
private Date updateTime = new Date();
@Column(name = "deleted", nullable = false)
private boolean deleted = false;
public Date getCreateTime() {
return createTime;
}
public Date getUpdateTime() {
return updateTime;
}
public void setUpdateTime(Date updateTime) {
this.updateTime = updateTime;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public void setCreateTime(Date createTime) {
this.createTime = createTime;
}
public boolean isDeleted() {
return deleted;
}
public void setDeleted(boolean deleted) {
this.deleted = deleted;
}
}备注
* @Id @GeneratedValue(strategy = GenerationType.AUTO) ID 自增
* 默认值：直接给变量设置初始值就可以了，create_time（创建时间）有点不一样，因为我不想以后改变值，因为需要设置updatable = false。
Repository(表操作接口)
有人习惯叫DAO或其他，JPA很重要的地方，使用JPA的语法简单直接的替代了大部分SQL。
示例
import cn.songhaiqing.autoadmin.entity.SysUser;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.springframework.stereotype.Repository;
@Repository
public interface SysUserRepository extends JpaRepository,JpaSpecificationExecutor {
SysUser findByAccount(String account);
long countByAccount(String account);
long countByAccountAndIdNot(String account, Long id);
} 查询
根据单查询（一条结果）
SysUser findByAccount(String account);需要确保返回的结果最多只有一条，否则会报错
根据单查询（多条结果）
List findByAccount(String account); 多条件查询
SysUser findByAccountAndPassword(String account, String password);查询第一条
SysUser findFirstByAccount(String account);查询前10条
SysUser findTop10ByAccount(String account);排序
SysUser findTop10ByAccount(String account);JPA语法
| Keyword | Sample | JPQL snippet |
|---|---|---|
| And | findByLastnameAndFirstname | … where x.lastname = ?1 and x.firstname = ?2 |
| Or | findByLastnameOrFirstname | … where x.lastname = ?1 or x.firstname = ?2 |
| Is,Equals | findByFirstname | … where x.firstname = ?1 |
| findByFirstnameIs | ||
| findByFirstnameEquals | ||
| 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 ages) | … 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) |
分页复杂查询
示例
List orders = new ArrayList<>();
orders.add(new Sort.Order(Sort.Direction.DESC,"id"));
Sort sort = new Sort(orders);
Page page = sysUserRepository.findAll(new Specification(){
@Override
public Predicate toPredicate(Root root, CriteriaQuery criteriaQuery, CriteriaBuilder criteriaBuilder) {
List predicate = new ArrayList<>();
// 此处添加过滤条件
Predicate[] pre = new Predicate[predicate.size()];
return criteriaQuery.where(predicate.toArray(pre)).getRestriction();
}
},new PageRequest(query.getPage() - 1, query.getLimit(),sort));
BaseResponseList result = new BaseResponseList<>();
result.setCount(page.getTotalElements());
List models = new ArrayList<>();
for (SysUser sysUser : page.getContent()) {
SysUserViewModel model = new SysUserViewModel();
model.setId(sysUser.getId());
model.setAccount(sysUser.getAccount());
model.setName(sysUser.getName());
models.add(model);
}
result.setData(models);
return result; 此例中结合了分页、排序、过滤功能。
参考