Spring data jpa实现CRUD的三种方式

1. 继承JpaRepository

    JpaRepository继承PagingAndSortingRepository因此可以很好的实现分页和排序功能。

    public interface JpaRepository<T, ID extends Serializable>
extends CrudRepository<T, ID> {

Iterable<T> findAll(Sort sort);

Page<T> findAll(Pageable pageable);
}
2. 使用 jpql语句

public interface UserRepository extends JpaRepository<User, Long> {

@Query("select u from User u where u.emailAddress = ?1")
User findByEmailAddress(String emailAddress);
}

3. 使用实体处理器

package com.jike.usermanage.repository;

import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;

import org.springframework.transaction.annotation.Transactional;

import com.jike.usermanage.model.Interest;
import com.jike.usermanage.model.User;

public class UserRepositoryImpl {

@PersistenceContext
private EntityManager entityManager;

@Transactional
public void add(User user) {
entityManager.persist(user);

}
@Transactional
public User update(User user) {
User userUpdate = entityManager.find(User.class, user.getId());
userUpdate.setName(user.getName());
userUpdate.setPhone(user.getPhone());
return userUpdate;
}
@Transactional
public User addOrUpdate(User user) {

return entityManager.merge(user);
}
@Transactional
public void delete(User user) {
entityManager.remove(user);

}

public User findOne(Integer id) {

return entityManager.find(User.class, id);
}
@Transactional
public List<User> findAll() {

/*
* + , - , *, /
*
* =, >, <, >=, <=, <>
*
* between, like, in, is null, is empty, member of, not , and ,or
*
* */

String queryString = "select u from User u where :interest member of u.interests";
Query query = entityManager.createQuery(queryString);
Interest interest = new Interest();
interest.setId(1L);
query.setParameter("interest", interest);
List list = query.getResultList();
/*if (list!=null){
List<User> userList = new ArrayList<User>();
for(int i=0; i<list.size(); i++){

Object[] o = (Object[]) list.get(i);
User user = new User();
user.setName(o[0].toString());
user.setInCome(new BigDecimal(o[1].toString()));
userList.add(user);

}
return userList;

}else
return null;*/
return list;

}

@Transactional
public List<Object> findObject(int uid) {

/*
* 基本语法：select 实体属性 聚合函数（实体属性） from 实体 group by 实体属性 having 条件
*
* avg(distinct...),sum(distinct...),count(distinct...),min,max
*
* */

String queryString = "select new com.jike.usermanage.model.User(u.id,u.name) from User u where u.id=:id";
//Query query = entityManager.createQuery(queryString);
Query query =entityManager.createNativeQuery("select id_,name_ from t_user where id_=1");
query.setParameter("id", uid);
List list = query.getResultList();
return list;

}

}


相关文档参考：http://docs.spring.io/spring-data/jpa/docs/current/reference/html/