使用SpringDataJpa完成需求

package com.cedric.dao;
import com.cedric.domain.Customer;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
/**
 * 符合SpringData的dao层的接口规范
 *      JpaRepository<操作的实体类型，实体类中主键的类型>
 *             * 封装了基本CRUD操作
 *      JpaSpecificationExecutor<操作的实体类型>
 *              * 封装了复杂查询（分页）
 */
public interface CustomerDao extends JpaRepository<Customer,Long>, JpaSpecificationExecutor<Customer> {
}

package com.cedric.test;
import com.cedric.dao.CustomerDao;
import com.cedric.domain.Customer;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import java.util.List;
@RunWith(SpringJUnit4ClassRunner.class) //声明spring提供的单元测试
@ContextConfiguration(locations = "classpath:applicationContext.xml") //指定spring容器的配置信息
public class CustomerDaoTest {
    @Autowired
    private CustomerDao customerDao;
    /**
     * 根据id查询
     */
    @Test
    public void testFindOne(){
        Customer customer = customerDao.findOne(3l);
        System.out.println(customer);
    }
    /**
     * save:保存或更新
     *      根据传递的对象是否存在主键id，
     *      如果没有id主键属性：保存
     *      存在id主键属性，根据id查询数据，更新数据
     */
    @Test
    public void testSave(){
        Customer customer = new Customer();
        customer.setCustName("农夫山泉");
        customer.setCustLevel("Vip");
        customer.setCustIndustry("营销");
        customerDao.save(customer);
    }
    @Test
    public void testUpdate(){
        Customer customer = new Customer();
        customer.setCustId(4l);
        customer.setCustName("农夫山泉有点甜");
        customerDao.save(customer);
    }
    @Test
    public void testDelete(){
        customerDao.delete(5l);
    }
    /**
     * 查询所有
     */
    @Test
    public void testFindAll(){
        List<Customer> list = customerDao.findAll();
        for (Customer customer : list){
            System.out.println(customer);
        }
    }
}