spring data jpa Query By Example(QBE)

java代码   

1. //首先是表的映射  
2. public class OperLog implements Serializable {  
3.     private static final long serialVersionUID = 1L;  
4.       
5.     @Id  
6.     @GeneratedValue  
7.     private Integer id;  
8.     @Column  
9.     @JsonSerialize(using=DateJsonSerialize.class)  
10.     private Date stamp;  
11.     @Column  
12.     private String oper;  
13.     @Column  
14.     private String memo;  
15. }  
16. //DAO只要接口就可以了，  
17. public interface OperLogRepository extends CrudRepository<OperLog, Integer>,JpaSpecificationExecutor<OperLog> {  
18.   
19. }  
20. //service层  
21. @Service("dataservice")  
22. public class DataServiceImpl implements DataService {     
23.   
24.     public Pagenation<OperLog> pageOperLog(int page, int rows, String key, Date start,    Date end) {  
25.         Pageable pinfo = new PageRequest(page-1, rows,new Sort(Direction.DESC,"id"));  
26.         Page<OperLog> infos = olDao.findAll(buildOperSpecification(key, start,end), pinfo);  
27.         Pagenation<OperLog> pg = new Pagenation<OperLog>(page, rows);  
28.         pg.setRows(infos.getContent());  
29.         pg.setTotal(new Long(infos.getTotalElements()).intValue());  
30.         return pg;  
31.     }  
32.       
33.     private Specification<OperLog> buildOperSpecification(final String key,  
34.             final Date start, final Date end) {  
35.         return new Specification<OperLog>() {  
36.             public Predicate toPredicate(Root<OperLog> root,  CriteriaQuery<?> q, CriteriaBuilder cb) {  
37.                 List<Predicate> predicates = new ArrayList<Predicate>();  
38.                 if(StringUtils.hasText(key)){  
39.                     Path<String> np = root.get("oper");  
40.                     predicates.add(cb.like(np, "%" + key + "%"));  
41.                 }  
42.                 if(start!=null){  
43.                     Path<Date> np = root.get("stamp");  
44.                     predicates.add(cb.greaterThanOrEqualTo(np, start));  
45.                 }  
46.                 if(end!=null){  
47.                     Path<Date> np = root.get("stamp");  
48.                     predicates.add(cb.greaterThanOrEqualTo(np, end));  
49.                 }  
50.                 if (predicates.size() > 0) {  
51.                     return cb.and(predicates.toArray(new Predicate[predicates.size()]));  
52.                 }  
53.                 return cb.conjunction();  
54.             }  
55.               
56.         };  
57.     }  
58.   
59.   
60.     @Autowired  
61.     OperLogRepository olDao;  

这里千万要注意的是PageRequest的页码是从0开始的，而我自己页码是从1开始的！所以导致分页的时候，只做了一个count语句，记录没有取！血的教训啊！ 

下面是一些配置文件 

Xml代码   

1. <bean id="myEmf"  
2.         class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">  
3.         <property name="dataSource" ref="dataSource" />  
4.         <property name="packagesToScan" value="com.fox.dataws.model" />  
5.         <property name="jpaVendorAdapter">  
6.             <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">  
7.                 <property name="showSql" value="${hibernate.show_sql}" />  
8.                 <property name="generateDdl" value="${jpa.generateDdl}" />  
9.                 <property name="databasePlatform" value="${persistence.dialect}" />  
10.             </bean>  
11.         </property>  
12.     </bean>  
13.     <bean id="dataSource"  
14.         class="org.springframework.jdbc.datasource.DriverManagerDataSource">  
15.         <property name="driverClassName" value="${db.driver}" />  
16.         <property name="url" value="${db.url}" />  
17.         <property name="username" value="${db.uid}" />  
18.         <property name="password" value="${db.pwd}" />  
19.     </bean>  
20.     <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">  
21.         <property name="entityManagerFactory" ref="myEmf" />  
22.     </bean>  
23.     <tx:annotation-driven transaction-manager="transactionManager" />  
24.       
25.     <jpa:repositories base-package="com.fox.dataws.repo" />