spring data jpa Query By Example(QBE)

//首先是表的映射
public class OperLog implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue
    private Integer id;
    @Column
    @JsonSerialize(using=DateJsonSerialize.class)
    private Date stamp;
    @Column
    private String oper;
    @Column
    private String memo;
}
//DAO只要接口就可以了，
public interface OperLogRepository extends CrudRepository<OperLog, Integer>,JpaSpecificationExecutor<OperLog> {

}
//service层
@Service("dataservice")
public class DataServiceImpl implements DataService {

    public Pagenation<OperLog> pageOperLog(int page, int rows, String key, Date start,    Date end) {
        Pageable pinfo = new PageRequest(page-1, rows,new Sort(Direction.DESC,"id"));
        Page<OperLog> infos = olDao.findAll(buildOperSpecification(key, start,end), pinfo);
        Pagenation<OperLog> pg = new Pagenation<OperLog>(page, rows);
        pg.setRows(infos.getContent());
        pg.setTotal(new Long(infos.getTotalElements()).intValue());
        return pg;
    }

    private Specification<OperLog> buildOperSpecification(final String key,
            final Date start, final Date end) {
        return new Specification<OperLog>() {
            public Predicate toPredicate(Root<OperLog> root,  CriteriaQuery<?> q, CriteriaBuilder cb) {
                List<Predicate> predicates = new ArrayList<Predicate>();
                if(StringUtils.hasText(key)){
                    Path<String> np = root.get("oper");
                    predicates.add(cb.like(np, "%" + key + "%"));
                }
                if(start!=null){
                    Path<Date> np = root.get("stamp");
                    predicates.add(cb.greaterThanOrEqualTo(np, start));
                }
                if(end!=null){
                    Path<Date> np = root.get("stamp");
                    predicates.add(cb.greaterThanOrEqualTo(np, end));
                }
                if (predicates.size() > 0) {
                    return cb.and(predicates.toArray(new Predicate[predicates.size()]));
                }
                return cb.conjunction();
            }

        };
    }


    @Autowired
    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 

<bean id="myEmf"
        class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="packagesToScan" value="com.fox.dataws.model" />
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
                <property name="showSql" value="${hibernate.show_sql}" />
                <property name="generateDdl" value="${jpa.generateDdl}" />
                <property name="databasePlatform" value="${persistence.dialect}" />
            </bean>
        </property>
    </bean>
    <bean id="dataSource"
        class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="${db.driver}" />
        <property name="url" value="${db.url}" />
        <property name="username" value="${db.uid}" />
        <property name="password" value="${db.pwd}" />
    </bean>
    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="entityManagerFactory" ref="myEmf" />
    </bean>
    <tx:annotation-driven transaction-manager="transactionManager" />

    <jpa:repositories base-package="com.fox.dataws.repo" />