关于 hibernate 查询中实现order by的 NULLS LAST 和 NULLS FIRST

关于 hibernate 查询中实现order by的 NULLS LAST 和 NULLS FIRST

 

1:创建一个CustomNullsFirstInterceptor类

 

public class CustomNullsFirstInterceptor extends EmptyInterceptor {
    private static final long serialVersionUID = -3156853534261313031L;

    private static final String ORDER_BY_TOKEN = "order by";

    public String onPrepareStatement(String sql) {

        int orderByStart = sql.toLowerCase().indexOf(ORDER_BY_TOKEN);
        if (orderByStart == -1) {
            return super.onPrepareStatement(sql);
        }
        orderByStart += ORDER_BY_TOKEN.length() + 1;
        int orderByEnd = sql.indexOf(")", orderByStart);
        if (orderByEnd == -1) {
            orderByEnd = sql.indexOf(" UNION ", orderByStart);
            if (orderByEnd == -1) {
                orderByEnd = sql.length();
            }
        }
        String orderByContent = sql.substring(orderByStart, orderByEnd);
        String[] orderByNames = orderByContent.split("\\,");
        for (int i=0; i<orderByNames.length; i++) {
            if (orderByNames[i].trim().length() > 0) {
                if (orderByNames[i].trim().toLowerCase().endsWith("desc")) {
                    orderByNames[i] += " NULLS LAST";
                } else {
                    orderByNames[i] += " NULLS FIRST";
                }
            }
        }
        orderByContent = StringUtils.join(orderByNames, ",");
        sql = sql.substring(0, orderByStart) + orderByContent + sql.substring(orderByEnd);
        return super.onPrepareStatement(sql);
    }

}

 

 

 

2：加入配置

<bean id="sessionFactory"
		class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
		<property name="dataSource" ref="dataSource" />
		<property name="packagesToScan">
			<list>
				<value>com.skywin.law.workflow.domain</value>
				<!--<value>com.skywin.common.fileupload.domain</value>-->
				<value>com.skywin.common.domain</value>
				<value>com.skywin.chat.domain</value>
				<value>com.skywin.law.assistflow.domain</value>
			</list>
		</property>
		<property name="mappingResources" ref="sessionFactoryMappingResources"></property>
		<property name="hibernateProperties">
			<props>

				<prop key="hibernate.dialect">${hibernate.dialect}</prop>
				<prop key="hibernate.cache.use_second_level_cache">true</prop>
				<!-- <prop key="hibernate.cache.provider_configuration_file_resource_path">diss-override-ehcache.xml</prop> -->
				<prop key="hibernate.cache.region.factory_class">net.sf.ehcache.hibernate.EhCacheRegionFactory</prop>
				<!-- ＜prop key="hibernate.cache.provider_class"＞org.hibernate.cache.EhCacheProvider＜/prop＞ -->
				
				<prop key="hibernate.cache.use_query_cache">true</prop>
				<prop key="hibernate.show_sql">true</prop>
			 <!-- <prop key="hibernate.hbm2ddl.auto">update</prop> -->
				<prop key="hibernate.format_sql">true</prop>
				<prop key="hibernate.jdbc.batch_size">0</prop>
			    <prop key="hibernate.hbm2ddl.import_files">import-install.sql</prop>
			</props>
		</property>
		
		<property name="entityCacheStrategies">
				<props>
					<prop key="org.jbpm.pvm.internal.task.TaskImpl">read-write</prop>
				</props>
		</property>
		
		<property name="entityInterceptor">

		<bean id ="customNullsFirstInterceptor" class="com.skywin.common.hibernate3.CustomNullsFirstInterceptor" />
		
		</property>


	</bean>