java.lang.ClassCastException: java.util.ArrayList cannot be cast to com.github.pagehelper.Page page...

本文详细解析了在使用PageHelper分页插件时遇到的ClassCastException异常,即ArrayList无法转换为Page类型的问题,并提供了调整代码逻辑的解决方案,避免在PageHelper设置分页参数后进行其他查询操作。

摘要生成于 C知道 ,由 DeepSeek-R1 满血版支持, 前往体验 >

报错信息:

严重: Servlet.service() for servlet [springmvc] in context with path [] threw exception [Request processing failed; nested exception is java.lang.ClassCastException: java.util.ArrayList cannot be cast to com.github.pagehelper.Page] with root cause
java.lang.ClassCastException: java.util.ArrayList cannot be cast to com.github.pagehelper.Page
    at com.*.sellergoods.service.impl.ItemCatServiceImpl.findByParentId(ItemCatServiceImpl.java:124)
    at com.alibaba.dubbo.common.bytecode.Wrapper7.invokeMethod(Wrapper7.java)
    at com.alibaba.dubbo.rpc.proxy.javassist.JavassistProxyFactory$1.doInvoke(JavassistProxyFactory.java:47)
    at com.alibaba.dubbo.rpc.proxy.AbstractProxyInvoker.invoke(AbstractProxyInvoker.java:76)
    at com.alibaba.dubbo.config.invoker.DelegateProviderMetaDataInvoker.invoke(DelegateProviderMetaDataInvoker.java:52)
    at com.alibaba.dubbo.rpc.protocol.InvokerWrapper.invoke(InvokerWrapper.java:56)
    at com.alibaba.dubbo.rpc.filter.ExceptionFilter.invoke(ExceptionFilter.java:62)
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:72)
    at com.alibaba.dubbo.monitor.support.MonitorFilter.invoke(MonitorFilter.java:75)
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:72)
    at com.alibaba.dubbo.rpc.filter.TimeoutFilter.invoke(TimeoutFilter.java:42)
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:72)
    at com.alibaba.dubbo.rpc.protocol.dubbo.filter.TraceFilter.invoke(TraceFilter.java:78)
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:72)
    at com.alibaba.dubbo.rpc.filter.ContextFilter.invoke(ContextFilter.java:73)
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:72)
    at com.alibaba.dubbo.rpc.filter.GenericFilter.invoke(GenericFilter.java:138)
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:72)
    at com.alibaba.dubbo.rpc.filter.ClassLoaderFilter.invoke(ClassLoaderFilter.java:38)
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:72)
    at com.alibaba.dubbo.rpc.filter.EchoFilter.invoke(EchoFilter.java:38)
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:72)
    at com.alibaba.dubbo.rpc.protocol.dubbo.DubboProtocol$1.reply(DubboProtocol.java:104)
    at com.alibaba.dubbo.remoting.exchange.support.header.HeaderExchangeHandler.handleRequest(HeaderExchangeHandler.java:96)
    at com.alibaba.dubbo.remoting.exchange.support.header.HeaderExchangeHandler.received(HeaderExchangeHandler.java:173)
    at com.alibaba.dubbo.remoting.transport.DecodeHandler.received(DecodeHandler.java:51)
    at com.alibaba.dubbo.remoting.transport.dispatcher.ChannelEventRunnable.run(ChannelEventRunnable.java:57)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)

代码:

public PageResult findByParentId(Long parentId,int pageNum,int pageSize) {
   PageHelper.startPage(pageNum, pageSize);
TbItemCatExample example = new TbItemCatExample();
Criteria criteria = example.createCriteria();
criteria.andParentIdEqualTo(parentId);

List<TbItemCat> all = findAll();
System.out.println("==将类目数据写入reid==");
for (TbItemCat itemCat : all) {
redisTemplate.boundHashOps("itemCate").put(itemCat.getName(), itemCat.getTypeId());
}
System.out.println("==将类目数据写入reid结束==");

Page<TbItemCat> page= (Page<TbItemCat>)itemCatMapper.selectByExample(example);

return new PageResult(page.getTotal(), page.getResult());
}

  造成异常原因是代码红色部分,因为pagehelper在设置 PageHelper.startPage(pageNum, pageSize)后到使用 Page<TbItemCat> page= (Page<TbItemCat>)itemCatMapper.selectByExample(example);在这两段代码之前都不能都再进行任何查询不然就会造成类型转化异常。

  解决办法就是将红色代码在放在 pagehelper和Page之外:

public PageResult findByParentId(Long parentId,int pageNum,int pageSize) {
        System.out.println(pageNum);
        System.out.println(pageSize);
        System.out.println(parentId);

        PageHelper.startPage(pageNum, pageSize);
        TbItemCatExample example = new TbItemCatExample();
        Criteria criteria = example.createCriteria();
        criteria.andParentIdEqualTo(parentId);
        
        Page<TbItemCat> page= (Page<TbItemCat>)itemCatMapper.selectByExample(example);

        List<TbItemCat> all = findAll();
        System.out.println("==将类目数据写入reid==");
        for (TbItemCat itemCat : all) {
            redisTemplate.boundHashOps("itemCate").put(itemCat.getName(), itemCat.getTypeId());
        }
        System.out.println("==将类目数据写入reid结束==");

        return new PageResult(page.getTotal(), page.getResult());
    }

 

转载于:https://www.cnblogs.com/hwxxbc/p/10993699.html

评论
添加红包

请填写红包祝福语或标题

红包个数最小为10个

红包金额最低5元

当前余额3.43前往充值 >
需支付:10.00
成就一亿技术人!
领取后你会自动成为博主和红包主的粉丝 规则
hope_wisdom
发出的红包
实付
使用余额支付
点击重新获取
扫码支付
钱包余额 0

抵扣说明:

1.余额是钱包充值的虚拟货币,按照1:1的比例进行支付金额的抵扣。
2.余额无法直接购买下载,可以购买VIP、付费专栏及课程。

余额充值