java.lang.ClassCastException: cn.study.model.User_$$_javassist_0 cannot be cast to javassist.util.pr

本文解决了使用Hibernate框架中更新用户实例时出现的错误,通过将load方法替换为get方法来修正问题。提供了完整的代码示例,帮助开发者避免常见的错误并优化数据库操作。

<strong>	public static void main(String[] args) {
		// TODO Auto-generated method stub
		//addEmployee();
		//修改用户
		//获取一个会话
		Session session=MySessionFactory.getSessionFactory().openSession();
		
		Transaction ts=session.beginTransaction();
		//修改用户1.获取要修改的用户2.修改
		//load是通过主键属性,获取该对象的实例<--表的记录对应-->
		Employee emp=(Employee) session.load(Employee.class, 3);
		emp.setName("彩霞");
		emp.setEmail("546835@qq.com");
		ts.commit();session.close();
		
	}</strong>


解决方法:将load改成get即可:

<strong>Transaction ts=session.beginTransaction();
		//修改用户1.获取要修改的用户2.修改
		//load是通过主键属性,获取该对象的实例<--表的记录对应-->
		Employee emp=(Employee) session.get(Employee.class, 3);</strong>


mservice:null Key: tbmain TraceId:72b290561afc0636 Instance:mservice-347730737 发生时间:Mon Sep 08 08:55:27 GMT+08:00 2025 =================================================== 调用堆栈: kd.bos.exception.KDException: null at kd.bos.service.operation.OperationServiceImpl.localInvokeOperation(OperationServiceImpl.java:124) at kd.bos.service.operation.OperationServiceImpl.invokeOperation(OperationServiceImpl.java:53) at sun.reflect.GeneratedMethodAccessor493.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at kd.bos.service.DispatchServiceImpl.invoke(DispatchServiceImpl.java:47) at sun.reflect.GeneratedMethodAccessor492.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at kd.bos.mservice.rpc.dubbo.debug.LocalDebugProxy$1.lambda$invoke$0(LocalDebugProxy.java:61) at kd.bos.mservice.rpc.dubbo.debug.DubboDebugUtil.invoke(DubboDebugUtil.java:46) at kd.bos.mservice.rpc.dubbo.debug.LocalDebugProxy$1.invoke(LocalDebugProxy.java:58) at com.sun.proxy.$Proxy49.invoke(Unknown Source) at kd.bos.servicehelper.DispatchServiceHelper.invokeBOSService(DispatchServiceHelper.java:103) at kd.bos.servicehelper.operation.OperationServiceHelper.executeOperate(OperationServiceHelper.java:84) at ccpsp.pm.formPlugin.RequirementExamineFormPlugin.submit(RequirementExamineFormPlugin.java:375) at ccpsp.pm.formPlugin.RequirementExamineFormPlugin.afterDoOperation(RequirementExamineFormPlugin.java:340) at kd.bos.form.plugin.FormViewPluginProxy.lambda$fireAfterDoOperation$9(FormViewPluginProxy.java:262) at kd.bos.form.plugin.FormViewPluginProxy.invokeMethod(FormViewPluginProxy.java:163) at kd.bos.form.plugin.FormViewPluginProxy.fireAfterDoOperation(FormViewPluginProxy.java:260) at kd.bos.form.operate.FormOperate.afterInvokeOperation(FormOperate.java:441) at kd.bos.entity.operate.Submit.afterInvokeOperation(Submit.java:289) at kd.bos.form.operate.FormOperate.execute(FormOperate.java:316) at kd.bos.mvc.form.FormView.invokeOperation(FormView.java:637) at kd.bos.mvc.bill.BillView.invokeOperation(BillView.java:203) at kd.bos.mvc.form.FormView.invokeOperation(FormView.java:551) at kd.bos.form.control.Toolbar.itemClick(Toolbar.java:109) at sun.reflect.GeneratedMethodAccessor5863.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.apache.commons.beanutils.MethodUtils.invokeMethod(MethodUtils.java:278) at org.apache.commons.beanutils.MethodUtils.invokeMethod(MethodUtils.java:222) at kd.bos.mservice.form.FormServiceImpl.invokeMethod(FormServiceImpl.java:1566) at kd.bos.mservice.form.FormServiceImpl.invokeAction(FormServiceImpl.java:1002) at kd.bos.mservice.form.FormServiceImpl.batchInvokeAction(FormServiceImpl.java:652) at sun.reflect.GeneratedMethodAccessor1247.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at kd.bos.service.DispatchServiceImpl.invoke(DispatchServiceImpl.java:47) at com.alibaba.dubbo.common.bytecode.Wrapper1.invokeMethod(Wrapper1.java) at com.alibaba.dubbo.rpc.proxy.javassist.JavassistProxyFactory$1.doInvoke(JavassistProxyFactory.java:46) at com.alibaba.dubbo.rpc.proxy.AbstractProxyInvoker.invoke(AbstractProxyInvoker.java:72) at com.alibaba.dubbo.rpc.protocol.InvokerWrapper.invoke(InvokerWrapper.java:53) at com.alibaba.dubbo.rpc.filter.ExceptionFilter.invoke(ExceptionFilter.java:66) at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91) at kd.bos.mservice.rpc.dubbo.filter.RequestContextFilter.lambda$invokeProviderSide$0(RequestContextFilter.java:159) at kd.bos.mservice.rpc.dubbo.debug.DubboDebugUtil.invoke(DubboDebugUtil.java:46) at kd.bos.mservice.rpc.dubbo.filter.RequestContextFilter.invokeProviderSide(RequestContextFilter.java:150) at kd.bos.mservice.rpc.dubbo.filter.RequestContextFilter.invoke(RequestContextFilter.java:64) at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91) at com.alibaba.dubbo.rpc.filter.TimeoutFilter.invoke(TimeoutFilter.java:23) at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91) at com.alibaba.dubbo.rpc.protocol.dubbo.filter.TraceFilter.invoke(TraceFilter.java:78) at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91) at com.alibaba.dubbo.monitor.support.MonitorFilter.invoke(MonitorFilter.java:75) at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91) at kd.bos.mservice.rpc.dubbo.filter.ProviderMetricFilter.invoke(ProviderMetricFilter.java:94) at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91) at kd.bos.mservice.rpc.dubbo.filter.trace.ProviderSpanFilter.invoke(ProviderSpanFilter.java:84) at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91) at kd.bos.mservice.circuitbreaker.filter.dubbo.CircuitbreakerFilter.lambda$invoke$0(CircuitbreakerFilter.java:34) at kd.bos.mservice.circuitbreaker.noop.NoopCircuitbreaker.call(NoopCircuitbreaker.java:43) at kd.bos.mservice.circuitbreaker.filter.dubbo.CircuitbreakerFilter.invoke(CircuitbreakerFilter.java:33) at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91) at kd.bos.mservice.rpc.dubbo.filter.ThreadLifeCycleFilter.invoke(ThreadLifeCycleFilter.java:30) at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91) at com.alibaba.dubbo.rpc.filter.ContextFilter.invoke(ContextFilter.java:70) at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91) at com.alibaba.dubbo.rpc.filter.GenericFilter.invoke(GenericFilter.java:132) at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91) at com.alibaba.dubbo.rpc.filter.ClassLoaderFilter.invoke(ClassLoaderFilter.java:38) at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91) at com.alibaba.dubbo.rpc.filter.EchoFilter.invoke(EchoFilter.java:38) at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91) at com.alibaba.dubbo.rpc.protocol.dubbo.DubboProtocol$1.reply(DubboProtocol.java:75) at com.alibaba.dubbo.remoting.exchange.support.header.HeaderExchangeHandler.handleRequest(HeaderExchangeHandler.java:102) at com.alibaba.dubbo.remoting.exchange.support.header.HeaderExchangeHandler.received(HeaderExchangeHandler.java:264) at com.alibaba.dubbo.remoting.transport.DecodeHandler.received(DecodeHandler.java:52) at com.alibaba.dubbo.remoting.transport.dispatcher.ChannelEventRunnable._run(ChannelEventRunnable.java:105) at com.alibaba.dubbo.remoting.transport.dispatcher.ChannelEventRunnable.run(ChannelEventRunnable.java:67) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at java.lang.Thread.run(Thread.java:748) Caused by: java.lang.NullPointerException at ccpsp.pm.opplugin.PmRequirApplyAuditOpPlugin.lambda$afterExecuteOperationTransaction$2(PmRequirApplyAuditOpPlugin.java:61) at java.util.Spliterators$ArraySpliterator.forEachRemaining(Spliterators.java:948) at java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:580) at ccpsp.pm.opplugin.PmRequirApplyAuditOpPlugin.afterExecuteOperationTransaction(PmRequirApplyAuditOpPlugin.java:44) at kd.bos.entity.plugin.OperationServicePlugInProxy.lambda$fireAfterExecuteOperationTransaction$7(OperationServicePlugInProxy.java:292) at kd.bos.entity.plugin.OperationServicePlugInProxy.invokeMethod(OperationServicePlugInProxy.java:69) at kd.bos.entity.plugin.OperationServicePlugInProxy.fireAfterExecuteOperationTransaction(OperationServicePlugInProxy.java:289) at kd.bos.service.operation.EntityOperateService.doExcete(EntityOperateService.java:752) at kd.bos.service.operation.EntityOperateService.excute(EntityOperateService.java:403) at kd.bos.service.operation.EntityOperateService.excute(EntityOperateService.java:637) at kd.bos.service.operation.OperationServiceImpl.localInvokeOperation(OperationServiceImpl.java:100) ... 82 more 这个错误是什么意思
最新发布
09-09
### 问题解析 `java.lang.ClassCastException: java.util.HashMap cannot be cast to java.lang.String` 是由于尝试将 `HashMap` 对象强制转换为 `String` 类型所引发的运行时异常。这种错误通常发生在数据类型不匹配的情况下,尤其是在处理集合框架(如 List 或 Set)时未正确指定泛型或误用了对象类型的场景下。 以下是针对该问题的具体解决方案: --- ### 解决方案 #### 方法一:确认并修正泛型定义 如果程序中使用了未经泛型限定的集合类(如 `List`),可能导致存储的数据类型与预期不符。例如,当一个 `List<HashMap>` 被当作 `List<String>` 使用时,就会触发此异常[^2]。 确保在声明集合变量时明确定义其泛型类型,例如: ```java // 正确方式:显式指定泛型类型 List<Map<String, Object>> list = new ArrayList<>(); ``` 这样可以避免因类型推断错误而导致的隐式转换问题。 --- #### 方法二:安全地访问集合元素 在遍历集合前,应先验证其中的实际数据类型是否符合预期。可以通过 `instanceof` 关键字进行类型检查后再执行强转操作。例如: ```java Object obj = list.get(i); if (obj instanceof Map) { Map<String, Object> map = (Map<String, Object>) obj; // 安全地访问 Map 中的内容 } else { throw new IllegalArgumentException("Unexpected type found in the list."); } ``` 上述代码片段能够有效防止非法类型转换的发生[^5]。 --- #### 方法三:序列化/反序列化替代直接转换 对于复杂对象(如 `HashMap`),建议采用 JSON 序列化工具将其转化为字符串形式再进一步处理。这种方式不仅规避了潜在的类型冲突风险,还增强了代码的可读性和维护性[^4]。示例实现如下: ```java import com.google.gson.Gson; Gson gson = new Gson(); for (int i = 0; i < list.size(); i++) { String jsonString = gson.toJson(list.get(i)); System.out.println(jsonString); try { JSONObject jsonObject = new JSONObject(jsonString); System.out.println(jsonObject.getString("keyName")); } catch (JSONException e) { e.printStackTrace(); } } ``` --- #### 方法四:调整 Redis 数据存取逻辑 如果是基于 Redis 的应用场景,则需注意哈希表结构内的值类型一致性。若某些字段可能包含不同基础类型(如整数、布尔值等),则统一将其映射至字符串表示更为稳妥[^3]。具体做法见以下代码段: ```java import org.springframework.beans.BeanUtils; import cn.hutool.core.bean.copier.CopyOptions; import java.util.Map; public static void main(String[] args) { UserDTO userDTO = ... ; // 初始化 DTO 实体 // 将实体属性复制到 Map 并自动完成 toString 处理 Map<String, Object> userMap = BeanUtils.beanToMap( userDTO, new HashMap<>(), CopyOptions.create() .setIgnoreNullValue(true) .setFieldValueEditor((field, value) -> value != null ? value.toString() : "") ); redisTemplate.opsForHash().putAll("loginUser:" + userId, userMap); } ``` --- ### 总结 以上四种策略分别从根源控制、运行防护以及实际应用层面提供了应对措施。开发者可根据具体情况选用最合适的手段解决问题。 --- ###
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