ClassCastException当我查询 [英] ClassCastException when i query
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问题描述
我有以下代码：
public float getTotalCash（String year）{
CustomerPayment cp = null;
this.session = HibernateUtil.getSessionFactory（）。getCurrentSession（）;
尝试{
org.hibernate.Transaction tx = session.beginTransaction（）;
Query q = session.createQuery（从CustomerPayment c中选择c.type，c.date，sum（c.amount），其中c.date就像'％'+ year +''和c.type ='Cash ）;
cp =（CustomerPayment）q.uniqueResult（）;
} catch（Exception e）{
e.printStackTrace（）;
}
return totalCashAmount = cp.getAmount（）;
}
但是，它给出了ClassCastException。
堆栈跟踪：
java.lang.ClassCastException：[Ljava .lang.Object;无法转换为tekirmobile.CustomerPayment
at tekirmobile.clController.getTotalCash（clController.java:163）
at sun.reflect.NativeMethodAccessorImpl.invoke0（Native Method）
at sun.reflect.NativeMethodAccessorImpl .invoke（NativeMethodAccessorImpl.java:57）
at sun.reflect.DelegatingMethodAccessorImpl.invoke（DelegatingMethodAccessorImpl.java:43）$ b $ at java.lang.reflect.Method.invoke（Method.java:616）
at org.apache.el.parser.AstValue.invoke（AstValue.java:278）
at org.apache.el.MethodExpressionImpl.invoke（MethodExpressionImpl.java:274）
at com。 sun.faces.facelets.el.TagMethodExpression.invoke（TagMethodExpression.java:105）在javax.faces.event.MethodExpressionActionListener.processAction处使用
（MethodExpressionActionListener.java:148）在javax.faces.event处使用
。 ActionEvent.processListener（ActionEvent.java:88）
at javax.faces.component.UIComponentBase.broadcast（UIComponentBase.java:769）
at javax.faces.compone nt.UICommand.broadcast（UICommand.java:300）
at javax.faces.component.UIViewRoot.broadcastEvents（UIViewRoot.java:794）
at javax.faces.component.UIViewRoot.processApplication（UIViewRoot。
at com.sun.faces.lifecycle.InvokeApplicationPhase.execute（InvokeApplicationPhase.java:81）
at com.sun.faces.lifecycle.Phase.doPhase（Phase.java:101）
at com.sun.faces.lifecycle.LifecycleImpl.execute（LifecycleImpl.java:118）
at javax.faces.webapp.FacesServlet.service（FacesServlet.java:593）
at org .apache.catalina.core.ApplicationFilterChain.internalDoFilter（ApplicationFilterChain.java:305）
at org.apache.catalina.core.ApplicationFilterChain.doFilter（ApplicationFilterChain.java:210）
at org.apache.catalina .core.StandardWrapperValve.invoke（StandardWrapperValve.java:222）
at org.apache.catalina.core.StandardContextValve.invoke（StandardContextValve.java:123）
at org.apache.catalina.authenticator.AuthenticatorBase .invoke（AuthenticatorBase.java:472）
at org.apache.catalina.core.StandardHostValve.invoke（StandardHostValve.java:171）
at org.apache.catalina.valves.ErrorReportValve.invoke（ErrorReportValve .java：99）
at org.apache.catalina.valves.AccessLogValve.invoke（AccessLogValve.java:936）
at org.apache.catalina.core.StandardEngineValve.invoke（StandardEngineValve.java:118 ）
at org.apache.catalina.connector.CoyoteAdapter.service（CoyoteAdapter.java:407）
at org.apache.coyote.http11.AbstractHttp11Processor.process（AbstractHttp11Processor.java:1004）
在org.apache.coyote.AbstractProtocol $ AbstractConnectionHandler.process（AbstractProtocol.java:589）
在org.apache.tomcat.util.net.JIoEndpoint $ SocketProcessor.run（JIoEndpoint.java:312）
在java.util.concurrent.ThreadPoolExecutor.runWorker（ThreadPoolExecutor.java:1146）$ b $在java.util.concurrent.ThreadPoolExecutor $ Worker.run（ThreadPoolExecutor.java:615）$ b $在java.lang。线.run（Thread.java:679）
可能是什么原因？为什么我得到这个错误？是否有浮动返回的错误原因？可能是什么原因？为什么我得到这个错误？可能是什么原因？为什么我得到这个错误？
解决方案
您正在选择 c 的部分内容，而不是选择 c 对象。 下面是一些有效的HQL示例。我认为这会按照你想要的方式工作：
from CustomerPayment c where c.date like'％+ year + '和c.type ='现金'
但是，这样做不是很好，因为你可以在这里做一个SQL注入攻击。你应该把 year 变成一个变量。 这里有一些如何做到这一点的例子。
i have below code:
public float getTotalCash(String year) {
CustomerPayment cp = null;
this.session = HibernateUtil.getSessionFactory().getCurrentSession();
try {
org.hibernate.Transaction tx = session.beginTransaction();
Query q = session.createQuery("select c.type, c.date, sum(c.amount) from CustomerPayment c where c.date like '%" + year + "' and c.type='Cash'");
cp = (CustomerPayment) q.uniqueResult();
} catch (Exception e) {
e.printStackTrace();
}
return totalCashAmount = cp.getAmount();
}
However, it gives ClassCastException.
Stack trace:
java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to tekirmobile.CustomerPayment
at tekirmobile.clController.getTotalCash(clController.java:163)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at org.apache.el.parser.AstValue.invoke(AstValue.java:278)
at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:274)
at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105)
at javax.faces.event.MethodExpressionActionListener.processAction(MethodExpressionActionListener.java:148)
at javax.faces.event.ActionEvent.processListener(ActionEvent.java:88)
at javax.faces.component.UIComponentBase.broadcast(UIComponentBase.java:769)
at javax.faces.component.UICommand.broadcast(UICommand.java:300)
at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:794)
at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1259)
at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:593)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:936)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1004)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1146)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:679)
What might be the reason? Why i get this error? Is there a reason of that error because of float returning?What might be the reason? Why i get this error? What might be the reason? Why i get this error?
解决方案
You are selecting parts of the c instead of SELECTing a c object. Here are some examples of valid HQL. I think this will work the way you want:
"from CustomerPayment c where c.date like '%" + year + "' and c.type='Cash'"
But, that's not really great to do either because you can do a sql injection attack here. You should turn that year into a variable. Here are a bunch of examples of how to do that.
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