jsp – javax.el.PropertyNotFoundException：在com.example.Bean类型上找不到属性’foo’

我有结果

Query query = session.createQuery("From Pool as p left join fetch p.poolQuestion as s");

查询,我想在JSP上显示它.

我有循环

<c:forEach items="${pools}" var="pool"> 

    <p>${pool.name}</p>

</c:forEach>

我想显示poolQ​​uestion表的结果(这是Join表).我想显示的值是’answer’.

我该怎么做？

<c:forEach items="${pools}" var="pool"> 
    <p>${pool.answer}</p>
    <p>${pool.name}</p>             
</c:forEach>

上面的代码不起作用

错误是：

org.apache.jasper.JasperException: An exception occurred processing JSP page /WEB-INF/views/home.jsp at line 21

18:     <c:forEach items="${pools}" var="pool"> 
19:             
20:             <p>${pool.name}</p>
21:             <c:out value="${pool.poolQuestion.answer}"/>
22:             
23:     </c:forEach>
24: 

    SEVERE: Servlet.service() for servlet appServlet threw exception
javax.el.PropertyNotFoundException: Property 'answer' not found on type com.pool.app.domain.Pool
    at javax.el.BeanELResolver$BeanProperties.get(BeanELResolver.java:214)
    at javax.el.BeanELResolver$BeanProperties.access$400(BeanELResolver.java:191)
    at javax.el.BeanELResolver.property(BeanELResolver.java:300)
    at javax.el.BeanELResolver.getValue(BeanELResolver.java:81)
    at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:54)
    at org.apache.el.parser.AstValue.getValue(AstValue.java:123)
    at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:186)
    at org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:938)
    at org.apache.jsp.WEB_002dINF.views.home_jsp._jspx_meth_c_005fforEach_005f0(home_jsp.java:119)
    at org.apache.jsp.WEB_002dINF.views.home_jsp._jspService(home_jsp.java:78)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:388)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:646)
    at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:436)
    at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:374)
    at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:302)
    at org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:238)
    at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:250)
    at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1047)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:817)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:669)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:574)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:198)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:291)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:602)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    at java.lang.Thread.run(Thread.java:680)

模型是：

public List<Pool> getAll(){

    Session session = sessionFactory.getCurrentSession();

    Query query = session.createQuery("From Pool as p left join fetch p.poolQuestions as s");

    return query.list();

控制器是：

List<Pool> pool = poolService.getAll();

model.addAttribute("pools", pool);

而视图是：

<c:forEach items="${pools}" var="pool"> 

    <p>${pool.name}</p>
    <c:out value="${pool.answer}"/>

</c:forEach>

PS. ${pool.name}正确显示

javax.el.PropertyNotFoundException: Property ‘foo’ not found on type com.example.Bean

这意味着所提到的类com.example.Bean没有提供属性foo的public(非静态！)getter方法.请注意,这个领域本身是无关紧要的！

公共getter方法名称必须以get开头,后跟属性名称,只在Foo中的属性名称的第一个字母大写.

public Foo getFoo() {
    return foo;
}

因此,您需要确保有一个完全匹配属性名称的getter方法,并且该方法是public(非静态),并且该方法不接受任何参数,并返回非void.如果你有一个并且它仍然不起作用,那么很可能是你正在忙着编辑代码,而不是坚持清理构建,重建代码并重新部署/重新启动应用程序.你需要确保你已经这样做了.

对于boolean(不是Boolean！)属性,getter方法名必须以is而不是get开头.

public boolean isFoo() {
    return foo;
}

不管类型如何,因此foo字段本身的存在是不相关的.它可以有不同的名称,或者完全不存在,甚至是静态的.以下所有内容仍然可以通过${bean.foo}访问.

public Foo getFoo() {
    return bar;
}

public Foo getFoo() {
    return new Foo("foo");
}

public Foo getFoo() {
    return FOO_CONSTANT;
}

你看,这个领域不算什么,而是getter方法本身.请注意,属性名称本身不应在EL中大写.换句话说,${bean.Foo}将不会工作,它应该是${bean.foo}.

也可以看看：

> javax.el.PropertyNotFoundException: Property ‘foo’ not readable on type java.lang.Boolean
> How does Java expression language resolve boolean attributes? (in JSF 1.2)
> Identifying and solving javax.el.PropertyNotFoundException: Target Unreachable
> Outcommented Facelets code still invokes EL expressions like #{bean.action()} and causes javax.el.PropertyNotFoundException on #{bean.action}