Java 使用属性访问jsp上的列表元素

我想使用属性而不是索引号来访问JSP页面中的列表元素

第一：我在控制器中获得一个项目列表，如下所示：

List<Item> items;

但当我这么做时，我得到了一个例外：

java.lang.NumberFormatException: For input string: "code"
java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
java.lang.Integer.parseInt(Integer.java:449)
java.lang.Integer.parseInt(Integer.java:499)
javax.el.ArrayELResolver.coerce(ArrayELResolver.java:166)
javax.el.ArrayELResolver.getValue(ArrayELResolver.java:46)
org.apache.jasper.el.JasperELResolver.getValue(JasperELResolver.java:104)
org.apache.el.parser.AstValue.getValue(AstValue.java:183)
org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:185)
org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:1026)
org.apache.jsp.WEB_002dINF.pages.roles.roles_jsp._jspx_meth_c_005fforEach_005f0(roles_jsp.java:559)
org.apache.jsp.WEB_002dINF.pages.roles.roles_jsp._jspService(roles_jsp.java:352)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:209)
org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:267)
org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1221)
org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1005)
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:952)
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:870)
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:852)
javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)

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这个问题的原因是什么？如何准备使用这些属性？

我找到了解决方案。在我的例子中，为了将结果转换成真正的Java对象，我必须使用HQL而不是典型的SQL

我对这种方法进行了测试，它正在发挥作用

${role.code}

java.lang.NumberFormatException: For input string: "code"
java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
java.lang.Integer.parseInt(Integer.java:449)
java.lang.Integer.parseInt(Integer.java:499)
javax.el.ArrayELResolver.coerce(ArrayELResolver.java:166)
javax.el.ArrayELResolver.getValue(ArrayELResolver.java:46)
org.apache.jasper.el.JasperELResolver.getValue(JasperELResolver.java:104)
org.apache.el.parser.AstValue.getValue(AstValue.java:183)
org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:185)
org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:1026)
org.apache.jsp.WEB_002dINF.pages.roles.roles_jsp._jspx_meth_c_005fforEach_005f0(roles_jsp.java:559)
org.apache.jsp.WEB_002dINF.pages.roles.roles_jsp._jspService(roles_jsp.java:352)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:209)
org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:267)
org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1221)
org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1005)
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:952)
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:870)
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:852)
javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)