3
对于Java和JSTL,我真的很陌生,所以很抱歉,如果这是一个超级简单的问题。我试图通过一个我在网上找到的例子来让它起作用,但我似乎遇到了问题。假设发生的是你创建一个java bean并从java bean中访问属性。但相反,我得到一个空指针异常就行了,我打电话在JSTL的类jsp:useBean id =“students” class =“com.beans.Students”。这里是java类:将Java bean属性传递给JSTL
package com.beans;
public class Students implements java.io.Serializable
{
private String firstName = null;
private int age = 0;
public Students() {
}
public String getFirstName(){
return firstName;
}
public int getAge(){
return age;
}
public void setFirstName(String firstName){
this.firstName = firstName;
}
public void setAge(Integer age){
this.age = age;
}
}
JSTL中,我试图访问的Java bean:
<jsp:useBean id="students"
class="com.beans.Students">
<jsp:setProperty name="students" property="firstName"
value="Zara"/>
<jsp:setProperty name="students" property="age"
value="10"/>
</jsp:useBean>
<p>Student First Name:
<jsp:getProperty name="students" property="firstName"/>
</p>
<p>Student Age:
<jsp:getProperty name="students" property="age"/>
</p>
堆栈跟踪:
Caused by: org.apache.sling.api.SlingException: An exception occurred processing JSP page /students.jsp at line 18
at org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.handleJspExceptionInternal(JspServletWrapper.java:574)
at org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:499)
at org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:443)
at org.apache.sling.scripting.jsp.JspServletWrapperAdapter.service(JspServletWrapperAdapter.java:59)
at org.apache.sling.scripting.jsp.JspScriptEngineFactory$JspScriptEngine.eval(JspScriptEngineFactory.java:453)
at org.apache.sling.scripting.core.impl.DefaultSlingScript.call(DefaultSlingScript.java:358)
... 174 more
Caused by: java.lang.NullPointerException
at org.apache.sling.scripting.jsp.jasper.runtime.JspRuntimeLibrary.internalIntrospecthelper(JspRuntimeLibrary.java:322)
at org.apache.sling.scripting.jsp.jasper.runtime.JspRuntimeLibrary.introspecthelper(JspRuntimeLibrary.java:308)
at org.apache.jsp.students_002d_jsp._jspServ
任何帮助,不胜感激!
对不起@Reimeaus我真的很陌生这是什么意思,通过初始化?基于我的代码是不是已经被初始化了? – 2013-04-21 17:25:51
请粘贴整个stackTrace(),代码看起来OK! – NINCOMPOOP 2013-04-21 17:27:40
谢谢@NoobUnChained我粘贴了堆栈跟踪。 – 2013-04-21 17:33:25