3
對於Java和JSTL,我真的很陌生,所以很抱歉,如果這是一個超級簡單的問題。我試圖通過一個我在網上找到的例子來讓它起作用,但我似乎遇到了問題。假設發生的是你創建一個java bean並從java bean中訪問屬性。但相反,我得到一個空指針異常就行了,我打電話在JSTL的類jsp:useBean id =「students」 class =「com.beans.Students」。這裏是java類:將Java bean屬性傳遞給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,我試圖訪問的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>
堆棧跟蹤:
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
任何幫助,不勝感激!
對不起@Reimeaus我真的很陌生這是什麼意思,通過初始化?基於我的代碼是不是已經被初始化了? – 2013-04-21 17:25:51
請粘貼整個stackTrace(),代碼看起來OK! – NINCOMPOOP 2013-04-21 17:27:40
謝謝@NoobUnChained我粘貼了堆棧跟蹤。 – 2013-04-21 17:33:25