在portlet .jsp页面中，我连接一个applet，然后抛出异常

时间：2012-04-27 04:36:23

标签： java applet liferay portlet

在portlet的.jsp页面中，我连接了一个applet，然后抛出异常 Portlet系统是Liferay

＆＃34;＆＃39; portlet的名称＆＃39;暂时不可用。＆＃34;显示在页面上。

applet的html / jsp代码：

<APPLET name="SignApplet" mayscript code="SignApplet.class" 
archive="<%=renderResponse.encodeURL(renderRequest.getContextPath() + "/lib/SignApplet.jar")%>, 
<%=renderResponse.encodeURL(renderRequest.getContextPath() + "/lib/crypto.tsp.jar")%>, 
<%=renderResponse.encodeURL(renderRequest.getContextPath() + "/lib/crypto.gammaprov.jar")%>"
height=500 width=500 style="display:none;">
    <PARAM NAME="file" VALUE="<%
    byte[] array = (byte[])session.getAttribute("downloadedFile");
    out.print(new String(array));
           %>" />
</APPLET>

jsp的名字是LoadXLS。 这是日志：

ApplicationDispatcher[/ExecutePortlet] PWC1231: Servlet.service() for servlet jsp threw exception
java.lang.NullPointerException
    at java.lang.String.<init>(String.java:602)
    at org.apache.jsp.WEB_002dINF.jsp.LoadXLS_jsp._jspService(LoadXLS_jsp.java:232)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:111)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:403)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:492)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:378)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1539)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:343)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:217)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:72)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:113)
...

04:18:44,421 ERROR [PortletRequestDispatcherImpl:137] org.apache.jasper.JasperException: java.lang.NullPointerException
org.apache.jasper.JasperException: java.lang.NullPointerException
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:492)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:378)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1539)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:343)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:217)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:72)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:113)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilter.doFilter(InvokerFilter.java:70)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:217)
    at org.apache.catalina.core.ApplicationDispatcher.doInvoke(ApplicationDispatcher.java:785)
...


04:18:44,421 ERROR [PortletServlet:97] javax.portlet.PortletException: org.apache.jasper.JasperException: java.lang.NullPointerException
javax.portlet.PortletException: org.apache.jasper.JasperException: java.lang.NullPointerException
    at com.liferay.portlet.PortletRequestDispatcherImpl.include(PortletRequestDispatcherImpl.java:139)
    at com.test.ExecutePortlet.doView(ExecutePortlet.java:249)
    at javax.portlet.GenericPortlet.doDispatch(GenericPortlet.java:328)
    at javax.portlet.GenericPortlet.render(GenericPortlet.java:233)
    at com.liferay.portlet.FilterChainImpl.doFilter(FilterChainImpl.java:100)
    at com.liferay.portal.kernel.portlet.PortletFilterUtil.doFilter(PortletFilterUtil.java:64)
    at com.liferay.portal.kernel.servlet.PortletServlet.service(PortletServlet.java:93)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1539)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:343)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:217)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:72)
...


ApplicationDispatcher[/ExecutePortlet] PWC1231: Servlet.service() for servlet ExecutePortlet Servlet threw exception
javax.portlet.PortletException: org.apache.jasper.JasperException: java.lang.NullPointerException
    at com.liferay.portlet.PortletRequestDispatcherImpl.include(PortletRequestDispatcherImpl.java:139)
    at com.test.ExecutePortlet.doView(ExecutePortlet.java:249)
    at javax.portlet.GenericPortlet.doDispatch(GenericPortlet.java:328)
    at javax.portlet.GenericPortlet.render(GenericPortlet.java:233)
    at com.liferay.portlet.FilterChainImpl.doFilter(FilterChainImpl.java:100)
    at com.liferay.portal.kernel.portlet.PortletFilterUtil.doFilter(PortletFilterUtil.java:64)
    at com.liferay.portal.kernel.servlet.PortletServlet.service(PortletServlet.java:93)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1539)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:343)
...

04:18:44,437 ERROR [render_portlet_jsp:154] java.lang.NullPointerException
    at java.lang.String.<init>(String.java:602)
    at org.apache.jsp.WEB_002dINF.jsp.LoadXLS_jsp._jspService(LoadXLS_jsp.java:232)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:111)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:403)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:492)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:378)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
...

1 个答案:

答案 0 :(得分：2)

从堆栈跟踪看来你正在使用tomcat - 在Tomcat中找到NullpointerException的实际位置的一个很好的方法是转到JSP-Compiler生成的中间代码，通常在tomcat的工作文件夹中 - 转到tomcat / work / Catalina / localhost / your-web-app-name / org / apache / jsp / ...并在那里找到从JSP生成的Java代码（来自stacktrace，它名为LoadXLS_jsp.java。（“Catalina / localhost“是默认文件夹 - 可能在您的设置中有所不同）

stacktrace说，NullpointerException发生在第232行（at org.apache.jsp.WEB_002dINF.jsp.LoadXLS_jsp._jspService(LoadXLS_jsp.java:232) ） - 虽然整个文件是机器生成的并且读取不好，但将它映射回原始JSP应该非常简单。

我的赌注是 - 正如dragon66在你的问题的评论中所说的那样 - session.getAttribute（“downloadedFile”）为null，因此你在out.print(new String(array));中使用的构造函数会传递一个空值。行at java.lang.String.<init>(String.java:602)告诉您String构造函数是引起NullpointerException的地方，但是下一行 - 例如调用方法 - 告诉你字符串构造函数的调用位置。

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