我需要在 JSP 中定义一个类 -> 实例化它并通过序列化将其写入文件。 我能够进行实例化部分，但序列化部分失败。 我不确定它是否允许序列化在 jsp 内创建的类，但想询问我是否需要做任何额外的事情 非常感谢任何帮助。 谢谢。
JSP 文件:
<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1" %>
<%@page import="java.util.Date"%>
<%@page import="java.util.List"%>
<%@page import="java.util.GregorianCalendar"%>
<%@page import="java.util.Calendar"%>
<%@page import="java.beans.XMLEncoder"%>
<%@page import="java.beans.XMLDecoder"%>
<%@page import="java.io.*"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Export File</title>
</head>
<body>
<%!
public class ClassA implements java.io.Serializable {
private int i=10;
public ClassA(){ }
}
%>
<%!
public void WriteFolder(String applicationPath) throws FileNotFoundException,IOException{
ClassA folderToCopy=new ClassA();
String filename = applicationPath+"import\\test.txt";
FileOutputStream fos = new FileOutputStream(filename);
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(folderToCopy);
oos.close();
}
%>
<%
String applicationPath=application.getRealPath("/");
WriteFolder(applicationPath);
%>
</body>
</html>
错误:
> > Jan 27, 2015 1:39:46 PM org.apache.catalina.core.StandardWrapperValve invoke SEVERE:
> Servlet.service() for servlet [jsp] in context with path [] threw
> exception [An exception occurred processing JSP page
> /html/migrate/ImportTest.jsp at line 30 27: String filename =
> applicationPath+"import\\test.txt"; 28: FileOutputStream fos = new
> FileOutputStream(filename); 29: ObjectOutputStream oos = new
> ObjectOutputStream(fos); 30: oos.writeObject(folderToCopy); 31:
> oos.close(); 32: } 33: %> Stacktrace:] with root cause java.io.NotSerializableException: org.apache.el.ExpressionFactoryImpl
> at
> java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1183)
> at
> java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1547)
> at
> java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1508)
> at
> java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1431)
> at
> java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1177)
> at
> java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1547)
> at
> java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1508)
> at
> java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1431)
> at
> java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1177)
> at
> java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:347)
> at
> org.apache.jsp.html.migrate.ImportTest_jsp.WriteFolder(ImportTest_jsp.java:38)
> at
> org.apache.jsp.html.migrate.ImportTest_jsp._jspService(ImportTest_jsp.java:109)
> at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
> at javax.servlet.http.HttpServlet.service(HttpServlet.java:727) at
> org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
> at
> org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
> at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
> at javax.servlet.http.HttpServlet.service(HttpServlet.java:727) at
> org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
> at
> org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
> at
> org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
> at
> org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
> at
> org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
> at
> com.dotcms.repackage.org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:404)
> at
> org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
> at
> org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
> at com.dotmarketing.filters.CMSFilter.doFilter(CMSFilter.java:113)
> at
> org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
> at
> org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
> at
> com.dotmarketing.filters.AutoLoginFilter.doFilter(AutoLoginFilter.java:61)
> at
> org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
> at
> org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
> at
> com.dotmarketing.cms.urlmap.filters.URLMapFilter.doFilter(URLMapFilter.java:84)
> at
> org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
> at
> org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
> at
> com.dotmarketing.filters.TimeMachineFilter.doFilter(TimeMachineFilter.java:162)
> at
> org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
> at
> org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
> at
> com.dotmarketing.filters.CharsetEncodingFilter.doFilter(CharsetEncodingFilter.java:146)
> at
> org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
> at
> org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
> at
> org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
> at
> org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
> at
> org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
> at
> org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
> at
> org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
> at
> org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
> at
> org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
> at
> org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
> at
> org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040)
> at
> org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607)
> at
> org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:314)
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
> at
> org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
> at java.lang.Thread.run(Thread.java:745)
最佳答案
作为一般规则，除非内部类是静态，否则不能序列化内部类。这是因为非静态内部类需要外部类存在(它们有一个隐藏字段，其中包含对外部类的引用)。这意味着要读取内部类，Java 反序列化器首先需要外部类的实例。
关于java - 在jsp中有一个java类并序列化它，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/28165903/