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2.严重: Servlet.service() for servlet jsp threw exception java.lang.NullPointerException
3.javax.servlet.jsp.jspexceptionåªä¸ªjar
4.Servlet.service() for servlet jsp threw exception java.lang.NoSuchMethodError:
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<%@ page language="java" pageEncoding="gbk"%>
<%@ taglib uri="/struts-tags" prefix="s" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4. Transitional//EN">
<html>
<body>
<form action="<%=request.getContextPath()%>/UploadServlet" method="post" enctype="multipart/form-data">
username:<input type="text" name="username"><br>
password:<input type="password" name="password"><br>
file:<input type="file" name="file"><br>
<input type="submit" value="submit"><br>
</form>
</body>
</html>
3.ç¼åservlet
package cn.jci.upload.servlet;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet..jci.upload.servlet.UploadServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>UploadServlet</servlet-name>
<url-pattern>/UploadServlet</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>
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严重: Servlet.service() for servlet jsp threw exception java.lang.NullPointerException
出现此错误一般都是源码在jsp中使用了输出流(如输出验证码,文件下载等),下载没有妥善处理好的源码飞鱼知识付费源码原因。具体的下载原因就是在tomcat中jsp编译成servlet之后在函数_jspService(HttpServletRequestrequest,HttpServletResponseresponse)的最后有一段这样的代码finally{ if(_jspxFactory!=null)_jspxFactory.releasePageContext(_jspx_page_context);}这里是在释放在jsp中使用的对象,会调用response.getWriter(),源码uc usb源码因为这个方法是和response.getOutputStream()相冲突的!所以会出现以上这个异常。下载扑克双升源码然后当然是源码要提出解决的法,其实挺简单的下载(并不是和某些朋友说的那样--将jsp内的所有空格和回车符号所有都删除掉),在使用完输出流以后调用以下两行代码即可:out.clear();out=pageContext.pushBody();最后这里是源码一个输出彩色验证码例子(这样的例子几乎随处可见)imag.jsp)fc=;if(bc>)bc=;intr=fc+random.nextInt(bc-fc);intg=fc+random.nextInt(bc-fc);intb=fc+random.nextInt(bc-fc);returnnewColor(r,g,b);}%>如有不足之处,欢迎斧正!下载2getOutputStream()hasalreadybeencalledforthisresponse问题的源码解决在jsp向页面输出的时候,使用response.getOutputStream()会有这样的提示:java.lang.IllegalStateException:getOutputStream()hasalreadybeencalledforthisresponse,会抛出Exception原因一:JSP默认的输出流为PrintWriter,即以外的东西所默认的输出方式,如果你尝试在JSP中使用ServletOutputStream就会引起错误.要嘛直接改用Servlet输出(复写service方法),要嘛删除除%>0){ output.write(b,0,len);}output.flush();而不是把response.getOutputStream().write()放到循环体内在页面中直接写:将会出现错误消息如下:java.lang.IllegalStateException:getOutputStream()hasalreadybeencalledforthisresponseorg.apache.catalina.connector.Response.getWriter(Response.java:)org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:)org.apache.jasper.runtime.JspWriterImpl.initOut(JspWriterImpl.java:)org.apache.jasper.runtime.JspWriterImpl.flushBuffer(JspWriterImpl.java:)
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