页面返回问题

[shan1978]

小弟做了一个修改提交的页面，数据修改完后，不知道怎样返回到前一页面。
请各位大侠赐教。

[flyylf]

贴你的前一页的代码啊。

[xiejiangjun]

贴testjsp.jsp

[shan1978]

我找到原因了。谢谢各位。

[xiejiangjun]

response.sendRedirect("aaa.jsp")

[shan1978]

有错误。
Apache Tomcat/4.0.4 - HTTP Status 500 - Internal Server Error

--------------------------------------------------------------------------------

type Exception report

message Internal Server Error

description The server encountered an internal error (Internal Server Error) that prevented it from fulfilling this request.

exception

java.lang.NullPointerException
at org.apache.jsp.testjsp$jsp._jspService(testjsp$jsp.java:144)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:107)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.jasper.servlet.JspServlet$JspServletWrapper.service(JspServlet.java:201)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:381)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:473)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:243)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:190)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:475)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
at org.apache.catalina.valves.CertificatesValve.invoke(CertificatesValve.java:246)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2347)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:170)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:170)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:468)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
at org.apache.catalina.connector.http.HttpProcessor.process(HttpProcessor.java:1027)
at org.apache.catalina.connector.http.HttpProcessor.run(HttpProcessor.java:1125)
at java.lang.Thread.run(Thread.java:534)



--------------------------------------------------------------------------------

[shan1978]

up

[jamsband]

有空值啦,
你返回上一页是不是需要传递一些必要的参数呀,忘记传了

[shan1978]

没有呀。
因为我去掉response.sendRedirect("aaa.jsp")时，网页都是正确的。
写库也是正确的。

[kjeny2002]

什么都不要写.只写这一句试试.

response.sendRedirect("aaa.jsp")


或者你查看aaa.jsp有问题吗？?

[flyylf]

在你的前一页得到参数时判断一下参数值是否为空的，这样就不会总是nullpointerexception

如：
String strPara="";
if(request.getParameter("para")!=null && !"".equals(request.getParameter("para"))){
strPara=request.getParameter("para");

}

[shan1978]

错误同上。

[shan1978]

我加了。

[xiejiangjun]

贴代码出来

[shan1978]

up

[shan1978]

<%@ page contentType="text/html;charset=ISO8859_1"%>
<%@ page import="java.sql.*"%>
<%@ page import="java.io.*"%>
<%response.setContentType("text/html;Charset=GB2312");%>
<%!
public String getStr(String str) throws UnsupportedEncodingException
{

String temp=str;
return new String(temp.getBytes("ISO-8859-1"),"gb2312");

}
%>
<%
Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver").newInstance();
String url="jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=alltest";
//pubs为你的数据库的
String user="sa";
String password="sa";

Connection conn= DriverManager.getConnection(url,user,password);
Statement stmt=conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);

String id=request.getParameter("id");
String name=request.getParameter("name");
name=name.trim();
name=getStr(name);
String sex=request.getParameter("sex");
//sex=sex.trim();
//sex=getStr(sex);
String section=request.getParameter("section");
section=section.trim();
section=getStr(section);
String stature=request.getParameter("stature");
stature=stature.trim();
out.println(name+sex+section+stature);
String sql;
sql="update t_jsp set V_Name='"+name+"',V_Sex='"+sex+"',V_Section='"+section+"',D_Stature="+stature+" where id="+id;
stmt.executeUpdate(sql);
//String URL=request.getContextPath()+"/testjsp.jsp";
response.sendRedirect("testjsp.jsp");

%>

[bjsyl2003]

应该把那个testjsp.jsp也贴出来看看

[zkjbeyond]

我倒。用javascript算了。
<script language="javascript"> history.back();
</script>

[pleonheart]

<input type="button" name="goback" value="返回" onclick="javascript:history.back();">