response.sendRedirect的问题!
我有:

public class LoginAction extends Action
{

public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response)

LoginForm lf=(LoginForm)form;
String act=mapping.getParameter();
if(lf.getUsername().equals( " "))
{

response.sendRedirect( "err.jsp ");
}

}
没有写全,当if条件成立之后(我打出过),response.sendRedirect有错误,err.jsp存在.
错误如下:
The server encountered an internal error () that prevented it from fulfilling this request.

java.lang.IllegalStateException
org.apache.coyote.tomcat5.CoyoteResponseFacade.sendRedirect(CoyoteResponseFacade.java:399)
org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:385)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:231)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1164)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:415)
javax.servlet.http.HttpServlet.service(HttpServlet.java:763)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
请指教!

[解决办法]
response.sendRedirect();并不马上就执行重定向，而是继续执行该命令后面的代码

sendRedirect之后马上return即可
[解决办法]
最好在最后sendredirect，前面可以判断选择参数。
我的异常网推荐解决方案：The server encountered an internal error () that prevented it from fulfilling this request.,http://www.myexception.cn/java-web/317.html