写了个简单的jsp页面，用手机浏览器可以正常用，但是用微信打开就出现错误。
错误信息如下：
HTTP Status 500 - An exception occurred processing JSP page /main.jsp at line 11
type Exception report
message An exception occurred processing JSP page /main.jsp at line 11
description The server encountered an internal error that prevented it from fulfilling this request.
exception
org.apache.jasper.JasperException: An exception occurred processing JSP page /main.jsp at line 11
8: <%
9: String path = request.getContextPath();
10: String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
11: String str = new String(request.getParameter("wtdw").getBytes("iso-8859-1"), "utf-8");//瑙ｅ喅浼犺緭涓枃涔辩爜
12: String bb=request.getParameter("bgbh");
13: String wb=request.getParameter("wtbh");
14: String bb1 = bb.replaceAll("\s*", "");
Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:568)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:470)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
root cause
java.lang.NullPointerException
org.apache.jsp.main_jsp._jspService(main_jsp.java:77)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
note The full stack trace of the root cause is available in the Apache Tomcat/7.0.55 logs.
Apache Tomcat/7.0.55
这个问题可能是在这一条代码中String str = new String(request.getParameter("wtdw").getBytes("iso-8859-1"), "utf-8");
首先request.getParameter("wtdw").getBytes("iso-8859-1")这个代码很可能到时候到时候是null，所以会报错
String str = new String(null,"utf-8");很显然这会出错
打个断点就解决的问题， 没法打断点就每行代码输出一次日志， 先确定是哪一行代码产生的问题