Java가 널 포인터를 보고했습니다. 누군가 문제가 무엇인지 말해 줄 수 있습니까?
- php是最好的语言원래의
- 2018-08-04 11:24:411278검색
<a href="javascript:void(0);" onclick="clearCart()" id="clear" class="clear">清空购物车</a>
//cart.jsp 페이지에서 장바구니 이벤트를 삭제하려면 클릭
function clearCart(){
if(confirm("您是否要清空购物车？")){
location.href="${pageContext.request.contextPath }/product?method=clearCart";
}
}public void service(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {
req.setCharacterEncoding("UTF-8"); try { //1.获得请求对象的method的名称
String methodName = req.getParameter("methodName"); //2.获得当前被访问的对象的字节码对象
Class clazz = this.getClass();//ProductServlet.class 或者
//3.获得当前字节码对象中的指定方法
Method method = clazz.getMethod(methodName, HttpServletRequest.class,HttpServletResponse.class); //4执行相应功能方法
method.invoke(this, req,resp);
} catch (Exception e) {
e.printStackTrace();
}
}//장바구니 방법을 삭제하세요
public void clearCart(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
HttpSession session = request.getSession();
session.removeAttribute("cart"); //跳转回cart.jsp
response.sendRedirect(request.getContextPath()+"/cart.jsp");
}我点击清空就报异常了
java.lang.NullPointerException
at java.lang.Class.searchMethods(Class.java:2832)
at java.lang.Class.getMethod0(Class.java:2856)
at java.lang.Class.getMethod(Class.java:1668)
at com.itheima.web.servlet.BaseServlet.service(BaseServlet.java:25)
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 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:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
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$SocketProcessor.run(JIoEndpoint.java:315)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)<a href="javascript:void(0);" onclick="clearCart()" id="clear" class="clear">清空购物车</a>
//cart.jsp 페이지에서 장바구니 이벤트를 삭제하려면 클릭
function clearCart(){
if(confirm("您是否要清空购物车？")){
location.href="${pageContext.request.contextPath }/product?method=clearCart";
}
}public void service(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {
req.setCharacterEncoding("UTF-8"); try { //1.获得请求对象的method的名称
String methodName = req.getParameter("methodName"); //2.获得当前被访问的对象的字节码对象
Class clazz = this.getClass();//ProductServlet.class 或者
//3.获得当前字节码对象中的指定方法
Method method = clazz.getMethod(methodName, HttpServletRequest.class,HttpServletResponse.class); //4执行相应功能方法
method.invoke(this, req,resp);
} catch (Exception e) {
e.printStackTrace();
}
}/ /장바구니 삭제 방법
public void clearCart(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
HttpSession session = request.getSession();
session.removeAttribute("cart"); //跳转回cart.jsp
response.sendRedirect(request.getContextPath()+"/cart.jsp");
}我点击清空就报异常了
java.lang.NullPointerException
at java.lang.Class.searchMethods(Class.java:2832)
at java.lang.Class.getMethod0(Class.java:2856)
at java.lang.Class.getMethod(Class.java:1668)
at com.itheima.web.servlet.BaseServlet.service(BaseServlet.java:25)
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 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:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
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$SocketProcessor.run(JIoEndpoint.java:315)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745) 관련 기사:
마스터님, 이 널 포인터 예외를 해결하는 방법을 알려주세요
PHP 환경을 맞추는 중에 어려운 문제가 발생했습니다. 도와주세요!
위 내용은 Java가 널 포인터를 보고했습니다. 누군가 문제가 무엇인지 말해 줄 수 있습니까?의 상세 내용입니다. 자세한 내용은 PHP 중국어 웹사이트의 기타 관련 기사를 참조하세요!
성명：
본 글의 내용은 네티즌들의 자발적인 기여로 작성되었으며, 저작권은 원저작자에게 있습니다. 본 사이트는 이에 상응하는 법적 책임을 지지 않습니다. 표절이나 침해가 의심되는 콘텐츠를 발견한 경우 admin@php.cn으로 문의하세요.