<a href="javascript:void(0);" onclick="clearcart()" id="clear" class="clear">清空购物车</a>
//cart.jsp页面上点击清空购物车事件
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(); } }
//清空购物车方法
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页面上点击清空购物车事件
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(); } }
//清空购物车方法
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)
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