Servlet访问第一次500，刷新后404的解决办法

第一次运行
错误：
HTTP Status 500 -

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

type Exception report

message

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

exception

javax.servlet.ServletException: Wrapper cannot find servlet class org.xhb.HelloServlet or a class it depends on
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:877)
org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:594)
org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1675)
java.lang.Thread.run(Thread.java:619)

root cause

java.lang.ClassNotFoundException: test.ResponseTest1
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1680)
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1526)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:877)
org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:594)
org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1675)

Java.lang.Thread.run(Thread.java:619

解决办法：

1.代码没有编译，清空一下，选择自动编译，然后关掉重启eclipse。

project-》Build Automatically

一定要重启，否则不起作用

2.servlet class在web.xml的路径错误。注解@WebServlet配置servlet的话注意web.xml中的配置如下：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://xmlns.jcp.org/xml/ns/javaee"
    xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
    id="WebApp_ID" version="3.1" metadata-complete="false">
    <display-name>servlet-web-test</display-name>
</web-app>